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Sample records for alpine tundra

  1. Carbon cycling of alpine tundra ecosystems on Changbai Mountain and its comparison with arctic tundra

    Institute of Scientific and Technical Information of China (English)

    代力民; 吴钢; 赵景柱; 孔红梅; 邵国凡; 邓红兵

    2002-01-01

    The alpine tundra on Changbai Mountain was formed as a left-over ‘island' in higher elevations after the glacier retrieved from the mid-latitude of Northern Hemisphere to the Arctic during the fourth ice age. The alpine tundra on Changbai Mountain also represents the best-reserved tundra ecosystems and the highest biodiversity in northeast Eurasia. This paper examines the quantity of carbon assimilation, litters, respiration rate of soil, and storage of organic carbon within the alpine tundra ecosystems on Changbai Mountain. The annual net storage of organic carbon was 2092 t/a, the total storage of organic carbon was 33457 t, the annual net storage of organic carbon in soil was 1054 t/a, the total organic carbon storage was 316203 t, and the annual respiration rate of soil was 92.9% and was 0.52 times more than that of the Arctic. The tundra-soil ecosystems in alpine Changbai Mountain had 456081 t of carbon storage, of which, organic carbon accounted for 76.7% whereas the mineral carbon accounted for 23.3%.

  2. Atmospheric methane sources: Alaskan tundra bogs, an alpine fen, and a subarctic boreal marsh

    OpenAIRE

    Sebacher, Daniel I.; Harriss, Robert C.; Bartlett, Karen B.; Sebacher, Shirley M.; Grice, Shirley S.

    2011-01-01

    Methane (CH4) flux measurements from Alaskan tundra bogs, an alpine fen, and a subarctic boreal marsh were obtained at field sites ranging from Prudhoe Bay on the coast of the Arctic Ocean to the Alaskan Range south of Fairbanks during August 1984. In the tundra, average CH4 emission rates varied from 4.9 mg CH4 m-2 d-1 (moist tundra) to 119 mg CH4 m-2 d-1 (waterlogged tundra). Fluxes averaged 40 mg CH4 m-2 d-1 from wet tussock meadows in the Brooks Range and 289 mg CH4 m-2 d-1 from an alpine...

  3. Spatial pattern of soil carbon and nutrient storage at the Alpine tundra ecosystem of Changbai Mountain, China

    Institute of Scientific and Technical Information of China (English)

    WEIJing; WUGang; DENGHong-bing; ZHAOJing-zhu

    2004-01-01

    In August 2003, we investigated spatial pattern in soil carbon and nutrients in the Alpine tundra of Changbai Mountain, Jilin Province, China. The analytical results showed that the soil C concentrations at different depths were significantly(p<0.05) higher in Meadow alpine tundra vegetation than that in other vegetation types; the soil C (including inorganic carbon)concentrations at layer below 10 cm are significantly (p<0.05) higher than at layer of 10-20 cm among the different vegetation types; the spatial distribution of soil N concentration at top surface of 0-10 cm depth was similar to that at 10-20 cm; the soil P concentrations at different depths were significantly (p<0.05) lower at Lithic alpine tundra vegetation than that at other vegetation types; soil K concentration was significantly (p<0.05) higher in Felsenmeer alpine tundra vegetation and Lithic alpine tundra vegetation than that in Typical alpine tundra, Meadow alpine tundra, and Swamp alpine tundra vegetations.. However, the soil K had not significant change at different soil depths of each vegetation type. Soil S concentration was dramatically higher in Meadow alpine tundra vegetation than that in other vegetation types. For each vegetation type, the ratios of C: N, C: P, C: K and C: S generally decreased with soil depth. The ratio of C: N was significantly higher at 0-10 cm than that at 10-20 cm for all vegetation types except at the top layer of the Swamp alpine tundra vegetation. Our study showed that soil C and nutrients storage were significantly spatial heterogeneity.

  4. Snowmelt runoff from northern alpine tundra hillslopes: major processes and methods of simulation

    Directory of Open Access Journals (Sweden)

    W. L. Quinton

    2004-01-01

    Full Text Available In northern alpine tundra, large slope gradients, late-lying snow drifts and shallow soils overlying impermeable substrates all contribute to large hillslope runoff volumes during the spring freshet. Understanding the processes and pathways of hillslope runoff in this environment is, therefore, critical to understanding the water cycle within northern alpine tundra ecosystems. This study: (a presents the results of a field study on runoff from a sub-alpine tundra hillslope with a large snow drift during the spring melt period; (b identifies the major runoff processes that must be represented in simulations of snowmelt runoff from sub-alpine tundra hillslopes; (c describes how these processes can be represented in a numerical simulation model; and d compares field measurements with modelled output to validate or refute the conceptual understanding of runoff generation embodied in the process simulations. The study was conducted at Granger Creek catchment, 15 km south of Whitehorse, Yukon Territory, Canada, on a north-facing slope below a late-lying snow drift. For the freshet period, the major processes to be represented in a runoff model include the rate of meltwater release from the late-lying snowdrift, the elevation and thickness of the saturated layer, the magnitude of the soil permeability and its variation with depth. The daily cycle of net all-wave radiation was observed to drive the diurnal pulses of melt water from the drift; this, in turn, was found to control the daily pulses of flow through the hillslope subsurface and in the stream channel. The computed rate of frost table lowering fell within the observed values; however, there was wide variation among the measured frost table depths. Spatial variability in frost table depth would result in spatial variabilities in saturated layer depth and thickness, which would, in turn, produce variations in subsurface flow rates over the slope, including preferential flowpaths. Keywords

  5. Microbial diversity in alpine tundra soils correlates with snow cover dynamics.

    Science.gov (United States)

    Zinger, Lucie; Shahnavaz, Bahar; Baptist, Florence; Geremia, Roberto A; Choler, Philippe

    2009-07-01

    The temporal and spatial snow cover dynamics is the primary factor controlling the plant communities' composition and biogeochemical cycles in arctic and alpine tundra. However, the relationships between the distribution of snow and the diversity of soil microbial communities remain largely unexplored. Over a period of 2 years, we monitored soil microbial communities at three sites, including contiguous alpine meadows of late and early snowmelt locations (LSM and ESM, respectively). Bacterial and fungal communities were characterized by using molecular fingerprinting and cloning/sequencing of microbial ribosomal DNA extracted from the soil. Herein, we show that the spatial and temporal distribution of snow strongly correlates with microbial community composition. High seasonal contrast in ESM is associated with marked seasonal shifts for bacterial communities; whereas less contrasted seasons because of long-lasting snowpack in LSM is associated with increased fungal diversity. Finally, our results indicate that, similar to plant communities, microbial communities exhibit important shifts in composition at two extremes of the snow cover gradient. However, winter conditions lead to the convergence of microbial communities independently of snow cover presence. This study provides new insights into the distribution of microbial communities in alpine tundra in relation to snow cover dynamics, and may be helpful in predicting the future of microbial communities and biogeochemical cycles in arctic and alpine tundra in the context of a warmer climate.

  6. Wet meadow ecosystems contribute the majority of overwinter soil respiration from snow-scoured alpine tundra

    Science.gov (United States)

    Knowles, John F.; Blanken, Peter D.; Williams, Mark W.

    2016-04-01

    We measured soil respiration across a soil moisture gradient ranging from dry to wet snow-scoured alpine tundra soils throughout three winters and two summers. In the absence of snow accumulation, soil moisture variability was principally determined by the combination of mesotopographical hydrological focusing and shallow subsurface permeability, which resulted in a patchwork of comingled ecosystem types along a single alpine ridge. To constrain the subsequent carbon cycling variability, we compared three measures of effective diffusivity and three methods to calculate gradient method soil respiration from four typical vegetation communities. Overwinter soil respiration was primarily restricted to wet meadow locations, and a conservative estimate of the rate of overwinter soil respiration from snow-scoured wet meadow tundra was 69-90% of the maximum carbon dioxide (CO2) respired by seasonally snow-covered soils within this same catchment. This was attributed to higher overwinter soil temperatures at wet meadow locations relative to fellfield, dry meadow, and moist meadow communities, which supported liquid water and heterotrophic respiration throughout the winter. These results were corroborated by eddy covariance-based measurements that demonstrated an average of 272 g C m-2 overwinter carbon loss during the study period. As a result, we updated a conceptual model of soil respiration versus snow cover to express the potential for soil respiration variability from snow-scoured alpine tundra.

  7. Element cycling in the dominant plant community in the Alpine tundra zone of Changbai Mountains, China

    Institute of Scientific and Technical Information of China (English)

    LIU Jing-shuang; YU Jun-bao

    2005-01-01

    Element cycling in the dominant plant communities including Rh. aureum, Rh. redowskianum and Vaccinium uliginosum in the Alpine tundra zone of Changbai Mountains in northeast China was studied. The results indicate that the amount of elements from litter decomposition was less than that of the plant uptake from soil, but that from plant uptake was higher than that in soil with mineralization process released. On the other hand, in the open system including precipitation input and soil leaching output, because of great number of elements from precipitation into the open system, the element cycling(except N, P) in the Alpine tundra ecosystem was in a dynamic balance. In this study, it was also found that different organ of plants had significant difference in accumulating elements. Ca, Mg, P and N were accumulated more obviously in leaves, while Fe was in roots. The degree of concentration of elements in different tissues of the same organ of the plants also was different, a higher concentration of Ca, Mg, P and N in mesophyll than in nerve but Fe was in a reversed order. The phenomenon indicates (1) a variety of biochemical functions of different elements, (2) the elements in mesophyll were with a shorter turnover period than those in nerve or fibre, but higher utilization rate for plant. Therefore, this study implies the significance of keeping element dynamic balance in the alpine tundra ecosystem of Changbai Mountains.

  8. Nitrogen deposition but not climate warming promotes Deyeuxia angustifolia encroachment in alpine tundra of the Changbai Mountains, Northeast China.

    Science.gov (United States)

    Zong, Shengwei; Jin, Yinghua; Xu, Jiawei; Wu, Zhengfang; He, Hongshi; Du, Haibo; Wang, Lei

    2016-02-15

    Vegetation in the alpine tundra area of the Changbai Mountains, one of two alpine tundra areas in China, has undergone great changes in recent decades. The aggressive herb species Deyeuxia angustifolia (Komarov) Y. L. Chang, a narrow-leaf small reed, was currently encroaching upon the alpine landscape and threatening tundra biota. The alpine tundra of the Changbai Mountains has been experiencing a warmer climate and receiving a high load of atmospheric nitrogen deposition. In this study, we aimed to assess the respective roles of climate warming and atmospheric nitrogen deposition in promoting the upward encroachment of D. angustifolia. We conducted experiments for three years to examine the response of D. angustifolia and a native alpine shrub, Rhododendron chrysanthum, to the conditions in which temperature and nitrogen were increased. Treatments consisting of temperature increase, nitrogen addition, temperature increase combined with nitrogen addition, and controls were conducted on the D. angustifolia communities with three encroachment levels (low, medium, and high levels). Results showed that 1) D. angustifolia grew in response to added nutrients but did not grow well when temperature increased. R. chrysanthum showed negligible responses to the simulated environmental changes. 2) Compared to R. chrysanthum, D. angustifolia could effectively occupy the above-ground space by increasing tillers and growing rapidly by efficiently using nitrogen. The difference in nitrogen uptake abilities between the two species contributed to expansion of D. angustifolia. 3) D. angustifolia encroachment could deeply change the biodiversity of tundra vegetation and may eventually result in the replacement of native biota, especially with nitrogen addition. Our research indicated that nutrient perturbation may be more important than temperature perturbation in promoting D. angustifolia encroachment upon the nutrient- and species-poor alpine tundra ecosystem in the Changbai

  9. Conifer seedling recruitment across a gradient from forest to alpine tundra: effects of species, provenance, and site

    Science.gov (United States)

    Castanha, C.; Torn, M.S.; Germino, M.J.; Weibel, B.; Kueppers, L.M.

    2013-01-01

    Background: Seedling germination and survival is a critical control on forest ecosystem boundaries, such as at the alpine–treeline ecotone. In addition, while it is known that species respond individualistically to the same suite of environmental drivers, the potential additional effect of local adaptation on seedling success has not been evaluated. Aims: To determine whether local adaptation may influence the position and movement of forest ecosystem boundaries, we quantified conifer seedling recruitment in common gardens across a subalpine forest to alpine tundra gradient at Niwot Ridge, Colorado, USA. Methods: We studied Pinus flexilis and Picea engelmannii grown from seed collected locally at High (3400 m a.s.l.) and Low (3060 m a.s.l.) elevations. We monitored emergence and survival of seeds sown directly into plots and survival of seedlings germinated indoors and transplanted after snowmelt. Results: Emergence and survival through the first growing season was greater for P. flexilis than P. engelmannii and for Low compared with High provenances. Yet survival through the second growing season was similar for both species and provenances. Seedling emergence and survival tended to be greatest in the subalpine forest and lowest in the alpine tundra. Survival was greater for transplants than for field-germinated seedlings. Conclusions: These results suggest that survival through the first few weeks is critical to the establishment of natural germinants. In addition, even small distances between seed sources can have a significant effect on early demographic performance – a factor that has rarely been considered in previous studies of tree recruitment and species range shifts.

  10. Distinct soil bacterial communities along a small-scale elevational gradient in alpine tundra

    Directory of Open Access Journals (Sweden)

    Congcong eShen

    2015-06-01

    Full Text Available The elevational diversity pattern for microorganisms has received great attention recently but is still understudied, and phylogenetic relatedness is rarely studied for microbial elevational distributions. Using a bar-coded pyrosequencing technique, we examined the biodiversity patterns for soil bacterial communities of tundra ecosystem along 2000–2500 m elevations on Changbai Mountain in China. Bacterial taxonomic richness displayed a linear decreasing trend with increasing elevation. Phylogenetic diversity and mean nearest taxon distance (MNTD exhibited a unimodal pattern with elevation. Bacterial communities were more phylogenetically clustered than expected by chance at all elevations based on the standardized effect size of MNTD metric. The bacterial communities differed dramatically among elevations, and the community composition was significantly correlated with soil total carbon, total nitrogen, C:N ratio, and dissolved organic carbon. Multiple ordinary least squares regression analysis showed that the observed biodiversity patterns strongly correlated with soil total carbon and C:N ratio. Taken together, this is the first time that a significant bacterial diversity pattern has been observed across a small-scale elevational gradient. Our results indicated that soil carbon and nitrogen contents were the critical environmental factors affecting bacterial elevational distribution in Changbai Mountain tundra. This suggested that ecological niche-based environmental filtering processes related to soil carbon and nitrogen contents could play a dominant role in structuring bacterial communities along the elevational gradient.

  11. IMPACT OF CRITICAL ANION SOIL SOLUTION CONCENTRATION ON ALUMINUM ACTIVITY IN ALPINE TUNDRA SOIL Andrew Evans, Jr.1 , Michael B. Jacobs2, and Jason R. Janke1, (1) Metropolitan State University of Denver, Dept. of Earth and Atmospheric Sciences, (2) Dept. of Chemistry, Denver, CO, United States.

    Science.gov (United States)

    Evans, A.

    2015-12-01

    Soil solution anionic composition can impact both plant and microbial activity in alpine tundra soils by altering biochemical cycling within the soil, either through base cation leaching, or shifts in aluminum controlling solid phases. Although anions play a critical role in the aqueous speciation of metals, relatively few high altitude field studies have examined their impact on aluminum controlling solid phases and aluminum speciation in soil water. For this study, thirty sampling sites were selected on Trail Ridge Road in Rocky Mountain National Park, Estes Park, CO, and sampled during July, the middle of the growing season. Sampling elevations ranged from approximately 3560 - 3710 m. Soil samples were collected to a depth of 15.24 cm, and the anions were extracted using a 2:1 D.I. water to soil ratio. Filtered extracts were analyzed using IC and ICP-MS. Soil solution NO3- concentrations were significantly higher for sampling locations east of Iceberg Pass (EIBP) (mean = 86.94 ± 119.8 mg/L) compared to locations west of Iceberg Pass (WIBP) (mean 1.481 ± 2.444 mg/L). Both F- and PO43- soil solution concentrations, 0.533 and 0.440 mg/L, respectively, were substantially lower, for sampling sites located EIBP, while locations WIBP averaged 0.773 and 0.829 mg/L respectively, for F- and PO43-. Sulfate concentration averaged 3.869 ± 3.059 mg/L for locations EIBP, and 3.891 ± 3.1970 for locations WIBP. Geochemical modeling of Al3+ in the soil solution indicated that a suite of aluminum hydroxyl sulfate minerals controlled Al3+ activity in the alpine tundra soil, with shifts between controlling solid phases occurring in the presence of elevated F- concentrations.

  12. How to preserve the tundra in a warming climate?

    Science.gov (United States)

    Käyhkö, Jukka

    2014-05-01

    The warming climate of the polar regions may change much of the current arctic-alpine tundra to forest or dense scrubland. This modification requires adaptation by traditional livelihoods such as reindeer herding, which relies on diverse, seasonal pasturelands. Vegetation change may also trigger positive warming feedbacks, where more abundant forest-scrub vegetation will decrease the global albedo. NCoE Tundra team investigates the complex climate-animal-plant interaction of the tundra ecosystem and aim to unravel the capability of herbivorous mammals to control the expansion of woody vegetation. Our interdisciplinary approach involves several work packages, whose results will be summarised in the presentation. In the ecological WPs, we study the dynamics of the natural food chains involving small herbivorous and the impacts of reindeer on the vegetation and the population dynamics of those arctic-alpine plants, which are most likely to become threatened in a warmer climate. Our study demonstrates the potential of a relatively sparse reindeer stocks (2-5 heads per km2) together with natural populations of arvicoline rodents to prevent the expansion of erect woody plants at the arctic-alpine timberline. In the climatic WPs we study the impact of grazing-dependent vegetation differences on the fraction of solar energy converted to heat. In the socio-economic WPs, we study the conditions for maintaining the economic and cultural viability of reindeer herding while managing the land use so that the arctic-alpine biota would be preserved.

  13. Soil nitrogen dynamics and productivity of snowpack Sanguisorba sitchensis community in alpine tundra of Changbai Mountain, China%长白山高山苔原雪斑大白花地榆群落土壤氮素动态与生产力的关系

    Institute of Scientific and Technical Information of China (English)

    徐倩倩; 刘琪璟; 张国春

    2011-01-01

    Aims Snowpack plant communities in alpine tundra are active in comparison with surrounding vegetation, despite the short growing season due to thick snow cover. Our objective was to understand the growth mechanism of snowpack communities.Methods The nutrient dynamics and primary productivity of snowpack Sanguisorba sitchensis community in alpine tundra of Changbai Mountain was investigated in different seasons.Important findings Soil temperature under snowpack during winter was warmer than snow-free areas, and the minimum temperature was significantly higher. Litter decomposition and nitrogen mineralization under snowpack were active even in winter, and nitrogen content was high with rapid mineralization. Annual net primary productivity was 4 046 kg·hm-2·a-1. The unique hydro-thermo conditions, nutrient cycling features and high leaf area index were key factors maintaining community structure and primary productivity.%在高山苔原冬季积雪覆盖的群落生长季短,但明显比周围群落生长茂盛.为了说明雪斑地段群落生长机理,对长白山苔原雪斑土壤氮素动态以及大白花地榆(Sanguisorba sitchensis)群落生产力进行了连续测定.雪斑群落土壤冬季相对温暖,最低日平均温度-1.4℃,裸露地段-16.9℃,全年水分条件充足;积雪期凋落物分解和氮矿化均在进行,土壤具有很高的氮素含量及矿化速率.大白花地榆地上部分净初级生产力为4 046 kg·hm·a.正是独特的水热条件和养分条件,以及具有很大的叶面积同化器官,高山苔原雪斑地段的大白花地榆群落才得以维持生存并表现出很高的生产力水平.

  14. Roots in the tundra

    NARCIS (Netherlands)

    Wang, Peng

    2016-01-01

    Global climate has been warming up for the last decades and it will continue in this century. The Arctic is the part of the globe that warms fastest and is more sensitive to climate warming. Aboveground productivity of Arctic tundra has been shown to increase in response to warmer climates. However,

  15. Tundra in the rain

    DEFF Research Database (Denmark)

    Keuper, Frida; Parmentier, Frans-Jan; Blok, Daan;

    2012-01-01

    tundra (northeast Siberia) and a dry Sphagnum fuscum-dominated bog (northern Sweden). Positive responses to approximately doubled ambient precipitation (an increase of 200 mm year-1) were observed at the Siberian site, for B. nana (30 % larger length increments), Salix pulchra (leaf size and length...

  16. Shrub expansion in tundra ecosystems: dynamics, impacts and research priorities

    Science.gov (United States)

    Myers-Smith, Isla H.; Forbes, Bruce C.; Wilmking, Martin; Hallinger, Martin; Lantz, Trevor; Blok, Daan; Tape, Ken D.; Macias-Fauria, Marc; Sass-Klaassen, Ute; Lévesque, Esther; Boudreau, Stéphane; Ropars, Pascale; Hermanutz, Luise; Trant, Andrew; Siegwart Collier, Laura; Weijers, Stef; Rozema, Jelte; Rayback, Shelly A.; Schmidt, Niels Martin; Schaepman-Strub, Gabriela; Wipf, Sonja; Rixen, Christian; Ménard, Cécile B.; Venn, Susanna; Goetz, Scott; Andreu-Hayles, Laia; Elmendorf, Sarah; Ravolainen, Virve; Welker, Jeffrey; Grogan, Paul; Epstein, Howard E.; Hik, David S.

    2011-12-01

    Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra ecosystems. Here, we (1) synthesize these findings, (2) present a conceptual framework that identifies mechanisms and constraints on shrub increase, (3) explore causes, feedbacks and implications of the increased shrub cover in tundra ecosystems, and (4) address potential lines of investigation for future research. Satellite observations from around the circumpolar Arctic, showing increased productivity, measured as changes in ‘greenness’, have coincided with a general rise in high-latitude air temperatures and have been partly attributed to increases in shrub cover. Studies indicate that warming temperatures, changes in snow cover, altered disturbance regimes as a result of permafrost thaw, tundra fires, and anthropogenic activities or changes in herbivory intensity are all contributing to observed changes in shrub abundance. A large-scale increase in shrub cover will change the structure of tundra ecosystems and alter energy fluxes, regional climate, soil-atmosphere exchange of water, carbon and nutrients, and ecological interactions between species. In order to project future rates of shrub expansion and understand the feedbacks to ecosystem and climate processes, future research should investigate the species or trait-specific responses of shrubs to climate change including: (1) the temperature sensitivity of shrub growth, (2) factors controlling the recruitment of new individuals, and (3) the relative influence of the positive and negative feedbacks involved in shrub expansion.

  17. An integrated geographic information system approach for modeling the suitability of conifer habitat in an alpine environment

    Science.gov (United States)

    McGregor, Stephen J.

    1998-01-01

    Alpine periglacial environments within the forest-alpine tundra ecotone (FATE) may be among the first to reflect changes in habitat characteristics as a consequence of climatic change. Previous FATE studies used Integrated Geographic Information System (IGIS) techniques to collect and model biophysical data but lacked the necessary detail to model the micro-scale patterns and compositions of habitat within alpine periglacial environments. This paper describes several promising data collection, integration, and cartographic modeling techniques used in an IGIS approach to model alpine periglacial environments in Glacier National Park (GNP), Montana, USA. High-resolution (I X I m) multi-spectral remote sensing data and differentially corrected Global Positioning System (DGPS) data were integrated with other biophysical data using a raster-based IGIS approach. Biophysical factors, hypothesized to influence the pattern and composition of the FATE and the alpine tundra ecosystem, were derived from the high-resolution remote sensing data, in-situ GPS data, high-resolution models of digital elevation, and other thematic data using image processing techniques and cartographic modeling. Suitability models of conifer habitat were created using indices generated from the IGIS database. This IGIS approach identified suitable conifer habitat within the FATE and permitted the modeling of micro-scale periglacial features and alpine tundra communities that are absent from traditional approaches of landscape-scale (30 X 30 m) modeling.

  18. Alpine dams

    Directory of Open Access Journals (Sweden)

    Alain Marnezy

    2009-03-01

    Full Text Available Les barrages-réservoirs de montagne ont été réalisés initialement dans les Alpes pour répondre à la demande d’énergie en période hivernale. Une certaine diversification des usages de l’eau s’est ensuite progressivement développée, en relation avec le développement touristique des collectivités locales. Aujourd’hui, la participation des ouvrages d’Électricité De France à la production de neige de culture représente une nouvelle étape. Dans les régions où les aménagements hydroélectriques sont nombreux, les besoins en eau pour la production de neige peuvent être résolus par prélèvements à partir des adductions EDF. Les gestionnaires de stations échappent ainsi aux inconvénients liés à la construction et à la gestion des « retenues collinaires ». Cette évolution, qui concerne déjà quelques régions alpines comme la haute Maurienne ou le Beaufortin, apparaît comme une forme renouvelée d’intégration territoriale de la ressource en eau.Mountain reservoirs were initially built in the Alps to meet energy needs in the winter. A certain diversification in the uses of water then gradually developed, related to tourism development in the local communities. Today, the use of facilities belonging to EDF (French Electricity Authority to provide water for winter resorts to make artificial snow represents a new phase. By taking water from EDF resources to supply snow-making equipment, resort managers are thus able to avoid the problems related to the construction and management of small headwater dams. This new orientation in the use of mountain water resources already affects a number of alpine regions such as the Upper Maurienne valley and Beaufortain massif and represents a renewed form of the territorial integration of water resources.

  19. A boreal invasion in response to climate change? Range shifts and community effects in the borderland between forest and tundra

    OpenAIRE

    Elmhagen, Bodil; Kindberg, Jonas; Hellström, Peter; Angerbjörn, Anders

    2015-01-01

    It has been hypothesized that climate warming will allow southern species to advance north and invade northern ecosystems. We review the changes in the Swedish mammal and bird community in boreal forest and alpine tundra since the nineteenth century, as well as suggested drivers of change. Observed changes include (1) range expansion and increased abundance in southern birds, ungulates, and carnivores; (2) range contraction and decline in northern birds and carnivores; and (3) abundance decli...

  20. Complete genome sequence of Granulicella tundricola type strain MP5ACTX9T, an Acidobacteria from tundra soil

    OpenAIRE

    Rawat, Suman R.; Männistö, Minna K.; Starovoytov, Valentin; Goodwin, Lynne; Nolan, Matt; Hauser, Loren; Land, Miriam; Davenport, Karen Walston; Woyke, Tanja; Häggblom, Max M.

    2013-01-01

    Granulicella tundricola strain MP5ACTX9T is a novel species of the genus Granulicella in subdivision 1 Acidobacteria . G. tundricola is a predominant member of soil bacterial communities, active at low temperatures and nutrient limiting conditions in Arctic alpine tundra. The organism is a cold-adapted acidophile and a versatile heterotroph that hydrolyzes a suite of sugars and complex polysaccharides. Genome analysis revealed metabolic versatility with genes involved in metabolism and transp...

  1. Complete genome sequence of Granulicella mallensis type strain MP5ACTX8T, an acidobacterium from tundra soil

    OpenAIRE

    Rawat, Suman R.; Männistö, Minna K.; Starovoytov, Valentin; Goodwin, Lynne; Nolan, Matt; Loren J Hauser; Land, Miriam; Davenport, Karen Walston; Woyke, Tanja; Häggblom, Max M.

    2013-01-01

    Granulicella mallensis MP5ACTX8T is a novel species of the genus Granulicella in subdivision 1of Acidobacteria . G. mallensis is of ecological interest being a member of the dominant soil bacterial community active at low temperatures and nutrient limiting conditions in Arctic alpine tundra. G. mallensis is a cold-adapted acidophile and a versatile heterotroph that hydrolyzes a suite of sugars and complex polysaccharides. Genome analysis revealed metabolic versatility with genes involved in m...

  2. Plants in alpine environments

    Science.gov (United States)

    Germino, Matthew J.

    2014-01-01

    Alpine and subalpine plant species are of special interest in ecology and ecophysiology because they represent life at the climate limit and changes in their relative abundances can be a bellwether for climate-change impacts. Perennial life forms dominate alpine plant communities, and their form and function reflect various avoidance, tolerance, or resistance strategies to interactions of cold temperature, radiation, wind, and desiccation stresses that prevail in the short growing seasons common (but not ubiquitous) in alpine areas. Plant microclimate is typically uncoupled from the harsh climate of the alpine, often leading to substantially warmer plant temperatures than air temperatures recorded by weather stations. Low atmospheric pressure is the most pervasive, fundamental, and unifying factor for alpine environments, but the resulting decrease in partial pressure of CO2 does not significantly limit carbon gain by alpine plants. Factors such as tree islands and topographic features create strong heterogeneous mosaics of microclimate and snow cover that are reflected in plant community composition. Factors affecting tree establishment and growth and formation of treeline are key to understanding alpine ecology. Carbohydrate and other carbon storage, rapid development in a short growing season, and physiological function at low temperature are prevailing attributes of alpine plants. A major contemporary research theme asks whether chilling at alpine-treeline affects the ability of trees to assimilate the growth resources and particularly carbon needed for growth or whether the growth itself is limited by the alpine environment. Alpine areas tend to be among the best conserved, globally, yet they are increasingly showing response to a range of anthropogenic impacts, such as atmospheric deposition.

  3. International Tundra Experiment ITEX Manual Second Edition

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Nonforest plots of Long Term Ecological Monitoring sites follow protocols developed for the International Tundra Experiment Walker et al. 1993, Walker 1996.

  4. Koyukuk NWR tundra/trumpeter swan survey

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A tundra/trumpeter swan survey was conducted on the Koyukuk National Wildlife Refuge from 14 August to 23 August 1984. Twenty-four six mile square plots were...

  5. Research on dynamics of tundra ecosystems and their potential response to energy research development. Progress report, 1 April 1982-March 1983

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.

    1983-02-15

    Bryophyte species distributions were analyzed with respect to microtopography at an alpine tundra site in central Alaska which is dominated by tussocks of Eriophorum vaginatum. Bryophyte distributions were found to be significantly correlated with slope but not with azimuth. Different types of tussocks and hollows and mats between tussocks also supported different bryophyte floras. Water loss resistances of three species of moss did not account for differences in their distributions.

  6. A boreal invasion in response to climate change? Range shifts and community effects in the borderland between forest and tundra.

    Science.gov (United States)

    Elmhagen, Bodil; Kindberg, Jonas; Hellström, Peter; Angerbjörn, Anders

    2015-01-01

    It has been hypothesized that climate warming will allow southern species to advance north and invade northern ecosystems. We review the changes in the Swedish mammal and bird community in boreal forest and alpine tundra since the nineteenth century, as well as suggested drivers of change. Observed changes include (1) range expansion and increased abundance in southern birds, ungulates, and carnivores; (2) range contraction and decline in northern birds and carnivores; and (3) abundance decline or periodically disrupted dynamics in cyclic populations of small and medium-sized mammals and birds. The first warm spell, 1930-1960, stands out as a period of substantial faunal change. However, in addition to climate warming, suggested drivers of change include land use and other anthropogenic factors. We hypothesize all these drivers interacted, primarily favoring southern generalists. Future research should aim to distinguish between effects of climate and land-use change in boreal and tundra ecosystems. PMID:25576279

  7. Tundra Rehabilitation in Alaska's Arctic

    Science.gov (United States)

    Lynn, L. A.

    2012-12-01

    Oil exploration in Alaska's Arctic has been conducted for more than 40 years, resulting in over 3,640 ha of gravel fill placed for roads, pads, and airstrips to support the industry. Likewise, tundra disturbance from burying power lines and by tundra vehicle travel are also common. Rehabilitation of disturbed sites began around 2002, with well over 150 ha that has been previously treated or is currently being rehabilitated. Two primary goals of rehabilitation efforts have been 1) revegetation by indigenous species, and 2) limiting thermokarst. Early efforts were concerned that removing gravel and having exposed bare ground would lead to extensive subsidence and eolian erosion. Native grass cultivars (e.g. Poa glauca, Arctagrostis latifolia, and Festuca rubra) were seeded to create vegetation cover quickly with the expectation that these grasses would survive only temporarily. The root masses and leaf litter were also expected to trap indigenous seed to enhance natural recolonization by indigenous plants. Due to the remote location of these sites, many of which are only accessible by helicopter, most are visited only two to three times following cultivation treatments, providing a limited data pool. At many sites, the total live seeded grass cover declined about 15% over the first 5¬-6 years (from around 30% to 15% cover), while total live indigenous vascular cover increased from no or trace cover to an average of 10% cover in that time. Cover of indigenous vascular plants at sites that were not seeded with native grass cultivars averaged just less than 10% after 10 years, showing no appreciable difference between the two approaches. Final surface elevations at the sites affect local hydrology and soil moisture. Other factors that influence the success of vegetation cover are proximity to the Arctic coast (salt effects), depth of remaining gravel, and changes in characteristics of the near-surface soil. Further development of rehabilitation techniques and the

  8. Vegetation shifts observed in arctic tundra 17 years after fire

    NARCIS (Netherlands)

    Barret, K.; Rocha, A.V.; Weg, van de M.J.; Shaver, G

    2012-01-01

    With anticipated climate change, tundra fires are expected to occur more frequently in the future, but data on the long-term effects of fire on tundra vegetation composition are scarce. This study addresses changes in vegetation structure that have persisted for 17 years after a tundra fire on the N

  9. Aspects of the grammar of Tundra Yukaghir

    NARCIS (Netherlands)

    M. Schmalz

    2013-01-01

    The present thesis is an attempt at a grammatical description of Tundra Yukaghir (TY), based on a variety of primary data including those collected by the author during three field trips from 2009 till 2012. TY is a highly endangered minority language spoken in north-eastern Russia. It has slightly

  10. Spatial contexts for temporal variability in alpine vegetation under ongoing climate change

    Science.gov (United States)

    Fagre, Daniel B.; George P. Malanson; George P. Malanson

    2013-01-01

    A framework to monitor mountain summit vegetation (The Global Observation Research Initiative in Alpine Environments, GLORIA) was initiated in 1997. GLORIA results should be taken within a regional context of the spatial variability of alpine tundra. Changes observed at GLORIA sites in Glacier National Park, Montana, USA are quantified within the context of the range of variability observed in alpine tundra across much of western North America. Dissimilarity is calculated and used in nonmetric multidimensional scaling for repeated measures of vascular species cover at 14 GLORIA sites with 525 nearby sites and with 436 sites in western North America. The lengths of the trajectories of the GLORIA sites in ordination space are compared to the dimensions of the space created by the larger datasets. The absolute amount of change on the GLORIA summits over 5 years is high, but the degree of change is small relative to the geographical context. The GLORIA sites are on the margin of the ordination volumes with the large datasets. The GLORIA summit vegetation appears to be specialized, arguing for the intrinsic value of early observed change in limited niche space.

  11. Tundra vegetation effects on pan-Arctic albedo

    International Nuclear Information System (INIS)

    Recent field experiments in tundra ecosystems describe how increased shrub cover reduces winter albedo, and how subsequent changes in surface net radiation lead to altered rates of snowmelt. These findings imply that tundra vegetation change will alter regional energy budgets, but to date the effects have not been documented at regional or greater scales. Using satellite observations and a pan-Arctic vegetation map, we examined the effects of shrub vegetation on albedo across the terrestrial Arctic. We included vegetation classes dominated by low shrubs, dwarf shrubs, tussock-dominated graminoid tundra, and non-tussock graminoid tundra. Each class was further stratified by bioclimate subzones. Low-shrub tundra had higher normalized difference vegetation index values and earlier albedo decline in spring than dwarf-shrub tundra, but for tussock tundra, spring albedo declined earlier than for low-shrub tundra. Our results illustrate how relatively small changes in vegetation properties result in differences in albedo dynamics, regardless of shrub growth, that may lead to differences in net radiation upwards of 50 W m-2 at weekly time scales. Further, our findings imply that changes to the terrestrial Arctic energy budget during this important seasonal transition are under way regardless of whether recent satellite observed productivity trends are the result of shrub expansion. We conclude that a better understanding of changes in vegetation productivity and distribution in Arctic tundra is essential for accurately quantifying and predicting carbon and energy fluxes and associated climate feedbacks.

  12. The unseen iceberg: plant roots in arctic tundra.

    Science.gov (United States)

    Iversen, Colleen M; Sloan, Victoria L; Sullivan, Patrick F; Euskirchen, Eugenie S; McGuire, A David; Norby, Richard J; Walker, Anthony P; Warren, Jeffrey M; Wullschleger, Stan D

    2015-01-01

    Plant roots play a critical role in ecosystem function in arctic tundra, but root dynamics in these ecosystems are poorly understood. To address this knowledge gap, we synthesized available literature on tundra roots, including their distribution, dynamics and contribution to ecosystem carbon and nutrient fluxes, and highlighted key aspects of their representation in terrestrial biosphere models. Across all tundra ecosystems, belowground plant biomass exceeded aboveground biomass, with the exception of polar desert tundra. Roots were shallowly distributed in the thin layer of soil that thaws annually, and were often found in surface organic soil horizons. Root traits - including distribution, chemistry, anatomy and resource partitioning - play an important role in controlling plant species competition, and therefore ecosystem carbon and nutrient fluxes, under changing climatic conditions, but have only been quantified for a small fraction of tundra plants. Further, the annual production and mortality of fine roots are key components of ecosystem processes in tundra, but extant data are sparse. Tundra root traits and dynamics should be the focus of future research efforts. Better representation of the dynamics and characteristics of tundra roots will improve the utility of models for the evaluation of the responses of tundra ecosystems to changing environmental conditions.

  13. Consequences for selected high-elevation butterflies and moths from the spread of Pinus mugo into the alpine zone in the High Sudetes Mountains

    Science.gov (United States)

    Šipoš, Jan; Kindlmann, Pavel; Kuras, Tomáš

    2016-01-01

    Due to changes in the global climate, isolated alpine sites have become one of the most vulnerable habitats worldwide. The indigenous fauna in these habitats is threatened by an invasive species, dwarf pine (Pinus mugo), which is highly competitive and could be important in determining the composition of the invertebrate community. In this study, the association of species richness and abundance of butterflies with the extent of Pinus mugo cover at individual alpine sites was determined. Butterflies at alpine sites in the High Sudetes Mountains (Mts.) were sampled using Moericke yellow water traps. The results of a Canonical Correspondence Analysis (CCA) indicated that at a local scale the area of alpine habitats is the main limiting factor for native species of alpine butterflies. Butterfly assemblages are associated with distance to the tree-line with the optimum situated in the lower forest zone. In addition the CCA revealed that biotic factors (i.e. Pinus mugo and alpine tundra vegetation) accounted for a significant amount of the variability in species data. Regionally, the CCA identified that the species composition of butterflies and moths is associated with presence and origin of Pinus mugo. Our study provides evidence that the structure of the Lepidopteran fauna that formed during the postglacial period and also the present composition of species assemblages is associated with the presence of Pinus mugo. With global warming, Pinus mugo has the potential to spread further into alpine areas and negatively affect the local species communities. PMID:27330857

  14. Evidence and Implications of Frequent Fires in Ancient Shrub Tundra

    Energy Technology Data Exchange (ETDEWEB)

    Higuera, P E; Brubaker, L B; Anderson, P M; Brown, T A; Kennedy, A T; Hu, F S

    2008-03-06

    Understanding feedbacks between terrestrial and atmospheric systems is vital for predicting the consequences of global change, particularly in the rapidly changing Arctic. Fire is a key process in this context, but the consequences of altered fire regimes in tundra ecosystems are rarely considered, largely because tundra fires occur infrequently on the modern landscape. We present paleoecological data that indicate frequent tundra fires in northcentral Alaska between 14,000 and 10,000 years ago. Charcoal and pollen from lake sediments reveal that ancient birchdominated shrub tundra burned as often as modern boreal forests in the region, every 144 years on average (+/- 90 s.d.; n = 44). Although paleoclimate interpretations and data from modern tundra fires suggest that increased burning was aided by low effective moisture, vegetation cover clearly played a critical role in facilitating the paleo-fires by creating an abundance of fine fuels. These records suggest that greater fire activity will likely accompany temperature-related increases in shrub-dominated tundra predicted for the 21st century and beyond. Increased tundra burning will have broad impacts on physical and biological systems as well as land-atmosphere interactions in the Arctic, including the potential to release stored organic carbon to the atmosphere.

  15. Recent Arctic tundra fire initiates widespread thermokarst development

    Science.gov (United States)

    Jones, Benjamin M.; Grosse, Guido; Arp, Christopher D.; Miller, Eric K.; Liu, Lingli; Hayes, Daniel J.; Larsen, Christopher F.

    2015-01-01

    Fire-induced permafrost degradation is well documented in boreal forests, but the role of fires in initiating thermokarst development in Arctic tundra is less well understood. Here we show that Arctic tundra fires may induce widespread thaw subsidence of permafrost terrain in the first seven years following the disturbance. Quantitative analysis of airborne LiDAR data acquired two and seven years post-fire, detected permafrost thaw subsidence across 34% of the burned tundra area studied, compared to less than 1% in similar undisturbed, ice-rich tundra terrain units. The variability in thermokarst development appears to be influenced by the interaction of tundra fire burn severity and near-surface, ground-ice content. Subsidence was greatest in severely burned, ice-rich upland terrain (yedoma), accounting for ~50% of the detected subsidence, despite representing only 30% of the fire disturbed study area. Microtopography increased by 340% in this terrain unit as a result of ice wedge degradation. Increases in the frequency, magnitude, and severity of tundra fires will contribute to future thermokarst development and associated landscape change in Arctic tundra regions.

  16. Complete genome sequence of Granulicella mallensis type strain MP5ACTX8(T), an acidobacterium from tundra soil

    Energy Technology Data Exchange (ETDEWEB)

    Rawat, Suman R. [Rutgers University; Mannisto, Minna [Finnish Forest Research Institute, Parkano, Finland; Starovoytov, Valentin [Rutgers University; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Davenport, Karen W. [Los Alamos National Laboratory (LANL); Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Haggblom, Max [Rutgers University

    2013-01-01

    Granulicella mallensis MP5ACTX8(T) is a novel species of the genus Granulicella in subdivision 1 of Acidobacteria. G. mallensis is of ecological interest being a member of the dominant soil bacterial community active at low temperatures and nutrient limiting conditions in Arctic alpine tundra. G. mallensis is a cold-adapted acidophile and a versatile heterotroph that hydrolyzes a suite of sugars and complex polysaccharides. Genome analysis revealed metabolic versatility with genes involved in metabolism and transport of carbohydrates. These include gene modules encoding the carbohydrate-active enzyme (CAZyme) family involved in breakdown, utilization and biosynthesis of diverse structural and storage polysaccharides including plant based carbon polymers. The genome of Granulicella mallensis MP5ACTX8(T) consists of a single replicon of 6,237,577 base pairs (bp) with 4,907 protein-coding genes and 53 RNA

  17. Les barrages alpins

    Directory of Open Access Journals (Sweden)

    Alain Marnezy

    2009-03-01

    Full Text Available Les barrages-réservoirs de montagne ont été réalisés initialement dans les Alpes pour répondre à la demande d’énergie en période hivernale. Une certaine diversification des usages de l’eau s’est ensuite progressivement développée, en relation avec le développement touristique des collectivités locales. Aujourd’hui, la participation des ouvrages d’Électricité De France à la production de neige de culture représente une nouvelle étape. Dans les régions où les aménagements hydroélectriques sont nombreux, les besoins en eau pour la production de neige peuvent être résolus par prélèvements à partir des adductions EDF. Les gestionnaires de stations échappent ainsi aux inconvénients liés à la construction et à la gestion des « retenues collinaires ». Cette évolution, qui concerne déjà quelques régions alpines comme la haute Maurienne ou le Beaufortin, apparaît comme une forme renouvelée d’intégration territoriale de la ressource en eau.Mountain reservoirs were initially built in the Alps to meet energy needs in the winter. A certain diversification in the uses of water then gradually developed, related to tourism development in the local communities. Today, the use of facilities belonging to EDF (French Electricity Authority to provide water for winter resorts to make artificial snow represents a new phase. By taking water from EDF resources to supply snow-making equipment, resort managers are thus able to avoid the problems related to the construction and management of small headwater dams. This new orientation in the use of mountain water resources already affects a number of alpine regions such as the Upper Maurienne valley and Beaufortain massif and represents a renewed form of the territorial integration of water resources.

  18. Design of alpine skis

    Science.gov (United States)

    Nordt, Alison Audrey

    Models were developed to calculate the mechanical properties and the turning characteristics of alpine skis. The skis considered are constructed of layers of materials which may include wood, foam, metal, plastics, and fiber reinforced composites. The ski may be manufactured with or without camber and sidecut. The first model, and the corresponding SKI-MECH computer code, yields the mass, the bending and torsional stiffness distributions along the length, the flex, the twist, the natural frequencies, and the pressure distribution along the base of the ski. The second model, and the corresponding SKI-TURN code, simulates the motion of a skier of given height, weight, and skill level going down a smooth slope while executing a constant radius turn. The computer code provides the time it requires the skier to complete the turn. Both the SKI-MECH and SKI-TURN codes were verified by comparing the outputs of these codes to laboratory data and to data generated by skiers executing turns on a hill. The results of the model and the data are in good agreement lending confidence to the models and the computer codes. Numerical results are also presented which illustrate the usefulness of the computer codes for assessing the performance of skis and shed light on the role sidecut plays in affecting an efficient turn.

  19. Beyond arctic and alpine: the influence of winter climate on temperate ecosystems.

    Science.gov (United States)

    Ladwig, Laura M; Ratajczak, Zak R; Ocheltree, Troy W; Hafich, Katya A; Churchill, Amber C; Frey, Sarah J K; Fuss, Colin B; Kazanski, Clare E; Muñoz, Juan D; Petrie, Matthew D; Reinmann, Andrew B; Smith, Jane G

    2016-02-01

    Winter climate is expected to change under future climate scenarios, yet the majority of winter ecology research is focused in cold-climate ecosystems. In many temperate systems, it is unclear how winter climate relates to biotic responses during the growing season. The objective of this study was to examine how winter weather relates to plant and animal communities in a variety of terrestrial ecosystems ranging from warm deserts to alpine tundra. Specifically, we examined the association between winter weather and plant phenology, plant species richness, consumer abundance, and consumer richness in 11 terrestrial ecosystems associated with the U.S. Long-Term Ecological Research (LTER) Network. To varying degrees, winter precipitation and temperature were correlated with all biotic response variables. Bud break was tightly aligned with end of winter temperatures. For half the sites, winter weather was a better predictor of plant species richness than growing season weather. Warmer winters were correlated with lower consumer abundances in both temperate and alpine systems. Our findings suggest winter weather may have a strong influence on biotic activity during the growing season and should be considered in future studies investigating the effects of climate change on both alpine and temperate systems. PMID:27145612

  20. Isoprene emissions from a tundra ecosystem

    Directory of Open Access Journals (Sweden)

    M. J. Potosnak

    2013-02-01

    Full Text Available Whole-system fluxes of isoprene from a moist acidic tundra ecosystem and leaf-level emission rates of isoprene from a common species (Salix pulchra in that same ecosystem were measured during three separate field campaigns. The field campaigns were conducted during the summers of 2005, 2010 and 2011 and took place at the Toolik Field Station (68.6° N, 149.6° W on the north slope of the Brooks Range in Alaska, USA. The maximum rate of whole-system isoprene flux measured was over 1.2 mg C m−2 h−1 with an air temperature of 22 °C and a PAR level over 1500 μmol m−2 s−1. Leaf-level isoprene emission rates for S. pulchra averaged 12.4 nmol m−2 s−1 (27.4 μg C gdw−1 h−1 extrapolated to standard conditions (PAR = 1000 μmol m−2 s−1 and leaf temperature = 30 °C. Leaf-level isoprene emission rates were well characterized by the Guenther algorithm for temperature with published coefficients, but less so for light. Chamber measurements from a nearby moist acidic tundra ecosystem with little S. pulchra emitted significant amounts of isoprene, but at lower rates (0.45 mg C m−2 h−1 suggesting other significant isoprene emitters. Comparison of our results to predictions from a global model found broad agreement, but a detailed analysis revealed some significant discrepancies. An atmospheric chemistry box model predicts that the observed isoprene emissions have a significant impact on Arctic atmospheric chemistry, including a reduction of hydroxyl radical (OH concentrations. Our results support the prediction that isoprene emissions from Arctic ecosystems will increase with global climate change.

  1. Isoprene emissions from a tundra ecosystem

    Directory of Open Access Journals (Sweden)

    M. J. Potosnak

    2012-10-01

    Full Text Available Whole-system fluxes of isoprene from a~moist acidic tundra ecosystem and leaf-level emission rates of isoprene from a common species (Salix pulchra in that same ecosystem were measured during three separate field campaigns. The field campaigns were conducted during the summers of 2005, 2010 and 2011 and took place at the Toolik Field Station (68.6° N, 149.6° W on the north slope of the Brooks Range in Alaska, USA. The maximum rate of whole-system isoprene flux measured was over 1.2 mg C m−2 h−1 with an air temperature of 22 ° C and a PAR level over 1500 μmol m−2 s−1. Leaf-level isoprene emission rates for S. pulchra averaged 12.4 nmol m−2 s−1 (27.4 μg C gdw−1 h−1 extrapolated to standard conditions (PAR = 1000 μmol m−2 s−1 and leaf temperature = 30° C. Leaf-level isoprene emission rates were well characterized by the Guenther algorithm for temperature, but less so for light. Chamber measurements from a nearby moist acidic tundra ecosystem with less S. pulchra emitted significant amounts of isoprene, but at lower rates (0.45 mg C m−2 h−1. Comparison of our results to predictions from a global model found broad agreement, but a detailed analysis revealed some significant discrepancies. An atmospheric chemistry box model predicts that the observed isoprene emissions have a significant impact on Arctic atmospheric chemistry, including the hydroxyl radical (OH. Our results support the prediction that isoprene emissions from Arctic ecosystems will increase with global climate change.

  2. Automatic Detection of Small Single Trees in the Forest-Tundra Ecotone Using Airborne Laser Scanning

    Directory of Open Access Journals (Sweden)

    Nadja Stumberg

    2014-10-01

    Full Text Available A large proportion of Norway’s land area is occupied by the forest-tundra ecotone. The vegetation of this temperature-sensitive ecosystem between mountain forest and the alpine zone is expected to be highly affected by climate change and effective monitoring techniques are required. For the detection of such small pioneer trees, airborne laser scanning (ALS has been proposed as a useful tool employing laser height data. The objective of this study was to assess the capability of an unsupervised classification for automated monitoring programs of small individual trees using high-density ALS data. Field and ALS data were collected along a 1500 km long transect stretching from northern to southern Norway. Different laser and tree height thresholds were tested in various combinations within an unsupervised classification of tree and nontree raster cells employing different cell sizes. Suitable initial cell sizes for the exclusion of large treeless areas as well as an optimal cell size for tree cell detection were determined. High rates of successful tree cell detection involved high levels of commission error at lower laser height thresholds, however, exceeding the 20 cm laser height threshold, the rates of commission error decreased substantially with a still satisfying rate of successful tree cell detection.

  3. La recherche alpine aujourd’hui

    Directory of Open Access Journals (Sweden)

    Jean-Jacques Brun

    2009-06-01

    Full Text Available Alpine research benefits from several international coordination networks, only one of which – ISCAR (the International Scientific Committee on Research in the Alps – works solely in the Alpine arc. The creation of ISCAR is a consequence of the input and involvement of various Alpine partners around the Alpine Convention. Alpine research now aims to promote an integrated vision of Alpine territories focusing on creating and maintaining spatial and temporal networks of sustainable relationships between humans and the other components of the ecosphere. It combines resource usage with conservation of the biological and cultural diversity that makes up the Alpine identity. This article aims to show: (1 how international Alpine research coordination is organised; (2 the role played by the Alpine Convention as a framework of reference for specifically Alpine research; and (3 the role that the ISCAR international commit-tee and the Interreg “Alpine Space” programmes play in uniting research around territorial challenges relating to biodiversity conservation and territorial development.La recherche sur les Alpes bénéficie de plusieurs réseaux de coordination internationaux dont un seul, le comité international recherche alpine (ISCAR, se consacre exclusivement à l’arc alpin. La création de l’ISCAR est une retombée de la mobilisation des divers partenaires alpins autour de la mise en place de la Convention alpine. Aujourd’hui, la recherche alpine vise à promouvoir une vision intégrée des territoires centrée sur la création et le maintien d’un réseau spatial et temporel de relations durables entre les hommes et les autres composantes de l’écosphère. Elle associe étroitement la mise en valeur des ressources et la conservation des diversités biologiques et culturelles qui constituent l’identité alpine. Cet article a pour ambition de montrer : (1 comment s’organise la coordination internationale des recherches sur les

  4. Simulating the effects of temperature and precipitation change on vegetation composition in Arctic tundra ecosystems

    OpenAIRE

    Van Der Kolk, H; M. M. P. D. Heijmans; Van Huissteden, J.; Pullens, J. W. M.; Berendse, F.

    2016-01-01

    Over the past decades, vegetation has changed significantly along with climatic changes in the Arctic. Deciduous shrub cover is often assumed to expand in tundra landscapes, but more frequent abrupt permafrost thaw resulting in formation of thaw ponds could lead to vegetation shifts towards graminoid dominated wetland. Which mechanisms drive vegetation changes in the tundra ecosystem is still not sufficiently clear. In this study, the dynamic tundra vegetation model NUCOM-tundra was used to e...

  5. Acid neutralizing processes in an alpine watershed front range, Colorado, U.S.A.-1: Buffering capacity of dissolved organic carbon in soil solutions

    Science.gov (United States)

    Iggy, Litaor M.; Thurman, E.M.

    1988-01-01

    Soil interstitial waters in the Green Lakes Valley, Front Range, Colorado were studied to evaluate the capacity of the soil system to buffer acid deposition. In order to determine the contribution of humic substances to the buffering capacity of a given soil, dissolved organic carbon (DOC) and pH of the soil solutions were measured. The concentration of the organic anion, Ai-, derived from DOC at sample pH and the concentration of organic anion, Ax- at the equivalence point were calculated using carboxyl contents from isolated and purified humic material from soil solutions. Subtracting Ax- from Ai- yields the contribution of humic substances to the buffering capacity (Aequiv.-). Using this method, one can evaluate the relative contribution of inorganic and organic constituents to the acid neutralizing capacity (ANC) of the soil solutions. The relative contribution of organic acids to the overall ANC was found to be extremely important in the alpine wetland (52%) and the forest-tundra ecotone (40%), and somewhat less important in the alpine tundra sites (20%). A failure to recognize the importance of organic acids in soil solutions to the ANC will result in erroneous estimates of the buffering capacity in the alpine environment of the Front Range, Colorado. ?? 1988.

  6. Plant community and soil chemistry responses to long-term nitrogen inputs drive changes in alpine bacterial communities.

    Science.gov (United States)

    Yuan, Xia; Knelman, Joseph E; Gasarch, Eve; Wang, Deli; Nemergut, Diana R; Seastedt, Timothy R

    2016-06-01

    Bacterial community composition and diversity was studied in alpine tundra soils across a plant species and moisture gradient in 20 y-old experimental plots with four nutrient addition regimes (control, nitrogen (N), phosphorus (P) or both nutrients). Different bacterial communities inhabited different alpine meadows, reflecting differences in moisture, nutrients and plant species. Bacterial community alpha-diversity metrics were strongly correlated with plant richness and the production of forbs. After meadow type, N addition proved the strongest determinant of bacterial community structure. Structural Equation Modeling demonstrated that tundra bacterial community responses to N addition occur via changes in plant community composition and soil pH resulting from N inputs, thus disentangling the influence of direct (resource availability) vs. indirect (changes in plant community structure and soil pH) N effects that have remained unexplored in past work examining bacterial responses to long-term N inputs in these vulnerable environments. Across meadow types, the relative influence of these indirect N effects on bacterial community structure varied. In explicitly evaluating the relative importance of direct and indirect effects of long-term N addition on bacterial communities, this study provides new mechanistic understandings of the interaction between plant and microbial community responses to N inputs amidst environmental change.

  7. Alpine Skiing in the Classroom

    Science.gov (United States)

    Mendez-Gimenez, Antonio; Fernandez-Rio, Javier

    2012-01-01

    Many students settle indoors in the winter. However, this does not mean that winter should be a period of time with no physical activity. Several snow activities could be practiced during those months, such as ice-skating, ice-hockey, snowshoeing, cross-country skiing, alpine skiing, or snowboarding. In order to counteract the tendency for…

  8. 氮沉降对长白山苔原植被影响的试验研究%Experimental Study on the Effects of Nitrogen Deposition on the Tundra Vegetation of the Changbai Mountains

    Institute of Scientific and Technical Information of China (English)

    靳英华; 许嘉巍; 宗盛伟; 王鹏

    2014-01-01

    为了探讨氮沉降增加对苔原植被的影响,特别是对草本植物侵入苔原的作用,在长白山高山苔原带进行了连续4 a的人工氮沉降模拟实验,测定3种设定的氮沉降水平下牛皮杜鹃(Rhododendron chrysanthum)、笃斯越橘(Vaccinium uliginosum)和小叶章(Deyeuxia angustifolia)的生长状况和群落结构变化。研究结果表明:①与牛皮杜鹃、笃斯越橘等苔原本地种相比,氮沉降量增加更有利于侵入的小叶章生长;牛皮杜鹃生长对氮沉降量变化响应微弱,氮沉降量增加能明显抑制笃斯越橘的生长。②无小叶章侵入的牛皮杜鹃和笃斯越橘斑块在不同氮沉降量条件下,群落结构变化不明显,氮沉降增加不是小叶章侵入苔原带的直接原因。③在小叶章侵入牛皮杜鹃和笃斯越橘斑块后,氮沉降量增加强化了小叶章的竞争能力,逐渐取代牛皮杜鹃或笃斯越橘,成为优势种,推动高山苔原向高山草甸转化。因此,随着氮沉降量的不断增加,长白山苔原带将面临退化与草甸化。%In order to explore the effects of increased nitrogen deposition on alpine tundra vegetation change, es-pecially the herb invasion, in Changbai Mountains, the experiments of simulated increased nitrogen deposition were conducted over four years in the alpine tundra zone of the Changbai Mountains. The experiment included three nitrogen deposition treatments. The changes of growth and community structure were measured for Rho⁃dodendron chrysanthum, Vaccinium uliginosum and Deyeuxia angustifolia. The main results were as follows:1) Compared to the Rhododendron chrysanthum, Vaccinium uliginosum and other tundra native species, the in-crease of nitrogen deposition is more conducive to the growth of Deyeuxia angustifolia, it was no significant re-sponse to increase of nitrogen deposition for growth of Rhododendron chrysanthum, it was significantly sup-pressed by increase

  9. Investigation phytochimique de plantes alpines

    OpenAIRE

    Munari, Caroline

    2006-01-01

    As a part of our ongoing investigations of alpine plants from the Valley of Aoste (Italy), the methanol and dichloromethane extracts of 45 plants have been studied from a phytochemical view point. These species grow at altitudes from 2200 to 2700 meters in extreme habitat. Thus, 100 extracts were investigated for their free radical scavenging activity against DPPH and antifungal activities with different tests: against the plant pathogenic fungus Cladosporium cucumerinum by direct bioautograp...

  10. The Voest-Alpine surface miner

    Energy Technology Data Exchange (ETDEWEB)

    1988-08-01

    The Voest-Alpine Surface Miner (VASM) is developed by Voest-Alpine Maschinenbau, Zeltweg, Australia. It is designed to be the excavation machine of an integrated continuous mining system which will cut, load and transfer the material from the face to a continuous haulage system composed of mobile transfer conveyors, shiftable or movable bench conveyors and stationary extendable out-of-the-pit conveyors. Voest-Alpine claims that more efficient and economical solutions in surface mining are provided by this new mining system. This paper also contains a brief description of the Voest-Alpine Pulse Cutting system (VAPCUT) which is a hydraulically activated cutting tool system. 5 figs.

  11. Digital Necrobacillosis in Norwegian Wild Tundra Reindeer (Rangifer tarandus tarandus)

    DEFF Research Database (Denmark)

    Handeland, K.; Boye, Mette; Bergsjø, B.;

    2010-01-01

    Outbreaks of digital necrobacillosis in Norwegian wild tundra reindeer (Rangifer tarandus tarandus) are described. The outbreaks occurred in late summer and autumn 2007 and 2008, subsequent to periods with an unusually high number of days with precipitation and high air temperature. Lesions were...

  12. [The gene pool of native inhabitants of the Samburg tundra].

    Science.gov (United States)

    Osipova, L P; Posukh, O L; Ivakin, E A; Kriukov, Iu A; Karafet, T M

    1996-06-01

    This study continues a series of investigations of the gene pool of native Siberian ethnic groups. In a population of Tundra Nentsi (Northern Samoyeds) and a group of Komi-Zyryans (Finno-Ugrian) (Samburg settlement, Tyumenskaya oblast, Yamalo-Nenetskii Autonomous okrug), gene markers of the following genetic systems were studied: blood groups (ABO, MNSs, Rhesus, Kell, Duffy, and P), erythrocyte acid phosphatase (AcP), phosphoglucomutase 1 (PGM 1), haptoglobin (Hp), and transferrin (Tf). The population of Samburg Tundra Nentsi was shown to have a close genetic relationship with the "core" of the Forest Nentsi population. In Northern Samoyeds, three carriers of the rare allele K (blood group Kell) were found for the first time. It is suggested that this allele was transferred into the population of Tundra Nentsi from Komi. Samburg Tundra Nentsi are found to have the maximum frequency of the allele PGM 1 (Posphoglucomutase 1) among aboriginal populations of northern Asia. Analysis of original data and the literature revealed a significant genetic distance between the Komi and Northern Samoyed populations. It was shown that Samburg Komi occupy an intermediate position between the clusters of Nenets populations and Finno-Ugrians (Komi) living in Komi Republic.

  13. Comparative phylogeography highlights the double-edged sword of climate change faced by arctic- and alpine-adapted mammals.

    Directory of Open Access Journals (Sweden)

    Hayley C Lanier

    Full Text Available Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the

  14. Comparative phylogeography highlights the double-edged sword of climate change faced by arctic- and alpine-adapted mammals.

    Science.gov (United States)

    Lanier, Hayley C; Gunderson, Aren M; Weksler, Marcelo; Fedorov, Vadim B; Olson, Link E

    2015-01-01

    Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles) vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival) that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the generation of

  15. Emissions of biogenic sulfur gases from Alaskan tundra

    Science.gov (United States)

    Hines, Mark E.; Morrison, Michael C.

    1992-01-01

    Fluxes of the biogenic sulfur gases carbonyl sulfide (COS), dimethyl sulfide (DMS), methyl mercaptan (MeSH), and carbon disulfide (CS2) were determined for several freshwater and coastal marine tundra habitats using a dynamic enclosure method and gas chromatography. In the freshwater tundra sites, highest emissions, with a mean of 6.0 nmol/m(sup -2)H(sup -1) (1.5-10) occurred in the water-saturated wet meadow areas inhabited by grasses, sedges, and Sphagnum mosses. In the drier upland tundra sites, highest fluxes occurred in areas inhabited by mixed vegetation and labrador tea at 3.0 nmol/m(sup -2)h(sup -1) (0-8.3) and lowest fluxes were from lichen-dominated areas at 0.9 nmol/m(sup -2)h(sup -1). Sulfur emissions from a lake surface were also low at 0.8 nmol/m(sup -2)h(sup -1). Of the compounds measured, DMS was the dominant gas emitted from all of these sites. Sulfure emissions from the marine sites were up to 20-fold greater than fluxes in the freshwater habitats and were also dominated by DMS. Emissions of DMS were highest from intertidal soils inhabited by Carex subspathacea (150-250 nmol/m(sup -2)h(sup -1)). This Carex sp. was grazed thoroughly by geese and DMS fluxes doubled when goose feces were left within the flux chamber. Emissions were much lower from other types of vegetation which were more spatially dominant. Sulfure emissions from tundra were among the lowest reported in the literature. When emission data were extrapolated to include all tundra globally, the global flux of biogenic sulfur from this biome is 2-3 x 10(exp 8) g/yr. This represents less than 0.001 percent of the estimated annual global flux (approximately 50 Tg) of biogenic sulfur and less than 0.01 percent of the estimated terrestrial flux. The low emissions are attributed to the low availability of sulfate, certain hydrological characteristics of tundra, and the tendency for tundra to accumulate organic matter.

  16. Sensitivity of subalpine tree seedlings and alpine plants to natural and manipulated climate variation: Initial results from an Alpine Treeline Warming Experiment (Invited)

    Science.gov (United States)

    Kueppers, L. M.

    2010-12-01

    Niche models and paleoecological studies indicate that future climate change will alter the geographic distributions of plant species. Changes in temperature, snowmelt timing, or moisture conditions at one edge of a species’ range may have different consequences for recruitment, carbon exchange, phenology, and survival than changes at another edge. Similarly, local genetic adaptation may constrain species and community responses to climate change. We have established a new experiment to investigate potential shifts in the distribution of subalpine tree species, and the alpine species they might replace. We are asking how tree species recruitment and alpine species growth and reproduction vary within their current ranges, and in response to temperature and soil moisture manipulations. We are also examining whether genetic provenance and ecosystem processes constrain tree seedling and alpine herb responses. Our Alpine Treeline Warming Experiment is located across three sites at Niwot Ridge, CO, ranging from near the lower limit of subalpine forest to alpine tundra. We use infrared heaters to raise growing season surface soil temperatures by 4-5°C, and to lengthen the growing season. The warming treatment is crossed with a soil moisture manipulation to distinguish effects due to higher temperatures from those due to drier soil. Each plot is a common garden sown with high and low elevation provenances of limber pine (Pinus flexilis) and Engelmann spruce (Picea engelmannii). We established an additional set of experimental plots to examine treatment effects on alpine species phenology, growth and reproduction. Under ambient conditions in 2009, tree seedling germination rate, lifespan, and first season survival was higher within the species’ current range than in the alpine, and for Engelmann spruce, was higher at the low elevation limit than the high elevation limit. Source population (low vs. high elevation) was a significant factor explaining natural variation in

  17. Paenibacillus tundrae sp. nov. and Paenibacillus xylanexedens sp. nov., Psychrotolerant, Xylan-Degrading, Bacteria from Alaskan Tundra

    Science.gov (United States)

    Psychrotolerant, xylan-degrading, strains of bacteria were isolated from soil beneath moist non-acidic and acidic tundra in northern Alaska. Phylogenetic analysis based on 16S rRNA gene sequences revealed that each strain belonged to the genus Paenibacillus. The highest levels of 16S rRNA gene sim...

  18. Identifying nitrogen limitations to organic sediments accumulation in various vegetation types of arctic tundra (Hornsund, Svalbard)

    Science.gov (United States)

    Skrzypek, G.; Wojtuń, B.; Hua, Q.; Richter, D.; Jakubas, D.; Wojczulanis-Jakubas, K.; Samecka-Cymerman, A.

    2015-12-01

    Arctic and subarctic regions play important roles in the global carbon balance. However, nitrogen (N) deficiency is a major constraint for organic carbon sequestration in the High Arctic. Hence, the identification of the relative contributions from different N-sources is critical for understanding the constraints that limit tundra growth. The stable nitrogen composition of the three main N-sources and numerous plants were analyzed in ten tundra types in the Fuglebekken catchment (Hornsund Fjord, Svalbard, 77°N 15°E). The percentage of the total tundra N-pool provided by seabirds' feces (colonially breeding, planktivorous Alle alle), ranged from 0-21% in Patterned-ground tundra to 100% in Ornithocoprophilous tundra. The total N-pool utilized by tundra plants in the studied catchment was built in 36% by birds, 38% by atmospheric deposition, and 26% by N2-fixation. The results clearly show that N-pool in the tundra is significantly supplemented by nesting seabirds. Thus, if they experienced substantial negative environmental pressure associated with climate change, it would adversely influence the tundra N-budget [1]. The growth rates and the sediment thickness (climatic conditions but also by birds' contribution to the tundra N-pool. [1] Skrzypek G, Wojtuń B, Richter D, Jakubas D, Wojczulanis-Jakubas K, Samecka-Cymerman A, 2015. Diversification of nitrogen sources in various tundra vegetation types in the high Arctic. PLoS ONE (in review).

  19. Ericaceous plant-fungus network in a harsh alpine-subalpine environment.

    Science.gov (United States)

    Toju, H; Tanabe, A S; Ishii, H S

    2016-07-01

    In terrestrial ecosystems, plant species and diverse root-associated fungi form complex networks of host-symbiont associations. Recent studies have revealed that structures of those below-ground plant-fungus networks differ between arbuscular mycorrhizal and ectomycorrhizal symbioses. Nonetheless, we still remain ignorant of how ericaceous plant species, which dominate arctic and alpine tundra, constitute networks with their root-associated fungi. Based on a high-throughput DNA sequencing data set, we characterized the statistical properties of a network involving 16 ericaceous plant species and more than 500 fungal taxa in the alpine-subalpine region of Mt. Tateyama, central Japan. While all the 16 ericaceous species were associated mainly with fungi in the order Helotiales, they varied remarkably in association with fungi in other orders such as Sebacinales, Atheliales, Agaricales, Russulales and Thelephorales. The ericaceous plant-fungus network was characterized by high symbiont/host preferences. Moreover, the network had a characteristic structure called 'anti-nestedness', which has been previously reported in ectomycorrhizal plant-fungus networks. The results lead to the hypothesis that ericaceous plants in harsh environments can host unexpectedly diverse root-associated fungal taxa, constituting networks whose structures are similar to those of previously reported ectomycorrhizal networks but not to those of arbuscular mycorrhizal ones. PMID:27136380

  20. Wintertime ecosystem respiration shifts tundra from carbon sink to carbon source at tundra warming experiment

    Science.gov (United States)

    Webb, E.; Schuur, E. A.; Natali, S.; Bracho, R.

    2013-12-01

    Northern latitude ecosystems play a significant role in the global carbon (C) budget due to the roughly 1700 Pg of C stored in permafrost soils. As high latitudes warm, previously frozen C is expected to decompose, thereby increasing CO2 fluxes to the atmosphere and potentially creating a positive feedback to climate warming. While warming has been shown to increase plant C uptake during the growing season, these seasonal C gains may be offset on an annual basis by ecosystem respiration (Reco) during the remaining seven months of the year. Here we present research from the Carbon in Permafrost Experimental Heating Research (CiPEHR) project, a tundra ecosystem warming experiment in interior Alaska. We partitioned the non-growing season into three segments: fall (October 1 until first snow), winter (snow-covered period until spring), and spring (snow depth less than 30cm until melt out). During fall, we measured net ecosystem exchange and Reco using a static flux chamber. In winter, we measured Reco using chamber measurements and soda lime. For spring, we modeled fluxes based on known relationships between snow depth and photosynthetic rate of arctic evergreen species. We found that ecosystem warming caused plants to photosynthesize later in fall and increased C uptake during spring but also enhanced respiration during the long winter. We combined these off-season estimates with measurements from growing season auto-chamber data and found that despite the C gained during the growing season, ecosystem warming resulted in net annual C loss for the two years measured. This annual C loss was dependent on the magnitude of wintertime Reco. Our results indicate that snow depth, soil temperature, and day of season are the major determinants of wintertime Reco. Some climate models predict that arctic ecosystems will experience warmer winters with more snow. Thus, despite increased plant productivity during the growing season, we document that increased wintertime temperatures

  1. Diversification of Nitrogen Sources in Various Tundra Vegetation Types in the High Arctic.

    Directory of Open Access Journals (Sweden)

    Grzegorz Skrzypek

    Full Text Available Low nitrogen availability in the high Arctic represents a major constraint for plant growth, which limits the tundra capacity for carbon retention and determines tundra vegetation types. The limited terrestrial nitrogen (N pool in the tundra is augmented significantly by nesting seabirds, such as the planktivorous Little Auk (Alle alle. Therefore, N delivered by these birds may significantly influence the N cycling in the tundra locally and the carbon budget more globally. Moreover, should these birds experience substantial negative environmental pressure associated with climate change, this will adversely influence the tundra N-budget. Hence, assessment of bird-originated N-input to the tundra is important for understanding biological cycles in polar regions. This study analyzed the stable nitrogen composition of the three main N-sources in the High Arctic and in numerous plants that access different N-pools in ten tundra vegetation types in an experimental catchment in Hornsund (Svalbard. The percentage of the total tundra N-pool provided by birds, ranged from 0-21% in Patterned-ground tundra to 100% in Ornithocoprophilous tundra. The total N-pool utilized by tundra plants in the studied catchment was built in 36% by birds, 38% by atmospheric deposition, and 26% by atmospheric N2-fixation. The stable nitrogen isotope mixing mass balance, in contrast to direct methods that measure actual deposition, indicates the ratio between the actual N-loads acquired by plants from different N-sources. Our results enhance our understanding of the importance of different N-sources in the Arctic tundra and the used methodological approach can be applied elsewhere.

  2. Global assessment of experimental climate warming on tundra vegetation

    DEFF Research Database (Denmark)

    Elmendorf, Sarah C.; Henry, Gregory H.R.; Hollister, Robert D.;

    2012-01-01

    Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations...... of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups...... to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed...

  3. Climate sensitivity of shrub growth across the tundra biome

    DEFF Research Database (Denmark)

    Myers-Smith, Isla H; Elmendorf, Sarah C; Beck, Pieter SA;

    2015-01-01

    Rapid climate warming in the tundra biome has been linked to increasing shrub dominance1–4. Shrub expansion can modify climate by altering surface albedo, energy and water balance, and permafrost2,5–8, yet the drivers of shrub growth remain poorly understood. Dendroecological data consisting...... or upper elevational range edges. Across latitude, climate sensitivity of growth was greatest at the boundary between the Low and High Arctic, where permafrost is thawing4 and most of the global permafrost soil carbon pool is stored9. The observed variation in climate–shrub growth relationships should...... be incorporated into Earth system models to improve future projections of climate change impacts across the tundra biome....

  4. Alpine cloud climatology: regional effects

    Science.gov (United States)

    Kaestner, Martina; Kriebel, Karl T.

    1996-12-01

    The present understanding of moist atmospheric processes and the role of clouds in the hydrologic cycle shows severe gaps of knowledge. Water vapor plays an essential part in atmospheric dynamics. For example, the release of large amounts of latent heat, due to the condensation in convective clouds, plays an important role in the general circulation. Knowledge of the distribution of clouds and its transport is essential to understand atmospheric dynamics. Clouds can have a positive as well as a negative contribution to the greenhouse effect. A cloud cover climatology in a 15 km grid resolution has been retrieved by means of the APOLLO algorithm using the 5 calibrated AVHRR channels. The monthly means of total cloud cover are about 15 percent too high compared to conventional data, the standard deviation is +/- 12 percent. The high resolution cloud cover maps show topometeorological features like 'Fohn' on single days but not in monthly means, because these events are too rare. But increased cloud cover in the luff regions are detected in monthly means as well as some cloud sparse regions like Lake Garda, Ticino or the Swiss Rhone valley. The different annual cycles of cloud cover show the different climatic regions, which are temperate, Alpine, and Mediterranean climate. This is indicated, for example, by the remarkably smaller cloud cover in the Alpine region in winter as compared to the northern and southern forelands.

  5. Changes in the Alpine environment

    Directory of Open Access Journals (Sweden)

    Philippe Schoeneich

    2009-03-01

    Full Text Available L’évolution de l’environnement alpin au XXIe siècle sera conditionnée par le changement climatique. Celui-ci pourrait conduire à des climats inconnus à ce jour dans les Alpes, avec comme conséquence une crise environnementale majeure et durable. Face à ces défis, les financements de recherche restent insuffisants pour la recherche appliquée aux milieux de montagne. Les financements nationaux privilégient souvent la recherche polaire au détriment des hautes altitudes, alors que les financements de type Interreg prennent insuffisamment en compte les besoins de recherche fondamentale, préalable nécessaire à l’élaboration de scénarios. Une évolution se dessine depuis deux ou trois ans vers des projets en réseau à l’échelle alpine. Le présent article fait le point sur les principaux enjeux qui attendent la recherche environnementale alpine et sur la capacité des programmes de recherche à répondre aux besoins. La première partie sur les changements climatiques est fondée sur les rapports récents : rapport de synthèse IPCC 2007 (IPCC 2007, rapport IPCC sur l’Europe (Alcamo et al. 2007, rapport de synthèse du programme ClimChAlp (Prudent-Richard et al., 2008. On y trouvera des bibliographies complètes et circonstanciées. La deuxième partie se base sur une analyse des appels d’offres récents ou en cours, et des projets soumis et financés.The way the Alpine environment will evolve in the 21st century depends upon climate change. This could lead to climates never before seen in the Alps, resulting in a major and lasting environmental crisis. In the face of these challenges, funding is still insufficient for specialised research on mountain environments. State funding often prioritises polar research at the expense of high altitude areas, whereas funding schemes from bodies such as Interreg do not sufficiently address the need for fundamental research, which is nevertheless a necessary first step prior to

  6. Cold season emissions dominate the Arctic tundra methane budget.

    Science.gov (United States)

    Zona, Donatella; Gioli, Beniamino; Commane, Róisín; Lindaas, Jakob; Wofsy, Steven C; Miller, Charles E; Dinardo, Steven J; Dengel, Sigrid; Sweeney, Colm; Karion, Anna; Chang, Rachel Y-W; Henderson, John M; Murphy, Patrick C; Goodrich, Jordan P; Moreaux, Virginie; Liljedahl, Anna; Watts, Jennifer D; Kimball, John S; Lipson, David A; Oechel, Walter C

    2016-01-01

    Arctic terrestrial ecosystems are major global sources of methane (CH4); hence, it is important to understand the seasonal and climatic controls on CH4 emissions from these systems. Here, we report year-round CH4 emissions from Alaskan Arctic tundra eddy flux sites and regional fluxes derived from aircraft data. We find that emissions during the cold season (September to May) account for ≥ 50% of the annual CH4 flux, with the highest emissions from noninundated upland tundra. A major fraction of cold season emissions occur during the "zero curtain" period, when subsurface soil temperatures are poised near 0 °C. The zero curtain may persist longer than the growing season, and CH4 emissions are enhanced when the duration is extended by a deep thawed layer as can occur with thick snow cover. Regional scale fluxes of CH4 derived from aircraft data demonstrate the large spatial extent of late season CH4 emissions. Scaled to the circumpolar Arctic, cold season fluxes from tundra total 12 ± 5 (95% confidence interval) Tg CH4 y(-1), ∼ 25% of global emissions from extratropical wetlands, or ∼ 6% of total global wetland methane emissions. The dominance of late-season emissions, sensitivity to soil environmental conditions, and importance of dry tundra are not currently simulated in most global climate models. Because Arctic warming disproportionally impacts the cold season, our results suggest that higher cold-season CH4 emissions will result from observed and predicted increases in snow thickness, active layer depth, and soil temperature, representing important positive feedbacks on climate warming. PMID:26699476

  7. Biogeochemical modeling of tundra recovery following thermal erosion of permafrost

    Science.gov (United States)

    Pearce, A. R.; Rastetter, E. B.; Bowden, W. B.

    2011-12-01

    We simulate the biogeochemical recovery of tundra from a thermal erosion disturbance using the Multiple Element Limitation model (MEL) and compare model results with soil organic matter and nutrient chemistry measurements collected across a chronosequence of thermal erosion features. Thermal erosion of permafrost initially depletes the tundra of much of its vegetation and shallow soil organic matter. However, several decades later, there is often little distinguishing these scars from the surrounding undisturbed tundra. As thermal erosion features become more abundant on the arctic landscape, we desire to understand how the pools of carbon and nutrients rebuild after these disturbances. MEL is a plot-scale, process-based model that optimizes the acquisition of eight resources (light, water, CO2, PO4, NH4, NO3, DON and N-fixation) by vegetation based on how much of each is required and the effort needed to acquire it. Model output includes pool sizes of carbon, nitrogen and phosphorus in vegetation, litter, young soil organic matter and old soil organic matter and the fluxes among these pools over time. This calibration of MEL, operating on a daily timestep, was created with published data collected at or near the Toolik Field Station (Toolik Lake, AK, USA) from moist acidic tussock tundra sites. We corroborate our calibration with data from plot manipulations (N and P fertilization, greenhouse, and shade house) performed as part of the NSF Arctic LTER project. The initial conditions for the recovery simulations reflect post-failure observations of some of the variation in soil organic matter, and soil and water nutrient chemistry. With sufficient nutrients from residual soil or supplied in soil water from upslope, the model indicates that vegetation can recover within several decades, but recovery of C and nutrients lost from soils may take hundreds of years.

  8. Analysis of state of vehicular scars on Arctic Tundra, Alaska

    Science.gov (United States)

    Lathram, E. H.

    1974-01-01

    Identification on ERTS images of severe vehicular scars in the northern Alaska tundra suggests that, if such scars are of an intensity or have spread to a dimension such that they can be resolved by ERTS sensors (20 meters), they can be identified and their state monitored by the use of ERTS images. Field review of the state of vehicular scars in the Umiat area indicates that all are revegetating at varying rates and are approaching a stable state.

  9. Anurans in a Subarctic Tundra Landscape Near Cape Churchill, Manitoba

    Science.gov (United States)

    Reiter, M.E.; Boal, C.W.; Andersen, D.E.

    2008-01-01

    Distribution, abundance, and habitat relationships of anurans inhabiting subarctic regions are poorly understood, and anuran monitoring protocols developed for temperate regions may not be applicable across large roadless areas of northern landscapes. In addition, arctic and subarctic regions of North America are predicted to experience changes in climate and, in some areas, are experiencing habitat alteration due to high rates of herbivory by breeding and migrating waterfowl. To better understand subarctic anuran abundance, distribution, and habitat associations, we conducted anuran calling surveys in the Cape Churchill region of Wapusk National Park, Manitoba, Canada, in 2004 and 2005. We conducted surveys along ~l-km transects distributed across three landscape types (coastal tundra, interior sedge meadow-tundra, and boreal forest-tundra interface) to estimate densities and probabilities of detection of Boreal Chorus Frogs (Pseudacris maculata) and Wood Frogs (Lithobates sylvaticus). We detected a Wood Frog or Boreal Chorus Frog on 22 (87%) of 26 transects surveyed, but probability of detection varied between years and species and among landscape types. Estimated densities of both species increased from the coastal zone inland toward the boreal forest edge. Our results suggest anurans occur across all three landscape types in our study area, but that species-specific spatial patterns exist in their abundances. Considerations for both spatial and temporal variation in abundance and detection probability need to be incorporated into surveys and monitoring programs for subarctic anurans.

  10. Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes

    Directory of Open Access Journals (Sweden)

    A. Ekici

    2014-09-01

    Full Text Available Modelling soil thermal dynamics at high latitudes and altitudes requires representations of specific physical processes such as snow insulation, soil freezing/thawing, as well as subsurface conditions like soil water/ice content and soil texture type. We have compared six different land models (JSBACH, ORCHIDEE, JULES, COUP, HYBRID8, LPJ-GUESS at four different sites with distinct cold region landscape types (i.e. Schilthorn-Alpine, Bayelva-high Arctic, Samoylov-wet polygonal tundra, Nuuk-non permafrost Arctic to quantify the importance of physical processes in capturing observed temperature dynamics in soils. This work shows how a range of models can represent distinct soil temperature regimes in permafrost and non-permafrost soils. Snow insulation is of major importance for estimating topsoil conditions and must be combined with accurate subsoil temperature dynamics to correctly estimate active layer thicknesses. Analyses show that land models need more realistic surface processes (such as detailed snow dynamics and moss cover with changing thickness/wetness as well as better representations of subsoil thermal dynamics (i.e. soil heat transfer mechanism and correct parameterization of heat conductivity/capacities.

  11. Complete genome sequence of Granulicella tundricola type strain MP5ACTX9T, an Acidobacteria from tundra soil

    Energy Technology Data Exchange (ETDEWEB)

    Rawat, Suman R. [Rutgers University; Mannisto, Minna [Finnish Forest Research Institute, Parkano, Finland; Starovoytov, Valentin [Rutgers University; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Davenport, Karen W. [Los Alamos National Laboratory (LANL); Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Haggblom, Max [Rutgers University

    2013-01-01

    Granulicella tundricola strain MP5ACTX9T is a novel species of the genus Granulicella in subdivision 1 Acidobacteria. G. tundricola is a predominant member of soil bacterial communities, active at low temperatures and nutrient limiting conditions in Arctic alpine tundra. The organism is a cold-adapted acidophile and a versatile heterotroph that hydro-lyzes a suite of sugars and complex polysaccharides. Genome analysis revealed metabolic versatility with genes involved in metabolism and transport of carbohydrates, including gene modules encoding for the carbohydrate-active enzyme (CAZy) families for the break-down, utilization and biosynthesis of diverse structural and storage polysaccharides such as plant based carbon polymers. The genome of G. tundricola strain MP5ACTX9T consists of 4,309,151 bp of a circular chromosome and five mega plasmids with a total genome con-tent of 5,503,984 bp. The genome comprises 4,705 protein-coding genes and 52 RNA genes.

  12. Changing Seasonality of Tundra Vegetation and Associated Climatic Variables

    Science.gov (United States)

    Bhatt, U. S.; Walker, D. A.; Raynolds, M. K.; Bieniek, P.; Epstein, H. E.; Comiso, J. C.; Pinzon, J.; Tucker, C. J.; Steele, M.; Ermold, W. S.; Zhang, J.

    2014-12-01

    This study documents changes in the seasonality of tundra vegetation productivity and its associated climate variables using long-term data sets. An overall increase of Pan-Arctic tundra greenness potential corresponds to increased land surface temperatures and declining sea ice concentrations. While sea ice has continued to decline, summer land surface temperature and vegetation productivity increases have stalled during the last decade in parts of the Arctic. To understand the processes behind these features we investigate additional climate parameters. This study employs remotely sensed weekly 25-km sea ice concentration, weekly surface temperature, and bi-weekly NDVI from 1982 to 2013. Maximum NDVI (MaxNDVI, Maximum Normalized Difference Vegetation Index), Time Integrated NDVI (TI-NDVI), Summer Warmth Index (SWI, sum of degree months above freezing during May-August), ocean heat content (PIOMAS, model incorporating ocean data assimilation), and snow water equivalent (GlobSnow, assimilated snow data set) are explored. We analyzed the data for the full period (1982-2013) and for two sub-periods (1982-1998 and 1999-2013), which were chosen based on the declining Pan-Arctic SWI since 1998. MaxNDVI has increased from 1982-2013 over most of the Arctic but has declined from 1999 to 2013 over western Eurasia, northern Canada, and southwest Alaska. TI-NDVI has trends that are similar to those for MaxNDVI for the full period but displays widespread declines over the 1999-2013 period. Therefore, as the MaxNDVI has continued to increase overall for the Arctic, TI-NDVI has been declining since 1999. SWI has large relative increases over the 1982-2013 period in eastern Canada and Greenland and strong declines in western Eurasia and southern Canadian tundra. Weekly Pan-Arctic tundra land surface temperatures warmed throughout the summer during the 1982-1998 period but display midsummer declines from 1999-2013. Weekly snow water equivalent over Arctic tundra has declined over

  13. Alaska North Slope Tundra Travel Model and Validation Study

    Energy Technology Data Exchange (ETDEWEB)

    Harry R. Bader; Jacynthe Guimond

    2006-03-01

    The Alaska Department of Natural Resources (DNR), Division of Mining, Land, and Water manages cross-country travel, typically associated with hydrocarbon exploration and development, on Alaska's arctic North Slope. This project is intended to provide natural resource managers with objective, quantitative data to assist decision making regarding opening of the tundra to cross-country travel. DNR designed standardized, controlled field trials, with baseline data, to investigate the relationships present between winter exploration vehicle treatments and the independent variables of ground hardness, snow depth, and snow slab thickness, as they relate to the dependent variables of active layer depth, soil moisture, and photosynthetically active radiation (a proxy for plant disturbance). Changes in the dependent variables were used as indicators of tundra disturbance. Two main tundra community types were studied: Coastal Plain (wet graminoid/moist sedge shrub) and Foothills (tussock). DNR constructed four models to address physical soil properties: two models for each main community type, one predicting change in depth of active layer and a second predicting change in soil moisture. DNR also investigated the limited potential management utility in using soil temperature, the amount of photosynthetically active radiation (PAR) absorbed by plants, and changes in microphotography as tools for the identification of disturbance in the field. DNR operated under the assumption that changes in the abiotic factors of active layer depth and soil moisture drive alteration in tundra vegetation structure and composition. Statistically significant differences in depth of active layer, soil moisture at a 15 cm depth, soil temperature at a 15 cm depth, and the absorption of photosynthetically active radiation were found among treatment cells and among treatment types. The models were unable to thoroughly investigate the interacting role between snow depth and disturbance due to a

  14. Experience with the Alpine Breaker Line Support

    Energy Technology Data Exchange (ETDEWEB)

    Habnicht, H.; Halbmayer, C.

    1989-01-01

    The Alpine Breaker Line Support is new, mechanised support equipment for stabilising the caving edge during depillaring operations. A short discussion is presented of some panel geometry variations used, and of performance data achieved. 5 figs.

  15. SERVICE QUALITY ANALYSIS - HOTEL ALPIN (POIANA BRASOV

    Directory of Open Access Journals (Sweden)

    MADAR ANCA

    2013-12-01

    Full Text Available Hotel Alpin was built in 1971 in Poiana Brasov resort and has a 4 star quality ranking at the moment with the apart hotel having a 5 stars ranking. At the moment in the tourism market the service quality and client satisfaction are very important for being successful. This paper is analyzing through market research, clients’ satisfaction towards the service quality provided by Hotel Alpin. The purpose of this research is to validate the reputation of the hotel.

  16. Survey of Disturbance to Alpine Tundra in Atigun Gorge from Snow-Vehicle Traffic in November 2003

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Snow vehicles operated by Alyeska Pipeline Service Company Alyeska traveled from the Dalton Highway into Atigun Gorge in the Arctic National Wildlife Refuge in...

  17. Shrubs in the cold : interactions between vegetation, permafrost and climate in Siberian tundra

    NARCIS (Netherlands)

    Blok, D.

    2011-01-01

    The Arctic is experiencing strong increases in air temperature during the last decades. High-latitude tundra regions are very responsive to changes in temperature and may cause a shift in tundra vegetation composition towards greater dominance of deciduous shrubs. With increasing deciduous shrub cov

  18. The Cooling Capacity of Mosses: Controls on Water and Energy Fluxes in a Siberian Tundra Site

    NARCIS (Netherlands)

    Blok, D.; Heijmans, M.M.P.D.; Schaepman-Strub, G.; Ruijven, van J.; Parmentier, F.J.W.; Maximov, T.C.; Berendse, F.

    2011-01-01

    Arctic tundra vegetation composition is expected to undergo rapid changes during the coming decades because of changes in climate. Higher air temperatures generally favor growth of deciduous shrubs, often at the cost of moss growth. Mosses are considered to be very important to critical tundra ecosy

  19. Estimating Forest Carbon Stock in Alpine and Arctic Ecotones of the Urals

    Directory of Open Access Journals (Sweden)

    V. A. Usoltsev

    2014-10-01

    Full Text Available This paper reports on measured carbon stocks in the forests of two tree line ecotones of the Ural region where climate change might improve growing conditions. The first is an alpine ecotone that is represented by an altitudinal gradient of the spruce-dominated forests on the Western slope of the Tylaiskii Kamen Mountain (Western part of the Konzhakovskii-Tylaiskii-Serebryanskii Mountain system, 59°30′N, 59°00′E, at the alpine timber line that has risen from 864 to 960 m above sea level in the course of the last 100 years. The second is an arctic ecotone in larch-dominated forests at the lower course of the Pur river (67°N, 78°E, at the transition zone between closed floodplain forests and open or island-like communities of upland forests on tundra permafrost. According to our results, there are large differences in the carbon of the aboveground biomass of both ecotones across environmental gradients. In the alpine tree line ecotone, a 19-fold drop of the carbon stocks was detected between the lower and higher altitudinal levels. In the arctic ecotone the aboveground biomass carbon stock of forests of similar densities (1300 to 1700 trees per ha was 7 times as much in the river flood bed, and 5 times as much in mature, dense forests as the low density forests at higher elevations. Twelve regression equations describing dependencies of the aboveground tree biomass (stems, branches, foliage, total aboveground part upon stem diameter of the tree are proposed, which can be used to estimating the biological productivity (carbon of spruce and larch forests on Tylaiskii Kamen Mountain and the lower Pur river and on surrounding areas on the base of traditional forest mensuration have been proposed. In order to reduce the labor intensity of a coming determination of forest biomass the average values of density and dry matter content in the biomass fractions are given that were obtained by taking our sample trees.The results can be useful in

  20. Alpine radar conversion for LAWR

    Science.gov (United States)

    Savina, M.; Burlando, P.

    2012-04-01

    The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this

  1. Carbon dioxide and methane dynamics in Russian tundra

    DEFF Research Database (Denmark)

    Johansson, Paul Torbjörn; Kiepe, Isabell; Herbst, Mathias;

    interactions and the annual carbon dynamics. Here we present eddy correlation measurements of CO2 and CH4 exchange during the period from early spring to late autumn, covering the full growing season, i.e., mid June to mid September. We present preliminary seasonal budgets of carbon, greenhouse gas exchange......, and discuss possible implications of climatic change on this lowland tundra ecosystem. This study have been conducted as a part of the CARBO-North project (2006-2010), a project within the EU 6th framework programme, aiming at quantifying the carbon budget in Northern Russia across temporal and spatial scales....

  2. Frost resistance in alpine woody plants.

    Science.gov (United States)

    Neuner, Gilbert

    2014-01-01

    This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone.

  3. Sorting out non-sorted circles: Effects of winter climate change on the Collembola community of cryoturbated subarctic tundra

    Science.gov (United States)

    Krab, Eveline; Monteux, Sylvain; Becher, Marina; Blume-Werry, Gesche; Keuper, Frida; Klaminder, Jonatan; Kobayashi, Makoto; Lundin, Erik J.; Milbau, Ann; Roennefarth, Jonas; Teuber, Laurenz Michael; Weedon, James; Dorrepaal, Ellen

    2015-04-01

    Non-sorted circles (NSC) are a common type of cryoturbated (frost-disturbed) soil in the arctic and store large amounts of soil organic carbon (SOC) by the burial of organic matter. They appear as sparsely vegetated areas surrounded by denser tundra vegetation, creating patterned ground. Snowfall in the arctic is expected to increase, which will modify freezing intensity and freeze-thaw cycles in soils, thereby impacting on SOC dynamics. Vegetation, soil fauna and microorganisms, important drivers of carbon turnover, may benefit directly from the altered winter conditions and the resulting reduction in cryoturbation, but may also impact each other through trophic cascading. We investigated how Collembola, important decomposer soil fauna in high latitude ecosystems, are affected by increased winter insulation and vegetation cover. We subjected NSC in North-Swedish subarctic alpine tundra to two years of increased thermal insulation (snow fences or fiber cloth) in winter and spring, increasing soil temperatures and strongly reducing freeze-thaw frequency. From these NSC we sampled the Collembola community in: (i) the non-vegetated center, (ii) sparsely vegetated parts in the center and (iii) the vegetated domain surrounding NSC. To link changes in Collembola density and community composition to SOC dynamics, we included measurements of decomposer activity, dissolved organic carbon (DOC) and total extractable nitrogen (TN). We observed differences in Collembola density, community composition and soil fauna activity between the sampling points in the NSC. Specifically Collembola diversity increased with the presence of vegetation and density was higher in the vegetated outer domains. Increased winter insulation did not affect diversity but seemed to negatively affect density and decomposer activity in the vegetated outer domains. Interestingly, SOM distribution over NSC changed with snow addition (also to a lesser extent with fleece insulation) towards less SOM in the

  4. Can antibrowsing defense regulate the spread of woody vegetation in arctic tundra?

    Science.gov (United States)

    Bryant, John P.; Joly, Kyle; Chapin, F. Stuart; DeAngelis, Donald L.; Kielland, Knut

    2014-01-01

    Global climate warming is projected to promote the increase of woody plants, especially shrubs, in arctic tundra. Many factors may affect the extent of this increase, including browsing by mammals. We hypothesize that across the Arctic the effect of browsing will vary because of regional variation in antibrowsing chemical defense. Using birch (Betula) as a case study, we propose that browsing is unlikely to retard birch expansion in the region extending eastward from the Lena River in central Siberia across Beringia and the continental tundra of central and eastern Canada where the more effectively defended resin birches predominate. Browsing is more likely to retard birch expansion in tundra west of the Lena to Fennoscandia, Iceland, Greenland and South Baffin Island where the less effectively defended non-resin birches predominate. Evidence from the literature supports this hypothesis. We further suggest that the effect of warming on the supply of plant-available nitrogen will not significantly change either this pan-Arctic pattern of variation in antibrowsing defense or the resultant effect that browsing has on birch expansion in tundra. However, within central and east Beringia warming-caused increases in plant-available nitrogen combined with wildfire could initiate amplifying feedback loops that could accelerate shrubification of tundra by the more effectively defended resin birches. This accelerated shrubification of tundra by resin birch, if extensive, could reduce the food supply of caribou causing population declines. We conclude with a brief discussion of modeling methods that show promise in projecting invasion of tundra by woody plants.

  5. Frequent fires in ancient shrub tundra: implications of paleorecords for arctic environmental change.

    Science.gov (United States)

    Higuera, Philip E; Brubaker, Linda B; Anderson, Patricia M; Brown, Thomas A; Kennedy, Alison T; Hu, Feng Sheng

    2008-01-01

    Understanding feedbacks between terrestrial and atmospheric systems is vital for predicting the consequences of global change, particularly in the rapidly changing Arctic. Fire is a key process in this context, but the consequences of altered fire regimes in tundra ecosystems are rarely considered, largely because tundra fires occur infrequently on the modern landscape. We present paleoecological data that indicate frequent tundra fires in northcentral Alaska between 14,000 and 10,000 years ago. Charcoal and pollen from lake sediments reveal that ancient birch-dominated shrub tundra burned as often as modern boreal forests in the region, every 144 years on average (+/- 90 s.d.; n = 44). Although paleoclimate interpretations and data from modern tundra fires suggest that increased burning was aided by low effective moisture, vegetation cover clearly played a critical role in facilitating the paleofires by creating an abundance of fine fuels. These records suggest that greater fire activity will likely accompany temperature-related increases in shrub-dominated tundra predicted for the 21(st) century and beyond. Increased tundra burning will have broad impacts on physical and biological systems as well as on land-atmosphere interactions in the Arctic, including the potential to release stored organic carbon to the atmosphere. PMID:18320025

  6. Frequent fires in ancient shrub tundra: implications of paleorecords for arctic environmental change.

    Directory of Open Access Journals (Sweden)

    Philip E Higuera

    Full Text Available Understanding feedbacks between terrestrial and atmospheric systems is vital for predicting the consequences of global change, particularly in the rapidly changing Arctic. Fire is a key process in this context, but the consequences of altered fire regimes in tundra ecosystems are rarely considered, largely because tundra fires occur infrequently on the modern landscape. We present paleoecological data that indicate frequent tundra fires in northcentral Alaska between 14,000 and 10,000 years ago. Charcoal and pollen from lake sediments reveal that ancient birch-dominated shrub tundra burned as often as modern boreal forests in the region, every 144 years on average (+/- 90 s.d.; n = 44. Although paleoclimate interpretations and data from modern tundra fires suggest that increased burning was aided by low effective moisture, vegetation cover clearly played a critical role in facilitating the paleofires by creating an abundance of fine fuels. These records suggest that greater fire activity will likely accompany temperature-related increases in shrub-dominated tundra predicted for the 21(st century and beyond. Increased tundra burning will have broad impacts on physical and biological systems as well as on land-atmosphere interactions in the Arctic, including the potential to release stored organic carbon to the atmosphere.

  7. Succession Stages of Tundra Plant Communities Following Wildfire Disturbance in Arctic Alaska

    Science.gov (United States)

    Breen, A. L.; Hollingsworth, T. N.; Mack, M. C.; Jones, B. M.

    2015-12-01

    Rapid climate change is affecting climate-sensitive disturbance regimes throughout the world. In particular, the impacts of climate change on Arctic disturbance regimes are poorly understood because landscape-scale disturbances are infrequent or occur in remote localities. Wildfire in Arctic Alaska is presently limited by ignition source and favorable burn weather. With rapid climate change, a lengthening growing season, and subsequent increase in plant biomass and productivity, wildfire frequency and annual area burned in tundra ecosystems is expected to increase over the next century. Yet, post-fire tundra vegetation succession is inadequately characterized except at a few point locations. We identify succession stages of tussock tundra communities following wildfire using a chronosequence of 65 relevés in 10 tundra fire scars (1971-2011) and nearby unburned tundra from sites on the Seward Peninsula and northern foothills of the Brooks Range. We used the Braun-Blanquét approach to classify plant communities, and applied nonmetric multidimentional scaling (NMDS) to identify ecological gradients underlying community differentiation. The ordination revealed a clear differentiation between unburned and burned tundra communities. Ecological gradients, reflected by ordination axes, correspond to fire history (e.g., time since last fire, number of times burned, burn severity) and a complex productivity gradient. Post-fire species richness is less than unburned tundra; primarily reflected as a decrease in lichen species and turnover of bryophyte species immediately post-fire. Species richness of grasses increases post-fire and is greatest in communities that burned more than once in the past 30 years. Shrub cover and total aboveground biomass are greatest in repeat burn sites. We review and discuss our results focusing on the implications of a changing tundra fire regime, its effect on vegetation succession trajectories, and subsequent rates of carbon sequestration and

  8. Snow, ice and water in alpine regions

    International Nuclear Information System (INIS)

    This article takes a look at how climate change will have a deep impact on alpine regions. The findings discussed at a conference organised by the Swiss Hydrologic Commission are presented and discussed. Flooding incidents that occurred 'once in a century' are now becoming more frequent and were considered at the conference as being an indicator of climate change. Changing hydrological factors are also discussed and the influence of climate factors in alpine regions on the water quantities in the rivers are looked at. Also, the spontaneous emptying of glacial lakes as has already happened in Switzerland and the consequences to be drawn from such incidences are discussed.

  9. BRDF characteristics of tundra vegetation communities in Yamal, Western Siberia

    Science.gov (United States)

    Buchhorn, Marcel; Heim, Birgit; Walker, Donald A. Skip; Epstein, Howard; Leibman, Marina

    2013-04-01

    Satellite data from platforms with pointing capabilities (CHRIS/Proba, RapidEye) or from sensors with wide swath (AVHRR, MODIS, MERIS) is influenced by the bidirectional reflectance distribution function (BRDF). This effect can cause significant changes in the measured spectral surface reflectance depending on the solar illumination geometry and sensor viewing conditions. The Environmental Mapping and Analysis Program (EnMAP), a German hyperspectral mission with expected launch in 2016, will provide high spectral resolution observations with a ground sampling distance of 30 meters. Since the EnMAP sensor has pointing capabilities, both spectral and directional reflection characteristics need to be taken into account for the algorithms development for vegetation parameters. The 'hyperspectral method development for Arctic VEGetation biomes' (hy-Arc-VEG) project is part of the national preparation program for the EnMAP mission. Within the EnMAP projcect hy-Arc-VEG we developed a portable field spectro-goniometer, named ManTIS (Manual Transportable Instrument for Spherical BRDF observations), for the in-situ measurements of anisotropic effects of tundra surfaces (national and international patent pending - DE 102011117713.6). The goniometer was designed for field use in difficult as well as challenging terrain and climate. It is therefore of low weight, without electrical devices and weatherproof. It can be disassembled and packed into small boxes for transport. The current off-nadir viewing capacity is matched to the EnMAP sensor configuration (up to 30°). We carried out spectral field and goniometer measurements on the joint YAMAL 2011 expedition (RU-US-DE) organized by the Earth-Cryosphere Institute (ECI) in August 2011 on the Yamal Peninsula, northwestern Siberia, Russia. The field goniometer measurements (conducted under varying sun zenith angles) as well as field spectro-radiometrical measurements were carried out at the NASA Yamal Land Cover/Land Use Change

  10. Dynamics of the recovery of damaged tundra vegetation. Annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Amundsen, C.C.

    1976-01-01

    A study, begun in 1971, continues to document the environmental factors which affect the recovery of damaged tundra landscapes. A measurement technique was developed on Amchitka Island to allow the rapid acquisition of data on species presence and frequency across areas disturbed at various times and in various ways. Samples across all examples of aspect, slope steepness and exposure are taken. Studies now include Adak Island and the Point Barrow area. We have concluded that there was no directional secondary succession on the Aleutian tundra, although there was vigorous recovery on organic soils. Our study led to recommendations which resulted in less intensive reclamation management at a considerable financial saving and without further biological perturbation. Because of the increasing activity on tundra landscapes, for energy extraction, transportation or production, military or other reasons, we have expanded our sampling to other tundra areas where landscape disruption is occurring or is predicted.

  11. Tundra swan populations, productivity, and local movements on Selawik National Wildlife Refuge, northwest Alaska, 1985

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the monitoring of populations and production of tundra swans on Selawik National Wildlife Refuge in 1985 as part of a long-term study. Radio...

  12. Potential responses of tundra ecosystems to perturbations from energy development. Part I. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.

    1986-01-01

    This report discusses research conducted to understand the effects of energy development on changes in nutrient status, changes in water flow and water availability, and changes in surface energy balance of the arctic tundra. (ACR)

  13. Tundra Disturbance and Recovery Nine Years After Winter Seismic Exploration in Northern Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Seismic exploration was conducted during the winters of 1984 and 1985 on the coastal plain tundra of the Arctic National Wildlife Refuge, Alaska. In 1986, 1989, and...

  14. Pacific Flyway management plan for the Western Population of tundra swans

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this plan is to establish guidelines for the cooperative management of the Western Population (WP) of tundra swans (Cygnus c. columbianus). This...

  15. Tundra swan populations, productivity, and local movements on Selawik National Wildlife Refuge, 1983 and 1984

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Studies were initiated in 1983 to document the abundance, productivity, and local movements of tundra swans on Selawik National Wildlife Refuge. An estimated 2700 -...

  16. Terrestrial bird populations and habitat use on coastal plain tundra of the Arctic National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report covers terrestrial bird populations and habitat use on the coastal plain tundra of the Arctic National Wildlife Refuge. Bird census plots were...

  17. Fourfold higher tundra volatile emissions due to arctic summer warming

    Science.gov (United States)

    Lindwall, Frida; Schollert, Michelle; Michelsen, Anders; Blok, Daan; Rinnan, Riikka

    2016-03-01

    Biogenic volatile organic compounds (BVOCs), which are mainly emitted by vegetation, may create either positive or negative climate forcing feedbacks. In the Subarctic, BVOC emissions are highly responsive to temperature, but the effects of climatic warming on BVOC emissions have not been assessed in more extreme arctic ecosystems. The Arctic undergoes rapid climate change, with air temperatures increasing at twice the rate of the global mean. Also, the amount of winter precipitation is projected to increase in large areas of the Arctic, and it is unknown how winter snow depth affects BVOC emissions during summer. Here we examine the responses of BVOC emissions to experimental summer warming and winter snow addition—each treatment alone and in combination—in an arctic heath during two growing seasons. We observed a 280% increase relative to ambient in BVOC emissions in response to a 4°C summer warming. Snow addition had minor effects on growing season BVOC emissions after one winter but decreased BVOC emissions after the second winter. We also examined differences between canopy and air temperatures and found that the tundra canopy surface was on average 7.7°C and maximum 21.6°C warmer than air. This large difference suggests that the tundra surface temperature is an important driver for emissions of BVOCs, which are temperature dependent. Our results demonstrate a strong response of BVOC emissions to increasing temperatures in the Arctic, suggesting that emission rates will increase with climate warming and thereby feed back to regional climate change.

  18. Alpine-hydrological observations at the "Zugspitzplatt"

    Science.gov (United States)

    Schulz, Karsten; Bernhardt, Matthias; Wetzel, Karl F.; Haerer, Stefan

    2013-04-01

    Alpine Regions are considered to be important sources of freshwater for large regions world wide. The storage of water as snow and/or ice, as well as subsequent melting processes during spring and summer are important factors for water resources management and flood control. However, alpine regions and relevant hydrological processes are generally not very well investigated and therefore poorly understood. This is mainly due to the difficulties of setting up and maintaining monitoring stations in often remote places, under harsh environmental conditions. The "Environmental Research Station Schneefernerhaus" (UFS) located at 2700 m altitude within the "Zugspitzplatt"/Wettersteingebirge, close to Garmisch-Partenkirchen, Germany, is managed by the Bavarian Government and is run by 10 universities and research institutions as consortium partners. Within this "Centre for altitude, climate and environment research in Bavaria", the Universities of Augsburg and Munich have recently intensified their research on alpine hydrological processes in order to improve the aforementioned limitations. The Zugspitzplatt catchment serves as a typical representation of the northern "Kalkalpen". Its unique geological structure serve as an ideal natural lysimeter, allowing water and solute mass balances to be derived and closed from meteorological and hydrological measurements. Long term meteorological data and a large variety of newly implemented (snow-)hydrological, micrometeorological and remote sensing instrumentation will allow detailed and long term studies on the dynamics of alpine hydrological processes. In our contribution we will present the research catchment and its instrumentation as well as first results from last years measurements.

  19. Belowground plant biomass allocation in tundra ecosystems and its relationship with temperature

    Science.gov (United States)

    Wang, Peng; Heijmans, Monique M. P. D.; Mommer, Liesje; van Ruijven, Jasper; Maximov, Trofim C.; Berendse, Frank

    2016-05-01

    Climate warming is known to increase the aboveground productivity of tundra ecosystems. Recently, belowground biomass is receiving more attention, but the effects of climate warming on belowground productivity remain unclear. Enhanced understanding of the belowground component of the tundra is important in the context of climate warming, since most carbon is sequestered belowground in these ecosystems. In this study we synthesized published tundra belowground biomass data from 36 field studies spanning a mean annual temperature (MAT) gradient from -20 °C to 0 °C across the tundra biome, and determined the relationships between different plant biomass pools and MAT. Our results show that the plant community biomass-temperature relationships are significantly different between above and belowground. Aboveground biomass clearly increased with MAT, whereas total belowground biomass and fine root biomass did not show a significant increase over the broad MAT gradient. Our results suggest that biomass allocation of tundra vegetation shifts towards aboveground in warmer conditions, which could impact on the carbon cycling in tundra ecosystems through altered litter input and distribution in the soil, as well as possible changes in root turnover.

  20. Belowground plant biomass allocation in tundra ecosystems and its relationship with temperature

    Science.gov (United States)

    Wang, Peng; Heijmans, Monique M. P. D.; Mommer, Liesje; van Ruijven, Jasper; Maximov, Trofim C.; Berendse, Frank

    2016-05-01

    Climate warming is known to increase the aboveground productivity of tundra ecosystems. Recently, belowground biomass is receiving more attention, but the effects of climate warming on belowground productivity remain unclear. Enhanced understanding of the belowground component of the tundra is important in the context of climate warming, since most carbon is sequestered belowground in these ecosystems. In this study we synthesized published tundra belowground biomass data from 36 field studies spanning a mean annual temperature (MAT) gradient from ‑20 °C to 0 °C across the tundra biome, and determined the relationships between different plant biomass pools and MAT. Our results show that the plant community biomass–temperature relationships are significantly different between above and belowground. Aboveground biomass clearly increased with MAT, whereas total belowground biomass and fine root biomass did not show a significant increase over the broad MAT gradient. Our results suggest that biomass allocation of tundra vegetation shifts towards aboveground in warmer conditions, which could impact on the carbon cycling in tundra ecosystems through altered litter input and distribution in the soil, as well as possible changes in root turnover.

  1. The potential for retreating alpine glaciers to alter alpine ecosystems in the Colorado Front Range

    Science.gov (United States)

    Hall, E.; Baron, J.

    2013-12-01

    Glaciers are retreating at an unprecedented rate. In mid-latitude alpine ecosystems the presence of glaciers and rock glaciers govern rates and ecology of alpine and sub-alpine ecosystems. Changes in the thermal environment due to the loss of isothermal habitat and inputs from glacier melt chemistry are altering alpine ecosystems in unpredictable ways. In particular, glacier may be a source of nitrogen that is altering alpine ecosystem dynamics. Loch Vale Watershed (LVWS) located within Rocky Mountain National Park. LVWS contains a surface glacier (Andrew's glacier) and a rock glacier (Taylor's glacier) at the headwater of each of the two drainages within the watershed. We collected precipitation from a National Atmospheric Deposition Site and surface water from multiple alpine lakes and streams during a particularly high and low snow year in the Colorado Front Range. We also sampled stream and lake sediments at each site to analyze the associated microbial community. Concentrations of nitrate and ammonium, relative abundance of amoA (the gene responsible for a key step in the microbial nitrification pathway), and the dual isotope signal to nitrate all point to snow melt as a key deliverer of nitrogen to ecosystems along the Colorado Front Range. However, late summer surface water chemistry is isotopically similar to the chemistry of glacial ice. This suggests that retreating glacier may be an additional source of N to alpine ecosystems and have the potential to alter microbial community composition, biogeochemical rate processes, and ecosystem function. These dynamics are most likely not unique to the Colorado Front Range and should be globally distributed as glaciers continue to retreat in high altitude ecosystems around the world.

  2. Shrub expansion and climate feedbacks in Arctic tundra

    Science.gov (United States)

    Loranty, Michael M.; Goetz, Scott J.

    2012-03-01

    Arctic tundra ecosystems stand to play a substantial role in both the magnitude and rate of global climate warming over the coming decades and centuries. The exact nature of this role will be determined by the combined effects of currently amplified rates of climate warming in the Arctic (Serreze et al 2000) and a series of related positive climate feedbacks that include mobilization of permafrost carbon (Schuur et al 2008), decreases in surface albedo (Chapin et al 2005) and evapotranspiration (ET) mediated increases in atmospheric water vapor (Swann et al 2010). Conceptually, these feedback mechanisms are intuitive and readily comprehensible: warming-induced permafrost thaw will make new soil carbon pools accessible for microbial respiration, and increased vegetation productivity, expansion of shrubs in particular, will lower surface reflectance and increase ET. However, our current understanding of these feedback mechanisms relies largely on limited and local field studies and, as such, the quantitative estimates of feedback effects on regional and global climate require spatial upscaling and uncertainty estimates derived from models. Moreover, the feedback mechanisms interact and their combined net effect on climate is highly variable and not well characterized. A recent study by Bonfils et al (2012) is among the first to explicitly examine how shrub expansion in tundra ecosystems will impact regional climate. Using an Earth system model, Bonfils et al find that an idealized 20% increase in shrub cover north of 60°N latitude will lead to annual temperature increases of 0.66 °C and 1.84 °C, respectively, when the shrubs are 0.5 m and 2 m tall. The modeled temperature increases arise from atmospheric heating as a combined consequence of decreased albedo and increased ET. The primary difference between the two cases is associated with the fact that tall shrubs protrude above the snow, thus reducing albedo year round, whereas short shrubs are completely

  3. Relationship of cyanobacterial and algal assemblages with vegetation in the high Arctic tundra (West Spitsbergen, Svalbard Archipelago

    Directory of Open Access Journals (Sweden)

    Richter Dorota

    2015-09-01

    Full Text Available The paper presents the results of a study of cyanobacteria and green algae assemblages occurring in various tundra types determined on the basis of mosses and vascular plants and habitat conditions. The research was carried out during summer in the years 2009-2013 on the north sea-coast of Hornsund fjord (West Spitsbergen, Svalbard Archipelago. 58 sites were studied in various tundra types differing in composition of vascular plants, mosses and in trophy and humidity. 141 cyanobacteria and green algae were noted in the research area in total. Cyanobacteria and green algae flora is a significant element of many tundra types and sometimes even dominate there. Despite its importance, it has not been hitherto taken into account in the description and classification of tundra. The aim of the present study was to demonstrate the legitimacy of using phycoflora in supplementing the descriptions of hitherto described tundra and distinguishing new tundra types. Numeric hierarchical-accumulative classification (MVSP 3.1 software methods were used to analyze the cyanobacterial and algal assemblages and their co-relations with particular tundra types. The analysis determined dominant and distinctive species in the communities in concordance with ecologically diverse types of tundra. The results show the importance of these organisms in the composition of the vegetation of tundra types and their role in the ecosystems of this part of the Arctic.

  4. Methane dynamics in warming tundra of Northeast European Russia

    Directory of Open Access Journals (Sweden)

    M. E. Marushchak

    2015-08-01

    Full Text Available Methane (CH4 fluxes were investigated in a subarctic Russian tundra site in a multi-approach study combining plot scale data, ecosystem scale eddy covariance (EC measurements and fine resolution land cover classification scheme for regional upscaling. The flux data as measured by the two independent techniques resulted in a seasonal (May–October 2008 cumulative CH4 emission of 2.4 (EC and 3.7 g CH4 m−2 (manual chambers for the source area representative of the footprint of the EC instruments. Upon upscaling for the entire study region of 98.6 km2, the chamber measured flux data yielded a regional flux estimate of 6.7 g CH4 m−2 yr−1. Our upscaling efforts accounted for the large spatial variability in the distribution of the various land cover types (LCTs predominant at our study site. In particular, wetlands with emissions ranging from 34 to 53 g CH4 m−2 yr−1 were the most dominant CH4 emitting surfaces. Emissions from thermokarst lakes were an order of magnitude lower, while the rest of the landscape (mineral tundra was a weak sink for atmospheric methane. Vascular plant cover was a key factor in explaining the spatial variability of CH4 emissions among wetland types, as indicated by the positive correlation of emissions with the leaf area index (LAI. As elucidated through a stable isotope analysis, the plant transport was the dominant CH4 release pathway that discriminates against heavier δ13C-CH4. The methane released from wetlands was lighter than that in the surface porewater and δ13C in the emitted CH4 correlated with the vascular plant cover (LAI implying that the plant-mediated CH4 release dominates. A mean value of δ13C obtained here for the emitted CH4, −68.2 ± 2.0 ‰, is within the range of values from other wetlands, thus reinforcing the use of inverse modeling tools to better constrain the CH4 budget. Based on the IPCC A1B emission scenario, a temperature increase of 7 °C has been predicted for the tundra region

  5. Methane dynamics in warming tundra of Northeast European Russia

    Science.gov (United States)

    Marushchak, M. E.; Friborg, T.; Biasi, C.; Herbst, M.; Johansson, T.; Kiepe, I.; Liimatainen, M.; Lind, S. E.; Martikainen, P. J.; Virtanen, T.; Soegaard, H.; Shurpali, N. J.

    2015-08-01

    Methane (CH4) fluxes were investigated in a subarctic Russian tundra site in a multi-approach study combining plot scale data, ecosystem scale eddy covariance (EC) measurements and fine resolution land cover classification scheme for regional upscaling. The flux data as measured by the two independent techniques resulted in a seasonal (May-October 2008) cumulative CH4 emission of 2.4 (EC) and 3.7 g CH4 m-2 (manual chambers) for the source area representative of the footprint of the EC instruments. Upon upscaling for the entire study region of 98.6 km2, the chamber measured flux data yielded a regional flux estimate of 6.7 g CH4 m-2 yr-1. Our upscaling efforts accounted for the large spatial variability in the distribution of the various land cover types (LCTs) predominant at our study site. In particular, wetlands with emissions ranging from 34 to 53 g CH4 m-2 yr-1 were the most dominant CH4 emitting surfaces. Emissions from thermokarst lakes were an order of magnitude lower, while the rest of the landscape (mineral tundra) was a weak sink for atmospheric methane. Vascular plant cover was a key factor in explaining the spatial variability of CH4 emissions among wetland types, as indicated by the positive correlation of emissions with the leaf area index (LAI). As elucidated through a stable isotope analysis, the plant transport was the dominant CH4 release pathway that discriminates against heavier δ13C-CH4. The methane released from wetlands was lighter than that in the surface porewater and δ13C in the emitted CH4 correlated with the vascular plant cover (LAI) implying that the plant-mediated CH4 release dominates. A mean value of δ13C obtained here for the emitted CH4, -68.2 ± 2.0 ‰, is within the range of values from other wetlands, thus reinforcing the use of inverse modeling tools to better constrain the CH4 budget. Based on the IPCC A1B emission scenario, a temperature increase of 7 °C has been predicted for the tundra region of European Russia by the

  6. Can lemmings control the expansion of woody plants on tundra?

    Science.gov (United States)

    Oksanen, Lauri; Oksanen, Tarja; Olofsson, Johan; Virtanen, Risto; Hoset, Katrine; Tuomi, Maria; Kyrö, Kukka

    2013-04-01

    The ongoing expansion of woody vegetation in the arctic, due to global warming, creates a positive feed back loop. Increasing abundance of woody plants reduces surface albedo both directly and via speeding up snow melt. Thus a successively greater fraction of incoming solar radiation is absorbed and converted to heat. Browsing mammals - both big and small - can prevent this by consuming woody plants. However, the grazer/browser community of many tundra areas is dominated by brown/Norwegian lemmings (Lemmus spp.) which eat graminoids and mosses and cannot use woody plants as forage. It would seem a priori likely that in such areas, mammalian herbivores speed up the expansion of woody plants by improving the chances of their seedlings to get established. We studied the impact of lemmings on woody plants by constructing lemming proof exclosures within piece high-altitude tundra at Joatkanjávri, northernmost Norway. The exclosures were constructed in 1998, during a period of low lemming densities, in snow-beds, where Norwegian lemmings (L. lemmus) were the only ecologically significant herbivorous mammals. (Reindeer migrate through the area in May, when snow-beds are inaccessible for them; during the fall migration, the area represents a dead end and is therefore avoided.) We chose pairs of maximally similar vegetation patches of 0.5 by 0.5 m and randomly assigned one of each pair to become an exclosure while the other plot was left open. The initial state of the vegetation was documented by the point frequency method. In 2008, after the 2007 lemming outbreak, the same documentation was repeated; thereafter the plots were harvested, the vegetation was sorted to species, oven dried and weighed. Exclusion of lemmings resulted to pronounced increase in community level plant biomass. Evergreen woody plants were especially favored by the exclusion of lemming: their above-ground biomass in exclosures was 14 times as great as their biomass on open reference plots. The

  7. Water track distribution and effects on carbon dioxide flux in an eastern Siberian upland tundra landscape

    International Nuclear Information System (INIS)

    Shrub expansion in tundra ecosystems may act as a positive feedback to climate warming, the strength of which depends on its spatial extent. Recent studies have shown that shrub expansion is more likely to occur in areas with high soil moisture and nutrient availability, conditions typically found in sub-surface water channels known as water tracks. Water tracks are 5–15 m wide channels of subsurface water drainage in permafrost landscapes and are characterized by deeper seasonal thaw depth, warmer soil temperatures, and higher soil moisture and nutrient content relative to adjacent tundra. Consequently, enhanced vegetation productivity, and dominance by tall deciduous shrubs, are typical in water tracks. Quantifying the distribution of water tracks may inform investigations of the extent of shrub expansion and associated impacts on tundra ecosystem carbon cycling. Here, we quantify the distribution of water tracks and their contribution to growing season CO2 dynamics for a Siberian tundra landscape using satellite observations, meteorological data, and field measurements. We find that water tracks occupy 7.4% of the 448 km2 study area, and account for a slightly larger proportion of growing season carbon uptake relative to surrounding tundra. For areas inside water tracks dominated by shrubs, field observations revealed higher shrub biomass and higher ecosystem respiration and gross primary productivity relative to adjacent upland tundra. Conversely, a comparison of graminoid-dominated areas in water tracks and inter-track tundra revealed that water track locations dominated by graminoids had lower shrub biomass yet increased net uptake of CO2. Our results show water tracks are an important component of this landscape. Their distribution will influence ecosystem structural and functional responses to climate, and is therefore of importance for modeling. (letter)

  8. ALPINE LAKES WILDERNESS STUDY AREA, WASHINGTON.

    Science.gov (United States)

    Gualtieri, J.L.; Thurber, H.K.

    1984-01-01

    The Alpine Lakes Wilderness study area, located in the central part of the Cascade Mountains of Washington was examined for its mineral-resource potential. On the basis of that study the area was found to contain deposits of copper, other base metals, and gold and silver. Probable or substantiated mineral-resource potential exists for these commodities in the southwest-central, northwest, and southeast-central parts of the area. The geologic terrane precludes the occurrence of fossil fuel resources.

  9. Stability of alpine meadow ecosystem on the Qinghai- Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    ZHOU Huakun; ZHOU Li; ZHAO Xinquan; LIU Wei; LI Yingnian; GU Song; ZHOU Xinmin

    2006-01-01

    The meadow ecosystem on the Qinghai-Tibetan Plateau is considered to be sensitive to climate change. An understanding of the alpine meadow ecosystem is therefore important for predicting the response of ecosystems to climate change. In this study, we use the coefficients of variation (Cv) and stability (E) obtained from the Haibei Alpine Meadow Ecosystem Research Station to characterize the ecosystem stability. The results suggest that the net primary production of the alpine meadow ecosystem was more stable (Cv = 13.18%) than annual precipitation (Cv = 16.55%) and annual mean air temperature (Cv = 28.82%). The net primary production was insensitive to either the precipitation (E = 0.0782) or air temperature (E = 0.1113). In summary, the alpine meadow ecosystem on the Qinghai- Tibetan Plateau is much stable. Comparison of alpine meadow ecosystem stability with other five natural grassland ecosystems in Israel and southern African indicates that the alpine meadow ecosystem on the Qinghai-Tibetan Plateau is the most stable ecosystem. The alpine meadow ecosystem with relatively simple structure has high stability, which indicates that community stability is not only correlated with biodiversity and community complicity but also with environmental stability. An average oscillation cycles of 3―4 years existed in annual precipitation, annual mean air temperature, net primary production and the population size of consumers at the Haibei natural ecosystem. The high stability of the alpine meadow ecosystem may be resulting also from the adaptation of the ecosystem to the alpine environment.

  10. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow.

    Directory of Open Access Journals (Sweden)

    Shu Liao

    Full Text Available Dissolved organic carbon (DOC and total dissolved nitrogen (TDN are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage and the growing season (early and late. After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes.

  11. What Does Matter?: Idols and Icons in the Nenets Tundra

    Directory of Open Access Journals (Sweden)

    Laur Vallikivi

    2011-08-01

    Full Text Available This paper examines a mission encounter in the Nenets reindeer herders’ tundra. In post-Soviet Arctic Russia, Pentecostal and Baptist missionaries of Russian and Ukrainian origin have been fighting against idolatry and trying to persuade the Nenets to burn their sacred images or khekhe’’. They claim that among the indigenous Siberians idolatry exists in its quintessential or prototypical form, as it is described in the Bible. I shall suggest that this encounter takes place in a gap, in which the Nenets and Protestant have different understandings of language and materiality. Missionaries rely simultaneously on the ‘modern’ ideology of signification and the ‘non-modern’ magic of the material. They argue that idols, which are ‘nothing’ according to the scriptures, dangerously bind the ‘pagans’’ minds. For reindeer herders, for whom sacred items occupy an important place in the family wellbeing, the main issue is how to sever the link with the spirits without doing any damage.

  12. Vectors and transmission dynamics for Setaria tundra (Filarioidea; Onchocercidae, a parasite of reindeer in Finland

    Directory of Open Access Journals (Sweden)

    Kuusela Jussi

    2009-01-01

    Full Text Available Abstract Background Recent studies have revealed expansion by an array of Filarioid nematodes' into the northern boreal region of Finland. The vector-borne nematode, Setaria tundra, caused a serious disease outbreak in the Finnish reindeer population in 2003–05. The main aim of this study was to understand the outbreak dynamics and the rapid expansion of S. tundra in the sub arctic. We describe the vectors of S. tundra, and its development in vectors, for the first time. Finally we discuss the results in the context of the host-parasite ecology of S. tundra in Finland Results Development of S. tundra to the infective stage occurs in mosquitoes, (genera Aedes and Anopheles. We consider Aedes spp. the most important vectors. The prevalence of S. tundra naturally infected mosquitoes from Finland varied from 0.5 to 2.5%. The rate of development in mosquitoes was temperature-dependent. Infective larvae were present approximately 14 days after a blood meal in mosquitoes maintained at room temperature (mean 21 C, but did not develop in mosquitoes maintained outside for 22 days at a mean temperature of 14.1 C. The third-stage (infective larvae were elongated (mean length 1411 μm (SD 207, and width 28 μm (SD 2. The anterior end was blunt, and bore two liplike structures, the posterior end slight tapering with a prominent terminal papilla. Infective larvae were distributed anteriorly in the insect's body, the highest abundance being 70 larvae in one mosquito. A questionnaire survey revealed that the peak activity of Culicidae in the reindeer herding areas of Finland was from the middle of June to the end of July and that warm summer weather was associated with reindeer flocking behaviour on mosquito-rich wetlands. Conclusion In the present work, S. tundra vectors and larval development were identified and described for the first time. Aedes spp. mosquitoes likely serve as the most important and competent vectors for S. tundra in Finland. Warm summers

  13. Carbon and nutrient responses to fire and climate warming in Alaskan arctic tundra

    Science.gov (United States)

    Jiang, Y.; Rastetter, E. B.; Shaver, G. R.; Rocha, A. V.; Kwiatkowski, B.; Pearce, A.; Zhuang, Q.; Mishra, U.

    2015-12-01

    Fire frequency has dramatically increased in the tundra of northern Alaska, which has major implications for the carbon budget of the region and the functioning of these ecosystems that support important wildlife species. We applied the Multiple Element Limitation (MEL) model to investigate both the short- and long-term post-fire succession of plant and soil carbon, nitrogen, and phosphorus fluxes and stocks along a burn severity gradient in the 2007 Anaktuvuk River Fire scar in northern Alaska. We compared the patterns of biomass and soil carbon, nitrogen and phosphorus recoveries with different burn severities and warming intensities. Modeling results indicated that the early regrowth of post-fire tundra vegetation was limited primarily by its canopy photosynthetic potential, rather than nutrient availability. The long-term recovery of C balance from fire disturbance is mainly determined by the internal redistribution of nutrients among ecosystem components, rather than the supply of nutrients from external sources (e.g., nitrogen deposition and fixation, phosphorus weathering). Soil organic matter is the principal source of plant-available nutrients and determines the spatial variation of vegetation biomass across the North Slope of Alaska. Across the North Slope of Alaska, we examined the effects of changes in N and P cycles on tundra C budgets under climate warming. Our results indicate that the ongoing climate warming in Arctic enhances mineralization and leads to a net transfer of nutrient from soil organic matter to vegetation, thereby stimulating tundra plant growth and increased C sequestration in the tundra ecosystems.

  14. Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau.

    Science.gov (United States)

    Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

    2016-01-01

    The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland. PMID:27494253

  15. Permafrost collapse after shrub removal shifts tundra ecosystem to a methane source

    DEFF Research Database (Denmark)

    Nauta, Ake L.; Heijmans, Monique P.D.; Blok, Daan;

    2015-01-01

    Arctic tundra ecosystems are warming almost twice as fast as the global average1. Permafrost thaw and the resulting release of greenhouse gases from decomposing soil organic carbon have the potential to accelerate climate warming2,3. In recent decades, Arctic tundra ecosystems have changed rapidly4......, including expansion of woody vegetation5,6, in response to changing climate conditions. How such vegetation changes contribute to stabilization or destabilization of the permafrost is unknown. Here we present six years of field observations in a shrub removal experiment at a Siberian tundra site. Removing...... the shrub part of the vegetation initiated thawing of ice-rich permafrost, resulting in collapse of the originally elevated shrub patches into waterlogged depressions within five years. This thaw pond development shifted the plots from a methane sink into a methane source. The results of our field...

  16. Modeling the spatiotemporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape

    Science.gov (United States)

    Kumar, Jitendra; Collier, Nathan; Bisht, Gautam; Mills, Richard T.; Thornton, Peter E.; Iversen, Colleen M.; Romanovsky, Vladimir

    2016-09-01

    Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to the atmosphere under warming climate scenarios. Ice-wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. This microtopography plays a critical role in regulating the fine-scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behavior under the current as well as changing climate. We present here an end-to-end effort for high-resolution numerical modeling of thermal hydrology at real-world field sites, utilizing the best available data to characterize and parameterize the models. We develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites near Barrow, Alaska, spanning across low to transitional to high-centered polygons, representing a broad polygonal tundra landscape. A multiphase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using a high-resolution lidar digital elevation model (DEM), microtopographic features of the landscape were characterized and represented in the high-resolution model mesh. The best available soil data from field observations and literature were utilized to represent the complex heterogeneous subsurface in the numerical model. Simulation results demonstrate the ability of the developed modeling approach to capture - without recourse to model calibration - several aspects of the complex thermal regimes across the sites, and provide insights into the critical role of polygonal tundra microtopography in regulating the thermal dynamics of the carbon-rich permafrost soils. Areas of significant disagreement between model results and observations highlight the importance of field-based observations of soil thermal and

  17. Shrub Abundance Mapping in Arctic Tundra with Misr

    Science.gov (United States)

    Duchesne, R.; Chopping, M. J.; Wang, Z.; Schaaf, C.; Tape, K. D.

    2013-12-01

    Over the last 60 years an increase in shrub abundance has been observed in the Arctic tundra in connection with a rapid surface warming trend. Rapid shrub expansion may have consequences in terms of ecosystem structure and function, albedo, and feedbacks to climate; however, its rate is not yet known. The goal of this research effort is thus to map large scale changes in Arctic tundra vegetation by exploiting the structural signal in moderate resolution satellite remote sensing images from NASA's Multiangle Imaging SpectroRadiometer (MISR), mapped onto a 250m Albers Conic Equal Area grid. We present here large area shrub mapping supported by reference data collated using extensive field inventory data and high resolution panchromatic imagery. MISR Level 1B2 Terrain radiance scenes from the Terra satellite from 15 June-31 July, 2000 - 2010 were converted to surface bidirectional reflectance factors (BRF) using MISR Toolkit routines and the MISR 1 km LAND product BRFs. The red band data in all available cameras were used to invert the RossThick-LiSparse-Reciprocal BRDF model to retrieve kernel weights, model-fitting RMSE, and Weights of Determination. The reference database was constructed using aerial survey, three field campaigns (field inventory for shrub count, cover, mean radius and height), and high resolution imagery. Tall shrub number, mean crown radius, cover, and mean height estimates were obtained from QuickBird and GeoEye panchromatic image chips using the CANAPI algorithm, and calibrated using field-based estimates, thus extending the database to over eight hundred locations. Tall shrub fractional cover maps for the North Slope of Alaska were constructed using the bootstrap forest machine learning algorithm that exploits the surface information provided by MISR. The reference database was divided into two datasets for training and validation. The model derived used a set of 19 independent variables(the three kernel weights, ratios and interaction terms

  18. Terrimonas arctica sp. nov., isolated from Arctic tundra soil.

    Science.gov (United States)

    Jiang, Fan; Qiu, Xia; Chang, Xulu; Qu, Zhihao; Ren, Lvzhi; Kan, Wenjing; Guo, Youhao; Fang, Chengxiang; Peng, Fang

    2014-11-01

    A novel, Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium, designated R9-86(T), was isolated from tundra soil collected near Ny-Ålesund, Svalbard Archipelago, Norway (78° N). Growth occurred at 4-28 °C (optimum, 22-25 °C) and at pH 6.0-9.0 (optimum, pH 7.0). Flexirubin-type pigments were absent. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain R9-86(T) belonged to the genus Terrimonas in the family Chitinophagaceae. 16S rRNA gene sequence similarities between strain R9-86(T) and the type strains of species of the genus Terrimonas with validly published names ranged from 93.7 to 95.0%. Strain R9-86(T) contained iso-C(15:1)-G (25.7%), iso-C(15:0) (24.5%), iso-C(17:0)-3OH (18.3%) and summed feature 3 (C(16:1)ω7c and/or C(16:1)ω6c, 8.7%) as its major cellular fatty acids; phosphatidylethanolamine and an unknown polar lipid as its main polar lipids, and MK-7 as its predominant respiratory quinone. The DNA G+C content was 48.4 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain R9-86(T) is considered to represent a novel species of the genus Terrimonas, for which the name Terrimonas arctica sp. nov. is proposed. The type strain is R9-86(T) ( =CCTCC AB 2011004(T) =NRRL B-59114(T)). PMID:25142212

  19. Modeling dynamics of tundra plant communities on the Yamal Peninsula, Russia

    Science.gov (United States)

    Yu, Q.; Epstein, H. E.; Walker, D. A.

    2010-12-01

    Multiple environmental drivers, including climate, soil conditions and herbivory, affect arctic tundra vegetation dynamics. These factors may have been evaluated individually in the past; however, their interactions contribute to more complicated tundra plant community dynamics and may represent a substantial source of uncertainty in predicting tundra ecosystem properties in the changing Arctic. This study investigates the effects of soils, grazing, and climate change on tundra plant communities at the plant functional type (PFT) level, based on previous integrated modeling research at the ecosystem level. The study area encompasses the Yamal Peninsula, northwestern Siberia, where soil and biomass data were collected along the Yamal Arctic Transect (YAT), to drive a nutrient-based tundra vegetation model (ArcVeg) and to validate the simulation results. We analyzed plant functional type biomass and net primary productivity (NPP), and found that with higher temperatures (+2°C mean growing season temperature), most plant functional types responded positively with increased biomass and NPP, while grazing suppressed such responses in both high and low soil organic nitrogen (SON) sites. The magnitudes of the responses to warming depended on SON and grazing intensity. Relatively, there were greater responses of biomass and NPP in low SON sites compared to high SON sites. Moss biomass (in contrast to other plant types) declined 34% with warming in the low SON site and 28% in the high SON site in subzone E (the most southern tundra subzone). Increases in Low Arctic shrub biomass with warming were 61% in the high SON site in subzone E and 96% in the low SON site. Decrease in moss biomass due to warming was mitigated about 2% by high grazing frequency (maximum of 25% of biomass removal every two years) in the high SON site in subzone E, with an opposite effect in the low SON site. High grazing frequency caused greater relative increases in total shrub biomass for both low

  20. Metagenomics Reveals Pervasive Bacterial Populations and Reduced Community Diversity across the Alaska Tundra Ecosystem.

    Science.gov (United States)

    Johnston, Eric R; Rodriguez-R, Luis M; Luo, Chengwei; Yuan, Mengting M; Wu, Liyou; He, Zhili; Schuur, Edward A G; Luo, Yiqi; Tiedje, James M; Zhou, Jizhong; Konstantinidis, Konstantinos T

    2016-01-01

    How soil microbial communities contrast with respect to taxonomic and functional composition within and between ecosystems remains an unresolved question that is central to predicting how global anthropogenic change will affect soil functioning and services. In particular, it remains unclear how small-scale observations of soil communities based on the typical volume sampled (1-2 g) are generalizable to ecosystem-scale responses and processes. This is especially relevant for remote, northern latitude soils, which are challenging to sample and are also thought to be more vulnerable to climate change compared to temperate soils. Here, we employed well-replicated shotgun metagenome and 16S rRNA gene amplicon sequencing to characterize community composition and metabolic potential in Alaskan tundra soils, combining our own datasets with those publically available from distant tundra and temperate grassland and agriculture habitats. We found that the abundance of many taxa and metabolic functions differed substantially between tundra soil metagenomes relative to those from temperate soils, and that a high degree of OTU-sharing exists between tundra locations. Tundra soils were an order of magnitude less complex than their temperate counterparts, allowing for near-complete coverage of microbial community richness (~92% breadth) by sequencing, and the recovery of 27 high-quality, almost complete (>80% completeness) population bins. These population bins, collectively, made up to ~10% of the metagenomic datasets, and represented diverse taxonomic groups and metabolic lifestyles tuned toward sulfur cycling, hydrogen metabolism, methanotrophy, and organic matter oxidation. Several population bins, including members of Acidobacteria, Actinobacteria, and Proteobacteria, were also present in geographically distant (~100-530 km apart) tundra habitats (full genome representation and up to 99.6% genome-derived average nucleotide identity). Collectively, our results revealed that

  1. Metagenomics reveals pervasive bacterial populations and reduced community diversity across the Alaska tundra ecosystem

    Directory of Open Access Journals (Sweden)

    Eric Robert Johnston

    2016-04-01

    Full Text Available How soil microbial communities contrast with respect to taxonomic and functional composition within and between ecosystems remains an unresolved question that is central to predicting how global anthropogenic change will affect soil functioning and services. In particular, it remains unclear how small-scale observations of soil communities based on the typical volume sampled (1-2 grams are generalizable to ecosystem-scale responses and processes. This is especially relevant for remote, northern latitude soils, which are challenging to sample and are also thought to be more vulnerable to climate change compared to temperate soils. Here, we employed well-replicated shotgun metagenome and 16S rRNA gene amplicon sequencing to characterize community composition and metabolic potential in Alaskan tundra soils, combining our own datasets with those publically available from distant tundra and temperate grassland and agriculture habitats. We found that the abundance of many taxa and metabolic functions differed substantially between tundra soil metagenomes relative to those from temperate soils, and that a high degree of OTU-sharing exists between tundra locations. Tundra soils were an order of magnitude less complex than their temperate counterparts, allowing for near-complete coverage of microbial community richness (~92% breadth by sequencing, and the recovery of twenty-seven high-quality, almost complete (>80% completeness population bins. These population bins, collectively, made up to ~10% of the metagenomic datasets, and represented diverse taxonomic groups and metabolic lifestyles tuned toward sulfur cycling, hydrogen metabolism, methanotrophy, and organic matter oxidation. Several population bins, including members of Acidobacteria, Actinobacteria, and Proteobacteria, were also present in geographically distant (~100-530 km apart tundra habitats (full genome representation and up to 99.6% genome-derived average nucleotide identity. Collectively

  2. Transient thermal effects in Alpine permafrost

    Directory of Open Access Journals (Sweden)

    J. Noetzli

    2008-04-01

    Full Text Available In high mountain areas, permafrost is important because it influences natural hazards and construction practices, and because it is an indicator of climate change. The modeling of its distribution and evolution over time is complicated by steep and complex topography, highly variable conditions at and below the surface, and varying climatic conditions. This paper presents a systematic investigation of effects of climate variability and topography that are important for subsurface temperatures in Alpine permafrost areas. The effects of both past and projected future ground surface temperature variations on the thermal state of Alpine permafrost are studied based on numerical experimentation with simplified mountain topography. For this purpose, we use a surface energy balance model together with a subsurface heat conduction scheme. The past climate variations that essentially influence the present-day permafrost temperatures at depth are the last glacial period and the major fluctuations in the past millennium. The influence of projected future warming was assessed to cause even larger transient effects in the subsurface thermal field because warming occurs on shorter time scales. Results further demonstrate the accelerating influence of multi-lateral warming in Alpine topography for a temperature signal entering the subsurface. The effects of thermal properties, porosity, and freezing characteristics were examined in sensitivity studies. A considerable influence of latent heat due to water in low-porosity bedrock was only shown for simulations over shorter time periods (i.e., decades to centuries. Finally, as an example of a real and complex topography, the modeled transient three-dimensional temperature distribution in the Matterhorn (Switzerland is given for today and in 200 years.

  3. Modelling vegetation dynamics for Alpine meadows

    Science.gov (United States)

    Della Chiesa, Stefano; Bertoldi, Giacomo; Wohlfahrt, Georg; Rist, Armin; Niedrist, Georg; Albertson, John D.; Tappeiner, Ulrike

    2010-05-01

    Regional climate scenarios predict a temperature increase and a summer precipitation decrease for the European Alps. This is expected to lead to longer vegetation periods, but also to drought stress in Alpine meadows ecosystems. It is therefore uncertain if the predicted climatic changes will lead to an increase or decrease of biomass production in these grassland ecosystems. Understanding plant growth requires to consider the complex interactions between soil, atmosphere and climate via its physiological properties, in particular LAI, stomatal resistance, rooting depth, albedo, surface roughness and effects on soil moisture. Vegetation Dynamic Models (VDM) coupled with hydrological models take into account these interactions in order to study and estimate biomass production quantitatively. In this contribution, the VDM previously developed by Montaldo et al. (2005) for semi-arid environments is extended to Alpine meadows in the Stubai Valley (Eastern Austria) which are typically not subjected to water and nutrient stresses, but undergoing low temperature limitations. The aim is to assess the model robustness. Moreover, the effects of mowing practice during the season were taken into consideration. The VDM has then been implemented in the distributed hydrological model GEOtop (Rigon et al., 2006). The VDM performed well in the considered case study. The validation and calibration of the model is presented and then the effects of increased temperature and decreased precipitation are investigated numerically. In order to evaluate in the field the effects of climatic change on Alpine grassland biomass production, the inner Alpine continental Mazia Valley (South Tyrol, Italy) has been chosen in 2009 for Long-Term Ecological Research. These climatic changes will be simulated by manipulations along an altitudinal gradient comprising measuring stations at about 1000 m, 1500 m and 2000 m a.s.l.. Meadow monoliths will be transplanted downslope to simulate temperature

  4. The Blazing Arctic? Linkages of Tundra Fire Regimes to Climatic Change and Implications for Carbon Cycling (Invited)

    Science.gov (United States)

    Hu, F.; Higuera, P. E.; Walsh, J. E.; Chapman, W.; Duffy, P.; Brubaker, L.; Chipman, M. L.

    2010-12-01

    Among the major challenges in anticipating Arctic changes are “surprises” stemming from changes in system components that have remained relatively stable in the historic record. Tundra burning is potentially one such component. We conducted charcoal analysis of lake sediments from several tundra regions to evaluate the uniqueness of recent tundra fires, and examined potential climatic controls of Alaskan tundra fires from CE 1950-2009. A striking example of tundra burning is the 2007 Anaktuvuk River (AR) Fire, an unusually large fire in the tundra of the Alaskan Arctic. This fire doubled the area burned north of 68 oN in that region since record keeping began in 1950. Analysis of lake-sediment cores reveals peak values of charcoal accumulation corresponding to the AR Fire in 2007, with no evidence of other fire events in that area throughout the past five millennia. However, a number of tundra fires, including one as large as the AR Fire, have occurred over the past 60 years in western Alaska, where average summer temperatures are substantially higher than the AR area. In addition, charcoal analysis of lake sediments from interior and northwestern Alaska suggests that during certain periods of the Late Glacial and Holocene, tundra fire frequencies were as high as those of the modern boreal forests. These records along with the AR and historic fires demonstrate that tundra ecosystems support diverse fire regimes and can burn frequently. Reconciling these dramatic differences in tundra fire regimes requires knowledge of climate-fire relationships. Atmospheric reanalysis suggests that the AR Fire was favored by exceptionally warm/dry weather conditions in summer and early autumn. Boosted regression tree modeling shows that warm, dry summer conditions can explain up to 95% of the inter-annual variability in tundra area burned throughout Alaska over the past 60 years and that the response of tundra burning to climatic warming is non-linear. Additionally, tundra area

  5. Chilling- and Freezing-Induced Alterations in Cytosine Methylation and Its Association with the Cold Tolerance of an Alpine Subnival Plant, Chorispora bungeana.

    Directory of Open Access Journals (Sweden)

    Yuan Song

    Full Text Available Chilling (0-18°C and freezing (<0°C are two distinct types of cold stresses. Epigenetic regulation can play an important role in plant adaptation to abiotic stresses. However, it is not yet clear whether and how epigenetic modification (i.e., DNA methylation mediates the adaptation to cold stresses in nature (e.g., in alpine regions. Especially, whether the adaptation to chilling and freezing is involved in differential epigenetic regulations in plants is largely unknown. Chorispora bungeana is an alpine subnival plant that is distributed in the freeze-thaw tundra in Asia, where chilling and freezing frequently fluctuate daily (24 h. To disentangle how C. bungeana copes with these intricate cold stresses through epigenetic modifications, plants of C. bungeana were treated at 4°C (chilling and -4°C (freezing over five periods of time (0-24 h. Methylation-sensitive amplified fragment-length polymorphism markers were used to investigate the variation in DNA methylation of C. bungeana in response to chilling and freezing. It was found that the alterations in DNA methylation of C. bungeana largely occurred over the period of chilling and freezing. Moreover, chilling and freezing appeared to gradually induce distinct DNA methylation variations, as the treatment went on (e.g., after 12 h. Forty-three cold-induced polymorphic fragments were randomly selected and further analyzed, and three of the cloned fragments were homologous to genes encoding alcohol dehydrogenase, UDP-glucosyltransferase and polygalacturonase-inhibiting protein. These candidate genes verified the existence of different expressive patterns between chilling and freezing. Our results showed that C. bungeana responded to cold stresses rapidly through the alterations of DNA methylation, and that chilling and freezing induced different DNA methylation changes. Therefore, we conclude that epigenetic modifications can potentially serve as a rapid and flexible mechanism for C. bungeana

  6. Metabolic Profiling of Alpine and Ecuadorian Lichens

    Directory of Open Access Journals (Sweden)

    Verena K. Mittermeier

    2015-10-01

    Full Text Available Non-targeted 1H-NMR methods were used to determine metabolite profiles from crude extracts of Alpine and Ecuadorian lichens collected from their natural habitats. In control experiments, the robustness of metabolite detection and quantification was estimated using replicate measurements of Stereocaulon alpinum extracts. The deviations in the overall metabolite fingerprints were low when analyzing S. alpinum collections from different locations or during different annual and seasonal periods. In contrast, metabolite profiles observed from extracts of different Alpine and Ecuadorian lichens clearly revealed genus- and species-specific profiles. The discriminating functions determining cluster formation in principle component analysis (PCA were due to differences in the amounts of genus-specific compounds such as sticticin from the Sticta species, but also in the amounts of ubiquitous metabolites, such as sugar alcohols or trehalose. However, varying concentrations of these metabolites from the same lichen species e.g., due to different environmental conditions appeared of minor relevance for the overall cluster formation in PCA. The metabolic clusters matched phylogenetic analyses using nuclear ribosomal DNA (nrDNA internal transcribed spacer (ITS sequences of lichen mycobionts, as exemplified for the genus Sticta. It can be concluded that NMR-based non-targeted metabolic profiling is a useful tool in the chemo-taxonomy of lichens. The same approach could also facilitate the discovery of novel lichen metabolites on a rapid and systematical basis.

  7. Responses Of Subalpine Conifer Seedling Germination And Survival To Soil Microclimate In The Alpine Treeline Warming Experiment

    Science.gov (United States)

    Castanha, C.; Moyes, A. B.; Torn, M. S.; Germino, M. J.; Kueppers, L. M.

    2011-12-01

    At Niwot Ridge, Colorado, we used common gardens and climate manipulations to investigate potential subalpine tree species range shifts due to climate change. In Fall 2009 we harvested seed from local populations of limber pine and Englemann spruce, which we sowed in 3 experimental sites spanning an elevation gradient from lower subalpine forest (3080m asl), to the upper subalpine treeline ecotone (3400m asl), to the alpine tundra (3550m asl). In October we turned on overhead infrared heaters designed to increase growing season surface soil temperature by 4-5°C, and following snowmelt in 2010 we crossed this heating treatment with manual watering, adding 3mm of water each week. Here we report on the species, site, and treatment effects on seedling emergence and survival as mediated by snowmelt date, soil temperature, and soil moisture. Depending on the site and plot, heating accelerated germination by 1 to 4 weeks. Germination degree days (heat accumulation required for seed germination) were greater for pine than for spruce and greater in drier plots. Seedling survival was explained by date of emergence, with older seedlings more likely to survive the season. Survival was also explained by drought degree days -- the number of days below critical soil moisture thresholds compounded by high temperature -- with lower thresholds for spruce than for pine. Our preliminary results indicate that a warmer environment will stimulate germination for both species, but that, survival - especially for spruce - will be critically modulated by summer soil moisture.

  8. Estimating carbon and energy fluxes in arctic tundra

    Science.gov (United States)

    Gokkaya, K.; Jiang, Y.; Rastetter, E.; Shaver, G. R.; Rocha, A. V.

    2013-12-01

    Arctic ecosystems are undergoing a very rapid change due to climate change and their response to climate change has important implications for the global energy budget and carbon (C) cycling. Therefore, it is important to understand how (C) and energy fluxes in the Arctic will respond to climate change. However, attribution of these responses to climate is challenging because measured fluxes are the sum of multiple processes that respond differently to environmental factors. For example, net ecosystem exchange of CO2 (NEE) is the net result of gross (C) uptake by plant photosynthesis (GPP) and (C) loss by ecosystem respiration (ER) and similarly, evapotranspiration (i.e. latent energy, LE) is the sum of transpiration and evaporation. Partitioning of NEE into GPP and ER requires nighttime measurements of NEE, when photosynthesis does not take place, to be extrapolated to daytime. This is challenging in the Arctic because of the long photoperiod during the growing season and the errors involved during the extrapolation. Transpiration (energy), photosynthesis (carbon), and vegetation phenology are inherently coupled because leaf stomata are the primary regulators of gas exchange. Our objectives in this study are to i) estimate canopy resistance (Rc) based on a light use efficiency model, ii) utilize the estimated Rc to predict GPP and transpiration using a coupled C and energy model and thus improve the partitioning of NEE and LE, and iii) to test ensemble Kalman filter (EnKF) to estimate model parameters and improve model predictions. Results from one growing season showed that the model predictions can explain 75 and 71% of the variance in GPP and LE in the Arctic tundra ecosystem, respectively. When the model was embedded within the EnKF for estimating Rc, the amount of variance explained for GPP increased to 81% but there was no improvement for the prediction of LE. This suggests that the factors controlling LE are not fully integrated in the model such as the

  9. Importance of Marine-Derived Nutrients Supplied by Planktivorous Seabirds to High Arctic Tundra Plant Communities

    Science.gov (United States)

    Zwolicki, Adrian; Zmudczyńska-Skarbek, Katarzyna; Richard, Pierre; Stempniewicz, Lech

    2016-01-01

    We studied the relative importance of several environmental factors for tundra plant communities in five locations across Svalbard (High Arctic) that differed in geographical location, oceanographic and climatic influence, and soil characteristics. The amount of marine-derived nitrogen in the soil supplied by seabirds was locally the most important of the studied environmental factors influencing the tundra plant community. We found a strong positive correlation between δ15N isotopic values and total N content in the soil, confirming the fundamental role of marine-derived matter to the generally nutrient-poor Arctic tundra ecosystem. We also recorded a strong correlation between the δ15N values of soil and of the tissues of vascular plants and mosses, but not of lichens. The relationship between soil δ15N values and vascular plant cover was linear. In the case of mosses, the percentage ground cover reached maximum around a soil δ 15N value of 8‰, as did plant community diversity. This soil δ15N value clearly separated the occurrence of plants with low nitrogen tolerance (e.g. Salix polaris) from those predominating on high N content soils (e.g. Cerastium arcticum, Poa alpina). Large colonies of planktivorous little auks have a great influence on Arctic tundra vegetation, either through enhancing plant abundance or in shaping plant community composition at a local scale. PMID:27149113

  10. Fungi benefit from two decades of increased nutrient availability in tundra heath soil

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Michelsen, Anders; Bååth, Erland

    2013-01-01

    of complex organic compounds such as vanillin, while warming has had no such effects. Furthermore, the NLFA-to-PLFA ratio for (13)C-incorporation from acetate increased in warmed plots but not in fertilized ones. Thus, fertilization cannot be used as a proxy for effects on warming in arctic tundra soils...

  11. Blood lead concentrations in Alaskan tundra swans: linking breeding and wintering areas with satellite telemetry

    Science.gov (United States)

    Ely, Craig R.; Franson, Christian

    2014-01-01

    Tundra swans (Cygnus columbianus) like many waterfowl species are susceptible to lead (Pb) poisoning, and Pb-induced mortality has been reported from many areas of their wintering range. Little is known however about Pb levels throughout the annual cycle of tundra swans, especially during summer when birds are on remote northern breeding areas where they are less likely to be exposed to anthropogenic sources of Pb. Our objective was to document summer Pb levels in tundra swans throughout their breeding range in Alaska to determine if there were population-specific differences in blood Pb concentrations that might pose a threat to swans and to humans that may consume them. We measured blood Pb concentrations in tundra swans at five locations in Alaska, representing birds that winter in both the Pacific Flyway and Atlantic Flyway. We also marked swans at each location with satellite transmitters and coded neck bands, to identify staging and wintering sites and determine if winter site use correlated with summer Pb concentrations. Blood Pb levels were generally low (return migration to Alaska, rather than on the summer breeding grounds. Blood Pb levels varied significantly across the five breeding areas, with highest concentrations in birds on the North Slope of Alaska (wintering in the Atlantic Flyway), and lowest in birds from the lower Alaska Peninsula that rarely migrate south for winter.

  12. Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time.

    Science.gov (United States)

    Elmendorf, Sarah C; Henry, Gregory H R; Hollister, Robert D; Björk, Robert G; Bjorkman, Anne D; Callaghan, Terry V; Collier, Laura Siegwart; Cooper, Elisabeth J; Cornelissen, Johannes H C; Day, Thomas A; Fosaa, Anna Maria; Gould, William A; Grétarsdóttir, Járngerður; Harte, John; Hermanutz, Luise; Hik, David S; Hofgaard, Annika; Jarrad, Frith; Jónsdóttir, Ingibjörg Svala; Keuper, Frida; Klanderud, Kari; Klein, Julia A; Koh, Saewan; Kudo, Gaku; Lang, Simone I; Loewen, Val; May, Jeremy L; Mercado, Joel; Michelsen, Anders; Molau, Ulf; Myers-Smith, Isla H; Oberbauer, Steven F; Pieper, Sara; Post, Eric; Rixen, Christian; Robinson, Clare H; Schmidt, Niels Martin; Shaver, Gaius R; Stenström, Anna; Tolvanen, Anne; Totland, Orjan; Troxler, Tiffany; Wahren, Carl-Henrik; Webber, Patrick J; Welker, Jeffery M; Wookey, Philip A

    2012-02-01

    Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation - and associated ecosystem consequences - have the potential to be much greater than we have observed to date.

  13. Importance of Marine-Derived Nutrients Supplied by Planktivorous Seabirds to High Arctic Tundra Plant Communities.

    Directory of Open Access Journals (Sweden)

    Adrian Zwolicki

    Full Text Available We studied the relative importance of several environmental factors for tundra plant communities in five locations across Svalbard (High Arctic that differed in geographical location, oceanographic and climatic influence, and soil characteristics. The amount of marine-derived nitrogen in the soil supplied by seabirds was locally the most important of the studied environmental factors influencing the tundra plant community. We found a strong positive correlation between δ15N isotopic values and total N content in the soil, confirming the fundamental role of marine-derived matter to the generally nutrient-poor Arctic tundra ecosystem. We also recorded a strong correlation between the δ15N values of soil and of the tissues of vascular plants and mosses, but not of lichens. The relationship between soil δ15N values and vascular plant cover was linear. In the case of mosses, the percentage ground cover reached maximum around a soil δ 15N value of 8‰, as did plant community diversity. This soil δ15N value clearly separated the occurrence of plants with low nitrogen tolerance (e.g. Salix polaris from those predominating on high N content soils (e.g. Cerastium arcticum, Poa alpina. Large colonies of planktivorous little auks have a great influence on Arctic tundra vegetation, either through enhancing plant abundance or in shaping plant community composition at a local scale.

  14. Importance of Marine-Derived Nutrients Supplied by Planktivorous Seabirds to High Arctic Tundra Plant Communities.

    Science.gov (United States)

    Zwolicki, Adrian; Zmudczyńska-Skarbek, Katarzyna; Richard, Pierre; Stempniewicz, Lech

    2016-01-01

    We studied the relative importance of several environmental factors for tundra plant communities in five locations across Svalbard (High Arctic) that differed in geographical location, oceanographic and climatic influence, and soil characteristics. The amount of marine-derived nitrogen in the soil supplied by seabirds was locally the most important of the studied environmental factors influencing the tundra plant community. We found a strong positive correlation between δ15N isotopic values and total N content in the soil, confirming the fundamental role of marine-derived matter to the generally nutrient-poor Arctic tundra ecosystem. We also recorded a strong correlation between the δ15N values of soil and of the tissues of vascular plants and mosses, but not of lichens. The relationship between soil δ15N values and vascular plant cover was linear. In the case of mosses, the percentage ground cover reached maximum around a soil δ 15N value of 8‰, as did plant community diversity. This soil δ15N value clearly separated the occurrence of plants with low nitrogen tolerance (e.g. Salix polaris) from those predominating on high N content soils (e.g. Cerastium arcticum, Poa alpina). Large colonies of planktivorous little auks have a great influence on Arctic tundra vegetation, either through enhancing plant abundance or in shaping plant community composition at a local scale. PMID:27149113

  15. Seasonal variability of leaf area index and foliar nitrogen in contrasting dry-mesic tundras

    DEFF Research Database (Denmark)

    Campioli, Matteo; Michelsen, Anders; Lemeur, Raoul;

    2009-01-01

    Assimilation and exchange of carbon for arctic ecosystems depend strongly on leaf area index (LAI) and total foliar nitrogen (TFN). For dry-mesic tundras, the seasonality of these characteristics is unexplored. We addressed this knowledge gap by measuring variations of LAI and TFN at five contras...

  16. Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

    NARCIS (Netherlands)

    Juszak, Inge; Eugster, Werner; Heijmans, Monique M.P.D.; Schaepman-Strub, Gabriela

    2016-01-01

    Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing.

  17. What are the main climate drivers for shrub growth in Northeastern Siberian tundra?

    NARCIS (Netherlands)

    Blok, D.; Sass-Klaassen, U.; Schaepman-Strub, G.; Heijmans, M.M.P.D.; Sauren, P.; Berendse, F.

    2011-01-01

    Deciduous shrubs are expected to rapidly expand in the Arctic during the coming decades due to climate warming. A transition towards more shrub-dominated tundra may have large implications for the regional surface energy balance, permafrost stability and carbon storage capacity, with consequences fo

  18. Pleistocene origin and population history of a neoendemic alpine butterfly.

    Science.gov (United States)

    Schoville, Sean D; Stuckey, Matthew; Roderick, George K

    2011-03-01

    Alpine environments underwent dramatic transformation during glacial-interglacial cycles, with the consequence that geographical, ecological and demographic changes of alpine populations provided the opportunity for formation of neoendemic species. Several biogeographical models have been proposed to account for the unique history of alpine populations, with different expectations of genetic divergence and speciation. The expanding alpine archipelago model proposes that alpine populations expand spatially and demographically during glacial events, dispersing between mountain ranges. Under this model, alpine populations are unlikely to diverge in isolation due to substantial interpopulation gene flow. In contrast, the alpine archipelago refuge model proposes that gene flow during glacial phases is limited and populations expand demographically during interglacial phases, increasing genetic isolation and the likelihood of speciation. We assess these models by reconstructing the evolutionary history of Colias behrii, a morphologically and ecologically distinct alpine butterfly restricted to the California Sierra Nevada. C. behrii exhibits very low genetic diversity at mitochondrial and nuclear loci, limited population structure and evidence of population expansion. C. behrii and Rocky Mountain C. meadii share identical mitochondrial haplotypes, while in contrast, nuclear data indicate common ancestry between C. behrii and Cascades Range Colias pelidne. The conflict in gene genealogies may be a result of recent expansion in North American Colias, but an isolation with migration analysis indicates that genetic patterns in C. behrii might result from differential introgression following hybridization. Based on the timing of population expansion and gene flow between mountain ranges, the expanding alpine archipelago model is supported in C. behrii. PMID:21244539

  19. Variation in bird's originating nitrogen availability limits High Arctic tundra development over last 2000 year (Hornsund, Svalbard)

    Science.gov (United States)

    Skrzypek, Grzegorz; Wojtuń, Bronisław; Hua, Quan; Richter, Dorota; Jakubas, Dariusz; Wojczulanis-Jakubas, Katarzyna; Samecka-Cymerman, Aleksandra

    2016-04-01

    Arctic and subarctic regions play important roles in the global carbon balance. However, nitrogen (N) deficiency is a major constraint for organic carbon sequestration in the High Arctic. Hence, the identification of the relative contributions from different N-sources is critical for understanding the constraints that limit tundra growth. The stable nitrogen composition of the three main N-sources and numerous plants were analyzed in ten tundra types (including those influenced by seabirds) in the Fuglebekken catchment (Hornsund, Svalbard, 77°N 15°E). The percentage of the total tundra N-pool provided by seabirds' feces (from planktivorous colonially breeding little auks Alle alle), ranged from 0-21% in Patterned-ground tundra to 100% in Ornithocoprophilous tundra. The total N-pool utilized by tundra plants in the studied catchment originated from birds (36%), atmospheric deposition (38%), and N2-fixation (26%). The results clearly show that N-pool in the tundra is significantly supplemented by nesting seabirds. Thus, if they experienced climate change induced substantial negative environmental pressure, it would adversely influence the tundra N-budget (Skrzypek et al. 2015). The growth rates and the sediment thickness (bird-N rich tundra with very diverse ages ranging from 235 to 2300 cal BP and thickness up to 110 cm. The growth rates for this tundra (62 cm core, 18 AMS 14C dates) were high (1.5-3.0 mm/yr) between 1568 and 1804 AD and then substantially declined for the period between 1804 and 1929 AD (0.2 mm/yr). These findings deliver an additional argument, that the organic matter accumulation is driven not only directly by climatic conditions but also by birds' contribution to the tundra N-pool. Skrzypek G, Wojtuń B, Richter D, Jakubas D, Wojczulanis-Jakubas K, Samecka-Cymerman A, 2015. Diversification of nitrogen sources in various tundra vegetation types in the high Arctic. PLoS ONE 10(9): e0136536.

  20. Will Arctic ground squirrels impede or accelerate climate-induced vegetation changes to the Arctic tundra?

    Science.gov (United States)

    Dalton, J.; Flower, C. E.; Brown, J.; Gonzalez-Meler, M. A.; Whelan, C.

    2014-12-01

    Considerable attention has been given to the climate feedbacks associated with predicted vegetation shifts in the Arctic tundra in response to global environmental change. However, little is known regarding the extent to which consumers can facilitate or respond to shrub expansion. Arctic ground squirrels, the largest and most northern ground squirrel, are abundant and widespread throughout the North American tundra. Their broad diet of seeds, flowers, herbage, bird's eggs and meat speaks to the need to breed, feed, and fatten in a span of some 12-16 weeks that separate their 8-9 month bouts of hibernation with the potential consequence to impact ecosystem dynamics. Therefore Arctic ground squirrels are a good candidate to evaluate whether consumers are mere responders (bottom-up effects) or drivers (top-down) of the observed and predicted vegetation changes. As a start towards this question, we measured the foraging intensity (giving-up densities) of Arctic ground squirrels in experimental food patches within which the squirrels experience diminishing returns as they seek the raisins and peanuts that we provided at the Toolik Lake field station in northern Alaska. If the squirrels show their highest feeding intensity in the shrubs, they may impede vegetation shifts by slowing the establishment and expansion of shrubs in the tundra. Conversely, if they show their lowest feeding intensity within shrub dominated areas, they may accelerate vegetation shifts. We found neither. Feeding intensity varied most among transects and times of day, and least along a tundra-to-shrub vegetation gradient. This suggests that the impacts of squirrels will be heterogeneous - in places responders and in others drivers. We should not be surprised then to see patches of accelerated and impeded vegetation changes in the tundra ecosystem. Some of these patterns may be predictable from the foraging behavior of Arctic ground squirrels.

  1. Greater shrub dominance alters breeding habitat and food resources for migratory songbirds in Alaskan arctic tundra.

    Science.gov (United States)

    Boelman, Natalie T; Gough, Laura; Wingfield, John; Goetz, Scott; Asmus, Ashley; Chmura, Helen E; Krause, Jesse S; Perez, Jonathan H; Sweet, Shannan K; Guay, Kevin C

    2015-04-01

    Climate warming is affecting the Arctic in multiple ways, including via increased dominance of deciduous shrubs. Although many studies have focused on how this vegetation shift is altering nutrient cycling and energy balance, few have explicitly considered effects on tundra fauna, such as the millions of migratory songbirds that breed in northern regions every year. To understand how increasing deciduous shrub dominance may alter breeding songbird habitat, we quantified vegetation and arthropod community characteristics in both graminoid and shrub dominated tundra. We combined measurements of preferred nest site characteristics for Lapland longspurs (Calcarius lapponicus) and Gambel's White-crowned sparrows (Zonotrichia leucophrys gambelii) with modeled predictions for the distribution of plant community types in the Alaskan arctic foothills region for the year 2050. Lapland longspur nests were found in sedge-dominated tussock tundra where shrub height does not exceed 20 cm, whereas White-crowned sparrows nested only under shrubs between 20 cm and 1 m in height, with no preference for shrub species. Shrub canopies had higher canopy-dwelling arthropod availability (i.e. small flies and spiders) but lower ground-dwelling arthropod availability (i.e. large spiders and beetles). Since flies are the birds' preferred prey, increasing shrubs may result in a net enhancement in preferred prey availability. Acknowledging the coarse resolution of existing tundra vegetation models, we predict that by 2050 there will be a northward shift in current White-crowned sparrow habitat range and a 20-60% increase in their preferred habitat extent, while Lapland longspur habitat extent will be equivalently reduced. Our findings can be used to make first approximations of future habitat change for species with similar nesting requirements. However, we contend that as exemplified by this study's findings, existing tundra modeling tools cannot yet simulate the fine-scale habitat

  2. Increasing alpine transit traffic through Switzerland will considerably enhance high altitude alpine pollutant levels

    Energy Technology Data Exchange (ETDEWEB)

    Prevot, A.S.H.; Dommen, J.; Furger, M.; Graber, W.K. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Within the EU-Project VOTALP (Vertical Ozone Transports in the Alps), we have shown that deep alpine valleys like the Mesolcina Valley very efficiently transport air out of the polluted valley up to altitudes between 2000 and near 4000 m asl (above sea level). Pollutants emitted in these valleys are very efficiently transported up to high altitudes. (author) 2 figs., 1 tab., 2 refs.

  3. Methods for measuring arctic and alpine shrub growth

    DEFF Research Database (Denmark)

    Myers-Smith, Isla; Hallinger, Martin; Blok, Daan;

    2015-01-01

    of tundra vegetation dynamics and environmental changes. However, dendrochronological methods developed for trees, need to be adapted for the morphology and growth eccentricity of shrubs. Here, we review current and developing methods to measure radial and axial growth, estimate age, and assess growth...

  4. Dynamics of tundra ecosystems and their potential response to energy research development. Soil chemical aspects of plant nutrition in alpine tundra at Eagle Summit, Alaska. II. Exchange chemistry of mineral and organic soils from Eagle Summit, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, L.

    1983-02-15

    Some aspects of the nutrient status of an arctic organic soil and an arctic mineral soil are described and contrasted with emphasis on soil properties which may be important in the availability of nutrients to plants. Field conditions related to the exchange chemistry of calcium, magnesium, and potassium, pH dependency of cation exchange capacity, exchange isotherms, and soil buffering power for pH, calcium, magnesium and potassium are discussed.

  5. Sustainable use of alpine and pre-alpine grassland soils in a changing climate (SUSALPS)

    Science.gov (United States)

    Zistl-Schlingmann, Marcus; Beck, Robert; Brandhuber, Robert; Butterbach-Bahl, Klaus; Garcia Franco, Noelia; von Gillhaußen, Phillip; Jentsch, Anke; Kiese, Ralf; Krämer, Alexander; Kögel-Knabner, Ingrid; Köllner, Thomas; Poppenborg, Patrick; Schloter, Michael; Schulz, Stefanie; Wiesmeier, Martin; Wolf, Benjamin; Dannenmann, Michael

    2016-04-01

    The development of ecologically as well as economically sustainable management options for the carbon- and nitrogen rich alpine and pre-alpine grassland soils in a changing climate poses a grand scientific and socio- economical challenge. The transdisciplinary SUSALPS project starting in 2016 aims to essentially improve the knowledge on the functionality of alpine and pre-alpine grassland soils using both natural-scientific/ technical and socio economical approaches. The project is building on existing infrastructure of German grassland-ecosystem-research like the pre-alpine TERENO (Terrestrial ecosystem observation network observatory) observatory sites, the EVENT and SIGNAL sites as well as long term LfL (Bayerische Landesanstalt für Landwirtschaft) sites, plus a new additional high elevation (1400m a.s.l) site in the Bavarian Alps. The site setup along the elevational gradient on the edge of the Alps (1400 m to 300 m) is used for space-for-time climate change experiments which are combined with extensive and intensive management treatments. A key focus of SUSALPS will be the characterization of combined climate change/management effects on carbon and nitrogen biogeochemistry. Hence, we will evaluate the influence of different management options and current and future climate changes on the soil microbiome and associated biogeochemical processes in the plant-soil-system, on nitrogen use efficiency, on biosphere-atmosphere exchange of greenhouse gases as well as on leaching of environmentally relevant compounds. For this purpose, we simulate the predicted climate change in the region by translocation of large lysimeters (1m2, 1.4m depth; TERENO lysimeters, translocated in 2011) for measurements of biosphere-atmosphere hydrosphere exchange of environmentally relevant C and N compounds as well as by newly transferred smaller plant-soil-mesocosms used for destructive biogeochemical process studies. By closely linking this experimental work with biogeochemical and

  6. The relationship between soil physical properties and alpine plant diversity on Qinghai-Tibet Plateau

    Directory of Open Access Journals (Sweden)

    Lin Tang

    2015-04-01

    Full Text Available Through a large-scale research, we examined the heterogeneity of soil properties and plant diversity, as well as their relationships across alpine grassland types on Qinghai-Tibet Plateau. The soil pH and EC value increased with the constant deepening of the soil in all the three alpine grassland types which in order of absolute value in every soil layer were alpine desert steppe, alpine steppe and alpine meadow. Among the three grassland types, the alpine meadow possessed the highest SM but the lowest SBD. For plant diversity, alpine meadow was the highest, alpine desert steppe ranked the second and alpine steppe was the last. SM and SBD were the highest influential soil physical properties to species richness, but with opposite effects.

  7. The effect of a permafrost disturbance on growing-season carbon-dioxide fluxes in a high Arctic tundra ecosystem

    Science.gov (United States)

    Cassidy, Alison E.; Christen, Andreas; Henry, Gregory H. R.

    2016-04-01

    Soil carbon stored in high-latitude permafrost landscapes is threatened by warming and could contribute significant amounts of carbon to the atmosphere and hydrosphere as permafrost thaws. Thermokarst and permafrost disturbances, especially active layer detachments and retrogressive thaw slumps, are present across the Fosheim Peninsula, Ellesmere Island, Canada. To determine the effects of retrogressive thaw slumps on net ecosystem exchange (NEE) of CO2 in high Arctic tundra, we used two eddy covariance (EC) tower systems to simultaneously and continuously measure CO2 fluxes from a disturbed site and the surrounding undisturbed tundra. During the 32-day measurement period in the 2014 growing season, the undisturbed tundra was a small net sink (NEE = -0.1 g C m-2 d-1); however, the disturbed terrain of the retrogressive thaw slump was a net source (NEE = +0.4 g C m-2 d-1). Over the measurement period, the undisturbed tundra sequestered 3.8 g C m-2, while the disturbed tundra released 12.5 g C m-2. Before full leaf-out in early July, the undisturbed tundra was a small source of CO2 but shifted to a sink for the remainder of the sampling season (July), whereas the disturbed tundra remained a source of CO2 throughout the season. A static chamber system was also used to measure daytime fluxes in the footprints of the two towers, in both disturbed and undisturbed tundra, and fluxes were partitioned into ecosystem respiration (Re) and gross primary production (GPP). Average GPP and Re found in disturbed tundra were smaller (+0.40 µmol m-2 s-1 and +0.55 µmol m-2 s-1, respectively) than those found in undisturbed tundra (+1.19 µmol m-2 s-1 and +1.04 µmol m-2 s-1, respectively). Our measurements indicated clearly that the permafrost disturbance changed the high Arctic tundra system from a sink to a source for CO2 during the majority of the growing season (late June and July).

  8. Changes in tundra vascular plant biomass over thirty years at Imnavait Creek, Alaska, and current ecosystem C and N dynamics.

    Science.gov (United States)

    Bret-Harte, M. S.; Shaver, G. R.; Euskirchen, E. S.; Huebner, D. C.; Drew, J. W.; Cherry, J. E.; Edgar, C.

    2015-12-01

    Understanding the magnitude of, and controls over, carbon fluxes in arctic ecosystems is essential for accurate assessment and prediction of their responses to climate change. In 2013, we harvested vegetation and soils in the most common plant community types in source areas for fluxes measured by eddy covariance towers located in three representative Alaska tundra ecosystems along a toposequence (a ridge site of heath tundra and moist non-acidic tundra, a mid-slope site of moist acidic tussock tundra, and a valley bottom site of wet sedge tundra and moist acidic tussock tundra) at Imnavait Creek, Alaska. This harvest sought to relate biomass, production, composition, and C and N stocks in soil and vegetation, to estimates of net ecosystem CO2 exchange obtained by micrometeorological methods. Soil C and N stocks in the seasonally unfrozen soil layer were greatest in the wet sedge community, and least in the heath community. In contrast, moist acidic tussock tundra at the valley bottom site had the highest C and N stocks in vascular plant biomass, while nearby wet sedge tundra had the lowest. Overall, soil C:N ratio was highest in moist acidic tussock tundra at the mid-slope site. Aboveground biomass of vascular plants in moist acidic tundra at the mid-slope site was nearly three times higher than that measured thirty years earlier in vegetation harvests of nearby areas at Imnavait Creek. Other harvests from sites near Toolik Field Station suggest that vascular plant biomass in moist acidic tundra has increased in multiple sites over this time period. Increased biomass in the mid-1990s corresponds with a switch from mostly negative to mostly positive spatially-averaged air temperature anomalies in the climate record. All our sites have been annual net sources of CO2 to the atmosphere over nine years of measurement, but in the last two years, the valley bottom site has been a particularly strong source, due to CO2 losses in fall and winter that correspond with a

  9. Central planning, market and subsistence from a tundra perspective: Field experience with reindeer herders in the Kola Peninsula

    Directory of Open Access Journals (Sweden)

    Dessislav Sabev

    2002-04-01

    Full Text Available This paper is based on field experience in the tundra camp of a reindeer-herding brigade with mixed ethnic background (Komi, Sami, Nenets, Russians belonging to the ex-Sovkhoz of Krasnoschelie. Its purpose is to situate the new critical issues facing the reindeer-herding collectives after the economic collapse in Russia in 1998. My main argument is that the increasing economic isolation of the tundra periphery forces the herders to redefine their relationship with both the centre(s and the other tundra actors. Reindeer herding on the Kola Peninsula is analysed in relation to its heterogeneous economic system defined by the old Sovkhoz-like management and the new Western buyer of reindeer meat. Furthermore, the social environment in the herding territories has changed since the deterioration of the central planning economy, implying new renewable resources' users. After massive loss of jobs, militaries, miners and geologists came into the tundra for substantial hunting and fishing and so became actors in the local informal economy. Finally, tundra-located herders and hunters seem to be somewhere unified by a discourse against the town-based administrative power and economic actors such as mining industry. Therefore herders have to deal with both an old administrative system in the agrocentre and new realities in the tundra. Based on a case study of herding/hunting activities in a tundra camp, the paper analyses the social relationships between the different actors in the post-Soviet Kola tundra and express their quest for solutions.

  10. Long-term recovery patterns of arctic tundra after winter seismic exploration.

    Science.gov (United States)

    Jorgenson, Janet C; Ver Hoef, Jay M; Jorgenson, M T

    2010-01-01

    In response to the increasing global demand for energy, oil exploration and development are expanding into frontier areas of the Arctic, where slow-growing tundra vegetation and the underlying permafrost soils are very sensitive to disturbance. The creation of vehicle trails on the tundra from seismic exploration for oil has accelerated in the past decade, and the cumulative impact represents a geographic footprint that covers a greater extent of Alaska's North Slope tundra than all other direct human impacts combined. Seismic exploration for oil and gas was conducted on the coastal plain of the Arctic National Wildlife Refuge, Alaska, USA, in the winters of 1984 and 1985. This study documents recovery of vegetation and permafrost soils over a two-decade period after vehicle traffic on snow-covered tundra. Paired permanent vegetation plots (disturbed vs. reference) were monitored six times from 1984 to 2002. Data were collected on percent vegetative cover by plant species and on soil and ground ice characteristics. We developed Bayesian hierarchical models, with temporally and spatially autocorrelated errors, to analyze the effects of vegetation type and initial disturbance levels on recovery patterns of the different plant growth forms as well as soil thaw depth. Plant community composition was altered on the trails by species-specific responses to initial disturbance and subsequent changes in substrate. Long-term changes included increased cover of graminoids and decreased cover of evergreen shrubs and mosses. Trails with low levels of initial disturbance usually improved well over time, whereas those with medium to high levels of initial disturbance recovered slowly. Trails on ice-poor, gravel substrates of riparian areas recovered better than those on ice-rich loamy soils of the uplands, even after severe initial damage. Recovery to pre-disturbance communities was not possible where trail subsidence occurred due to thawing of ground ice. Previous studies of

  11. Circumpolar Dynamics of Arctic Tundra Vegetation in Relation to Temperature Trends

    Science.gov (United States)

    Epstein, H. E.; Bhatt, U. S.; Raynolds, M. K.; Walker, D. A.; Reichle, L.

    2015-12-01

    Arctic tundra vegetation has generally exhibited a "greening" trend for at least the past three decades. However, these temporal trends in tundra vegetation are highly heterogeneous in space across different arctic regions, as well as showing variability over time. The factors controlling this variability are likely numerous with complex interactions, however, a first approach is to examine how vegetation dynamics relate to trends in temperature. We used a 32-year record (1982-2013) of the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperatures from Advanced Very High Resolution Radiometer (AVHRR) sensors onboard NOAA satellites (GIMMS 3g dataset) to analyze observed changes in both aboveground tundra vegetation and surface temperatures. We divided the circumpolar dataset into two continental regions (North America and Eurasia), as well as by tundra subzone (A-E) sensu the Circumpolar Arctic Vegetation Map (CAVM). We 1) compared temporal trends in both MaxNDVI (peak values) and TI-NDVI (seasonally integrated values) with those of the Summer Warmth Index (SWI - sum of mean monthly temperatures > 0 °C); 2) assessed how the detrended interannual variabilities in NDVI compared to those of SWI; and 3) analyzed current and prior year SWI, as well as prior year NDVI, as controls on current year NDVI. Interannual coefficients of variation for SWI were 2.0 - 2.5 times greater than those for NDVI, and the temporal trendlines for NDVI were much "tighter" with greater r² values than those for SWI. Interannual variability in NDVI was greatest in the "Mid-Low" Arctic, whereas interannual variability in SWI was greatest in the most southern Arctic. Surprisingly, the observed relative rates of change in NDVI were greater than those of SWI for the warmer subzones for both North America and Eurasia. Finally, the change in NDVI from one year to the next was only weakly correlated with current year SWI. These results suggest that 1) there are clearly factors

  12. Alaska tundra vegetation trends and their links to the large-scale climate

    Science.gov (United States)

    Bieniek, P. A.; Bhatt, U. S.; Walker, D. A.; Raynolds, M. K.; Comiso, J. C.

    2011-12-01

    The arctic Normalized Vegetation Index (NDVI) data set (a measure of vegetation photosynthetic capacity) has been used to document coherent temporal relationships between near-coastal sea ice, summer tundra land surface temperatures, and vegetation productivity throughout the Arctic (Bhatt et al. 2010). Land warming over North America has displayed larger trends (+30%) when compared to Eurasia (+16%) since 1982. In the tundra of northern Alaska the greatest change was found in absolute maximum NDVI along the Beaufort Sea coast (+14%). In contrast, tundra areas in southwest Alaska along the Bering Sea have seen a decline (-4%). Greenup date in these regions has been occurring as much as 1-4 days earlier per decade, but trends are mixed. Winter snow water equivalent (SWE) has only increased slightly (+0.1 mm/yr) in the Arctic region of Alaska since 1987 (R. Muskett, personal communication). These findings suggest that there have been changes in the seasonal climate in Alaska during the NDVI record. The tundra trends are further investigated by evaluating remotely sensed sea ice, surface air temperature, SWE, daily snow cover, and NDVI3g. While the snow data has a relatively short record (1999-2010), notable trends can be observed in snow melt, occurring as much 15 days earlier per decade in northern Alaska. Unfortunately, other snow data sets have been found to be problematic and could not be used to extend our analysis. This highlights the need for a long-term pan-arctic snow data set that is suitable for climate analysis. Possible climate drivers are also investigated. Results show that the summer tundra, in terms of NDVI and summer warmth index (SWI), has few direct links with the large-scale climate. However, the sea ice concentration along the coast of the tundra regions has strong preseason links to the large-scale climate. This suggests that the large-scale climate influences the sea ice concentration which then affects the NDVI and SWI. Three tundra regions

  13. InSAR detects increase in surface subsidence caused by an Arctic tundra fire

    Science.gov (United States)

    Liu, Lin; Jafarov, Elchin E.; Schaefer, Kevin M.; Jones, Benjamin M.; Zebker, Howard A.; Williams, Christopher A.; Rogan, John; Zhang, Tingjun

    2014-01-01

    Wildfire is a major disturbance in the Arctic tundra and boreal forests, having a significant impact on soil hydrology, carbon cycling, and permafrost dynamics. This study explores the use of the microwave Interferometric Synthetic Aperture Radar (InSAR) technique to map and quantify ground surface subsidence caused by the Anaktuvuk River fire on the North Slope of Alaska. We detected an increase of up to 8 cm of thaw-season ground subsidence after the fire, which is due to a combination of thickened active layer and permafrost thaw subsidence. Our results illustrate the effectiveness and potential of using InSAR to quantify fire impacts on the Arctic tundra, especially in regions underlain by ice-rich permafrost. Our study also suggests that surface subsidence is a more comprehensive indicator of fire impacts on ice-rich permafrost terrain than changes in active layer thickness alone.

  14. Ecological networks in the Alpine Arc

    Directory of Open Access Journals (Sweden)

    Thomas Scheurer

    2009-07-01

    Full Text Available In response to decreasing biodiversity and new phenomena such as climate change, the number of initiatives aimed at creating ecological networks is increasing. Research and activities based on the theme of ecological connectivity are generating a completely new perception of methods of protecting the natural environment: there is a shift from a conservationist approach to natural systems to one that is more functional. The place and role of protected areas within their regions are being redefined. Such areas are now situated in a wider territorial context and new cooperative arrangements are encouraged with local actors. The alpine approach adopted in establishing a transalpine ecological network, illustrated by several examples, underlines the importance of both an international framework for such activities and the need to extend them to include not only the classic actors in the protection of the natural environment, but also other sectors that until now have seldom been involved.Face au constat d’une perte accrue de biodiversité et de phénomènes nouveaux, tels le changement climatique, les initiatives de mise en place de réseaux écologiques se multiplient. Les réflexions et les actions conduites autour de la thématique de la connectivité écologique font naître une perception complètement nouvelle des pratiques de la protection de la nature : un changement d’une conception patrimoniale conservatrice vers une approche plus fonctionnelle des systèmes naturels. La place et le rôle des espaces protégés au sein de leur région sont redéfinis, les situant  dans un contexte territorial plus large et engendrant de nouvelles collaborations entre acteurs locaux. L’approche alpine pour la réalisation d’un réseau écologique transalpin, illustrée par différents exemples, souligne l’importance d’un cadre international pour ces démarches et d’une ouverture sur l’ensemble du territoire impliquant en plus des acteurs

  15. Bird communities of the arctic shrub tundra of Yamal: habitat specialists and generalists.

    Directory of Open Access Journals (Sweden)

    Vasiliy Sokolov

    Full Text Available BACKGROUND: The ratio of habitat generalists to specialists in birds has been suggested as a good indicator of ecosystem changes due to e.g. climate change and other anthropogenic perturbations. Most studies focusing on this functional component of biodiversity originate, however, from temperate regions. The Eurasian Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by domestic reindeer and growing human activity. METHODOLOGY/PRINCIPAL FINDINGS: Here we monitored bird communities in a tundra landscape harbouring shrub and open habitats in order to analyse bird habitat relationships and quantify habitat specialization. We used ordination methods to analyse habitat associations and estimated the proportions of specialists in each of the main habitats. Correspondence Analysis identified three main bird communities, inhabiting upland, lowland and dense willow shrubs. We documented a stable structure of communities despite large multiannual variations of bird density (from 90 to 175 pairs/km(2. Willow shrub thickets were a hotspot for bird density, but not for species richness. The thickets hosted many specialized species whose main distribution area was south of the tundra. CONCLUSION/SIGNIFICANCE: If current arctic changes result in a shrubification of the landscape as many studies suggested, we would expect an increase in the overall bird abundance together with an increase of local specialists, since they are associated with willow thickets. The majority of these species have a southern origin and their increase in abundance would represent a strengthening of the boreal component in the southern tundra, perhaps at the expense of species typical of the subarctic zone, which appear to be generalists within this zone.

  16. Soil Organic Matter Dynamics and Methane Fluxes at the Forest – Tundra Ecotone in Fennoscandia

    OpenAIRE

    Sjögersten, Sofie

    2003-01-01

    This thesis presents results from several studies that have focused on the carbon and nutrient dynamics in soils at the forest – tundra ecotone in Fennoscandia. The main objectives of the study were: (i) to investigate the links between the physical environment, above-ground vegetation communities, soil carbon storage, nutrient status and the chemical composition of the soil organic matter (SOM), and (ii) to quantify trace gas fluxes (methane and carbon dioxide) between mesic soils and the at...

  17. Regional and landscape-scale variability of Landsat-observed vegetation dynamics in northwest Siberian tundra

    International Nuclear Information System (INIS)

    Widespread increases in Arctic tundra productivity have been documented for decades using coarse-scale satellite observations, but finer-scale observations indicate that changes have been very uneven, with a high degree of landscape- and regional-scale heterogeneity. Here we analyze time-series of the Normalized Difference Vegetation Index (NDVI) observed by Landsat (1984–2012), to assess landscape- and regional-scale variability of tundra vegetation dynamics in the northwest Siberian Low Arctic, a little-studied region with varied soils, landscape histories, and permafrost attributes. We also estimate spatio-temporal rates of land-cover change associated with expansion of tall alder (Alnus) shrublands, by integrating Landsat time-series with very-high-resolution imagery dating to the mid-1960s. We compiled Landsat time-series for eleven widely-distributed landscapes, and performed linear regression of NDVI values on a per-pixel basis. We found positive net NDVI trends (‘greening’) in nine of eleven landscapes. Net greening occurred in alder shrublands in all landscapes, and strong greening tended to correspond to shrublands that developed since the 1960s. Much of the spatial variability of greening within landscapes was linked to landscape physiography and permafrost attributes, while between-landscape variability largely corresponded to differences in surficial geology. We conclude that continued increases in tundra productivity in the region are likely in upland tundra landscapes with fine-textured, cryoturbated soils; these areas currently tend to support discontinuous vegetation cover, but are highly susceptible to rapid increases in vegetation cover, as well as land-cover changes associated with the development of tall shrublands. (paper)

  18. CO2 flux from tundra lichen, moss, and tussock, Council, Alaska: Assessment of spatial representativeness

    Science.gov (United States)

    Kim, Y.; Chae, N.

    2012-12-01

    CO2 flux-measurement in dominant tundra vegetation on the Seward Peninsula of Alaska was examined for spatial representativeness, using a manual chamber system. In order to assess the representativeness of CO2 flux, a 40 m × 40 m (5-m interval; 81 total points) plot was used in June, August, and September of 2011. Average CO2 fluxes in lichen, moss, and tussock tundra were 3.4 ± 2.7, 4.5 ± 2.9, and 7.2 ± 5.7 mgCO2/m2/m during growing season, respectively, suggesting that tussock tundra is a significant CO2 source, especially considering the wide distribution of tussock tundra in the circumpolar region. Further, soil temperature, rather than soil moisture, held the key role in regulating CO2 flux at the study site: CO2 flux from tussock increased linearly as soil temperature increased, while the flux from lichen and moss followed soil temperature nearly exponentially, reflecting differences in surface area covered by the chamber system. Regarding sample size, the 81 total sampling points over June, August, and September satisfy an experimental average that falls within ±10% of full sample average, with a 95% confidence level. However, the number of sampling points for each variety of vegetation during each month must provide at least ±20%, with an 80% confidence level. In order to overcome the logistical constraints, we were required to identify the site's characteristics with a manual chamber system over a 40 m × 40 m plot and to subsequently employ an automated chamber for spatiotemporal representativeness.

  19. Variability of Water Chemistry in Tundra Lakes, Petuniabukta Coast, Central Spitsbergen, Svalbard

    OpenAIRE

    Małgorzata Mazurek; Renata Paluszkiewicz; Grzegorz Rachlewicz; Zbigniew Zwoliński

    2012-01-01

    Samples of water from small tundra lakes located on raised marine terraces on the eastern coast of Petuniabukta (Ebbadalen, Central Spitsbergen) were examined to assess the changes in water chemistry that had occurred during the summer seasons of 2001–2003 and 2006. The unique environmental conditions of the study region include the predominance of sedimentary carbonate and sulphate rocks, low precipitation values, and an active permafrost layer with a maximum thickness of 1.2 m. The average ...

  20. A shrub bending model to calculate the albedo of shrub-tundra

    OpenAIRE

    Ménard, Cécile B.; Essery, Richard; Pomeroy, John; Marsh, Philip; Clark, Douglas B.

    2014-01-01

    At high latitudes, the albedo and energy budget of shrub-tundra landscapes is determined by the relationship between the fractional snow cover and the fraction of vegetation protruding above the snowpack. The exposed vegetation fraction is affected by the bending and/or burial of shrubs in winter and their spring-up during melt. Little is known about the meteorological conditions and snowpack and shrub properties required to cause bending, and few quantitative measurements of bending processe...

  1. Recent Declines in Warming and Vegetation Greening Trends over Pan-Arctic Tundra

    OpenAIRE

    Polyakov, Igor V; Tucker, Compton J.; Pinzon, Jorge E; Epstein, Howard E.; Comiso, Josefino C; Peter A. Bieniek; Walker, Donald A.; Raynolds, Martha K.; Bhatt, Uma S.

    2013-01-01

    Vegetation productivity trends for the Arctic tundra are updated for the 1982–2011 period and examined in the context of land surface temperatures and coastal sea ice. Understanding mechanistic links between vegetation and climate parameters contributes to model advancements that are necessary for improving climate projections. This study employs remote sensing data: Global Inventory Modeling and Mapping Studies (GIMMS) Maximum Normalized Difference Vegetation Index (MaxNDVI), Special Sensor ...

  2. Ground-Based Hyperspectral Characterization of Alaska Tundra Vegetation along Environmental Gradients

    OpenAIRE

    Marcel Schwieder; Epstein, Howard E.; Raynolds, Martha K.; Marcel Buchhorn; Walker, Donald A.; Birgit Heim

    2013-01-01

    Remote sensing has become a valuable tool in monitoring arctic environments. The aim of this paper is ground-based hyperspectral characterization of Low Arctic Alaskan tundra communities along four environmental gradients (regional climate, soil pH, toposequence, and soil moisture) that all vary in ground cover, biomass, and dominating plant communities. Field spectroscopy in connection with vegetation analysis was carried out in summer 2012, along the North American Arctic Transect (NAAT). S...

  3. Ground-Based Hyperspectral Characterization of Alaska Tundra Vegetation along Environmental Gradients

    Directory of Open Access Journals (Sweden)

    Marcel Schwieder

    2013-08-01

    Full Text Available Remote sensing has become a valuable tool in monitoring arctic environments. The aim of this paper is ground-based hyperspectral characterization of Low Arctic Alaskan tundra communities along four environmental gradients (regional climate, soil pH, toposequence, and soil moisture that all vary in ground cover, biomass, and dominating plant communities. Field spectroscopy in connection with vegetation analysis was carried out in summer 2012, along the North American Arctic Transect (NAAT. Spectral metrics were extracted, including the averaged reflectance and absorption-related metrics such as absorption depths and area of continuum removal. The spectral metrics were investigated with respect to “greenness”, biomass, vegetation height, and soil moisture regimes. The results show that the surface reflectances of all sites are similar in shape with a reduced near-infrared (NIR reflectance that is specific for low-growing biomes. The main spectro-radiometric findings are: (i Southern sites along the climate gradient have taller shrubs and greater overall vegetation biomass, which leads to higher reflectance in the NIR. (ii Vegetation height and surface wetness are two antagonists that balance each other out with respect to the NIR reflectance along the toposequence and soil moisture gradients. (iii Moist acidic tundra (MAT sites have “greener” species, more leaf biomass, and green-colored moss species that lead to higher pigment absorption compared to moist non-acidic tundra (MNT sites. (iv MAT and MNT plant community separation via narrowband Normalized Difference Vegetation Index (NDVI shows the potential of hyperspectral remote sensing applications in the tundra.

  4. Distribution patterns of typical enzyme activities in tundra soils on the Fildes Peninsula of maritime Antarctica

    Institute of Scientific and Technical Information of China (English)

    DING Wei; WANG Qing; ZHU Renbin; MA Dawei

    2015-01-01

    Soil enzyme activities can be used as indicators of microbial activity and soil fertility. In this paper, the activities of invertase (IA), phosphatase (PA) and urease (UA) were investigated in tundra soils collected from marine animal colonies, areas of human activity and background areas on Fildes Peninsula, maritime Antarctica. Soil enzyme activities were in the range of 1.0–82.7 mg·kg-1·h-1 for IA, 0.2–8.2 mg·kg-1·h-1 for PA and 0.2–39.8 mg·kg-1·h-1 for UA. The spatial distribution patterns for soil enzyme activities corresponded strongly with marine animal activity and human activity. Significantly higher soil IA and PA activities occurred in penguin colony soils, whereas seal colony soils showed higher UA activity. Statistical analysis indicated that soil IA activity was controlled by the levels of soil nutrients (TOC, TN and TP), PA activity was closely related with TP, and UA activity was affected by the soil pH. Overall, the deposition amount of penguin guano or seal excreta could impact the distribution of enzyme activity in Antarctic tundra soils. Multiple stepwise regression models were established between the enzyme activities, soil physicochemical properties and heavy metals Cu and Zn ([IA]=0.7[TP]–0.2[Cu]+22.3[TN]+15.1, [PA]=0.3[TP]+0.03[Mc]+0.2, [UA]=16.7[pH]–0.5[Cu]+ 0.4[Zn]–72.6). These models could be used to predict enzyme activities in the tundra soils, which could be helpful to study the effects of marine animal activity and environmental change on tundra ecosystems in maritime Antarctica.

  5. Tundra soil carbon is vulnerable to rapid microbial decomposition under climate warming

    Science.gov (United States)

    Xue, Kai; M. Yuan, Mengting; J. Shi, Zhou; Qin, Yujia; Deng, Ye; Cheng, Lei; Wu, Liyou; He, Zhili; van Nostrand, Joy D.; Bracho, Rosvel; Natali, Susan; Schuur, Edward. A. G.; Luo, Chengwei; Konstantinidis, Konstantinos T.; Wang, Qiong; Cole, James R.; Tiedje, James M.; Luo, Yiqi; Zhou, Jizhong

    2016-06-01

    Microbial decomposition of soil carbon in high-latitude tundra underlain with permafrost is one of the most important, but poorly understood, potential positive feedbacks of greenhouse gas emissions from terrestrial ecosystems into the atmosphere in a warmer world. Using integrated metagenomic technologies, we showed that the microbial functional community structure in the active layer of tundra soil was significantly altered after only 1.5 years of warming, a rapid response demonstrating the high sensitivity of this ecosystem to warming. The abundances of microbial functional genes involved in both aerobic and anaerobic carbon decomposition were also markedly increased by this short-term warming. Consistent with this, ecosystem respiration (Reco) increased up to 38%. In addition, warming enhanced genes involved in nutrient cycling, which very likely contributed to an observed increase (30%) in gross primary productivity (GPP). However, the GPP increase did not offset the extra Reco, resulting in significantly more net carbon loss in warmed plots compared with control plots. Altogether, our results demonstrate the vulnerability of active-layer soil carbon in this permafrost-based tundra ecosystem to climate warming and the importance of microbial communities in mediating such vulnerability.

  6. Summertime surface O3 behavior and deposition to tundra in the Alaskan Arctic

    Science.gov (United States)

    Van Dam, Brie; Helmig, Detlev; Doskey, Paul V.; Oltmans, Samuel J.

    2016-07-01

    Atmospheric turbulence quantities, boundary layer ozone (O3) levels, and O3 deposition to the tundra surface were investigated at Toolik Lake, AK, during the 2011 summer season. Beginning immediately after snowmelt, a diurnal cycle of O3 in the atmospheric surface layer developed with daytime O3 maxima, and minima during low-light hours, resulting in a mean amplitude of 13 ppbv. This diurnal O3 cycle is far larger than observed at other high Arctic locations during the snow-free season. During the snow-free months of June, July, and August, O3 deposition velocities were ˜3 to 5 times faster than during May, when snow covered the ground most of the month. The overall mean O3 deposition velocity between June and August was 0.10 cm s-1. The month of June had the highest diurnal variation, with a median O3 deposition velocity of 0.2 cm s-1 during the daytime and 0.08 cm s-1 during low-light conditions. These values are slightly lower than previously reported summertime deposition velocities in northern latitudes over tundra or fen. O3 loss during low-light periods was attributed to a combination of surface deposition to the tundra and stable boundary layer conditions. We also hypothesize that emissions of reactive biogenic volatile organic compounds into the shallow boundary layer may contribute to nighttime O3 loss.

  7. Mapping wildfire burn severity in the Arctic Tundra from downsampled MODIS data

    Science.gov (United States)

    Kolden, Crystal A.; Rogan, John

    2013-01-01

    Wildfires are historically infrequent in the arctic tundra, but are projected to increase with climate warming. Fire effects on tundra ecosystems are poorly understood and difficult to quantify in a remote region where a short growing season severely limits ground data collection. Remote sensing has been widely utilized to characterize wildfire regimes, but primarily from the Landsat sensor, which has limited data acquisition in the Arctic. Here, coarse-resolution remotely sensed data are assessed as a means to quantify wildfire burn severity of the 2007 Anaktuvuk River Fire in Alaska, the largest tundra wildfire ever recorded on Alaska's North Slope. Data from Landsat Thematic Mapper (TM) and downsampled Moderate-resolution Imaging Spectroradiometer (MODIS) were processed to spectral indices and correlated to observed metrics of surface, subsurface, and comprehensive burn severity. Spectral indices were strongly correlated to surface severity (maximum R2 = 0.88) and slightly less strongly correlated to substrate severity. Downsampled MODIS data showed a decrease in severity one year post-fire, corroborating rapid vegetation regeneration observed on the burned site. These results indicate that widely-used spectral indices and downsampled coarse-resolution data provide a reasonable supplement to often-limited ground data collection for analysis and long-term monitoring of wildfire effects in arctic ecosystems.

  8. Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Snow Albedo Product (MCD43A) over Tundra

    Science.gov (United States)

    Wang, Zhuosen; Schaaf, Crystal B.; Chopping, Mark J.; Strahler, Alan H.; Wang, Jindi; Roman, Miguel O.; Rocha, Adrian V.; Woodcock, Curtis E.; Shuai, Yanmin

    2012-01-01

    This study assesses the MODIS standard Bidirectional Reflectance Distribution Function (BRDF)/Albedo product, and the daily Direct Broadcast BRDF/Albedo algorithm at tundra locations under large solar zenith angles and high anisotropic diffuse illumination and multiple scattering conditions. These products generally agree with ground-based albedo measurements during the snow cover period when the Solar Zenith Angle (SZA) is less than 70deg. An integrated validation strategy, including analysis of the representativeness of the surface heterogeneity, is performed to decide whether direct comparisons between field measurements and 500- m satellite products were appropriate or if the scaling of finer spatial resolution airborne or spaceborne data was necessary. Results indicate that the Root Mean Square Errors (RMSEs) are less than 0.047 during the snow covered periods for all MCD43 albedo products at several Alaskan tundra areas. The MCD43 1- day daily albedo product is particularly well suited to capture the rapidly changing surface conditions during the spring snow melt. Results also show that a full expression of the blue sky albedo is necessary at these large SZA snow covered areas because of the effects of anisotropic diffuse illumination and multiple scattering. In tundra locations with dark residue as a result of fire, the MODIS albedo values are lower than those at the unburned site from the start of snowmelt.

  9. Multisensor NDVI-Based Monitoring of the Tundra-Taiga Interface (Mealy Mountains, Labrador, Canada

    Directory of Open Access Journals (Sweden)

    Heather Ward

    2013-03-01

    Full Text Available The analysis of a series of five normalized difference vegetation index (NDVI images produced information about a Labrador (Canada portion of the tundra-taiga interface. The twenty-five year observation period ranges from 1983 to 2008. The series composed of Landsat, SPOT and ASTER images, provided insight into regional scale characteristics of the tundra-taiga interface that is usually monitored from coarse resolution images. The image set was analyzed by considering an ordinal classification of the NDVI to account for the cumulative effect of differences of near-infrared spectral resolutions, the temperature anomalies, and atmospheric conditions. An increasing trend of the median values in the low, intermediate and high NDVI classes is clearly marked while accounting for variations attributed to cross-sensor radiometry, phenology and atmospheric disturbances. An encroachment of the forest on the tundra for the whole study area was estimated at 0 to 60 m, depending on the period of observation, as calculated by the difference between the median retreat and advance of an estimated location of the tree line. In small sections, advances and retreats of up to 320 m are reported for the most recent four- and seven-year periods of observations.

  10. Fungal Biodiversity in the Alpine Tarfala Valley

    Directory of Open Access Journals (Sweden)

    Claudia Coleine

    2015-10-01

    Full Text Available Biological soil crusts (BSCs are distributed worldwide in all semiarid and arid lands, where they play a determinant role in element cycling and soil development. Although much work has concentrated on BSC microbial communities, free-living fungi have been hitherto largely overlooked. The aim of this study was to examine the fungal biodiversity, by cultural-dependent and cultural-independent approaches, in thirteen samples of Arctic BSCs collected at different sites in the Alpine Tarfala Valley, located on the slopes of Kebnekaise, the highest mountain in northern Scandinavia. Isolated fungi were identified by both microscopic observation and molecular approaches. Data revealed that the fungal assemblage composition was homogeneous among the BSCs analyzed, with low biodiversity and the presence of a few dominant species; the majority of fungi isolated belonged to the Ascomycota, and Cryptococcus gilvescens and Pezoloma ericae were the most frequently-recorded species. Ecological considerations for the species involved and the implication of our findings for future fungal research in BSCs are put forward.

  11. Environmental controls on alpine cirque size

    Science.gov (United States)

    Delmas, Magali; Gunnell, Yanni; Calvet, Marc

    2014-02-01

    Pleistocene alpine cirques are emblematic landforms of mountain scenery, yet their deceptively simple template conceals complex controlling variables. This comparative study presents a new database of 1071 cirques, the largest of its kind, located in the French eastern Pyrenees. It is embedded in a review of previous work on cirque morphometry and thus provides a perspective on a global scale. First-order cirque attributes of length, width, and amplitude were measured; and their power as predictors of climatic and lithological variables and as proxies for the duration of glacier activity was tested using ANOVA, simple and multiple linear regression, and their various post-hoc tests. Conventional variables such as cirque aspect, floor elevation, and exposure with respect to regional precipitation-bearing weather systems are shown to present some consistency in spatial patterns determined by solar radiation, the morning-afternoon effect, and wind-blown snow accumulation in the lee of ridgetops. This confirms in greater detail the previously encountered links between landforms and climate. A special focus on the influence of bedrock lithology, a previously neglected nonclimatic variable, highlights the potential for spurious relations in the use of cirque size as a proxy of past environmental conditions. Cirques are showcased as complex landforms resulting from the combination of many climatic and nonclimatic variables that remain difficult to rank by order of importance. Apart from a few statistically weak trends, several combinations of different factors in different proportions are shown to produce similar morphometric outcomes, suggesting a case of equifinality in landform development.

  12. Human behaviour towards climatic change during the 4th millennium BC in the Swiss Alpine forelands

    DEFF Research Database (Denmark)

    Karg, Sabine

    Human behaviour towards climatic change during the 4th millennium BC in the Swiss Alpine forelands.......Human behaviour towards climatic change during the 4th millennium BC in the Swiss Alpine forelands....

  13. Immune responses to Mycoplasma conjunctivae in alpine ibex, alpine chamois, and domestic sheep in Switzerland.

    Science.gov (United States)

    Degiorgis, M P; Abdo, E M; Nicolet, J; Frey, J; Mayer, D; Giacometti, M

    2000-04-01

    The humoral immune response of three alpine chamois (Rupicapra rupicapra rupicapra), two alpine ibex (Capra ibex ibex) and three domestic sheep naturally affected with infectious keratoconjunctivitis (IKC), and four ibex and two sheep experimentally infected with Mycoplasma conjunctivae was analysed. In addition, the local immune response to M. conjunctivae was analysed using conjunctival washes from chamois and sheep. Immunoblot analysis of sera using whole cell antigens of M. conjunctivae revealed the major immunogenic proteins which had molecular masses of 175, 83, 68, 60, 50, 42, 36, and 33 kDa. Major antigens were found at 83, 68, 60, and 42 kDa in both sera and conjunctival washes from naturally infected animals of all three Caprinae species. In experimentally infected animals, antibodies to the 68 and 60 kDa antigens were dominant. Naturally infected animals showed much stronger immune reactions than those experimentally infected, and specific antibodies appeared 2 to 4 wk after experimental infection. To evaluate possible cross-reactions, whole cell antigen of M. conjunctivae was analysed by immunoblot against hyperimmune sera of closely related Mycoplasma spp. Antibodies to the 175, 73, 68, 60, and 33 kDa antigens appeared to be specific to M. conjunctivae. Cross-reactions mainly with 83, 50, and 42 kDa antigens were detected, in particular with M. ovipneumoniae and M. bovoculi hyperimmune sera, but also with antisera against M. capricolum capricolum and M. putrefaciens.

  14. Changing Climate Sensitivity in Response to Forest-Tundra Snow Albedo Feedback during the mid to late Pliocene Cooling

    Science.gov (United States)

    Paiewonsky, P.

    2015-12-01

    The forest-tundra snow albedo feedback is an important feedback in Earth's climate system, especially due to its potential role in modulating glacial cycles. Until now, little research has been done on how the strength of this feedback might vary with the background climate state. Over the last 4 million years, I hypothesize that the feedback has been generally weaker under warm Northern Hemispheric conditions when tundra has been primarily confined to the high Arctic and forest has extended to most of the Arctic coastline than under cooler Northern Hemispheric conditions in which the forest-tundra boundary has generally lain to the south, extending across the interiors of the large continental land masses. To test the hypothesis of the weakened/strengthened feedback, I used an Earth System Model of Intermediate Complexity that consists of a dynamic terrestrial vegetation model coupled to a climate model. A set of time-slice experiments with different orbital and greenhouse gas concentrations were analyzed. In one set of experiments, the feedback gain with respect to annual average top-of-atmosphere net short wave radiation due to vegetation was 1.42 for modern conditions but only 1.14 for the mid-Pliocene. Additionally, we compared experiments with different shortwave-radiation parameterizations, which differed in the amount of shortwave energy flux reaching the surface (and subsequently affecting vegetative biomass). These techniques allowed us to isolate the mechanisms responsible for the varying strength of the forest-tundra snow albedo feedback. The results also show that many factors affect the strength of feedback. In this presentation I will concentrate on the availability of land for conversion of forest to tundra (and vice versa), cloud cover near the forest-tundra boundary, and the integrated surface insolation contrast between tundra and forest during the snow-covered season.

  15. Modeling dynamics of tundra plant communities on the Yamal Peninsula, Russia, in response to climate change and grazing pressure

    International Nuclear Information System (INIS)

    Understanding the responses of the arctic tundra biome to a changing climate requires knowledge of the complex interactions among the climate, soils and biological system. This study investigates the individual and interaction effects of climate change and reindeer grazing across a variety of climate zones and soil texture types on tundra vegetation community dynamics using an arctic vegetation model that incorporates the reindeer diet, where grazing is a function of both foliar nitrogen concentration and reindeer forage preference. We found that grazing is important, in addition to the latitudinal climate gradient, in controlling tundra plant community composition, explaining about 13% of the total variance in model simulations for all arctic tundra subzones. The decrease in biomass of lichen, deciduous shrub and graminoid plant functional types caused by grazing is potentially dampened by climate warming. Moss biomass had a nonlinear response to increased grazing intensity, and such responses were stronger when warming was present. Our results suggest that evergreen shrubs may benefit from increased grazing intensity due to their low palatability, yet a growth rate sensitivity analysis suggests that changes in nutrient uptake rates may result in different shrub responses to grazing pressure. Heavy grazing caused plant communities to shift from shrub tundra toward moss, graminoid-dominated tundra in subzones C and D when evergreen shrub growth rates were decreased in the model. The response of moss, lichen and forbs to warming varied across the different subzones. Initial vegetation responses to climate change during transient warming are different from the long term equilibrium responses due to shifts in the controlling mechanisms (nutrient limitation versus competition) within tundra plant communities.

  16. Modeling dynamics of tundra plant communities on the Yamal Peninsula, Russia, in response to climate change and grazing pressure

    Science.gov (United States)

    Yu, Q.; Epstein, H. E.; Walker, D. A.; Frost, G. V.; Forbes, B. C.

    2011-10-01

    Understanding the responses of the arctic tundra biome to a changing climate requires knowledge of the complex interactions among the climate, soils and biological system. This study investigates the individual and interaction effects of climate change and reindeer grazing across a variety of climate zones and soil texture types on tundra vegetation community dynamics using an arctic vegetation model that incorporates the reindeer diet, where grazing is a function of both foliar nitrogen concentration and reindeer forage preference. We found that grazing is important, in addition to the latitudinal climate gradient, in controlling tundra plant community composition, explaining about 13% of the total variance in model simulations for all arctic tundra subzones. The decrease in biomass of lichen, deciduous shrub and graminoid plant functional types caused by grazing is potentially dampened by climate warming. Moss biomass had a nonlinear response to increased grazing intensity, and such responses were stronger when warming was present. Our results suggest that evergreen shrubs may benefit from increased grazing intensity due to their low palatability, yet a growth rate sensitivity analysis suggests that changes in nutrient uptake rates may result in different shrub responses to grazing pressure. Heavy grazing caused plant communities to shift from shrub tundra toward moss, graminoid-dominated tundra in subzones C and D when evergreen shrub growth rates were decreased in the model. The response of moss, lichen and forbs to warming varied across the different subzones. Initial vegetation responses to climate change during transient warming are different from the long term equilibrium responses due to shifts in the controlling mechanisms (nutrient limitation versus competition) within tundra plant communities.

  17. Photochemistry and aerosol in alpine region: mixing and transport

    International Nuclear Information System (INIS)

    The Alpine arc deeply interacts with general circulation of atmosphere. By studying configurations in summer and winter over various Alpine areas, this work explains how mixing and transport of airborne pollutants happen, both gaseous and particulate matter, from their emission sources to free troposphere. Using observational results and a comprehensive Eulerian modelling system, one focuses on mechanisms of pollution by ozone in summer and by particulate matter and benzene in winter. After having validated the modelling system using datasets from field experiments POVA, GRENOPHOT and ESCOMPTE, it is applied on two periods with principal interest in the Grenoble area: one is the heat-wave August 2003 and the other is a long episode of thermal inversion in February 2005. Uncertainties are also calculated. One finishes by applying the modelling chain to understand how a stratospheric intrusion following a tropopause fold affected the Alpine region in July 2004. (author)

  18. Local Area Weather Radar in Alpine Setting

    Science.gov (United States)

    Savina, M.

    2012-04-01

    Space-time variability of precipitation in orographically complex regions is a challenging research topic. The difficult accessibility of remote regions and the high elevations make difficult the operation of conventional raingauges and reduce the visibility of large scale radars. A solution to this limitation might be the use of a number of cost-effective short-range X-band radars as complement to raingauges and conventional, large and expensive weather radars. This paper presents the results of a pilot experiment, which aimed at i) developing and assessing the performance of a cost-effective X-band Local Area Weather Radar (LAWR) located in the orographically complex Alpine region and ii) testing whether it could lead to better understanding of the nature of the precipitation process, e.g. identifying any possible dependence between precipitation and topography. The LAWR was deployed between August 2007 and October 2011 on the summit of the Kl. Matterhorn, located in the Swiss Alps at 3883 m a.s.l. (Valais, Switzerland). This was the first time that a cost-effective X-band radar was installed at such elevation and could be tested in operation-like conditions. Beside the technological improvements that were necessary for a reliable functioning of the LAWR hardware, much effort went into the development of a set of radar corrections and into the design of a new Alpine Radar COnversion Model (ARCOM), which includes the algorithms necessary to convert radar received echoes into precipitation rates, specifically accounting for the presence of the pronounced topography. The ARCOM was developed and tested on the basis of a set of precipitation events for which precipitation was measured also by 43 automatic raingauges located within 60 km range from the radar antenna. Conversely to the state-of-the-art conversion models, ARCOM accounts not only for the seasonal climatological condition but also of geometric and orographic forcings such as partial beam filling and beam

  19. Molecular detection of hematozoa infections in tundra swans relative to migration patterns and ecological conditions at breeding grounds.

    Directory of Open Access Journals (Sweden)

    Andrew M Ramey

    Full Text Available Tundra swans (Cygnus columbianus are broadly distributed in North America, use a wide variety of habitats, and exhibit diverse migration strategies. We investigated patterns of hematozoa infection in three populations of tundra swans that breed in Alaska using satellite tracking to infer host movement and molecular techniques to assess the prevalence and genetic diversity of parasites. We evaluated whether migratory patterns and environmental conditions at breeding areas explain the prevalence of blood parasites in migratory birds by contrasting the fit of competing models formulated in an occupancy modeling framework and calculating the detection probability of the top model using Akaike Information Criterion (AIC. We described genetic diversity of blood parasites in each population of swans by calculating the number of unique parasite haplotypes observed. Blood parasite infection was significantly different between populations of Alaska tundra swans, with the highest estimated prevalence occurring among birds occupying breeding areas with lower mean daily wind speeds and higher daily summer temperatures. Models including covariates of wind speed and temperature during summer months at breeding grounds better predicted hematozoa prevalence than those that included annual migration distance or duration. Genetic diversity of blood parasites in populations of tundra swans appeared to be relative to hematozoa prevalence. Our results suggest ecological conditions at breeding grounds may explain differences of hematozoa infection among populations of tundra swans that breed in Alaska.

  20. Molecular detection of hematozoa infections in tundra swans relative to migration patterns and ecological conditions at breeding grounds

    Science.gov (United States)

    Ramey, Andrew M.; Ely, Craig R.; Schmutz, Joel A.; Pearce, John M.; Heard, Darryl J.

    2012-01-01

    Tundra swans (Cygnus columbianus) are broadly distributed in North America, use a wide variety of habitats, and exhibit diverse migration strategies. We investigated patterns of hematozoa infection in three populations of tundra swans that breed in Alaska using satellite tracking to infer host movement and molecular techniques to assess the prevalence and genetic diversity of parasites. We evaluated whether migratory patterns and environmental conditions at breeding areas explain the prevalence of blood parasites in migratory birds by contrasting the fit of competing models formulated in an occupancy modeling framework and calculating the detection probability of the top model using Akaike Information Criterion (AIC). We described genetic diversity of blood parasites in each population of swans by calculating the number of unique parasite haplotypes observed. Blood parasite infection was significantly different between populations of Alaska tundra swans, with the highest estimated prevalence occurring among birds occupying breeding areas with lower mean daily wind speeds and higher daily summer temperatures. Models including covariates of wind speed and temperature during summer months at breeding grounds better predicted hematozoa prevalence than those that included annual migration distance or duration. Genetic diversity of blood parasites in populations of tundra swans appeared to be relative to hematozoa prevalence. Our results suggest ecological conditions at breeding grounds may explain differences of hematozoa infection among populations of tundra swans that breed in Alaska.

  1. Tagliamento, the king of Alpine rivers

    Science.gov (United States)

    Imbriani, Nadia

    2016-04-01

    The Tagliamento river is usually described as the king of the Alpine rivers because it is an extraordinary example of braided gravel-bed river in Europe. It flows in Friuli Venezia Giulia, a region in north-eastern Italy. It has preserved its original ecosystem which has never been changed significantly by irresponsible human interference. Therefore, vegetated islands and braid bars, due to the typical network of channels the river creates, have always been an uncontaminated natural habitat for a wide variety of species of flora and fauna. The Pinzano Bridge, near San Daniele del Friuli, collapsed on 4th November 1966 because of an overflow of water from Tagliamento. From that time, lowlands territorial authorities would like to build retention basins to prevent the river from floodings. A study about the bio-geological survey carried out from a Manzini High School project, chiefly aims to study this ecosystem, which combines the dynamic nature of the Tagliamento with the biodiversity of the whole area where it flows. In the previous years, some classes were involved in this school project. After visiting the river area and taking several photographs of it, the students had the opportunity to reflect upon the devastating environmental impact which the construction of retention basins would cause. They illustrated and analyzed both the solutions offered by some local governors and the objections raised by the World Wide Fund For Nature (WWF). In the near future, other students will continue studying the Tagliamento river so as to be able to appreciate one of the local rarities nature offers, in the hope that the unique geomorphological features of this site of undoubted scientific interest could be kept intact for a very long time.

  2. Transient thermal effects in Alpine permafrost

    Directory of Open Access Journals (Sweden)

    J. Noetzli

    2009-04-01

    Full Text Available In high mountain areas, permafrost is important because it influences the occurrence of natural hazards, because it has to be considered in construction practices, and because it is sensitive to climate change. The assessment of its distribution and evolution is challenging because of highly variable conditions at and below the surface, steep topography and varying climatic conditions. This paper presents a systematic investigation of effects of topography and climate variability that are important for subsurface temperatures in Alpine bedrock permafrost. We studied the effects of both, past and projected future ground surface temperature variations on the basis of numerical experimentation with simplified mountain topography in order to demonstrate the principal effects. The modeling approach applied combines a distributed surface energy balance model and a three-dimensional subsurface heat conduction scheme. Results show that the past climate variations that essentially influence present-day permafrost temperatures at depth of the idealized mountains are the last glacial period and the major fluctuations in the past millennium. Transient effects from projected future warming, however, are likely larger than those from past climate conditions because larger temperature changes at the surface occur in shorter time periods. We further demonstrate the accelerating influence of multi-lateral warming in steep and complex topography for a temperature signal entering the subsurface as compared to the situation in flat areas. The effects of varying and uncertain material properties (i.e., thermal properties, porosity, and freezing characteristics on the subsurface temperature field were examined in sensitivity studies. A considerable influence of latent heat due to water in low-porosity bedrock was only shown for simulations over time periods of decades to centuries. At the end, the model was applied to the topographic setting of the Matterhorn

  3. Estimating Temperature Fields from MODIS Land Surface Temperature and Air Temperature Observations in a Sub-Arctic Alpine Environment

    Directory of Open Access Journals (Sweden)

    Scott N. Williamson

    2014-01-01

    Full Text Available Spatially continuous satellite infrared temperature measurements are essential for understanding the consequences and drivers of change, at local and regional scales, especially in northern and alpine environments dominated by a complex cryosphere where in situ observations are scarce. We describe two methods for producing daily temperature fields using MODIS “clear-sky” day-time Land Surface Temperatures (LST. The Interpolated Curve Mean Daily Surface Temperature (ICM method, interpolates single daytime Terra LST values to daily means using the coincident diurnal air temperature curves. The second method calculates daily mean LST from daily maximum and minimum LST (MMM values from MODIS Aqua and Terra. These ICM and MMM models were compared to daily mean air temperatures recorded between April and October at seven locations in southwest Yukon, Canada, covering characteristic alpine land cover types (tundra, barren, glacier at elevations between 1,408 m and 2,319 m. Both methods for producing mean daily surface temperatures have advantages and disadvantages. ICM signals are strongly correlated with air temperature (R2 = 0.72 to 0.86, but have relatively large variability (RMSE = 4.09 to 4.90 K, while MMM values had a stronger correlation to air temperature (R2 = 0.90 and smaller variability (RMSE = 2.67 K. Finally, when comparing 8-day LST averages, aggregated from the MMM method, to air temperature, we found a high correlation (R2 = 0.84 with less variability (RMSE = 1.54 K. Where the trend was less steep and the y-intercept increased by 1.6 °C compared to the daily correlations. This effect is likely a consequence of LST temperature averages being differentially affected by cloud cover over warm and cold surfaces. We conclude that satellite infrared skin temperature (e.g., MODIS LST, which is often aggregated into multi-day composites to mitigate data reductions caused by cloud cover, changes in its relationship to air temperature

  4. OBSERVATION AND MODELING FOR TERRESTRIAL PROCESSES IN ALPINE MEADOW

    Institute of Scientific and Technical Information of China (English)

    姚德良; 张强; 李家春; 谢正桐; 沈振西

    2004-01-01

    The water-heat transfer process between land and atmosphere in Haibei alpine meadow area has been systematically observed. A multi-layer coupling model for landatmosphere interaction was presented with special attention paid to the moisture transfer in leaf stomata under unsaturated condition. A profound investigation on the physical process of turbulent transfer inside the vegetation has been performed with a revised formula of water absorption for root system. The present model facilitates the study of vertically distributed physical variables in detail. Numerical simulation was conducted according to the transfer process of Kinesia humility meadow in the area of Haibei Alpine Meadow Ecosystem Station, CAS. The calculated results agree well with observation.

  5. Photochemistry and aerosol in alpine region: mixing and transport; Photochimie et aerosol en region alpine: melange et transport

    Energy Technology Data Exchange (ETDEWEB)

    Chaxel, E

    2006-11-15

    The Alpine arc deeply interacts with general circulation of atmosphere. By studying configurations in summer and winter over various Alpine areas, this work explains how mixing and transport of airborne pollutants happen, both gaseous and particulate matter, from their emission sources to free troposphere. Using observational results and a comprehensive Eulerian modelling system, one focuses on mechanisms of pollution by ozone in summer and by particulate matter and benzene in winter. After having validated the modelling system using datasets from field experiments POVA, GRENOPHOT and ESCOMPTE, it is applied on two periods with principal interest in the Grenoble area: one is the heat-wave August 2003 and the other is a long episode of thermal inversion in February 2005. Uncertainties are also calculated. One finishes by applying the modelling chain to understand how a stratospheric intrusion following a tropopause fold affected the Alpine region in July 2004. (author)

  6. Multi-decadal changes in tundra environments and ecosystems: Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)

    DEFF Research Database (Denmark)

    Callaghan, Terry V.; Tweedie, Craig E.; Åkerman, Jonas;

    2011-01-01

    Understanding the responses of tundra systems to global change has global implications. Most tundra regions lack sustained environmental monitoring and one of the only ways to document multi-decadal change is to resample historic research sites. The International Polar Year (IPY) provided a uniqu...

  7. The role of summer precipitation and summer temperature in establishment and growth of dwarf shrub Betula nana in northeast Siberian tundra

    DEFF Research Database (Denmark)

    Li, Bingxi; Heijmans, Monique M P D; Berendse, Frank;

    2016-01-01

    It is widely believed that deciduous tundra-shrub dominance is increasing in the pan-Arctic region, mainly due to rising temperature. We sampled dwarf birch (Betula nana L.) at a northeastern Siberian tundra site and used dendrochronological methods to explore the relationship between climatic...

  8. Nitrogen accumulation and partitioning in a High Arctic tundra ecosystem from extreme atmospheric N deposition events.

    Science.gov (United States)

    Choudhary, Sonal; Blaud, Aimeric; Osborn, A Mark; Press, Malcolm C; Phoenix, Gareth K

    2016-06-01

    Arctic ecosystems are threatened by pollution from recently detected extreme atmospheric nitrogen (N) deposition events in which up to 90% of the annual N deposition can occur in just a few days. We undertook the first assessment of the fate of N from extreme deposition in High Arctic tundra and are presenting the results from the whole ecosystem (15)N labelling experiment. In 2010, we simulated N depositions at rates of 0, 0.04, 0.4 and 1.2 g Nm(-2)yr(-1), applied as (15)NH4(15)NO3 in Svalbard (79(°)N), during the summer. Separate applications of (15)NO3(-) and (15)NH4(+) were also made to determine the importance of N form in their retention. More than 95% of the total (15)N applied was recovered after one growing season (~90% after two), demonstrating a considerable capacity of Arctic tundra to retain N from these deposition events. Important sinks for the deposited N, regardless of its application rate or form, were non-vascular plants>vascular plants>organic soil>litter>mineral soil, suggesting that non-vascular plants could be the primary component of this ecosystem to undergo measurable changes due to N enrichment from extreme deposition events. Substantial retention of N by soil microbial biomass (70% and 39% of (15)N in organic and mineral horizon, respectively) during the initial partitioning demonstrated their capacity to act as effective buffers for N leaching. Between the two N forms, vascular plants (Salix polaris) in particular showed difference in their N recovery, incorporating four times greater (15)NO3(-) than (15)NH4(+), suggesting deposition rich in nitrate will impact them more. Overall, these findings show that despite the deposition rates being extreme in statistical terms, biologically they do not exceed the capacity of tundra to sequester pollutant N during the growing season. Therefore, current and future extreme events may represent a major source of eutrophication. PMID:26956177

  9. Phytomass patterns across a temperature gradient of the North American arctic tundra

    Science.gov (United States)

    Epstein, Howard E.; Walker, Donald A.; Raynolds, Martha K.; Jia, Gensuo J.; Kelley, Alexia M.

    2008-09-01

    Only a few studies to date have collectively examined the vegetation biomass and production of arctic tundra ecosystems and their relationships to broadly ranging climate variables. An additional complicating factor for studying vegetation of arctic tundra is the high spatial variability associated with small patterned-ground features, resulting from intense freeze-thaw processes. In this study, we sampled and analyzed the aboveground plant biomass components of patterned-ground ecosystems in the Arctic of northern Alaska and Canada along an 1800-km north-south gradient that spans approximately 11°C of mean July temperatures. Vegetation biomass was analyzed as functions of the summer warmth index (SWI-sum of mean monthly temperatures > 0°C). The total absolute biomass (g m-2) and biomass of shrubs increased monotonically with SWI, however, biomass of nonvascular species (mosses and lichens), were a parabolic function of SWI, with greatest values at the ends of the gradient. The components of plant biomass on patterned-ground features (i.e., on nonsorted circles or within small polygons) were constrained to a greater degree with colder climate than undisturbed tundra, likely due to the effect of frost heave disturbances on the vegetation. There were also clear differences in the relative abundances of vascular versus nonvascular plants on and off patterned-ground features along the SWI gradient. The spatial patterns of biomass differ among plant functional groups and suggest that plant community responses to temperature, and land-surface processes that produce patterned-ground features, are quite complex.

  10. Inter-annual carbon dioxide uptake of a wet sedge tundra ecosystem in the Arctic

    OpenAIRE

    Harazono, Yoshinobu; Mano, Masayoshi; Miyata, Akira; Zulueta, Rommel C.; Oechel, Walter C.

    2011-01-01

    The CO2 flux of a wet sedge tundra ecosystem in the Arctic, at Barrow, Alaska, has been measured by the eddy correlation method since spring 1999, and the CO2 uptake by the vegetation during the spring and growing periods was examined between 1999 and 2000. CO2 flux changed to a sink immediately after the spring thaw in 1999 and the photosynthetic activity was high in the first half of the growing period. At this time the air temperature was low and solar radiation was high. In the 2000 seaso...

  11. Phenological dynamics of arctic tundra vegetation and its implications on satellite imagery interpretation

    Science.gov (United States)

    Juutinen, Sari; Aurela, Mika; Mikola, Juha; Räsänen, Aleksi; Virtanen, Tarmo

    2016-04-01

    Remote sensing is a key methodology when monitoring the responses of arctic ecosystems to climatic warming. The short growing season and rapid vegetation development, however, set demands to the timing of image acquisition in the arctic. We used multispectral very high spatial resolution satellite images to study the effect of vegetation phenology on the spectral reflectance and image interpretation in the low arctic tundra in coastal Siberia (Tiksi, 71°35'39"N, 128°53'17"E). The study site mainly consists of peatlands, tussock, dwarf shrub, and grass tundra, and stony areas with some lichen and shrub patches. We tested the hypotheses that (1) plant phenology is responsive to the interannual weather variation and (2) the phenological state of vegetation has an impact on satellite image interpretation and the ability to distinguish between the plant communities. We used an empirical transfer function with temperature sums as drivers to reconstruct daily leaf area index (LAI) for the different plant communities for years 2005, and 2010-2014 based on measured LAI development in summer 2014. Satellite images, taken during growing seasons, were acquired for two years having late and early spring, and short and long growing season, respectively. LAI dynamics showed considerable interannual variation due to weather variation, and particularly the relative contribution of graminoid dominated communities was sensitive to these phenology shifts. We have also analyzed the differences in the reflectance values between the two satellite images taking account the LAI dynamics. These results will increase our understanding of the pitfalls that may arise from the timing of image acquisition when interpreting the vegetation structure in a heterogeneous tundra landscape. Very high spatial resolution multispectral images are available at reasonable cost, but not in high temporal resolution, which may lead to compromises when matching ground truth and the imagery. On the other hand

  12. Carbon dioxide exchange in three tundra sites show a dissimilar response to environmental variables

    DEFF Research Database (Denmark)

    Mbufong, Herbert Njuabe; Lund, Magnus; Christensen, Torben Røjle;

    2015-01-01

    variability. An improved understanding of the control of ancillary variables on net ecosystem exchange (NEE), gross primary production (GPP) and ecosystem respiration (Re) will improve the accuracy with which CO2 exchange seasonality in Arctic tundra ecosystems is modelled. Fluxes were measured with the eddy...... Lake. Growing season NEE correlated mainly to cumulative radiation and temperature-related variables at Zackenberg, while at Daring Lake the same variables showed significant correlations with the partitioned fluxes (GPP and Re). Stordalen was temperature dependent during the growing season. This study...

  13. Arctic Tundra Vegetation Functional Types Based on Photosynthetic Physiology and Optical Properties

    Science.gov (United States)

    Huemmrich, Karl Fred; Gamon, John A.; Tweedie, Craig E.; Campbell, Petya K. Entcheva; Landis, David R.; Middleton, Elizabeth M.

    2013-01-01

    Non-vascular plants (lichens and mosses) are significant components of tundra landscapes and may respond to climate change differently from vascular plants affecting ecosystem carbon balance. Remote sensing provides critical tools for monitoring plant cover types, as optical signals provide a way to scale from plot measurements to regional estimates of biophysical properties, for which spatial-temporal patterns may be analyzed. Gas exchange measurements were collected for pure patches of key vegetation functional types (lichens, mosses, and vascular plants) in sedge tundra at Barrow, AK. These functional types were found to have three significantly different values of light use efficiency (LUE) with values of 0.013 plus or minus 0.0002, 0.0018 plus or minus 0.0002, and 0.0012 plus or minus 0.0001 mol C mol (exp -1) absorbed quanta for vascular plants, mosses and lichens, respectively. Discriminant analysis of the spectra reflectance of these patches identified five spectral bands that separated each of these vegetation functional types as well as nongreen material (bare soil, standing water, and dead leaves). These results were tested along a 100 m transect where midsummer spectral reflectance and vegetation coverage were measured at one meter intervals. Along the transect, area-averaged canopy LUE estimated from coverage fractions of the three functional types varied widely, even over short distances. The patch-level statistical discriminant functions applied to in situ hyperspectral reflectance data collected along the transect successfully unmixed cover fractions of the vegetation functional types. The unmixing functions, developed from the transect data, were applied to 30 m spatial resolution Earth Observing-1 Hyperion imaging spectrometer data to examine variability in distribution of the vegetation functional types for an area near Barrow, AK. Spatial variability of LUE was derived from the observed functional type distributions. Across this landscape, a

  14. First Record of Setaria Tundra in Danish Roe Deer (Capreolus Capreolus)

    DEFF Research Database (Denmark)

    Enemark, Heidi L.; Harslund, Jakob le Fèvre; Oksanen, A.;

    2011-01-01

    No previous finds of the mosquito-borne filarioid nematode Setaria tundra have been reported from Denmark, although it was described decades ago in Swedish and Norwegian reindeer as well as in roe deer from Germany, Bulgaria and more recently also from Italy and Finland. Setaria spp. are usually...... and thereby larger numbers of mosquitoes, it is important to monitor this vector-borne parasite. This will not only increase the understanding of factors promoting its expansion but also help to predict disease outbreaks....

  15. Enhanced biological degradation of crude oil in a Spitsbergen tundra site

    International Nuclear Information System (INIS)

    A series of oil-contaminated tundra plots on Spitsbergen was treated with combinations of five different fertilizer additives. Both organic and mineral nutrient sources were used, alone or in combination. Biological degradation of oil was recorded in all of the plots. The extent of degradation depended on the type of fertilizer added. The local conditions influence oil degradation significantly, as well as the effect of the fertilizer. Urea, SkogAN (a slow releasing fertilizer), and a blend of fish meals all give high degrees of oil degradation. Both the microbial parameters and the total heterotrophic respiration are influenced by the addition of fertilizers. 6 refs., 13 figs., 3 tabs

  16. Carbon dioxide exchange of the Arctic tundra in the northern part of European Russia

    DEFF Research Database (Denmark)

    Kiepe, Isabell; Johansson, Paul Torbjörn; Friborg, Thomas;

    , in the Pechora basin of the northern Komi Republic. The site is of lowland tundra type (underlain by permafrost) with predominating grasses, low shrubs, lichens and mosses interspersed with thermokarst lakes. The max. active layer thickness ranges from 90 cm till over 160 cm on the mineral slope and from 35 till...... on the transition period at the end of the growth season, which is a part of the year when predicted changes in temperature is likely to have the most pronounced effects on the exchange of GHGs. The net ecosystem CO2 exchange reflects two important influences on the opposed fluxes, gross photosynthesis...

  17. Iberian plate kinematics and Alpine collision in the Pyrenees

    NARCIS (Netherlands)

    Vissers, R.L.M.; Meijer, P.Th.

    2012-01-01

    With the aim to unravel first-order motions associated with the Alpine collisional history of the Pyrenees in SW Europe, we perform a plate-kinematic analysis of Iberia motion since the latest Mesozoic in a six-plate circuit. This analysis leads to reconstructions of the North Atlantic for the lates

  18. Alpine glacial topography and the rate of rock column uplift

    DEFF Research Database (Denmark)

    Pedersen, Vivi Kathrine; Egholm, D.L.; Nielsen, S.B.

    2010-01-01

    The present study investigates the influence of alpine glacial erosion on the morphology and relief distribution of mountain regions associated with varying rock column uplift rates. We take a global approach and analyse the surface area distribution of all mountain regions affected by glacial er...

  19. Model Assessment of Permafrost Development for a Large Alpine Catchment

    Science.gov (United States)

    Voelksch, I.; Lehning, M.

    2005-12-01

    The extremely hot summer of 2003 saw increased rockfall and slope instability problems in the European Alps. This is generally attributed to permafrost thawing. Therefore, the development of permafrost in steep Alpine terrain under the observed warming trend needs to be investigated. We use ALPINE3D, a detailed model of Alpine surface processes to assess permafrost occurrence under the current climate and to predict an expected change under the warming scenario that future summers will be on average as the summer 2003. The ALPINE3D modules consist of a radiation balance model using a view factor approach and include short-wave scattering and long-wave emission from terrain and tall vegetation. The processes in the atmosphere are coupled to a distributed one-dimensional model of vegetation, snow and soil (SNOWPACK) using the assumption that lateral exchange is small in these media. Snow and soil processes are treated in much detail with adaptive multi-layer finite elements. The model modules can be run in a parallel (distributed) mode using a GRID infrastructure to allow such computationally demanding tasks. The application of ALPINE3D to the Cordevole river basin in the northern Italian Dolomites has been based on weather station data from seven locations in the area. A spatial resolution of 200 m is used for the simulation, which covers approximately 900 square kilometers. Typically, mass and energy exchange processes for 20 soil layers and up to 30 snow layers are calculated with an hourly time step and 15 years of data. In the steep terrain of the southern Alps, only a small area fraction has permafrost. Permafrost disappears almost completely under the warming scenario, which is achieved by simulating repeatedly the 2003 year.

  20. An assessment of the carbon balance of arctic tundra: comparisons among observations, process models, and atmospheric inversions

    Science.gov (United States)

    McGuire, A.D.; Christensen, T.R.; Hayes, D.; Heroult, A.; Euskirchen, E.; Yi, Y.; Kimball, J.S.; Koven, C.; Lafleur, P.; Miller, P.A.; Oechel, W.; Peylin, P.; Williams, M.

    2012-01-01

    Although arctic tundra has been estimated to cover only 8% of the global land surface, the large and potentially labile carbon pools currently stored in tundra soils have the potential for large emissions of carbon (C) under a warming climate. These emissions as radiatively active greenhouse gases in the form of both CO2 and CH4 could amplify global warming. Given the potential sensitivity of these ecosystems to climate change and the expectation that the Arctic will experience appreciable warming over the next century, it is important to assess whether responses of C exchange in tundra regions are likely to enhance or mitigate warming. In this study we compared analyses of C exchange of Arctic tundra between 1990–1999 and 2000–2006 among observations, regional and global applications of process-based terrestrial biosphere models, and atmospheric inversion models. Syntheses of the compilation of flux observations and of inversion model results indicate that the annual exchange of CO2 between arctic tundra and the atmosphere has large uncertainties that cannot be distinguished from neutral balance. The mean estimate from an ensemble of process-based model simulations suggests that arctic tundra acted as a sink for atmospheric CO2 in recent decades, but based on the uncertainty estimates it cannot be determined with confidence whether these ecosystems represent a weak or a strong sink. Tundra was 0.6 °C warmer in the 2000s compared to the 1990s. The central estimates of the observations, process-based models, and inversion models each identify stronger sinks in the 2000s compared with the 1990s. Similarly, the observations and the applications of regional process-based models suggest that CH4 emissions from arctic tundra have increased from the 1990s to 2000s. Based on our analyses of the estimates from observations, process-based models, and inversion models, we estimate that arctic tundra was a sink for atmospheric CO2 of 110 Tg C yr-1 (uncertainty between a

  1. Size and mass of grit in gizzards of Sandhill Cranes, Tundra Swans, and Mute Swans

    Science.gov (United States)

    Franson, J.C.; Hansen, S.P.; Duerr, A.E.; DeStefano, S.

    2001-01-01

    Because it has been suggested that waterbirds may ingest lost or discarded lead fishing weights as grit, we examined grit in the gizzards of Sandhill Cranes (Grus canadensis), Tundra Swans (Cygnus columbianus), and Mute Swans (Cygnus olor), three species where individuals have been poisoned by the ingestion of lead fishing weights. The greatest proportion (by mass) of grit in gizzards of Sandhill Cranes consisted of particles with a minimum dimension of 2.36-4.75 mm. Grit particles in swans were much smaller, with the most prevalent (by mass) being 0.6-1.18 mm. The greatest dimension of the largest grit particle found in cranes and swans was 17.4 mm and 14.0 mm, respectively. The U.S. Environmental Protection Agency has proposed a ban on lead fishing weights of ???25.4 mm in any dimension. Based on the size of grit particles that we found in gizzards of Sandhill Cranes, Mute Swans, and Tundra Swans, we believe it is unlikely that individuals of those species would ingest, as grit, lead fishing weights larger than 25.4 mm in any dimension. Received 10 January 2001, accepted 28 February 2001.

  2. Pan-Arctic ice-wedge degradation in warming permafrost and its influence on tundra hydrology

    Science.gov (United States)

    Liljedahl, Anna K.; Boike, Julia; Daanen, Ronald P.; Fedorov, Alexander N.; Frost, Gerald V.; Grosse, Guido; Hinzman, Larry D.; Iijma, Yoshihiro; Jorgenson, Janet C.; Matveyeva, Nadya; Necsoiu, Marius; Raynolds, Martha K.; Romanovsky, Vladimir E.; Schulla, Jörg; Tape, Ken D.; Walker, Donald A.; Wilson, Cathy J.; Yabuki, Hironori; Zona, Donatella

    2016-04-01

    Ice wedges are common features of the subsurface in permafrost regions. They develop by repeated frost cracking and ice vein growth over hundreds to thousands of years. Ice-wedge formation causes the archetypal polygonal patterns seen in tundra across the Arctic landscape. Here we use field and remote sensing observations to document polygon succession due to ice-wedge degradation and trough development in ten Arctic localities over sub-decadal timescales. Initial thaw drains polygon centres and forms disconnected troughs that hold isolated ponds. Continued ice-wedge melting leads to increased trough connectivity and an overall draining of the landscape. We find that melting at the tops of ice wedges over recent decades and subsequent decimetre-scale ground subsidence is a widespread Arctic phenomenon. Although permafrost temperatures have been increasing gradually, we find that ice-wedge degradation is occurring on sub-decadal timescales. Our hydrological model simulations show that advanced ice-wedge degradation can significantly alter the water balance of lowland tundra by reducing inundation and increasing runoff, in particular due to changes in snow distribution as troughs form. We predict that ice-wedge degradation and the hydrological changes associated with the resulting differential ground subsidence will expand and amplify in rapidly warming permafrost regions.

  3. Russian Arctic warming and ‘greening’ are closely tracked by tundra shrub willows

    Science.gov (United States)

    Forbes, B. C.; Macias Fauria, M.; Zetterberg, P.

    2009-12-01

    Growth in arctic vegetation is generally expected to increase under a warming climate, particularly among deciduous shrubs. We analyzed annual ring growth for an abundant and nearly circumpolar erect willow (Salix lanata L.) from the coastal zone of the northwest Russian Arctic (Nenets Autonomous Okrug). The resulting chronology is strongly related to summer temperature for the period 1942-2005. Remarkably high correlations occur at long distances (>1600 km) across the tundra and taiga zones of West Siberia and Eastern Europe. We also found a clear relationship with photosynthetic activity for upland vegetation at a regional scale for the period 1981-2005, confirming a parallel ‘greening’ trend reported for similarly warming North American portions of the tundra biome. The standardized growth curve suggests a significant increase in shrub willow growth over the last six decades. These findings are in line with field and remote sensing studies that have assigned a strong shrub component to the reported greening signal since the early 1980s. Furthermore, the growth trend agrees with qualitative observations by nomadic Nenets reindeer herders of recent increases in willow size in the region. The quality of the chronology as a climate proxy is exceptional. Given its wide geographic distribution and the ready preservation of wood in permafrost, S. lanata L. has great potential for extended temperature reconstructions in remote areas across the Arctic.

  4. Modelling the spatial pattern of ground thaw in a small basin in the arctic tundra

    Directory of Open Access Journals (Sweden)

    S. Endrizzi

    2011-01-01

    Full Text Available In the arctic tundra the ground is normally composed by a relatively thin organic soil layer, overlying mineral sediment. Subsurface water drainage generally occurs in the organic layer for its high hydraulic conductivity. However, the organic layer shows significant decrease of hydraulic conductivity with depth. The position and the topography of the frost table, which here acts as a relatively impermeable surface, are therefore crucial in determining the hillslope drainage rate. This work aims at understanding how the topography of the ground surface affects the spatial variability of the depth of thaw in a 1 km2 low-elevation arctic tundra basin with a fine resolution model that fully couples energy and water flow processes. The simulations indicate that the spatial patterns of ground thaw are not dominated by slope and aspect, but are instead entirely controlled by the spatial distribution of soil moisture, which is determined by subsurface flow patterns. Measured thaw depths have a similar range of variability to the simulated values for each stage of active layer development, although the model slightly overestimated the depth of thaw.

  5. Potential responses of tundra ecosystems to perturbations from energy development. Part I. Annual report, 1983

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.

    1986-01-01

    The necessity to determine general effects of perturbations in the arctic resulting from energy development is the impetus for this research which quantifies the patterns of water and nutrient flux from fellfield through tussock tundra into riparian plant communities. The evaluation of the effects of this mass flow on plant productivity is one of the objectives of the proposed research. The second major goal is to quantify the effects of changes of this water and nutrient flux resulting from slope perturbations, such as increased water flow, fertilizer application, blading and vehicle tracks. Demographic studies of fellfield, tussock tundra, and riparian vegetation and the dynamics of rodent activity in regard to nutrient transfer will broaden the understanding of the biology of a small watershed. Results of the integrated subprojects will be used to test the main hypotheses of this project which concern patterns of water and nutrient flux from slopes into the riparian vegetation as a results of slope perturbations. With the obtained information, nutrient and water flux routines of ARTUS will be expanded, and a specific slope and watershed model developed.

  6. Mobile Phone Revolution in the Tundra? Technological Change among Russian Reindeer Nomads

    Directory of Open Access Journals (Sweden)

    Florian M. Stammler

    2009-04-01

    Full Text Available This contribution looks at the influence of technological change thatnomads in the Russian North have undergone, using as examples two crucial innovations: the snowmobile and the mobile phone. I argue that the snowmobile did not have the same revolutionary impact on the Russian tundra as it did in Fennoscandia, for reasons connected to long distances, infrastructure, spare parts, availability of fuel, priorities of Soviet transport policy as well as the convenience of previously used practices of herd control using ‘sitting transport’. Different from that, I argue that mobile phones have the potential for a greater penetration into nomadic societies. Because they encourage equality rather than stratification, they are low maintenance; they are small enough to be embedded into existing social contexts. Connecting not only neighbours but the whole world, in principle, mobile phones may entail a significant socio-cultural change. The article presents first fieldwork evidence of such change among tundra nomads and relates this to existing theoretical studies on how mobile communication changes societies. Attention is paid to the particularities of a mobile type of communication introduced in mobile communities, that is, among nomads. In doing so, I explore similarities and differences in how technological change influences sedentary and nomadic societies.

  7. Prevalence, transmission, and genetic diversity of blood parasites infecting tundra-nesting geese in Alaska

    Science.gov (United States)

    Ramey, Andy M.; Reed, John A.; Schmutz, Joel A.; Fondell, Tom F.; Meixell, Brandt W.; Hupp, Jerry W.; Ward, David H.; Terenzi, John; Ely, Craig R.

    2014-01-01

    A total of 842 blood samples collected from five species of tundra-nesting geese in Alaska was screened for haemosporidian parasites using molecular techniques. Parasites of the generaLeucocytozoon Danilewsky, 1890, Haemoproteus Kruse, 1890, and Plasmodium Marchiafava and Celli, 1885 were detected in 169 (20%), 3 (parasites and assess variation relative to species, age, sex, geographic area, year, and decade. Species, age, and decade were identified as important in explaining differences in prevalence of Leucocytozoonparasites. Leucocytozoon parasites were detected in goslings sampled along the Arctic Coastal Plain using both historic and contemporary samples, which provided support for transmission in the North American Arctic. In contrast, lack of detection of Haemoproteus and Plasmodiumparasites in goslings (n = 238) provided evidence to suggest that the transmission of parasites of these genera may not occur among waterfowl using tundra habitats in Alaska, or alternatively, may only occur at low levels. Five haemosporidian genetic lineages shared among different species of geese sampled from two geographic areas were indicative of interspecies parasite transmission and supported broad parasite or vector distributions. However, identicalLeucocytozoon and Haemoproteus lineages on public databases were limited to waterfowl hosts suggesting constraints in the range of parasite hosts.

  8. Biomass partitioning and its relationship with the environmental factors at the alpine steppe in Northern Tibet.

    Directory of Open Access Journals (Sweden)

    Jianbo Wu

    Full Text Available Alpine steppe is considered to be the largest grassland type on the Tibetan Plateau. This grassland contributes to the global carbon cycle and is sensitive to climate changes. The allocation of biomass in an ecosystem affects plant growth and the overall functioning of the ecosystem. However, the mechanism by which plant biomass is allocated on the alpine steppe remains unclear. In this study, biomass allocation and its relationship to environmental factors on the alpine grassland were studied by a meta-analysis of 32 field sites across the alpine steppe of the northern Tibetan Plateau. We found that there is less above-ground biomass (M A and below-ground biomass (M B in the alpine steppe than there is in alpine meadows and temperate grasslands. By contrast, the root-to-shoot ratio (R:S in the alpine steppe is higher than it is in alpine meadows and temperate grasslands. Although temperature maintained the biomass in the alpine steppe, precipitation was found to considerably influence M A , M B , and R:S, as shown by ordination space partitioning. After standardized major axis (SMA analysis, we found that allocation of biomass on the alpine steppe is supported by the allometric biomass partitioning hypothesis rather than the isometric allocation hypothesis. Based on these results, we believe that M A and M B will decrease as a result of the increased aridity expected to occur in the future, which will reduce the landscape's capacity for carbon storage.

  9. Des broussailles dans les prairies alpines

    Directory of Open Access Journals (Sweden)

    Olivier Camacho

    2009-03-01

    Full Text Available Landscape closing due to the decline in agricultural activity is considered to be a major problem in the Alps. Abondance Valley provides a good example of this phenomenon and is also representative of a paradox commonly found in the Northern French Alps: the mountainsides and alpine pastures are still used, whereas they are becoming increasingly afforested. Environmental conditions play a major role in the localisation of agricultural land uses, but they are not sufficient to explain why pastures still in use are being invaded by shrub. Even if cutting makes it possible to effectively control the encroachment by woody species, this is not true for uncut pastures where grazing is not able to keep up with grass production. This situation is repeated every year and is the likely cause of the colonisation by woody species. To ensure their forage system and to simplify their work, farmers tend to establish grazing units that are oversized in relation to the needs of their animals. They implement compensatory practices that consist of mechanical maintenance as a complement to grazing to limit the dynamics of woody species. These labour-intensive practices are not used on all of the pastures. The analysis of farmers’ practices by agronomists is therefore a useful complement to studies of physical and socio-economic environments, at the level of the grazed field as well as at that of the valley as a whole.La dégradation des paysages par suite du recul de l’activité agricole est considérée comme un enjeu majeur dans les Alpes. La vallée d’Abondance illustre bien ce phénomène de fermeture de l’espace mais elle est en outre représentative d’un paradoxe assez répandu dans les Alpes du nord françaises : les versants et les alpages sont encore exploités et pourtant ils se boisent progressivement. Les conditions de milieux jouent un rôle majeur sur la localisation des usages agricoles de l'espace, mais elles ne peuvent pas suffire pour

  10. Regional-Scale Vegetation Dynamics in Patterned-Ground Ecosystems of Arctic Tundra

    Science.gov (United States)

    Epstein, H. E.; Kelley, A. M.; Walker, D. A.; Jia, G. J.; Raynolds, M. K.

    2006-12-01

    Regional-scale patterns of vegetation have been analyzed along a number of climate gradients throughout the world; these spatial dynamics provide important insights into the controlling factors of vegetation and the potential plant responses to environmental change. Only a few studies to date have collectively examined the vegetation biomass and production of arctic tundra ecosystems and their relationships to broadly ranging climate variables. No prior study has taken a systematic and consistent approach to examining vegetation biomass patterns along the full temperature gradient of the arctic biome. An additional complicating factor for studying vegetation of arctic tundra is the high spatial variability associated with small patterned-ground features (e.g. non-sorted circles and small non-sorted polygons), resulting from intense freeze-thaw processes. In this study, we sampled and analyzed the aboveground plant biomass components of patterned-ground ecosystems in the Arctic of northern Alaska and Canada along an 1800-km north-south gradient that spans approximately 11 degrees C of mean July temperatures. At each of ten locations along the regional temperature gradient, we ran several 50-m transects and harvested the aboveground biomass of three 20 x 50 cm plots for each transect. Vegetation biomass was dried, sorted by plant functional groups and tissue types, weighed, and analyzed as functions of the summer warmth index (SWI sum of mean monthly temperatures > 0). The absolute biomass (g/m2) of shrubs and graminoids increased exponentially with SWI, whereas forb and lichen biomass showed no change along the gradient. Moss biomass increased linearly with SWI, but with greater variabiliy than the other types. Relative aboveground biomass (% of total) of shrubs and graminoids increased with SWI, whereas percent lichen biomass decreased, and forbs again exhibited no significant change. Percentage of moss biomass was a parabolic function of SWI, with high relative

  11. Subsidence, stress regime and rotation(s) of a tectonically active sedimentary basin within the western Alpine Orogen: the Tertiary Piedmont Basin (Alpine domain, NW Italy)

    NARCIS (Netherlands)

    Carrapa, B.; Bertotti, G.; Krijgsman, W.

    2003-01-01

    The Oligocene to Miocene Tertiary Piedmont Basin (TPB) is located in the NW part of Italy at the junction between the Apennine and the Alpine thrust belts. The position of the TPB on top of the Alpine/Apennine Orogen poses fundamental questions as to the tectonics of the basin subsidence. Having und

  12. THE HYDRAULIC CHARACTERISTICS AND GEOCHEMISTRY OF HYPORHEIC AND PARAFLUVIAL ZONES IN ARCTIC TUNDRA STREAMS, NORTH SLOPE, ALASKA

    Science.gov (United States)

    Sodium bromide and Rhodamine WT were used as conservative tracers to examine the hydrologic characteristics of seven tundra streams in Arctic Alaska, during the summers of 1994-1996. Continuous tracer additions were conducted in seven rivers ranging from 1st to 5th order with sam...

  13. An application of plot-scale NDVI in predicting carbon dioxide exchange and leaf area index in heterogeneous subarctic tundra

    International Nuclear Information System (INIS)

    This paper reported on a study that examined the flow of carbon into and out of tundra ecosystems. It is necessary to accurately predict carbon dioxide (CO2) exchange in the Tundra because of the impacts of climate change on carbon stored in permafrost. Understanding the relationships between the normalized difference vegetation index (NDVI) and vegetation and CO2 exchange may explain how small-scale variation in vegetation community extends to remotely sensed estimates of landscape characteristics. In this study, CO2 fluxes were measured with a portable chamber in a range of Tundra vegetation communities. Biomass and leaf area were measured with destructive harvest, and NDVI was obtained using a hand-held infrared camera. There was a weak correlation between NDVI and leaf area index in some vegetation communities, but a significant correlation between NDVI and biomass, including mosses. NDVI was found to be strongly related to photosynthetic activity and net CO2 uptake in all vegetation groups. However, NDVI related to ecosystem respiration only in wet sedge. It was concluded that at plot scale, the ability of NDVI to predict ecosystem properties and CO2 exchange in heterogeneous Tundra vegetation is variable.

  14. Tree recruitment in the Forest-tundra Ecotone : Limitation and facilitation processes in contrasting climatic Regions

    OpenAIRE

    Albertsen, Elena

    2012-01-01

    Aim: The aim of this study was to analyse how abiotic and biotic constraint and facilitation agents determine tree recruitment in the alpine zone in climatically different regions as well as across species; Birch, pine and spruce. Location: The study was located to Grødalen, Haltdalen and Røros representing a coastal-inland gradient, where birch was included along the entire climatic gradient and all three species in one region (Haltdalen). Methods: Variables collected for seedling/...

  15. Dynamics and seismotectonics of the West-Alpine arc

    Science.gov (United States)

    Giglia, G.; Capponi, G.; Crispini, L.; Piazza, M.

    1996-12-01

    In this paper we present a comparative review of structural, seismic and focal mechanism data from the West-Alpine arc. In the Western Alps, seismic activity is concentrated along an external belt, corresponding to the Penninic front, and an internal belt, corresponding to the Austro-Alpine front and its southern extension. These seismic belts are connected in the NE by a seismic lineament, corresponding to the Simplon and Centovalli Line and in the south by the E-W-trending seismic Stura "couloir", located between the Argentera and Dora Maira massifs. The SimplondashCentovalli-Tonale system and the Stura "couloir" are dextral and sinistral strike-slip systems respectively; this implies a westward translation of the West-Alpine arc and the Po Plain. Based on these observations, a seismotectonic model is proposed in which the frontal Penninic thrust and the basal surface of the accretionary wedge corresponding to the Penninic sole thrust are reactivated. Activity along the frontal thrust increases the arcuate shape of the Western Alps and disengages them from the Central and the Ligurian Alps along the tear faults of the SimplondashCentovalli-Tonale system and the Stura "couloir" respectively. In the wider framework of northern Italy, the sector of the eastern Alps north of the Gailtal Line, is moving in an orogendashparallel direction towards the east. Areas with lateral escape in opposite directions, towards the west for the Po Plain and towards the east for the Eastern Alps, north of the Gailtal Line, are separated by the South Alpine Atesine indenter. A model postulating a double lateral escape and a central indenter matches most of the features of the models of "poinçonnement". The seismic features of northern Italy agree with the seismicity of the stable sector of northern Europe up to the North Sea. This area is fragmented into blocks bounded by seismic bands, some of which probably reactivate pre-existing structures. The overall stress field of Cratonic

  16. Innovation in the plural of the alpine cre-actors

    Directory of Open Access Journals (Sweden)

    Andréa Finger-Stich

    2009-06-01

    Full Text Available The capacity to innovate for a sustainable development of alpine territories cannot depend only on economic, legal and political conditions defined by the State at national and international levels. It depends also on local conditions that situate historically and geographically the actors in a continuity of social and ecological relationships. This approach highlights the collective – thus organisational – dimensions of the innovation process, including the imagination, the development, the implementation and even the diffusion of a new practice. Our point of view is that for contributing to the sustainable development of the Alps, innovations need to change the ecological, political, social and cultural relationships engaging the actors in these territories. This change affects as much the object territory as the subject actor of the territory. This is why innovating in the Alps means also innovating the Alps and the alpine actors (Cosalp, 2008. Based on a research about local people’s participation in the management of alpine communal forests, the article shows the importance of local interactions involving actors of diverse occupation, gender, age and origins1.La capacité d’innovation pour un développement durable des territoires alpins ne peut dépendre uniquement de conditions économiques, légales et politiques définies par les Etats aux échelles nationale et internationale. Elle dépend aussi de conditions locales, qui situent historiquement et géographiquement les acteurs dans une continuité de relations sociales et écologiques. Cette perspective accentue l’importance de la dimension collective, donc organisationnelle, du processus d’innovation, allant de l’imagination, puis au développement, à la réalisation – voire la diffusion – d’une nouvelle pratique. Le point de vue de cet article est qu’une innovation, pour contribuer au développement durable des Alpes, doit changer les relations

  17. Above and below ground carbon stocks in northeast Siberia tundra ecosystems: a comparison between disturbed and undisturbed areas

    Science.gov (United States)

    Weber, L. R.; Pena, H., III; Curasi, S. R.; Ramos, E.; Loranty, M. M.; Alexander, H. D.; Natali, S.

    2014-12-01

    Changes in arctic tundra vegetation have the potential to alter the regional carbon (C) budget, with feedback implications for global climate. A number of studies have documented both widespread increases in productivity as well as shifts in the dominant vegetation. In particular, shrubs have been replacing other vegetation, such as graminoids, in response to changes in their environment. Shrub expansion is thought to be facilitated by exposure of mineral soil and increased nutrient availability, which are often associated with disturbance. Such disturbances can be naturally occurring, typically associated with permafrost degradation or with direct anthropogenic causes such as infrastructure development. Mechanical disturbance associated with human development is not uncommon in tundra and will likely become more frequent as warming makes the Arctic more hospitable for resource extraction and other human activities. As such, this type of disturbance will become an increasingly important component of tundra C balance. Both increased productivity and shrub expansion have clear impacts on ecosystem C cycling through increased C uptake and aboveground (AG) storage. What is less clear, however, are the concurrent changes in belowground (BG) C storage. Here we inventoried AG and BG C stocks in disturbed and undisturbed tundra ecosystems to determine the effects of disturbance on tundra C balance. We measured differences in plant functional type, AG and BG biomass, soil C, and specific leaf area (SLA) for the dominant shrub (Salix) in 2 tundra ecosystems in northern Siberia—an undisturbed moist acidic tundra and an adjacent ecosystem that was used as a road ~50 years ago. Deciduous shrubs and grasses dominated both ecosystems, but biomass for both functional types was higher in the disturbed area. SLA was also higher inside the disturbance. Conversely, nonvascular plants and evergreen shrubs were less abundant in the disturbed area. BG plant biomass was substantially

  18. How spatial variation in areal extent and configuration of labile vegetation states affect the riparian bird community in Arctic tundra.

    Directory of Open Access Journals (Sweden)

    John-André Henden

    Full Text Available The Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by large herbivores and growing human activity. Thickets of tall shrubs represent a conspicuous vegetation state in northern and temperate ecosystems, where it serves important ecological functions, including habitat for wildlife. Thickets are however labile, as tall shrubs respond rapidly to both abiotic and biotic environmental drivers. Our aim was to assess how large-scale spatial variation in willow thicket areal extent, configuration and habitat structure affected bird abundance, occupancy rates and species richness so as to provide an empirical basis for predicting the outcome of environmental change for riparian tundra bird communities. Based on a 4-year count data series, obtained through a large-scale study design in low arctic tundra in northern Norway, statistical hierarchical community models were deployed to assess relations between habitat configuration and bird species occupancy and community richness. We found that species abundance, occupancy and richness were greatly affected by willow areal extent and configuration, habitat features likely to be affected by intense ungulate browsing as well as climate warming. In sum, total species richness was maximized in large and tall willow patches of small to intermediate degree of fragmentation. These community effects were mainly driven by responses in the occupancy rates of species depending on tall willows for foraging and breeding, while species favouring other vegetation states were not affected. In light of the predicted climate driven willow shrub encroachment in riparian tundra habitats, our study predicts that many bird species would increase in abundance, and that the bird community as a whole could become enriched. Conversely, in tundra regions where overabundance of large herbivores leads to decreased areal extent, reduced height and increased fragmentation

  19. Summer temperature increase has distinct effects on the ectomycorrhizal fungal communities of moist tussock and dry tundra in Arctic Alaska.

    Science.gov (United States)

    Morgado, Luis N; Semenova, Tatiana A; Welker, Jeffrey M; Walker, Marilyn D; Smets, Erik; Geml, József

    2015-02-01

    Arctic regions are experiencing the greatest rates of climate warming on the planet and marked changes have already been observed in terrestrial arctic ecosystems. While most studies have focused on the effects of warming on arctic vegetation and nutrient cycling, little is known about how belowground communities, such as fungi root-associated, respond to warming. Here, we investigate how long-term summer warming affects ectomycorrhizal (ECM) fungal communities. We used Ion Torrent sequencing of the rDNA internal transcribed spacer 2 (ITS2) region to compare ECM fungal communities in plots with and without long-term experimental warming in both dry and moist tussock tundra. Cortinarius was the most OTU-rich genus in the moist tundra, while the most diverse genus in the dry tundra was Tomentella. On the diversity level, in the moist tundra we found significant differences in community composition, and a sharp decrease in the richness of ECM fungi due to warming. On the functional level, our results indicate that warming induces shifts in the extramatrical properties of the communities, where the species with medium-distance exploration type seem to be favored with potential implications for the mobilization of different nutrient pools in the soil. In the dry tundra, neither community richness nor community composition was significantly altered by warming, similar to what had been observed in ECM host plants. There was, however, a marginally significant increase in OTUs identified as ECM fungi with the medium-distance exploration type in the warmed plots. Linking our findings of decreasing richness with previous results of increasing ECM fungal biomass suggests that certain ECM species are favored by warming and may become more abundant, while many other species may go locally extinct due to direct or indirect effects of warming. Such compositional shifts in the community might affect nutrient cycling and soil organic C storage. PMID:25156129

  20. Migration of Tundra Swans (Cygnus columbianus) Wintering in Japan Using Satellite Tracking: Identification of the Eastern Palearctic Flyway.

    Science.gov (United States)

    Chen, Wenbo; Doko, Tomoko; Fujita, Go; Hijikata, Naoya; Tokita, Ken-Ichi; Uchida, Kiyoshi; Konishi, Kan; Hiraoka, Emiko; Higuchi, Hiroyoshi

    2016-02-01

    Migration through the Eastern Palearctic (EP) flyway by tundra swans (Cygnus columbianus) has not been thoroughly documented. We satellite-tracked the migration of 16 tundra swans that winter in Japan. The objectives of this study were 1) to show the migration pattern of the EP flyway of tundra swans; 2) to compare this pattern with the migration pattern of whooper swans; and 3) to identify stopover sites that are important for these swans' conservation. Tundra swans were captured at Kutcharo Lake, Hokkaido, in 2009-2012 and satellite-tracked. A new method called the "MATCHED (Migratory Analytical Time Change Easy Detection) method" was developed. Based on median, the spring migration began on 18 April and ended on 27 May. Autumn migration began on 9 September and ended on 2 November. The median duration of the spring and autumn migrations were 48 and 50 days, respectively. The mean duration at one stopover site was 5.5 days and 6.8 days for the spring and autumn migrations, respectively. The number of stopover sites was 3.0 and 2.5 for the spring and autumn migrations, respectively. The mean travel distances for the spring and autumn migrations were 6471 and 6331 km, respectively. Seven migration routes passing Sakhalin, the Amur River, and/or Kamchatka were identified. There were 15, 32, and eight wintering, stopover, and breeding sites, respectively. The migration routes and staging areas of tundra swans partially overlap with those of whooper swans, whose migration patterns have been previously documented. The migration patterns of these two swan species that winter in Japan confirm the importance of the Amur River, Udyl' Lake, Shchastya Bay, Aniva Bay, zaliv Chayvo Lake, zal Piltun Lake, zaliv Baykal Lake, Kolyma River, Buyunda River, Sen-kyuyel' Lake, and northern coastal areas of the Sea of Okhotsk.

  1. Alpine Skiing With total knee ArthroPlasty (ASWAP)

    DEFF Research Database (Denmark)

    Kristensen, M.; Pötzelsberger, B.; Scheiber, P.;

    2015-01-01

    We investigated the effect of alpine skiing for 12 weeks on skeletal muscle characteristics and biomarkers of glucose homeostasis and cardiovascular risk factors. Twenty-three patients with a total knee arthroplasty (TKA) were studied 2.9 ± 0.9 years (mean ± SD) after the operation. Fourteen...... patients participated in the intervention group (IG) and nine in the control group (CG). Blood samples and muscle biopsies were obtained before (PRE) and 7.3 ± 0.8 days after (POST) the intervention, and blood samples again after a retention (RET) phase of 8 weeks. With skiing, glucose homeostasis improved...... I fibers increased with skiing in IG with no change in CG. Inflammatory biomarkers, plasma lipids, and mitochondrial proteins and activity did not change. Alpine skiing is metabolically beneficial and can be used as a training modality by elderly people with TKA....

  2. Impact of climatic change on alpine ecosystems: inference and prediction

    Directory of Open Access Journals (Sweden)

    Nigel G. Yoccoz

    2011-01-01

    Full Text Available Alpine ecosystems will be greatly impacted by climatic change, but other factors, such as land use and invasive species, are likely to play an important role too. Climate can influence ecosystems at several levels. We describe some of them, stressing methodological approaches and available data. Climate can modify species phenology, such as flowering date of plants and hatching date in insects. It can also change directly population demography (survival, reproduction, dispersal, and therefore species distribution. Finally it can effect interactions among species – snow cover for example can affect the success of some predators. One characteristic of alpine ecosystems is the presence of snow cover, but surprisingly the role played by snow is relatively poorly known, mainly for logistical reasons. Even if we have made important progress regarding the development of predictive models, particularly so for distribution of alpine plants, we still need to set up observational and experimental networks which properly take into account the variability of alpine ecosystems and of their interactions with climate.Les écosystèmes alpins vont être grandement influencés par les changements climatiques à venir, mais d’autres facteurs, tels que l’utilisation des terres ou les espèces invasives, pourront aussi jouer un rôle important. Le climat peut influencer les écosystèmes à différents niveaux, et nous en décrivons certains, en mettant l’accent sur les méthodes utilisées et les données disponibles. Le climat peut d’abord modifier la phénologie des espèces, comme la date de floraison des plantes ou la date d’éclosion des insectes. Il peut ensuite affecter directement la démographie des espèces (survie, reproduction, dispersion et donc à terme leur répartition. Il peut enfin agir sur les interactions entre espèces – le couvert neigeux par exemple modifie le succès de certains prédateurs. Une caractéristique des

  3. Continuous surface mining activities of the Voest-Alpine

    Energy Technology Data Exchange (ETDEWEB)

    Kisling, K.; Luerzer, D.

    1987-06-01

    About 10 years ago Voest-Alpine started developing continuous surface mining equipment for its own brown coal mines at Koeflach, Austria. Based on these first developments the Voest-Alpine mining equipment plant at Zeltweg is now in a position to provide a full range of compact bucket wheel excavators (BWEs) (150-1800 litre bucket volume), along with a complete range of auxiliary equipment for continuous haulage, spreading/stacking and reclaiming. Thirty-four continuous mining machines of different types have been sold to various countries operating surface mines, including Austria, Philippines, Hungary, the USSR and Yugoslavia. In addition 18 materials handling plants of different types have been supplied and installed. This paper reviews the company's performance, technology utilization and future in the surface coal mining industry. Specific operating examples of the Oberdorf coal mine in Austria and the Unong mine in the Philippines are given. 7 refs.

  4. Deep Fault Drilling Project—Alpine Fault, New Zealand

    Directory of Open Access Journals (Sweden)

    Rupert Sutherland

    2009-09-01

    Full Text Available The Alpine Fault, South Island, New Zealand, constitutes a globally significant natural laboratory for research into how active plate-bounding continental faults work and, in particular, how rocks exposed at the surface today relate to deep-seated processes of tectonic deformation, seismogenesis, and mineralization. The along-strike homogeneity of the hanging wall, rapid rate of dextral-reverse slip on an inclined fault plane, and relatively shallow depths to mechanical and chemical transitions make the Alpine Fault and the broader South Island plate boundary an important international site for multi-disciplinary research and a realistic target for an ambitious long-term program of scientific drilling investigations.

  5. Alpine treeline and timberline dynamics during the Holocene in the Northern Romanian Carpathians

    OpenAIRE

    Anca GEANTĂ; Mariusz GALKA; Ioan TANȚĂU; Simon M. HUTCHINSON; Marcel MÎNDRESCU; Feurdean, Angelica

    2014-01-01

    High altitude environments (treeline and alpine communities) are particularly sensitive to climate changes, disturbances and land-use changes due to their limited tolerance and adaptability range, habitat fragmentation and habitat restriction. The current and future climate warming is anticipated to shift the tree- and timberlines upwards thus affecting alpine plant communities and causing land-cover change and fragmentation of alpine habitats. An upslope movement of some trees, shrubs and co...

  6. Is grazing exclusion effective in restoring vegetation in degraded alpine grasslands in Tibet, China?

    OpenAIRE

    Yan Yan; Xuyang Lu

    2015-01-01

    Overgrazing is considered one of the key disturbance factors that results in alpine grassland degradation in Tibet. Grazing exclusion by fencing has been widely used as an approach to restore degraded grasslands in Tibet since 2004. Is the grazing exclusion management strategy effective for the vegetation restoration of degraded alpine grasslands? Three alpine grassland types were selected in Tibet to investigate the effect of grazing exclusion on plant community structure and biomass. Our re...

  7. Alpine lake sediment archives and catchment geomorphology : causal relationships and implications for paleoenvironmental reconstructions

    OpenAIRE

    Rubensdotter, Lena

    2006-01-01

    Lake sediments are frequently used as archives of climate and environmental change. Minerogenic sediment variability in alpine lakes is often used to reconstruct past glacier and slope process activity. Alpine lake sediments can however have many different origins, which may induce errors in paleoenvironmental reconstructions. The aim of this project was to enhance the understanding of minerogenic lake sedimentation in alpine lakes and improve their use as environmental archives. Catchment ge...

  8. Ultra-sensitive Alpine lakes and climate change

    OpenAIRE

    Schmidt, Roland; Kamenik, Christian; Thompson, Roy

    2005-01-01

    Global warming is one of the major issues with which mankind is being confronted, having vital ecological and economic consequences. Ice-cover, snow-cover and water temperatures in alpine catchments are controlled by air temperatures, and so are very susceptible to shifts in climate. Local factors such as wind exposure, shading, and snow patches that persist during cold summers can, however, modify the sensitivities of the relationships to air temperature. Thermistors exposed in 45 mountain l...

  9. Impact of climatic change on alpine ecosystems: inference and prediction

    OpenAIRE

    YOCCOZ, Nigel G.; Anne Delestrade; Anne Loison

    2011-01-01

    Alpine ecosystems will be greatly impacted by climatic change, but other factors, such as land use and invasive species, are likely to play an important role too. Climate can influence ecosystems at several levels. We describe some of them, stressing methodological approaches and available data. Climate can modify species phenology, such as flowering date of plants and hatching date in insects. It can also change directly population demography (survival, reproduction, dispersal), and therefor...

  10. Identifying key conservation threats to Alpine birds through expert knowledge.

    Science.gov (United States)

    Chamberlain, Dan E; Pedrini, Paolo; Brambilla, Mattia; Rolando, Antonio; Girardello, Marco

    2016-01-01

    Alpine biodiversity is subject to a range of increasing threats, but the scarcity of data for many taxa means that it is difficult to assess the level and likely future impact of a given threat. Expert opinion can be a useful tool to address knowledge gaps in the absence of adequate data. Experts with experience in Alpine ecology were approached to rank threat levels for 69 Alpine bird species over the next 50 years for the whole European Alps in relation to ten categories: land abandonment, climate change, renewable energy, fire, forestry practices, grazing practices, hunting, leisure, mining and urbanization. There was a high degree of concordance in ranking of perceived threats among experts for most threat categories. The major overall perceived threats to Alpine birds identified through expert knowledge were land abandonment, urbanization, leisure and forestry, although other perceived threats were ranked highly for particular species groups (renewable energy and hunting for raptors, hunting for gamebirds). For groups of species defined according to their breeding habitat, open habitat species and treeline species were perceived as the most threatened. A spatial risk assessment tool based on summed scores for the whole community showed threat levels were highest for bird communities of the northern and western Alps. Development of the approaches given in this paper, including addressing biases in the selection of experts and adopting a more detailed ranking procedure, could prove useful in the future in identifying future threats, and in carrying out risk assessments based on levels of threat to the whole bird community. PMID:26966659

  11. Can We Model the Scenic Beauty of an Alpine Landscape?

    OpenAIRE

    Erich Tasser; Ulrike Tappeiner; Georg Leitinger; Maria Bacher; Sonja Hölzler; Uta Schirpke

    2013-01-01

    During the last decade, agriculture has lost its importance in many European mountain regions and tourism, which benefits from attractive landscapes, has become a major source of income. Changes in landscape patterns and elements might affect scenic beauty and therefore the socio-economic welfare of a region. Our study aimed at modeling scenic beauty by quantifying the influence of landscape elements and patterns in relationship to distance. Focusing on Alpine landscapes in South and North Ty...

  12. Forgotten Edible alpine plants in the canton of Valais

    OpenAIRE

    Abbet, Christian Paul

    2014-01-01

    Tradition possesses plenty of forgotten wild edible plants and may help researchers in the quest for new food varieties. Swiss alpine cantons, especially the canton of Valais, have still had a viable tradition. However, societal changes and extensive urbanization have caused this knowledge to be confined to lateral valleys. This contribution aimed to document wild edible plants which were collected in the canton of Valais. 38 informants originating from four different valleys of the canton (V...

  13. What are the main climate drivers for shrub growth in Northeastern Siberian tundra?

    Directory of Open Access Journals (Sweden)

    D. Blok

    2011-01-01

    Full Text Available Deciduous shrubs are expected to rapidly expand in the Arctic during the coming decades due to climate warming. A transition towards more shrub-dominated tundra may have large implications for the regional surface energy balance, permafrost stability and carbon storage capacity, with consequences for the global climate system. However, little information is available on the natural long-term shrub growth response to climatic variability. Our aim was to determine the climate factor and time period that are most important to annual shrub growth in our research site in NE-Siberia. Therefore, we determined annual radial growth rates in Salix pulchra and Betula nana shrubs by measuring ring widths. We constructed shrub ring width chronologies and compared growth rates to regional climate and remotely sensed greenness data. Early summer temperature was the most important factor influencing ring width of S. pulchra (Pearson's r=0.73, p<0.001 and B. nana (Pearson's r=0.46, p<0.001. No effect of winter precipitation on shrub growth was observed. In contrast, summer precipitation of the previous year correlated positively with B. nana ring width (r=0.42, p<0.01, suggesting that wet summers facilitate shrub growth in the following growing season. S. pulchra ring width correlated positively with peak summer NDVI, despite the small coverage of S. pulchra shrubs (<5% surface cover in our research area. We provide the first climate-growth study on shrubs for Northeast Siberia, the largest tundra region in the world. We show that two deciduous shrub species with markedly different growth forms have a similar growth response to changes in climate. The obtained shrub growth response to climate variability in the past increases our understanding of the mechanisms underlying current shrub expansion, which is required to predict future climate-driven tundra vegetation shifts.

  14. What are the main climate drivers for shrub growth in Northeastern Siberian tundra?

    Directory of Open Access Journals (Sweden)

    D. Blok

    2011-05-01

    Full Text Available Deciduous shrubs are expected to rapidly expand in the Arctic during the coming decades due to climate warming. A transition towards more shrub-dominated tundra may have large implications for the regional surface energy balance, permafrost stability and carbon storage capacity, with consequences for the global climate system. However, little information is available on the natural long-term shrub growth response to climatic variability. Our aim was to determine the climate factor and time period that are most important to annual shrub growth in our research site in NE-Siberia. Therefore, we determined annual radial growth rates in Salix pulchra and Betula nana shrubs by measuring ring widths. We constructed shrub ring width chronologies and compared growth rates to regional climate and remotely sensed greenness data. Early summer temperature was the most important factor influencing ring width of S. pulchra (Pearson's r = 0.73, p < 0.001 and B. nana (Pearson's r = 0.46, p < 0.001. No effect of winter precipitation on shrub growth was observed. In contrast, summer precipitation of the previous year correlated positively with B. nana ring width (Pearson's r = 0.42, p < 0.01, suggesting that wet summers facilitate shrub growth in the following growing season. S. pulchra ring width correlated positively with peak summer NDVI, despite the small coverage of S. pulchra shrubs (< 5 % surface cover in our research area. We provide the first climate-growth study on shrubs for Northeast Siberia, the largest tundra region in the world. We show that two deciduous shrub species with markedly different growth forms have a similar growth response to changes in climate. The obtained shrub growth response to climate variability in the past increases our understanding of the mechanisms underlying current shrub expansion, which is required to predict future climate

  15. To the soil genesis in tundra-forest ecotone belt in the Northeastern European Russia

    Science.gov (United States)

    Shakhtarova, Olga; Rusanova, Galina; Lapteva, Elena

    2013-04-01

    Ecotone belt representing the gradual transition between different bioclimatic zones (taiga and tundra) is of specific research interest. This transition zone is characterized by variety of landscapes and soil cover affected by climate changes which were accompanied with shifts of natural zones during Holocene. Paleoclimate changes had complicated the specifity of pedogenesis in the ecotone. The aim of the study was to reveal soil geneses in forest-tundra ecotone zone. The study area is characterized by drained topography and soil forming deposits represented by silty loams covering watersheds, permafrost is massive island and up to 50 m thick, permafrost table located at depths of 0,5-8 m. Vegetation cover is birch-spruce light forests where lichen-moss ground cover dominates, tree height is up to 4-6 m. Fe-illuvial svetlozoms (according to Russian classification 2004) were chosen as the study objects. According to WRB (2007) these soils are classified as Cambisols. In this soil study the complex approach was used, it includes (i) analysis of both structural organization and differentiation of functioning products on undisturbed monolith structure using mezo-micromorthologic methods; (ii) reveal of main soil-forming processes based on physical-chemical soil analysis. Quantitative chemical analysis has been conducted at an accredited laboratory "Ecoanalit" affiliated at Institute of Biology Komi SC UB RAS (Syktyvkar). Studied Cambisols are developed in upland forest sites located in the forest-tundra subzone. These soils are recognized by combination of podzolic, Fe-illuvial and cryomethamorphic horizons in the soil profile. Using of present-day methods and approaches for soil profile studies allowed to reveal the polygenesis of Cambisols which structure represents two pedogenic stages. The basis to determine these stages are the morphological features (structural organization, differentiation of cutan complex) as well as recent and inherited features of pedogenic

  16. Understanding Pan-Arctic Tundra Vegetation Change Through Long-term Remotely Sensed Data

    Science.gov (United States)

    Bhatt, U.; Walker, D. A.; Bieniek, P.; Raynolds, M. K.; Epstein, H. E.; Comiso, J. C.; Pinzon, J. E.; Tucker, C. J.

    2012-12-01

    The goal of this paper is to present an analysis of the seasonality of tundra vegetation variability and change using long-term remotely sensed data as well as ground based measurements and reanalyses. An increase of Pan-Arctic tundra vegetation greenness has been documented using the remotely sensed Normalized Difference Vegetation Index (NDVI). Coherent variability between NDVI, springtime coastal sea ice (passive microwave) and land surface temperatures (AVHRR) has also been established. Satellite based snow and cloud cover data sets are being incorporated into this analysis. The Arctic tundra is divided into domains based on Treshnikov divisions that are modified based on floristic provinces. There is notable heterogeneity in Pan-Arctic vegetation and climate trends, which necessitates a regional analysis. This study uses remotely sensed weekly 25-km sea ice concentration, weekly surface temperature, and bi-weekly NDVI from 1982 to 2010. The GIMMS NDVI3g data has been corrected for biases during the spring and fall, with special focus on the Arctic. Trends of Maximum NDVI (MaxNDVI), Time Integrated NDVI (TI-NDVI), Summer Warmth Index (SWI, sum of degree months above freezing during May-August), and open water area are calculated for the Pan Arctic. Remotely sensed snow data trends suggest varying patterns throughout the Arctic and may in part explain the heterogeneous MaxNDVI trends. Standard climate data (station, reanalysis, and model data) and ground observations are used in the analysis to provide additional support for hypothesized mechanisms. Overall, we find that trends over the 30-year record are changing as evidenced by the following examples from recent years. The sea ice decline has increased in Eurasia and slowed in North America. The weekly AVHRR landsurface temperatures reveal that there has been summer cooling over Eurasia and that the warming over North America has slowed. The MaxNDVI rates of change have diverged between N. America and Eurasia

  17. Winter precipitation and snow accumulation drive the methane sink or source strength of Arctic tussock tundra.

    Science.gov (United States)

    Blanc-Betes, Elena; Welker, Jeffrey M; Sturchio, Neil C; Chanton, Jeffrey P; Gonzalez-Meler, Miquel A

    2016-08-01

    Arctic winter precipitation is projected to increase with global warming, but some areas will experience decreases in snow accumulation. Although Arctic CH4 emissions may represent a significant climate forcing feedback, long-term impacts of changes in snow accumulation on CH4 fluxes remain uncertain. We measured ecosystem CH4 fluxes and soil CH4 and CO2 concentrations and (13) C composition to investigate the metabolic pathways and transport mechanisms driving moist acidic tundra CH4 flux over the growing season (Jun-Aug) after 18 years of experimental snow depth increases and decreases. Deeper snow increased soil wetness and warming, reducing soil %O2 levels and increasing thaw depth. Soil moisture, through changes in soil %O2 saturation, determined predominance of methanotrophy or methanogenesis, with soil temperature regulating the ecosystem CH4 sink or source strength. Reduced snow (RS) increased the fraction of oxidized CH4 (Fox) by 75-120% compared to Ambient, switching the system from a small source to a net CH4 sink (21 ± 2 and -31 ± 1 mg CH4  m(-2)  season(-1) at Ambient and RS). Deeper snow reduced Fox by 35-40% and 90-100% in medium- (MS) and high- (HS) snow additions relative to Ambient, contributing to increasing the CH4 source strength of moist acidic tundra (464 ± 15 and 3561 ± 97 mg CH4  m(-2)  season(-1) at MS and HS). Decreases in Fox with deeper snow were partly due to increases in plant-mediated CH4 transport associated with the expansion of tall graminoids. Deeper snow enhanced CH4 production within newly thawed soils, responding mainly to soil warming rather than to increases in acetate fermentation expected from thaw-induced increases in SOC availability. Our results suggest that increased winter precipitation will increase the CH4 source strength of Arctic tundra, but the resulting positive feedback on climate change will depend on the balance between areas with more or less snow accumulation than they are currently

  18. Energy fluxes in a high Arctic tundra heath subjected to strong climate warming

    Science.gov (United States)

    Lund, M.; Hansen, B. U.; Pedersen, S. H.; Stiegler, C.; Tamstorf, M. P.

    2012-12-01

    During recent decades the observed warming in the Arctic has been almost twice as large as the global average. The implications of such strong warming on surface energy balance, regulating permafrost thaw, hydrology, soil stability and carbon mineralization, need to be assessed. In Zackenberg, northeast Greenland, measurements of energy balance components in various environments have been performed since late 90's, coordinated by Zackenberg Ecological Research Operations. During 1996-2009, mean annual temperature in the area has increased by ca. 0.15 °C yr-1; while maximum thaw depth has increased by 1.4-1.8 cm yr-1. Eddy covariance measurements of energy fluxes have been performed in a Cassiope heath plant community, a commonly occurring tundra ecosystem type in circumpolar middle and high Arctic areas, in Zackenberg allowing for detailed investigations of relationships between energy fluxes and meteorological and soil physical characteristics. As the available data set spans more than a decade, possible trends in energy flux components resulting from warming related changes such as earlier snow melt, increased active layer depth and higher temperatures can be investigated. This presentation will focus on the mid-summer period from which eddy covariance measurements are available. The summer-time energy partitioning at the Zackenberg tundra heath site will be characterized using ratios of sensible, latent and ground heat flux to net radiation and Bowen ratio, whereas the surface characteristics will be described using surface resistance, McNaughton and Jarvis Ω value and Priestley-Taylor α coefficient. Furthermore, we aim to estimate the full year, all energy balance components for the tundra heath site using Snow Model (Liston and Elder 2006) for the dark winter period during which no eddy covariance measurements are available. The snow cover duration in the area is a major regulator of the energy partitioning. Early results point towards high summer

  19. Tourism and Water: Themes of the Alpine Convention

    Science.gov (United States)

    Imhof, R.

    2012-04-01

    1) The contribution reflects the personal opinion of the author and does not necessarily reflect the point of view of the Permanent Secretariat. The Alpine Convention is a multilateral framework treaty signed in 1991 by the eight states of the Alpine bow as well as the European Community. Its main objectives are the sustainable development of the Alpine territory and the safeguarding of the interests of the people living within it, embracing the environmental, social and economic dimensions in the broadest sense. In order to achieve its objectives, over the years the Framework Convention has been equipped with a large number of thematic protocols, e.g. on tourism. The overall objective of the Protocol on Tourism, which first came into force in 2002, is to contribute to sustainable development in the Alpine region within the existing institutional framework, by encouraging environmentally-friendly tourism through specific measures and recommendations which take the interests of both the local population and tourists into account. The provisions of the Protocol on Tourism primarily concern tourism management and controlling tourist flows, structural developments such as ski lifts and ski slopes, accommodation and the balanced development of economically weak areas. Guidelines, development plans, sectoral plans have to be adopted at the appropriate territorial level in order to enable to assess the impact of tourism development on, inter alia, water. This extends also to ski slopes developments. For example the production of artificial snow production may be authorized only if the location's hydrological, climatic and ecological conditions allow. Water is listed among the twelve themes in relation to which the Contracting Parties are supposed to take measures and coordinate their policies (Article 2 of the Framework Convention). The Alpine Convention aims to preserve and re-establish healthy water systems, especially keeping waters clean and protecting the natural

  20. Comparison modeling for alpine vegetation distribution in an arid area.

    Science.gov (United States)

    Zhou, Jihua; Lai, Liming; Guan, Tianyu; Cai, Wetao; Gao, Nannan; Zhang, Xiaolong; Yang, Dawen; Cong, Zhentao; Zheng, Yuanrun

    2016-07-01

    Mapping and modeling vegetation distribution are fundamental topics in vegetation ecology. With the rise of powerful new statistical techniques and GIS tools, the development of predictive vegetation distribution models has increased rapidly. However, modeling alpine vegetation with high accuracy in arid areas is still a challenge because of the complexity and heterogeneity of the environment. Here, we used a set of 70 variables from ASTER GDEM, WorldClim, and Landsat-8 OLI (land surface albedo and spectral vegetation indices) data with decision tree (DT), maximum likelihood classification (MLC), and random forest (RF) models to discriminate the eight vegetation groups and 19 vegetation formations in the upper reaches of the Heihe River Basin in the Qilian Mountains, northwest China. The combination of variables clearly discriminated vegetation groups but failed to discriminate vegetation formations. Different variable combinations performed differently in each type of model, but the most consistently important parameter in alpine vegetation modeling was elevation. The best RF model was more accurate for vegetation modeling compared with the DT and MLC models for this alpine region, with an overall accuracy of 75 % and a kappa coefficient of 0.64 verified against field point data and an overall accuracy of 65 % and a kappa of 0.52 verified against vegetation map data. The accuracy of regional vegetation modeling differed depending on the variable combinations and models, resulting in different classifications for specific vegetation groups.

  1. Comparison modeling for alpine vegetation distribution in an arid area.

    Science.gov (United States)

    Zhou, Jihua; Lai, Liming; Guan, Tianyu; Cai, Wetao; Gao, Nannan; Zhang, Xiaolong; Yang, Dawen; Cong, Zhentao; Zheng, Yuanrun

    2016-07-01

    Mapping and modeling vegetation distribution are fundamental topics in vegetation ecology. With the rise of powerful new statistical techniques and GIS tools, the development of predictive vegetation distribution models has increased rapidly. However, modeling alpine vegetation with high accuracy in arid areas is still a challenge because of the complexity and heterogeneity of the environment. Here, we used a set of 70 variables from ASTER GDEM, WorldClim, and Landsat-8 OLI (land surface albedo and spectral vegetation indices) data with decision tree (DT), maximum likelihood classification (MLC), and random forest (RF) models to discriminate the eight vegetation groups and 19 vegetation formations in the upper reaches of the Heihe River Basin in the Qilian Mountains, northwest China. The combination of variables clearly discriminated vegetation groups but failed to discriminate vegetation formations. Different variable combinations performed differently in each type of model, but the most consistently important parameter in alpine vegetation modeling was elevation. The best RF model was more accurate for vegetation modeling compared with the DT and MLC models for this alpine region, with an overall accuracy of 75 % and a kappa coefficient of 0.64 verified against field point data and an overall accuracy of 65 % and a kappa of 0.52 verified against vegetation map data. The accuracy of regional vegetation modeling differed depending on the variable combinations and models, resulting in different classifications for specific vegetation groups. PMID:27307276

  2. Changes in alpine plant growth under future climate conditions

    Directory of Open Access Journals (Sweden)

    A. Rammig

    2010-06-01

    Full Text Available Alpine shrub- and grasslands are shaped by extreme climatic conditions such as a long-lasting snow cover and a short vegetation period. Such ecosystems are expected to be highly sensitive to global environmental change. Prolonged growing seasons and shifts in temperature and precipitation are likely to affect plant phenology and growth. In a unique experiment, climatology and plant growth was monitored for almost a decade at 17 snow meteorological stations in different alpine regions along the Swiss Alps. Regression analyses revealed highly significant correlations between mean air temperature in May/June and snow melt out, onset of plant growth, and plant height. These correlations were used to project plant growth phenology for future climate conditions based on the gridded output of a set of regional climate models runs. Melt out and onset of growth were projected to occur on average 17 days earlier by the end of the century than in the control period from 1971–2000 under the future climate conditions of the low resolution climate model ensemble. Plant height and biomass production were expected to increase by 77% and 45%, respectively. The earlier melt out and onset of growth will probably cause a considerable shift towards higher growing plants and thus increased biomass. Our results represent the first quantitative and spatially explicit estimates of climate change impacts on future growing season length and the respective productivity of alpine plant communities in the Swiss Alps.

  3. Alpine biodiversity and assisted migration: The case of the American pika (Ochotona princeps)

    Science.gov (United States)

    Wilkening, Jennifer L.; Ray, Chris; Ramsay, Nathan G.; Klingler, Kelly

    2015-01-01

    Alpine mammals are predicted to be among the species most threatened by climate change, due to the projected loss and further fragmentation of alpine habitats. As temperature or precipitation regimes change, alpine mammals may also be faced with insurmountable barriers to dispersal. The slow rate or inability to adjust to rapidly shifting environmental conditions may cause isolated alpine species to become locally extirpated, resulting in reduced biodiversity. One proposed method for mitigating the impacts of alpine species loss is assisted migration. This method, which involves translocating a species to an area with more favourable climate and habitat characteristics, has become the subject of debate and controversy in the conservation community. The uncertainty associated with climate change projections, coupled with the thermal sensitivity of many alpine mammals, makes it difficult to a priori assess the efficacy of this technique as a conservation management tool. Here we present the American pika (Ochotona princeps) as a case study. American pikas inhabit rocky areas throughout the western US, and populations in some mountainous areas have become locally extirpated in recent years. We review known climatic and habitat requirements for this species, and also propose protocols designed to reliably identify favourable relocation areas. We present data related to the physiological constraints of this species and outline specific requirements which must be addressed for translocation of viable populations, including wildlife disease and genetic considerations. Finally, we discuss potential impacts on other alpine species and alpine communities, and overall implications for conserving alpine biodiversity in a changing climate.

  4. The 'Guetsch' Alpine wind power test site; Alpine Test Site Guetsch. Handbuch und Fachtagung

    Energy Technology Data Exchange (ETDEWEB)

    Cattin, R.

    2008-12-15

    This final report for the Swiss Federal Office of Energy (SFOE) takes a look at the influence of icing-up on the operation of wind turbines in mountainous areas. Within the Swiss research project 'Alpine Test Site Guetsch', extensive icing studies were carried out at the Guetsch site near Andermatt, Switzerland. This document deals with the following subjects: Information about ice formation on structures, in particular with respect to wind turbines, standards and international research activities, wind measurements under icing-up conditions, estimation of the frequency of icing-up conditions, effects of icing-up on wind turbines, ice detection, measures available for de-icing and anti-icing as well as ice throw. A list of factors to be taken into account by the planners and operators of wind turbines in alpine environments is presented.

  5. Doubled volatile organic compound emissions from subarctic tundra under simulated climate warming

    DEFF Research Database (Denmark)

    Faubert, Patrick; Tiiva, Paivi; Rinnan, Åsmund;

    2010-01-01

    • Biogenic volatile organic compound (BVOC) emissions from arctic ecosystems are important in view of their role in global atmospheric chemistry and unknown feedbacks to global warming. These cold ecosystems are hotspots of climate warming, which will be more severe here than averaged over...... the globe. We assess the effects of climatic warming on non-methane BVOC emissions from a subarctic heath. • We performed ecosystem-based chamber measurements and gas chromatography-mass spectrometry (GC-MS) analyses of the BVOCs collected on adsorbent over two growing seasons at a wet subarctic tundra...... of a focus on BVOC emissions during climate change. The observed changes have implications for ecological interactions and feedback effects on climate change via impacts on aerosol formation and indirect greenhouse effects....

  6. Increased ectomycorrhizal fungal abundance after long-term fertilization and warming of two arctic tundra ecosystems

    DEFF Research Database (Denmark)

    Clemmensen, Karina Engelbrecht; Michelsen, Anders; Jonasson, Sven Evert;

    2006-01-01

    the response in EM fungal abundance to long-term warming and fertilization in two arctic ecosystems with contrasting responses of the EM shrub Betula nana. •  Ergosterol was used as a biomarker for living fungal biomass in roots and organic soil and ingrowth bags were used to estimate EM mycelial production......•  Shrub abundance is expected to increase with enhanced temperature and nutrient availability in the Arctic, and associated changes in abundance of ectomycorrhizal (EM) fungi could be a key link between plant responses and longer-term changes in soil organic matter storage. This study quantifies....... We measured 15N and 13C natural abundance to identify the EM-saprotrophic divide in fungal sporocarps and to validate the EM origin of mycelia in the ingrowth bags. •  Fungal biomass in soil and EM mycelial production increased with fertilization at both tundra sites, and with warming at one site...

  7. Microbial iron oxidation in the Arctic tundra and its implications for biogeochemical cycling.

    Science.gov (United States)

    Emerson, David; Scott, Jarrod J; Benes, Joshua; Bowden, William B

    2015-12-01

    The role that neutrophilic iron-oxidizing bacteria play in the Arctic tundra is unknown. This study surveyed chemosynthetic iron-oxidizing communities at the North Slope of Alaska near Toolik Field Station (TFS) at Toolik Lake (lat 68.63, long -149.60). Microbial iron mats were common in submerged habitats with stationary or slowly flowing water, and their greatest areal extent is in coating plant stems and sediments in wet sedge meadows. Some Fe-oxidizing bacteria (FeOB) produce easily recognized sheath or stalk morphotypes that were present and dominant in all the mats we observed. The cool water temperatures (9 to 11°C) and reduced pH (5.0 to 6.6) at all sites kinetically favor microbial iron oxidation. A microbial survey of five sites based on 16S rRNA genes found a predominance of Proteobacteria, with Betaproteobacteria and members of the family Comamonadaceae being the most prevalent operational taxonomic units (OTUs). In relative abundance, clades of lithotrophic FeOB composed 5 to 10% of the communities. OTUs related to cyanobacteria and chloroplasts accounted for 3 to 25% of the communities. Oxygen profiles showed evidence for oxygenic photosynthesis at the surface of some mats, indicating the coexistence of photosynthetic and FeOB populations. The relative abundance of OTUs belonging to putative Fe-reducing bacteria (FeRB) averaged around 11% in the sampled iron mats. Mats incubated anaerobically with 10 mM acetate rapidly initiated Fe reduction, indicating that active iron cycling is likely. The prevalence of iron mats on the tundra might impact the carbon cycle through lithoautotrophic chemosynthesis, anaerobic respiration of organic carbon coupled to iron reduction, and the suppression of methanogenesis, and it potentially influences phosphorus dynamics through the adsorption of phosphorus to iron oxides. PMID:26386054

  8. Isotopic insights into methane production, oxidation, and emissions in Arctic polygon tundra.

    Science.gov (United States)

    Vaughn, Lydia J S; Conrad, Mark E; Bill, Markus; Torn, Margaret S

    2016-10-01

    Arctic wetlands are currently net sources of atmospheric CH4 . Due to their complex biogeochemical controls and high spatial and temporal variability, current net CH4 emissions and gross CH4 processes have been difficult to quantify, and their predicted responses to climate change remain uncertain. We investigated CH4 production, oxidation, and surface emissions in Arctic polygon tundra, across a wet-to-dry permafrost degradation gradient from low-centered (intact) to flat- and high-centered (degraded) polygons. From 3 microtopographic positions (polygon centers, rims, and troughs) along the permafrost degradation gradient, we measured surface CH4 and CO2 fluxes, concentrations and stable isotope compositions of CH4 and DIC at three depths in the soil, and soil moisture and temperature. More degraded sites had lower CH4 emissions, a different primary methanogenic pathway, and greater CH4 oxidation than did intact permafrost sites, to a greater degree than soil moisture or temperature could explain. Surface CH4 flux decreased from 64 nmol m(-2)  s(-1) in intact polygons to 7 nmol m(-2)  s(-1) in degraded polygons, and stable isotope signatures of CH4 and DIC showed that acetate cleavage dominated CH4 production in low-centered polygons, while CO2 reduction was the primary pathway in degraded polygons. We see evidence that differences in water flow and vegetation between intact and degraded polygons contributed to these observations. In contrast to many previous studies, these findings document a mechanism whereby permafrost degradation can lead to local decreases in tundra CH4 emissions.

  9. Nitrogen availability increases in a tundra ecosystem during five years of experimental permafrost thaw.

    Science.gov (United States)

    Salmon, Verity G; Soucy, Patrick; Mauritz, Marguerite; Celis, Gerardo; Natali, Susan M; Mack, Michelle C; Schuur, Edward A G

    2016-05-01

    Perennially frozen soil in high latitude ecosystems (permafrost) currently stores 1330-1580 Pg of carbon (C). As these ecosystems warm, the thaw and decomposition of permafrost is expected to release large amounts of C to the atmosphere. Fortunately, losses from the permafrost C pool will be partially offset by increased plant productivity. The degree to which plants are able to sequester C, however, will be determined by changing nitrogen (N) availability in these thawing soil profiles. N availability currently limits plant productivity in tundra ecosystems but plant access to N is expected improve as decomposition increases in speed and extends to deeper soil horizons. To evaluate the relationship between permafrost thaw and N availability, we monitored N cycling during 5 years of experimentally induced permafrost thaw at the Carbon in Permafrost Experimental Heating Research (CiPEHR) project. Inorganic N availability increased significantly in response to deeper thaw and greater soil moisture induced by Soil warming. This treatment also prompted a 23% increase in aboveground biomass and a 49% increase in foliar N pools. The sedge Eriophorum vaginatum responded most strongly to warming: this species explained 91% of the change in aboveground biomass during the 5 year period. Air warming had little impact when applied alone, but when applied in combination with Soil warming, growing season soil inorganic N availability was significantly reduced. These results demonstrate that there is a strong positive relationship between the depth of permafrost thaw and N availability in tundra ecosystems but that this relationship can be diminished by interactions between increased thaw, warmer air temperatures, and higher levels of soil moisture. Within 5 years of permafrost thaw, plants actively incorporate newly available N into biomass but C storage in live vascular plant biomass is unlikely to be greater than losses from deep soil C pools. PMID:26718892

  10. Carbon dioxide balance of subarctic tundra from plot to regional scales

    Directory of Open Access Journals (Sweden)

    M. E. Marushchak

    2012-08-01

    Full Text Available We report here the carbon dioxide (CO2 budget of a 98.6-km2 subarctic tundra area in Northeast European Russia based on measurements at two different scales and two independent up-scaling approaches. Plot scale measurements (chambers on terrestrial surfaces, gas gradient method and bubble collectors on lakes were carried out from July 2007 to October 2008. The landscape scale eddy covariance (EC measurements covered the snow-free period 2008. The annual net ecosystem exchange (NEE of different land cover types ranged from −251 to 84 g C m−2. Leaf area index (LAI was an excellent predictor of the spatial variability in gross photosynthesis (GP, NEE and ecosystem respiration (ER. The plot scale CO2 fluxes were first scaled up to the EC source area and then to the whole study area using two data sets: a land cover classification and a LAI map, both based on field data and 2.4 m pixel-sized Quickbird satellite image. The good agreement of the CO2 balances for the EC footprint based on the different methods (−105 to −81 g C m−2 vs. −79 g C m−2; growing season 2008 justified the integration of the plot scale measurements over the larger area. The annual CO2 balance for the study region was −67 to −41 g C m−2. Due to the heterogeneity of tundra, the effect of climate change on CO2 uptake will vary strongly according to the land cover type and, moreover, likely changes in their relative coverage in future will have great impact on the regional CO2 balance.

  11. Longer thaw seasons increase nitrogen availability for leaching during fall in tundra soils

    Science.gov (United States)

    Treat, Claire C.; Wollheim, Wilfred M.; Varner, Ruth K.; Bowden, William B.

    2016-06-01

    Climate change has resulted in warmer soil temperatures, earlier spring thaw and later fall freeze-up, resulting in warmer soil temperatures and thawing of permafrost in tundra regions. While these changes in temperature metrics tend to lengthen the growing season for plants, light levels, especially in the fall, will continue to limit plant growth and nutrient uptake. We conducted a laboratory experiment using intact soil cores with and without vegetation from a tundra peatland to measure the effects of late freeze and early spring thaw on carbon dioxide (CO2) exchange, methane (CH4) emissions, dissolved organic carbon (DOC) and nitrogen (N) leaching from soils. We compared soil C exchange and N production with a 30 day longer seasonal thaw during a simulated annual cycle from spring thaw through freeze-up and thaw. Across all cores, fall N leaching accounted for ˜33% of total annual N loss despite significant increases in microbial biomass during this period. Nitrate ({{{{NO}}}3}-) leaching was highest during the fall (5.33 ± 1.45 mg N m-2 d-1) following plant senescence and lowest during the summer (0.43 ± 0.22 mg N m-2 d-1). In the late freeze and early thaw treatment, we found 25% higher total annual ecosystem respiration but no significant change in CH4 emissions or DOC loss due to high variability among samples. The late freeze period magnified N leaching and likely was derived from root turnover and microbial mineralization of soil organic matter coupled with little demand from plants or microbes. Large N leaching during the fall will affect N cycling in low-lying areas and streams and may alter terrestrial and aquatic ecosystem nitrogen budgets in the arctic.

  12. Age-specific survival of tundra swans on the lower Alaska Peninsula

    Science.gov (United States)

    Meixell, Brandt W.; Lindberg, Mark S.; Conn, Paul B.; Dau, Christian P.; Sarvis, John E.; Sowl, Kristine M.

    2013-01-01

    The population of Tundra Swans (Cygnus columbianus columbianus) breeding on the lower Alaska Peninsula represents the southern extremity of the species' range and is uniquely nonmigratory. We used data on recaptures, resightings, and recoveries of neck-collared Tundra Swans on the lower Alaska Peninsula to estimate collar loss, annual apparent survival, and other demographic parameters for the years 1978–1989. Annual collar loss was greater for adult males fitted with either the thinner collar type (0.34) or the thicker collar type (0.15) than for other age/sex classes (thinner: 0.10, thicker: 0.04). The apparent mean probability of survival of adults (0.61) was higher than that of immatures (0.41) and for both age classes varied considerably by year (adult range: 0.44–0.95, immature range: 0.25–0.90). To assess effects of permanent emigration by age and breeding class, we analyzed post hoc the encounter histories of swans known to breed in our study area. The apparent mean survival of known breeders (0.65) was generally higher than that of the entire marked sample but still varied considerably by year (range 0.26–1.00) and indicated that permanent emigration of breeding swans was likely. We suggest that reductions in apparent survival probability were influenced primarily by high and variable rates of permanent emigration and that immigration by swans from elsewhere may be important in sustaining a breeding population at and near Izembek National Wildlife Refuge.

  13. Variability of Water Chemistry in Tundra Lakes, Petuniabukta Coast, Central Spitsbergen, Svalbard

    Directory of Open Access Journals (Sweden)

    Małgorzata Mazurek

    2012-01-01

    Full Text Available Samples of water from small tundra lakes located on raised marine terraces on the eastern coast of Petuniabukta (Ebbadalen, Central Spitsbergen were examined to assess the changes in water chemistry that had occurred during the summer seasons of 2001–2003 and 2006. The unique environmental conditions of the study region include the predominance of sedimentary carbonate and sulphate rocks, low precipitation values, and an active permafrost layer with a maximum thickness of 1.2 m. The average specific electric conductivity (EC values for the three summer seasons in the four lakes ranged from 242 to 398 μS cm−1. The highest EC values were observed when the air temperature decreased and an ice cover formed (cryochemical effects. The ion composition was dominated by calcium (50.7 to 86.6%, bicarbonates (39.5 to 86.4%, and sulphate anions. The high concentrations of HCO3−, SO42−, and Ca2+ ions were attributed to the composition of the bedrock, which mainly consists of gypsum and anhydrite. The average proportion of marine components in the total load found in the Ebbadalen tundra lake waters was estimated to be 8.1%. Precipitation supplies sulphates (as much as 69–81% and chlorides (14–36% of nonsea origin. The chief source of these compounds may be contamination from the town of Longyearbyen. Most ions originate in the crust, the active layer of permafrost, but some are atmospheric in origin and are either transported or generated in biochemical processes. The concentrations of most components tend to increase during the summer months, reaching a maximum during freezing and partially precipitating onto the bottom sediments.

  14. Arctic biodiversity: Increasing richness accompanies shrinking refugia for a cold-associated tundra fauna

    Science.gov (United States)

    Hope, Andrew; Waltari, Eric; Malaney, Jason L.; Payer, David C.; Cook, J.A.; Talbot, Sandra

    2015-01-01

    As ancestral biodiversity responded dynamically to late-Quaternary climate changes, so are extant organisms responding to the warming trajectory of the Anthropocene. Ecological predictive modeling, statistical hypothesis tests, and genetic signatures of demographic change can provide a powerful integrated toolset for investigating these biodiversity responses to climate change, and relative resiliency across different communities. Within the biotic province of Beringia, we analyzed specimen localities and DNA sequences from 28 mammal species associated with boreal forest and Arctic tundra biomes to assess both historical distributional and evolutionary responses and then forecasted future changes based on statistical assessments of past and present trajectories, and quantified distributional and demographic changes in relation to major management regions within the study area. We addressed three sets of hypotheses associated with aspects of methodological, biological, and socio-political importance by asking (1) what is the consistency among implications of predicted changes based on the results of both ecological and evolutionary analyses; (2) what are the ecological and evolutionary implications of climate change considering either total regional diversity or distinct communities associated with major biomes; and (3) are there differences in management implications across regions? Our results indicate increasing Arctic richness through time that highlights a potential state shift across the Arctic landscape. However, within distinct ecological communities, we found a predicted decline in the range and effective population size of tundra species into several discrete refugial areas. Consistency in results based on a combination of both ecological and evolutionary approaches demonstrates increased statistical confidence by applying cross-discipline comparative analyses to conservation of biodiversity, particularly considering variable management regimes that seek

  15. Could 4 degrees warming change Arctic tundra from carbon sink to carbon source?

    Science.gov (United States)

    Torn, M. S.; Abramoff, R. Z.; Chafe, O.; Curtis, J. B.; Smith, L. J.; Wullschleger, S. D.

    2015-12-01

    We have set up a controlled, active warming experiment in permafrost tundra on the North Slope of Alaska. The aim of this micro-warming experiment is to investigate the direct effect of soil warming on microbial decomposition of soil organic matter. We are testing the feasibility of small, short-term, in situ warming that can be run off batteries for distributed deployment and that preserves plant-soil relations and natural variability in wind, temperature, and precipitation. Based on preliminary results, the approach looks promising. One resistance heater cable per plot (25 cm diameter plots) was inserted vertically to 50 cm, spanning the full active layer (maximum thaw depth was 40 cm in 2014). Heaters were turned on August 1, 2015, and heated plots reached the 4ºC warming target within 1-3 days. We are measuring soil microclimate, thaw depth, CO2 and CH4 fluxes, and 14CO2, and microbial composition, as part of the DOE Next Generation Ecosystem Experiments (NGEE-Arctic). Ecosystem respiration increased immediately in the heated plots, and net ecosystem exchange under clear chambers changed from net uptake to net CO2 source in two of the four plots. CH4 flux shifted toward reduced net emissions or greater net uptake in all plots. These rapid responses demonstrate direct changes in decomposition without complications from microbial acclimation, altered community structure or changes in substrate availability. However, future Arctic tundra carbon balance will depend on both short term and long term microbial responses, as well as the links between warming, decomposition, nitrogen mineralization, and plant growth. Thus, we envision that distributed micro-warming plots could be combined with new approaches to aboveground passive warming being developed in NGEE, gradient studies, and modeling.

  16. Longer thaw seasons increase nitrogen availability for leaching during fall in tundra soils

    Science.gov (United States)

    Treat, Claire C.; Wollheim, Wilfred M.; Varner, Ruth K.; Bowden, William B.

    2016-06-01

    Climate change has resulted in warmer soil temperatures, earlier spring thaw and later fall freeze-up, resulting in warmer soil temperatures and thawing of permafrost in tundra regions. While these changes in temperature metrics tend to lengthen the growing season for plants, light levels, especially in the fall, will continue to limit plant growth and nutrient uptake. We conducted a laboratory experiment using intact soil cores with and without vegetation from a tundra peatland to measure the effects of late freeze and early spring thaw on carbon dioxide (CO2) exchange, methane (CH4) emissions, dissolved organic carbon (DOC) and nitrogen (N) leaching from soils. We compared soil C exchange and N production with a 30 day longer seasonal thaw during a simulated annual cycle from spring thaw through freeze-up and thaw. Across all cores, fall N leaching accounted for ∼33% of total annual N loss despite significant increases in microbial biomass during this period. Nitrate ({{{{NO}}}3}-) leaching was highest during the fall (5.33 ± 1.45 mg N m‑2 d‑1) following plant senescence and lowest during the summer (0.43 ± 0.22 mg N m‑2 d‑1). In the late freeze and early thaw treatment, we found 25% higher total annual ecosystem respiration but no significant change in CH4 emissions or DOC loss due to high variability among samples. The late freeze period magnified N leaching and likely was derived from root turnover and microbial mineralization of soil organic matter coupled with little demand from plants or microbes. Large N leaching during the fall will affect N cycling in low-lying areas and streams and may alter terrestrial and aquatic ecosystem nitrogen budgets in the arctic.

  17. Elevation, Substrate, & Climate effects on Alpine & Sub-Alpine Plant Distribution in California & Nevada's High Mountains: Preliminary Data from the California and Nevada GLORIA Project

    Science.gov (United States)

    Barber, A.; Millar, C.

    2014-12-01

    Documenting plant response to global climate change in sensitive zones, such as the alpine, is a major goal for global change biology. Basic information on alpine plant distribution by elevation and substrate provides a basis for anticipating which species may decline in a warming climate. The Global Observation Research Initiative in Alpine Environments (GLORIA) is a worldwide effort to document vegetation changes over time in alpine settings using permanent multi-summit plots. The California/Nevada group currently monitors seven permanent GLORIA target regions, composed of 29 summits in alpine and subalpine zones. Summits range in elevations from 2918m to 4325m on substrates including dolomite, granite, quartzite, and volcanics. High-resolution plant occurrence and cover data from the upper 10 meters of each summit are presented. Plants from our target regions can be divided into three groups: summit specialists found only on the highest peaks, alpine species found predominantly within the alpine zone, and broadly distributed species found in the alpine zone and below. Rock substrate and microsite soil development have a strong influence on plant communities and species richness. We present the first set of five-year resurvey and temperature data from 18 summits. We have documented some annual variation in species presence/absence at almost all sites, but no dramatic changes in total diversity. Consistent with the expectation of rising global temperatures, our soil temperature loggers have documented temperature increases at most of our sites. These data are a baseline for assessing bioclimatic shifts and future plant composition in California and Nevada's alpine zone.

  18. Impacts of permafrost changes on alpine ecosystem in Qinghai-Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG; Genxu; LI; Yuanshou

    2006-01-01

    Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem. The vegetation coverage,grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau. The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer, permafrost thickness and mean annual ground temperature (MAGTs). Based on the statistics model of GPTR for MAGTs and annual air temperatures, an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems. Under the climate change and human engineering activities, the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun Mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper. The results showed that the permafrost changes have a different influence on different alpine ecosystems. With the increase in the thickness of active layer, the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction, the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease, and the surface soil materials become coarse and gravelly. The alpine cold steppe ecosystem, however, seems to have a relatively weak relation to the permafrost environment.Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98% and alpine cold swamp decreased by 28.11% under the permafrost environment degradation during recent 15 years. In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions, among them the alpine cold meadow and swamp ecosystem located in the Iow mountain and plateau area will have a relatively

  19. Vegetation biomass, leaf area index, and NDVI patterns and relationships along two latitudinal transects in arctic tundra

    Science.gov (United States)

    Epstein, H. E.; Walker, D. A.; Raynolds, M. K.; Kelley, A. M.; Jia, G.; Ping, C.; Michaelson, G.; Leibman, M. O.; Kaarlejärvi, E.; Khomutov, A.; Kuss, P.; Moskalenko, N.; Orekhov, P.; Matyshak, G.; Forbes, B. C.; Yu, Q.

    2009-12-01

    Analyses of vegetation properties along climatic gradients provide first order approximations as to how vegetation might respond to a temporally dynamic climate. Until recently, no systematic study of tundra vegetation had been conducted along bioclimatic transects that represent the full latitudinal extent of the arctic tundra biome. Since 1999, we have been collecting data on arctic tundra vegetation and soil properties along two such transects, the North American Arctic Transect (NAAT) and the Yamal Arctic Transect (YAT). The NAAT spans the arctic tundra from the Low Arctic of the North Slope of Alaska to the polar desert of Cape Isachsen on Ellef Ringnes Island in the Canadian Archipelago. The Yamal Arctic Transect located in northwest Siberia, Russia, presently ranges from the forest-tundra transition at Nadym to the High Arctic tundra on Belyy Ostrov off the north coast of the Yamal Peninsula. The summer warmth indices (SWI - sum of mean monthly temperatures greater than 0°C) range from approximately 40 °C months to 3 °C months from south to north. For largely zonal sites along these transects, we systematically collected leaf area index (LAI-2000 Plant Canopy Analyzer), normalized difference vegetation index (NDVI - PSII hand-held spectro-radiometer), and vegetation biomass (clip harvests). Site-averaged LAI ranges from 1.08 to 0 along the transects, yet can be highly variable at the landscape scale. Site-averaged NDVI ranges from 0.67 to 0.26 along the transects, and is less variable than LAI at the landscape scale. Total aboveground live biomass ranges from approximately 700 g m-2 to < 50 g m-2 along the NAAT, and from approximately 1100 g m-2 to < 400 g m-2 along the YAT (not including tree biomass at Nadym). LAI and NDVI are highly correlated logarithmically (r = 0.80) for the entire dataset. LAI is significantly related to total aboveground (live plus dead) vascular plant biomass, although there is some variability in the data (r = 0.63). NDVI is

  20. Flux Of Carbon from an Airborne Laboratory (FOCAL): Synergy of airborne and surface measures of carbon emission and isotopologue content from tundra landscape in Alaska

    Science.gov (United States)

    Dobosy, R.; Dumas, E.; Sayres, D. S.; Kochendorfer, J.

    2013-12-01

    Arctic tundra, recognized as a potential major source of new atmospheric carbon, is characterized by low topographic relief and small-scale heterogeneity consisting of small lakes and intervening tundra vegetation. This fits well the flux-fragment method (FFM) of analysis of data from low-flying aircraft. The FFM draws on 1)airborne eddy-covariance flux measurements, 2)a classified surface-characteristics map (e.g. open water vs tundra), 3)a footprint model, and 4)companion surface-based eddy-covariance flux measurements. The FOCAL, a collaboration among Harvard University's Anderson Group, NOAA's Atmospheric Turbulence and Diffusion Division (ATDD), and Aurora Flight Sciences, Inc., made coordinated flights in 2013 August with a collaborating surface site. The FOCAL gathers not only flux data for CH4 and CO2 but also the corresponding carbon-isotopologue content of these gases. The surface site provides a continuous sample of carbon flux from interstitial tundra over time throughout the period of the campaign. The FFM draws samples from the aircraft data over many instances of tundra and also open water. From this we will determine how representative the surface site is of the larger area (100 km linear scale), and how much the open water differs from the tundra as a source of carbon.

  1. Isolated fracture of the fibular shaft due to alpine skiing; a specific injury

    OpenAIRE

    Yıldız, Atıl Atilla, Ozkan Kose, Ferhat Guler, H

    2013-01-01

    Although musculoskeletal injuries of lower leg due to alpine skiing is well known and widely reported, an acute isolated fibula fracture as a specific ski injury has not been reported in the relevant literature. Herein, we present a case of isolated fibula fracture which is missed at initial admission, and discuss the mechanism of injury and relationship with alpine skiing equipment.

  2. High solar radiation hinders tree regeneration above the alpine treeline in northern Ecuador

    NARCIS (Netherlands)

    Bader, M.; Geloof, van I.; Rietkerk, M.

    2007-01-01

    Many tropical alpine treelines lie below their climatic potential, because of natural or anthropogenic causes. Forest extension above the treeline depends on the ability of trees to establish in the alpine environment. This ability may be limited by different factors, such as low temperatures, exces

  3. THE RESPONSES OF CYPERACEAE PFTS PLANT TO SIMULATING WARMING IN ALPINE KOBRESIA HUMILIS MEADOW%模拟增温对矮嵩草草甸莎草科功能群植物的影响

    Institute of Scientific and Technical Information of China (English)

    赵建中; 刘伟; 周玉碧

    2012-01-01

    本论文以青藏高原矮嵩草草甸植物群落为主要研究对象,采用国际冻原计划(ITEX)模拟增温对植物影响的研究方法设置模拟增温样地,探讨了模拟增温对高寒矮嵩草草甸莎草科功能群植物的影响,结果表明,莎草科功能群植物的生物量随温度的逐渐升高先增大后减小;盖度在试验第一、二年均随温度的升高先增加后减小,在试验第三年盖度随温度的升高逐渐减小;植物高度随温度的升高逐渐增大;重要值在试验第一、二年随温度的升高先增大后减小,在试验第三年随温度的升高而逐渐增大。%The plant communities in alpine Kobresia humilis meadow as the main research object, we set the artificial warming and natural warming plots, and they based on the international tundra program ( ITEX ) simu- lation of temperature effect on plant research methods. The Responses of Cyperaceae Pb-Ts ( Plant Functional Type) plant to simulating warming in alpine Kobresia humilis meadow was discussed. The results showed that biomass of Cyperaceae PFTs plants increased at first with temperature increasing and then decreased. Coverage and important value of Cyperaceae PFTs plants increased at first with temperature increasing and then decreased in 2008, 2009, but it decreased with warming in 2010. Plant height increased with temperature increasing.

  4. Quantification of DOC concentrations in relation with soil properties of soils in tundra and taiga of Northern European Russia

    Directory of Open Access Journals (Sweden)

    M. R. Oosterwoud

    2010-05-01

    Full Text Available Potential mobilization and transport of Dissolved Organic Carbon (DOC in subarctic river basins towards the oceans is enormous, because 23–48% of the worlds Soil Organic Carbon (SOC is stored in northern regions. As climate changes, the amount and composition of DOC exported from these basins are expected to change. The transfer of organic carbon between soils and rivers results in fractionation of organic carbon compounds. The aim of this research is to determine the DOC concentrations, its fractions, i.e. humic (HA, fulvic (FA, and hydrophilic (HY acids, and soil characteristics that influence the DOC sorptive properties of different soil types within a tundra and taiga catchment of Northern European Russia. DOC in taiga and tundra soil profiles (soil solution consisted only of HY and FA, where HY became more abundant with increasing depth. Adsorption of DOC on mineral phases is the key geochemical process for release and removal of DOC from potentially soluble carbon pool. We found that adsorbed organic carbon may desorb easily and can release DOC quickly, without being dependent on mineralization and degradation. Although Extractable Organic Carbon (EOC comprise only a small part of SOC, it is a significant buffering pool for DOC. We found that about 80–90% of released EOC was previously adsorbed. Fractionation of EOC is also influenced by the fact that predominantly HA and FA adsorbed to soil and therefore also are the main compounds released when desorbed. Flowpaths vary between taiga and tundra and through seasons, which likely affects DOC concentration found in streams. As climate changes, also flowpaths of water through soils may change, especially in tundra caused by thawing soils. Therefore, adsorptive properties of thawing soils exert a major control on DOC leaching to rivers. To better understand the process of DOC ad- and de-sorption in soils, process based soil chemical modelling, which could bring more insight in solution

  5. Alpine Snow Cover - Water Resources in Arid Regions

    Science.gov (United States)

    Czyzowska, E. H.; Van Leeuwen, W. J.; Hirschboeck, K. K.; Wisniewski, W. T.; Marsh, S. E.

    2013-12-01

    There is an undisputed need to increase accuracy of snow cover estimation in regions of complex terrain, especially in areas dependent on winter snow accumulation for a substantial portion of their water supply, such as the Western United States, Central Asia, and the Andes. Presently, the most pertinent monitoring and research needs related to alpine snow cover extent (SCE) are: (1) to improve SCE monitoring by providing detailed fractional snow cover (FSC) products which perform well in temporal/spatial heterogeneous forested and/or alpine terrains; (2) to provide accurate measurements of FSC at the watershed scale for use in snow water equivalent (SWE) estimation for regional water management; (3) to provide detailed distributions of FSC in mountainous regions to investigate the temporal/spatial distribution of SCE/SWE in relation to recent climate changes; (4) to use FSC products as input for climate models at multiple scales; and (5) to estimate SCE and SWE for use in ecological studies (e.g., vegetation cover, water stress, primary production, fire, insect outbreaks, and pulses in tree demography). To address the above our approach is based on Landsat/MODIS Fractional Snow Cover (LandsatFSC, ModisFSC), as a measure of the temporal/spatial distribution of alpine SCE. We used a fusion methodology between remotely sensed multispectral data from Landsat TM/ETM+/MODIS and Ikonos utilized at their highest respective spatial resolutions. Artificial Neural Networks (ANNs) are used to capture the multi-scale information structure of the data by means of the ANN training process, followed by the ANN extracting FSC from all available information in the Landsat images. The LandsatFSC/ModisFSC algorithms were validated (RMSE ~ 0.09; mean error ~ 0.001-0.01 FSC) in watersheds characterized by diverse environmental factors such as: terrain, slope, exposition, vegetation cover, and wide-ranging snow cover conditions.

  6. Warming Contracts Flowering Phenology in an Alpine Ecosystem

    Science.gov (United States)

    Jabis, M. D.; Winkler, D. E.; Kueppers, L. M.

    2015-12-01

    In alpine ecosystems where temperature increases associated with anthropogenic climate change are likely to be amplified, the flowering phenology of plants may be particularly sensitive to changes in environmental signals. For example, earlier snowmelt and higher temperature have been found to be important factors driving plant emergence and onset of flowering. However, few studies have examined the interactive role of soil moisture in response to warming. Using infrared heating to actively warm plots crossed with manual watering over the growing season in a moist alpine meadow at Niwot Ridge, Colorado, our preliminary results indicate that community-level phenology (length of flowering time across all species) was contracted with heating but was unaffected by watering. At the species level, additional water extended the length of the flowering season by one week for almost half (43%) of species. Heating, which raised plant and surface soil temperatures (+1.5 C) advanced snowmelt by ~7.6 days days and reduced soil moisture by ~2%, advanced flowering phenology for 86% of species. The response of flowering phenology to combined heating and watering was predominantly a heating effect. However, watering did appear to mitigate advances in end of flowering for 22% of species. The length of flowering season, for some species, appears to be tied, in part, to moisture availability as alleviating ambient soil moisture stress delayed phenology in unheated plots. Therefore, we conclude that both temperature and moisture appear to be important factors driving flowering phenology in this alpine ecosystem. The relationship between flowering phenology and species- or community-level productivity is not well established, but heating advanced community peak productivity by 5.4 days, and also reduced peak productivity unless additional water was provided, indicating some consistency between drivers of productivity and drivers of flowering phenology.

  7. Experimental evaluation of seed limitation in alpine snowbed plants.

    Directory of Open Access Journals (Sweden)

    Stefan Dullinger

    Full Text Available BACKGROUND: The distribution and abundance of plants is controlled by the availability of seeds and of sites suitable for establishment. The relative importance of these two constraints is still contentious and possibly varies among species and ecosystems. In alpine landscapes, the role of seed limitation has traditionally been neglected, and the role of abiotic gradients emphasized. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated the importance of seed limitation for the incidence of four alpine snowbed species (Achillea atrata L., Achillea clusiana Tausch, Arabis caerulea L., Gnaphalium hoppeanum W. D. J. Koch in local plant communities by comparing seedling emergence, seedling, juvenile and adult survival, juvenile and adult growth, flowering frequency as well as population growth rates λ of experimental plants transplanted into snowbed patches which were either occupied or unoccupied by the focal species. In addition, we accounted for possible effects of competition or facilitation on these rates by including a measure of neighbourhood biomass into the analysis. We found that only A. caerulea had significantly lower seedling and adult survival as well as a lower population growth rate in unoccupied sites whereas the vital rates of the other three species did not differ among occupied and unoccupied sites. By contrast, all species were sensitive to competitive effects of the surrounding vegetation in terms of at least one of the studied rates. CONCLUSIONS/SIGNIFICANCE: We conclude that seed and site limitation jointly determine the species composition of these snowbed plant communities and that constraining site factors include both abiotic conditions and biotic interactions. The traditional focus on abiotic gradients for explaining alpine plant distribution hence appears lopsided. The influence of seed limitation on the current distribution of these plants casts doubt on their ability to readily track shifting habitats under climate change

  8. Subsidence, stress regime and rotation(s) of a tectonically active sedimentary basin within the western Alpine Orogen: the Tertiary Piedmont Basin (Alpine domain, NW Italy)

    OpenAIRE

    Carrapa, B.; Bertotti, G.; Krijgsman, W.

    2003-01-01

    The Oligocene to Miocene Tertiary Piedmont Basin (TPB) is located in the NW part of Italy at the junction between the Apennine and the Alpine thrust belts. The position of the TPB on top of the Alpine/Apennine Orogen poses fundamental questions as to the tectonics of the basin subsidence. Having undergone little deformation, the TPB sediments provide an insight into the stress regime and rotations in the kinematically very complex area surrounding the basin itself. In this study we integrate ...

  9. Continuous recording of seismic signals in Alpine permafrost

    Science.gov (United States)

    Hausmann, H.; Krainer, K.; Staudinger, M.; Brückl, E.

    2009-04-01

    Over the past years various geophysical methods were applied to study the internal structure and the temporal variation of permafrost whereof seismic is of importance. For most seismic investigations in Alpine permafrost 24-channel equipment in combination with long data and trigger cables is used. Due to the harsh environment source and geophone layouts are often limited to 2D profiles. With prospect for future 3D-layouts we introduce an alternative of seismic equipment that can be used for several applications in Alpine permafrost. This study is focussed on controlled and natural source seismic experiments in Alpine permafrost using continuous data recording. With recent data from an ongoing project ("Permafrost in Austria") we will highlight the potential of the used seismic equipment for three applications: (a) seismic permafrost mapping of unconsolidated sediments, (b) seismic tomography in rock mass, and (c) passive seismic monitoring of rock falls. Single recording units (REFTEK 130, 6 channels) are used to continuously record the waveforms of both the seismic signals and a trigger signal. The combination of a small number of recording units with different types of geophones or a trigger allow numerous applications in Alpine permafrost with regard to a high efficiency and flexible seismic layouts (2D, 3D, 4D). The efficiency of the light and robust seismic equipment is achieved by the simple acquisition and the flexible and fast deployment of the (omni-directional) geophones. Further advantages are short (data and trigger) cables and the prevention of trigger errors. The processing of the data is aided by 'Seismon' which is an open source software project based on Matlab® and MySQL (see SM1.0). For active-source experiments automatic stacking of the seismic signals is implemented. For passive data a program for automatic detection of events (e.g. rock falls) is available which allows event localization. In summer 2008 the seismic equipment was used for the

  10. Protective equipment for emergency rescue in alpine-cold region

    Institute of Scientific and Technical Information of China (English)

    Ma Tian; Feng Xinxing; Wang Qizhi; Hao Limin

    2013-01-01

    Alpine-cold regions are characterized as hypoxia,strong wind,heavy rain,cold climate,huge temperature difference between day and night,and vertical climate.All these make it difficult for an emergency rescue when a natural disaster such as earthquake happens.Based on the characteristics of emergency rescue in alpinecold region,several multifunctional protective equipments have been developed by the Quartermaster Equipment Institute of General Logistics Department (GLD) of the Chinese People' s Liberation Army (CPLA).These equipments are lightweight,durable and environment adaptable.

  11. Radiocarbon microanalysis on ice impurities for dating of Alpine glaciers

    OpenAIRE

    May, Barbara Luise

    2009-01-01

    The main objective of this thesis is the deployment of radiometric dating on Alpine ice archives, where conventional, stratigraphical dating techniques fail. To this end a 14C analysis of particulate and, in a novel attempt, also of dissolved organic carbon contained in the ice matrix is developed. Aimed at minimizing the required ice sample size, the designed ice processing line allows for handling of up to 700 g ice and is shown to involve blank levels small enough to ensure reliable 14C an...

  12. The role of endophytic methane-oxidizing bacteria in submerged Sphagnum in determining methane emissions of Northeastern Siberian tundra

    Directory of Open Access Journals (Sweden)

    T. C. Maximov

    2011-05-01

    Full Text Available The role of the microbial processes governing methane emissions from tundra ecosystems is receiving increasing attention. Recently, cooperation between methanotrophic bacteria and submerged Sphagnum was shown to reduce methane emissions but also to supply CO2 for photosynthesis for the plant. Although this process was shown to be important in the laboratory, the differences that exist in methane emissions from inundated vegetation types with or without Sphagnum in the field have not been linked to these bacteria before. In this study, chamber flux measurements, an incubation study and a process model were used to investigate the drivers and controls on the relative difference in methane emissions between a submerged Sphagnum/sedge vegetation type and an inundated sedge vegetation type without Sphagnum. It was found that methane emissions in the Sphagnum-dominated vegetation type were 50 % lower than in the vegetation type without Sphagnum. A model sensitivity analysis showed that these differences could not sufficiently be explained by differences in methane production and plant transport. The model, combined with an incubation study, indicated that methane oxidation by endophytic bacteria, living in cooperation with submerged Sphagnum, plays a significant role in methane cycling at this site. This result is important for spatial upscaling as oxidation by these bacteria is likely involved in 15 % of the net methane emissions at this tundra site. Our findings support the notion that methane-oxidizing bacteria are an important factor in understanding the processes behind methane emissions in tundra.

  13. Cesium-137 inventories in Alaskan Tundra, lake and marine sediments: An indicator of recent organic material transport?

    International Nuclear Information System (INIS)

    Tundra sampling was accomplished in 1989--1990 at Imnavait Creek, Alaska (68 degree 37' N, 149 degree 17' W). Inventories of 137Cs (102--162 mBq/cm2) are close to expectations, based upon measured atmospheric deposition for this latitude. Accumulated inventories of 137Cs in tundra decrease by up to 50% along a transect to Prudhoe Bay (70 degree 13' N, 148 degree 30' W). Atmospheric deposition of 137Cs decreased with latitude in the Arctic, but declines in deposition would have been relatively small over this distance (200 km). This suggests a recent loss of 137Cs and possibly associated organic matter from tundra over the northern portions of the transect between Imnavait Creek and Prudhoe Bay. Sediments from Toolik Lake (68 degree 38' N, 149 degree 38' W) showed widely varying 137Cs inventories, from a low of 22 mBq/cm2 away from the lake inlet, to a high between 140 to >200 mBq/cm2 near the main stream inflow. This was indicative of recent accumulation of cesium and possibly organic material associated with it in arctic lakes, although additional sampling is needed

  14. Acidobacteria dominate the active bacterial communities of Arctic tundra with widely divergent winter-time snow accumulation and soil temperatures.

    Science.gov (United States)

    Männistö, Minna K; Kurhela, Emilia; Tiirola, Marja; Häggblom, Max M

    2013-04-01

    The timing and extent of snow cover is a major controller of soil temperature and hence winter-time microbial activity and plant diversity in Arctic tundra ecosystems. To understand how snow dynamics shape the bacterial communities, we analyzed the bacterial community composition of windswept and snow-accumulating shrub-dominated tundra heaths of northern Finland using DNA- and RNA-based 16S rRNA gene community fingerprinting (terminal restriction fragment polymorphism) and clone library analysis. Members of the Acidobacteria and Proteobacteria dominated the bacterial communities of both windswept and snow-accumulating habitats with the most abundant phylotypes corresponding to subdivision (SD) 1 and 2 Acidobacteria in both the DNA- and RNA-derived community profiles. However, different phylotypes within Acidobacteria were found to dominate at different sampling dates and in the DNA- vs. RNA-based community profiles. The results suggest that different species within SD1 and SD2 Acidobacteria respond to environmental conditions differently and highlight the wide functional diversity of these organisms even within the SD level. The acidic tundra soils dominated by ericoid shrubs appear to select for diverse stress-tolerant Acidobacteria that are able to compete in the nutrient poor, phenolic-rich soils. Overall, these communities seem stable and relatively insensitive to the predicted changes in the winter-time snow cover.

  15. Drivers of post-fire successional trajectories in arctic tundra: the importance of physical and biophysical interactions

    Science.gov (United States)

    Rocha, A. V.; Jiang, Y.; Rastetter, E. B.; Drysdale, J.; Kremers, K.; Shaver, G. R.

    2013-12-01

    Fires in arctic tundra are rare with return intervals in the hundreds to thousands of years, but these events have large implications for carbon and energy fluxes in an environmentally changing and sensitive ecosystem. Permafrost degradation, species composition shifts, and ecosystem function alterations are just a few of the potential consequences of fire that could feedback on future climate change. Here we describe remote sensing, eddy covariance, thaw depth, and biomass measurements along an arctic tundra chronosequence to understand long-term post-fire carbon and energy budgets. Historical remote sensing and fire perimeter data were used to choose sites that were representative of a 0-6, 18, and 36 year old fire scar, which were paired with a representative nearby unburned control. Fires caused successional changes to carbon and energy budgets through changes to the soil thermal regime, caused by decreased organic layer from combustion, and shifts from tussock to grass and shrub dominated systems. Measurements and modeling with the Multiple Element Limitation (MEL) model indicate that nutrients played a key role in these shifts and that these dynamics change are controlled by biophysical conditions immediately after fire (i.e. residual organic layer depth) and climate during early succession. Results highlight the importance of initial conditions in determining the successional trajectory of arctic tundra and yield important insights on how these systems will respond to future climate change.

  16. The Changing Seasonality of Tundra Nutrient Cycling: Implications for Arctic Ecosystem Function

    Science.gov (United States)

    Weintraub, M. N.; Steltzer, H.; Sullivan, P.; Schimel, J.; Wallenstein, M. D.; Darrouzet-Nardi, A.; Segal, A. D.

    2011-12-01

    Arctic soils contain large stores of carbon (C) and may act as a significant CO2 source with warming. However, the key to understanding tundra soil processes is nitrogen (N), as both plant growth and decomposition are N limited. However, current models of tundra ecosystems assume that while N limits plant growth, C limits decomposition. In addition, N availability is strongly seasonal with relatively high concentrations early in the growing season followed by a pronounced crash. We need to understand the controls on this seasonality to predict responses to climate change, but there are multiple questions that need answers: 1) What causes the seasonality in N? 2) Does microbial activity switch seasonally between C and N limitation? 3) How will a lengthening of the growing season alter overall ecosystem C and N dynamics, as a result of differential extension of the periods before and after the nutrient crash? We hypothesized that microbial activity is C limited early in the growing season, when N availability is higher and root exudate C is unavailable, and that microbial activity becomes N limited in response to plant N uptake and immobilization stimulated by root C. To address these questions we are conducting an accelerated snow-melt X warming field experiment in an Alaskan moist acidic arctic tundra community, and following plant and soil dynamics. Changes in the timing of C and N interactions in the different treatments will enable us to develop an enhanced mechanistic understanding of why the nutrient crash occurs and what the implications are for a lengthening of the arctic growing season. In 2010 we successfully accelerated snowmelt by 4 days. Both earlier snowmelt and warming accelerated early season plant life history events, with a few exceptions. However, responses to the combined treatment could not always be predicted from single factor effects. End of season life history events occurred later in response to the treatments, again with a few exceptions

  17. Increasing shrub abundance and N addition in Arctic tundra affect leaf and root litter decomposition differently

    Science.gov (United States)

    McLaren, J.; van de Weg, M. J.; Shaver, G. R.; Gough, L.

    2013-12-01

    Changes in global climate have resulted in a ';greening' of the Arctic as the abundance of deciduous shrub species increases. Consequently, not only the living plant community, but also the litter composition changes, which in turn can affect carbon turnover patterns in the Arctic. We examined effects of changing litter composition (both root and leaf litter) on decomposition rates with a litter bag study, and specifically focused on the impact of deciduous shrub Betula nana litter on litter decomposition from two evergreen shrubs (Ledum palustre, and Vaccinium vitis-idaea) and one graminoid (Eriophorum vaginatum) species. Additionally, we investigated how decomposition was affected by nutrient availability by placing the litterbags in an ambient and a fertilized moist acidic tundra environment. Measurements were carried out seasonally over 2 years (after snow melt, mid-growing season, end growing season). We measured litter mass loss over time, as well as the respiration rates (standardized for temperature and moisture) and temperature sensitivity of litter respiration at the time of harvesting the litter bags. For leaves, Betula litter decomposed faster than the other three species, with Eriophorum leaves decomposing the slowest. This pattern was observed for both mass loss and litter respiration rates, although the differences in respiration became smaller over time. Surprisingly, combining Betula with any other species resulted in slower overall weight loss rates than would be predicted based on monoculture weight loss rates. This contrasted with litter respiration at the time of sampling, which showed a positive mixing effect of adding Betula leaf liter to the other species. Apparently, during the first winter months (September - May) Betula litter decomposition is negatively affected by mixing the species and this legacy can still be observed in the total mass loss results later in the year. For root litter there were fewer effects of species identity on root

  18. Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

    Science.gov (United States)

    Juszak, Inge; Eugster, Werner; Heijmans, Monique M. P. D.; Schaepman-Strub, Gabriela

    2016-07-01

    Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0.15 ± 0.01, for sedges it was higher (0.17 ± 0.02). Dwarf shrub transmittance was 0.36 ± 0.07 on average, and sedge transmittance was 0.28 ± 0.08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17 cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and

  19. Long-term Nutrient Fertilization Increases CO2 Loss in Arctic Tundra

    Science.gov (United States)

    Graham, L. M.; Natali, S.; Rastetter, E. B.; Shaver, G. R.; Risk, D. A.; Loranty, M. M.; Jastrow, J. D.

    2015-12-01

    As anthropogenic climate change warms the Arctic, organic carbon (C) trapped in permafrost is at an increased risk of being released to the atmosphere as carbon dioxide (CO2). At the same time, higher rates of decomposition may increase nutrient availability and enhance plant growth, leading to an uptake of C that may offset respiratory losses. Arctic tundra ecosystems are highly nitrogen (N) limited, and the indirect effects of warming on nutrient availability will be the most likely outcome of increased temperature on plant productivity. This study aims to understand the effects of nutrient addition on arctic CO2 and H2O exchange in a tundra ecosystem at Toolik Lake Field Station, Alaska. The nutrient addition experiment, which began in 2006, is comprised of 7 fertilization treatments: 0.5, 1, 2, 5, and 10 g m-2 of N as NO3- and NH4+ (1:1) with 0.25, 0.5, 1, 2.5, and 5 g m-2 of phosphorus as PO43-; 5 g m-2 of N as NO3-; 5 g m-2 of N as NH4+, and one control plot. Plot-level CO2 and H2O exchange was measured at 5 light levels 7 times over a four-week period in June and July 2015. We measured ecosystem CO2 and H2O exchange using a rectangular plexiglass chamber (0.49 m2) that was connected to an infrared gas analyzer (LI-840). Other ecosystem variables measured include thaw depth, soil moisture and temperature, and normalized difference vegetation index. After 10 years of nutrient addition, fertilization significantly altered ecosystem C cycling. Soil respiration was greatest in the highest fertilization treatment (2.97 μmol m-2 s-1), increasing linearly with nutrient level at a rate of 0.133 μmol m-2 s-1 per g m-2 of N added (R2=0.914). Net CO2 uptake was greatest under highest fertilization (-2.06 μmol m-2 s-1), decreasing linearly with nutrient addition at a rate of -0.068 μmol m-2 s-1 per g m-2 of N added (R2=0.687). These results suggest that as nutrients become more available under a warmer climate, plant productivity increases may not offset respiratory

  20. Consequences of artic ground squirrels on soil carbon loss from Siberian tundra

    Science.gov (United States)

    Golden, N. A.; Natali, S.; Zimov, N.

    2014-12-01

    A large pool of organic carbon (C) has been accumulating in the Arctic for thousands of years. Much of this C has been frozen in permafrost and unavailable for microbial decomposition. As the climate warms and permafrost thaws, the fate of this large C pool will be driven not only by climatic conditions, but also by ecosystem changes brought about by arctic animal populations. In this project we studied arctic ground squirrels (Spermophilus parryii), which are widely-distributed throughout the Arctic. These social mammals create subterranean burrows that mix soil layers, increase aeration, alter soil moisture and temperature, and redistribute soil nutrients, all of which may impact microbial decomposition. We examined the effects of arctic ground squirrel activity on soil C mineralization in dry heath tundra underlain by continuous permafrost in the Kolyma River watershed in northeast Siberia, Russia. Vegetation cover was greatly reduced on the ground squirrel burrows (80% of ground un-vegetated), compared to undisturbed sites (35% of ground un-vegetated). Soils from ground squirrel burrows were also significantly dryer and warmer. To examine effects of ground squirrel activity on microbial respiration, we conducted an 8-day incubation of soil fromburrows and from adjacent undisturbed tundra. In addition, we assessed the impact of nutrient addition by including treatments with low and high levels of nitrogen addition. Microbial respiration (per gram soil) was three-fold higher in incubated soils from the undisturbed sites compared to soils collected from the burrows. The lower rates of respiration from the disturbed soils may have been a result of lower carbon quality or low soil moisture. High nitrogen addition significantly increased respiration in the undisturbed soils, but not in the disturbed burrow soils, which suggests that microbial respiration in the burrow soils was not primarily limited by nitrogen. These results demonstrate the importance of wildlife

  1. Sea Ice, Hydrocarbon Extraction, Rain-on-Snow and Tundra Reindeer Nomadism in Arctic Russia

    Science.gov (United States)

    Forbes, B. C.; Kumpula, T.; Meschtyb, N.; Laptander, R.; Macias-Fauria, M.; Zetterberg, P.; Verdonen, M.

    2015-12-01

    It is assumed that retreating sea ice in the Eurasian Arctic will accelerate hydrocarbon development and associated tanker traffic along Russia's Northern Sea Route. However, oil and gas extraction along the Kara and Barents Sea coasts will likely keep developing rapidly regardless of whether the Northwest Eurasian climate continues to warm. Less certain are the real and potential linkages to regional biota and social-ecological systems. Reindeer nomadism continues to be a vitally important livelihood for indigenous tundra Nenets and their large herds of semi-domestic reindeer. Warming summer air temperatures over the NW Russian Arctic have been linked to increases in tundra productivity, longer growing seasons, and accelerated growth of tall deciduous shrubs. These temperature increases have, in turn, been linked to more frequent and sustained summer high-pressure systems over West Siberia, but not to sea ice retreat. At the same time, winters have been warming and rain-on-snow (ROS) events have become more frequent and intense, leading to record-breaking winter and spring mortality of reindeer. What is driving this increase in ROS frequency and intensity is not clear. Recent modelling and simulation have found statistically significant near-surface atmospheric warming and precipitation increases during autumn and winter over Arctic coastal lands in proximity to regions of sea-ice loss. During the winter of 2013-14 an extensive and lasting ROS event led to the starvation of 61,000 reindeer out of a population of ca. 300,000 animals on Yamal Peninsula, West Siberia. Historically, this is the region's largest recorded mortality episode. More than a year later, participatory fieldwork with nomadic herders during spring-summer 2015 revealed that the ecological and socio-economic impacts from this extreme event will unfold for years to come. There is an urgent need to understand whether and how ongoing Barents and Kara Sea ice retreat may affect the region's ancient

  2. Domibacillus tundrae sp. nov., isolated from active layer soil of tussock tundra in Alaska, and emended description of the genus Domibacillus.

    Science.gov (United States)

    Gyeong, Hye Ryeon; Baek, Kiwoon; Hwang, Chung Yeon; Park, Key Hun; Kim, Hye Min; Lee, Hong Kum; Lee, Yoo Kyung

    2015-10-01

    A novel Gram-stain-positive, spore-forming, aerobic, motile and rod-shaped bacterium designated strain PAMC 80007T was isolated from an active layer soil sample of Council, Alaska. Optimal growth of strain PAMC 80007T was observed at 30 °C, pH 7.0 and in the presence of 2 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain PAMC 80007T belonged to the genus Domibacillus. This strain was closely related to Domibacillus enclensis (98.3 %), Domibacillus robiginosus (98.3 %) and Domibacillus indicus (97.2 %). Genomic DNA G+C content was 43.5 mol% and genomic relatedness analyses based on the average nucleotide identity and the genome-to-genome distance showed that strain PAMC 80007T is clearly distinguished from the closely related species of the genus Domibacillus. The major fatty acids (>5 %) were iso-C15 : 0 (24.7 %), C16 : 1ω11c (16.8 %), anteiso-C15 : 0 (16.5 %), C16 : 0 (15.6 %) and anteiso-C17 : 0 (8.7 %). The major respiratory isoprenoid quinones were menaquinone-6 (MK-6) and menaquinone-7 (MK-7), and the polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, phospholipid and two unidentified lipids. meso-Diaminopimelic acid (type A1γ) was present in the cell-wall peptidoglycan, and the major whole-cell sugar was ribose with a minor quantity of glucose. Results from a polyphasic study suggested that strain PAMC 80007T represents a novel species of the genus Domibacillus for which the name Domibacillus tundrae sp. nov. is proposed. The type strain is PAMC 80007T ( = JCM 30371T = KCTC 33549T = DSM 29572T). An emended description of the genus Domibacillus is also provided.

  3. Estimation of Alpine Skier Posture Using Machine Learning Techniques

    Directory of Open Access Journals (Sweden)

    Bojan Nemec

    2014-10-01

    Full Text Available High precision Global Navigation Satellite System (GNSS measurements are becoming more and more popular in alpine skiing due to the relatively undemanding setup and excellent performance. However, GNSS provides only single-point measurements that are defined with the antenna placed typically behind the skier’s neck. A key issue is how to estimate other more relevant parameters of the skier’s body, like the center of mass (COM and ski trajectories. Previously, these parameters were estimated by modeling the skier’s body with an inverted-pendulum model that oversimplified the skier’s body. In this study, we propose two machine learning methods that overcome this shortcoming and estimate COM and skis trajectories based on a more faithful approximation of the skier’s body with nine degrees-of-freedom. The first method utilizes a well-established approach of artificial neural networks, while the second method is based on a state-of-the-art statistical generalization method. Both methods were evaluated using the reference measurements obtained on a typical giant slalom course and compared with the inverted-pendulum method. Our results outperform the results of commonly used inverted-pendulum methods and demonstrate the applicability of machine learning techniques in biomechanical measurements of alpine skiing.

  4. Estimation of Alpine Skier Posture Using Machine Learning Techniques

    Science.gov (United States)

    Nemec, Bojan; Petrič, Tadej; Babič, Jan; Supej, Matej

    2014-01-01

    High precision Global Navigation Satellite System (GNSS) measurements are becoming more and more popular in alpine skiing due to the relatively undemanding setup and excellent performance. However, GNSS provides only single-point measurements that are defined with the antenna placed typically behind the skier's neck. A key issue is how to estimate other more relevant parameters of the skier's body, like the center of mass (COM) and ski trajectories. Previously, these parameters were estimated by modeling the skier's body with an inverted-pendulum model that oversimplified the skier's body. In this study, we propose two machine learning methods that overcome this shortcoming and estimate COM and skis trajectories based on a more faithful approximation of the skier's body with nine degrees-of-freedom. The first method utilizes a well-established approach of artificial neural networks, while the second method is based on a state-of-the-art statistical generalization method. Both methods were evaluated using the reference measurements obtained on a typical giant slalom course and compared with the inverted-pendulum method. Our results outperform the results of commonly used inverted-pendulum methods and demonstrate the applicability of machine learning techniques in biomechanical measurements of alpine skiing. PMID:25313492

  5. [Ecomorphological explanations of passerines coexistence in alpine meadow].

    Science.gov (United States)

    Liu, Li-Hua; Chen, Xiao-Cheng; Chu, Hui; Sun, Jia-Chen; Zhang, Xiao-Ai; Zhao, Liang

    2013-06-01

    Species ecomorphological characteristics are the evolutionary results of selective pressures that have enabled individuals of a given species to survive and reproduce. Closely related species co-occurring in homogeneous environments should be morphologically distinct to partition limited resources, so as to minimize interspecific competition. From 1983 to 2012, we studied the ecomorphological characteristics of nine passerine species in alpine meadow. Results showed six ecomorphological characteristics of the nine species were significantly different. Approximately, 92.0% of samples were correctly classified and the correct rates ranged from 84.5% to 100.0%, except for the Oriental Skylark (Eremophila alpestris), which was 79.2%. Accordingly, the nine species were divided into five guilds based on their characteristics. Results indicated that the niches of all species were divergent, and the ecomorphological characteristics of the specific species in each guild were related to their habitats and foraging behaviors. These results also explained the possible mechanisms of different species coexistence in alpine meadow. PMID:23775990

  6. Project SHARE Sustainable Hydropower in Alpine Rivers Ecosystems

    Science.gov (United States)

    Mammoliti Mochet, Andrea

    2010-05-01

    SHARE - Sustainable Hydropower in Alpine Rivers Ecosystems is a running project early approved and co funded by the European regional development fund in the context of the European Territorial Cooperation Alpine Space programme 2007 - 2013: the project is formally ongoing from August 2009 and it will end July 2012. Hydropower is the most important renewable resource for electricity production in alpine areas: it has advantages for the global CO2 balance but creates serious environmental impacts. RES-e Directives require renewable electricity enhance but, at the same time, the Water Framework Directive obliges member States to reach or maintain a water bodies "good" ecological status, intrinsically limiting the hydropower exploitation. Administrators daily face an increasing demand of water abstraction but lack reliable tools to rigorously evaluate their effects on mountain rivers and the social and economical outputs on longer time scale. The project intends to develop, test and promote a decision support system to merge on an unprejudiced base, river ecosystems and hydropower requirements. This approach will be led using existing scientific tools, adjustable to transnational, national and local normative and carried on by permanent panel of administrators and stakeholders. Scientific knowledge related to HP & river management will be "translated" by the communication tools and spent as a concrete added value to build a decision support system. In particular, the Multicriteria Analysis (MCA) will be applied to assess different management alternatives where a single-criterion approach (such as cost-benefit analysis) falls short, especially where environmental, technical, economic and social criteria can't be quantified by monetary values. All the existing monitoring databases will be used and harmonized with new information collected during the Pilot case studies. At the same time, all information collected will be available to end users and actors of related

  7. Évolution de l’environnement alpin

    Directory of Open Access Journals (Sweden)

    Philippe Schoeneich

    2009-03-01

    Full Text Available L’évolution de l’environnement alpin au XXIe siècle sera conditionnée par le changement climatique. Celui-ci pourrait conduire à des climats inconnus à ce jour dans les Alpes, avec comme conséquence une crise environnementale majeure et durable. Face à ces défis, les financements de recherche restent insuffisants pour la recherche appliquée aux milieux de montagne. Les financements nationaux privilégient souvent la recherche polaire au détriment des hautes altitudes, alors que les financements de type Interreg prennent insuffisamment en compte les besoins de recherche fondamentale, préalable nécessaire à l’élaboration de scénarios. Une évolution se dessine depuis deux ou trois ans vers des projets en réseau à l’échelle alpine. Le présent article fait le point sur les principaux enjeux qui attendent la recherche environnementale alpine et sur la capacité des programmes de recherche à répondre aux besoins. La première partie sur les changements climatiques est fondée sur les rapports récents : rapport de synthèse IPCC 2007 (IPCC 2007, rapport IPCC sur l’Europe (Alcamo et al. 2007, rapport de synthèse du programme ClimChAlp (Prudent-Richard et al., 2008. On y trouvera des bibliographies complètes et circonstanciées. La deuxième partie se base sur une analyse des appels d’offres récents ou en cours, et des projets soumis et financés.The way the Alpine environment will evolve in the 21st century depends upon climate change. This could lead to climates never before seen in the Alps, resulting in a major and lasting environmental crisis. In the face of these challenges, funding is still insufficient for specialised research on mountain environments. State funding often prioritises polar research at the expense of high altitude areas, whereas funding schemes from bodies such as Interreg do not sufficiently address the need for fundamental research, which is nevertheless a necessary first step prior to

  8. Differences in Sensation Seeking Between Alpine Skiers, Snowboarders and Ski Tourers.

    Science.gov (United States)

    Kopp, Martin; Wolf, Mirjam; Ruedl, Gerhard; Burtscher, Martin

    2016-03-01

    Despite different injury rates and injury patterns previous personality related research in the field of downhill winter sports did not subdivide between different alpine slope users. In this study, we tried to find out whether the personality trait sensation seeking differs between skiers, snowboarders and ski tourers. In a cross-sectional survey 1185 persons (726 alpine skiers, 321 snowboarders and 138 ski tourers comparable in age and sex) were electronically questioned with the sensation seeking scale (SSS-V) comprising the four factors thrill and adventure seeking, experiences seeking, disinhibition and boredom susceptibility. Kruskal-Wallis Tests revealed a significantly higher total score of the SSS-V for snowboarders in comparison to alpine skiers and ski tourers (H(2) = 41.5, p seeking" and "experience-seeking" than alpine skiers. Furthermore, snowboarders showed higher scores in "disinhibition" related to alpine skiers and ski tourers and "boredom susceptibility" compared to alpine skiers. Data show differences in the personality trait sensation seeking in people practising different winter sports. As snowboarders showed higher SS-scores compared to alpine skiers and ski tourers prevention and information programs might benefit from a selective approach focusing on special characteristics of the respective group. Key pointsIt is the very first research trying to identify differences between different types of winter sport slope usersObtained results show higher sensation seeking scores in snowboardersThese results might stimulate new approaches in educational campaigns to reduce accident rates in winter sports. PMID:26957921

  9. Differences in Sensation Seeking Between Alpine Skiers, Snowboarders and Ski Tourers

    Directory of Open Access Journals (Sweden)

    Martin Kopp, Mirjam Wolf, Gerhard Ruedl, Martin Burtscher

    2016-03-01

    Full Text Available Despite different injury rates and injury patterns previous personality related research in the field of downhill winter sports did not subdivide between different alpine slope users. In this study, we tried to find out whether the personality trait sensation seeking differs between skiers, snowboarders and ski tourers. In a cross-sectional survey 1185 persons (726 alpine skiers, 321 snowboarders and 138 ski tourers comparable in age and sex were electronically questioned with the sensation seeking scale (SSS-V comprising the four factors thrill and adventure seeking, experiences seeking, disinhibition and boredom susceptibility. Kruskal-Wallis Tests revealed a significantly higher total score of the SSS-V for snowboarders in comparison to alpine skiers and ski tourers (H(2 = 41.5, p < 0.001. Ski tourers and snowboarders scored significantly higher in the dimensions “thrill- and adventure-seeking” and “experience-seeking” than alpine skiers. Furthermore, snowboarders showed higher scores in “disinhibition” related to alpine skiers and ski tourers and “boredom susceptibility” compared to alpine skiers. Data show differences in the personality trait sensation seeking in people practising different winter sports. As snowboarders showed higher SS-scores compared to alpine skiers and ski tourers prevention and information programs might benefit from a selective approach focusing on special characteristics of the respective group.

  10. Will greater shrub abundance greatly impact tundra surface-atmosphere exchanges of energy and carbon?

    Science.gov (United States)

    Humphreys, E.; Lafleur, P.

    2015-12-01

    Increasing deciduous shrub abundance, productivity, and range in the Arctic comes with the potential for both negative and positive feedbacks to the climate system. This study presents six seasons of eddy covariance measurements of carbon dioxide (CO2) and latent and sensible heat fluxes along a shrub gradient in Canada's Low Arctic. Three flux tower sites with 17, 45, and 64% dwarf birch cover were established within a few kilometers of each other to investigate differences in microclimate, energy and carbon exchanges. As expected, there was greater winter snow depth but less summer soil thaw with greater shrub cover. However, snowmelt timing and speed were usually similar among sites. Despite a reduction in albedo in spring and greater leaf area through summer, latent heat fluxes were consistently lower with greater shrub cover. Offset by small differences in sensible heat fluxes, total seasonal atmospheric heating (combined sensible and latent heat fluxes) was similar among sites. We anticipated greater net uptake of CO2 through the growing season with greater shrub cover. However, that was only the case in some years. There was much more week-to-week and year-to-year variability in CO2 fluxes at the shrubbiest site suggesting photosynthesis and respiration processes were more sensitive to weather variations. Shrub abundance does impact tundra surface-atmosphere exchanges of energy and carbon but these observations also highlight the complexity involved in predicting the net climate feedback effect of current and future Arctic vegetation change.

  11. Annual survival rates of adult and immature eastern population tundra swans

    Science.gov (United States)

    Nichols, J.D.; Bart, J.; Limpert, R.J.; Sladen, William J. L.; Hines, J.E.

    1992-01-01

    Tundra swans (Cygnus columbianus ) of the eastern population were neckbanded in Maryland, North Carolina, and Alaska from 1966 through 1990. These swans were resighted and recaptured during autumn, winter, and spring, 1966-1990. Although the original motivation for this study involved swan movements, we wanted to use the resulting data to test hypotheses about sources of variation in swan survival rates. Recaptures of legbanded and neckbanded swans permitted us to estimate neckband loss rates, which were found to vary with age and sex of swans, and number of years since initial application. Estimates of annual neckband retention rate ranged from about 0.50 for adult male swans greater than or equal to 2 years after initial neckbanding to > 0.96 for immature swans and adult females the first year following neckbanding. This variation in neckband loss rates prevented the simple correction of survival estimates to account for such loss. Consequently, we developed a series of multinomial models parameterized with survival, sighting, and neckband retention probabilities for use with the recapture and resighting data.

  12. The effect of silver nanoparticles on seasonal change in arctic tundra bacterial and fungal assemblages.

    Directory of Open Access Journals (Sweden)

    Niraj Kumar

    Full Text Available The impact of silver nanoparticles (NPs and microparticles (MPs on bacterial and fungal assemblages was studied in soils collected from a low arctic site. Two different concentrations (0.066% and 6.6% of Ag NPs and Ag MPs were tested in microcosms that were exposed to temperatures mimicking a winter to summer transition. Toxicity was monitored by differential respiration, phospholipid fatty acid analysis, polymerase chain reaction-denaturing gradient gel electrophoresis and DNA sequencing. Notwithstanding the effect of Ag MPs, nanosilver had an obvious, additional impact on the microbial community, underscoring the importance of particle size in toxicity. This impact was evidenced by levels of differential respiration in 0.066% Ag NP-treated soil that were only half that of control soils, a decrease in signature bacterial fatty acids, and changes in both richness and evenness in bacterial and fungal DNA sequence assemblages. Prominent after Ag NP-treatment were Hypocreales fungi, which increased to 70%, from only 1% of fungal sequences under control conditions. Genera within this Order known for their antioxidant properties (Cordyceps/Isaria dominated the fungal assemblage after NP addition. In contrast, sequences attributed to the nitrogen-fixing Rhizobiales bacteria appeared vulnerable to Ag NP-mediated toxicity. This combination of physiological, biochemical and molecular studies clearly demonstrate that Ag NPs can severely disrupt the natural seasonal progression of tundra assemblages.

  13. The effect of silver nanoparticles on seasonal change in arctic tundra bacterial and fungal assemblages.

    Science.gov (United States)

    Kumar, Niraj; Palmer, Gerald R; Shah, Vishal; Walker, Virginia K

    2014-01-01

    The impact of silver nanoparticles (NPs) and microparticles (MPs) on bacterial and fungal assemblages was studied in soils collected from a low arctic site. Two different concentrations (0.066% and 6.6%) of Ag NPs and Ag MPs were tested in microcosms that were exposed to temperatures mimicking a winter to summer transition. Toxicity was monitored by differential respiration, phospholipid fatty acid analysis, polymerase chain reaction-denaturing gradient gel electrophoresis and DNA sequencing. Notwithstanding the effect of Ag MPs, nanosilver had an obvious, additional impact on the microbial community, underscoring the importance of particle size in toxicity. This impact was evidenced by levels of differential respiration in 0.066% Ag NP-treated soil that were only half that of control soils, a decrease in signature bacterial fatty acids, and changes in both richness and evenness in bacterial and fungal DNA sequence assemblages. Prominent after Ag NP-treatment were Hypocreales fungi, which increased to 70%, from only 1% of fungal sequences under control conditions. Genera within this Order known for their antioxidant properties (Cordyceps/Isaria) dominated the fungal assemblage after NP addition. In contrast, sequences attributed to the nitrogen-fixing Rhizobiales bacteria appeared vulnerable to Ag NP-mediated toxicity. This combination of physiological, biochemical and molecular studies clearly demonstrate that Ag NPs can severely disrupt the natural seasonal progression of tundra assemblages. PMID:24926877

  14. Pollen Morphology of Tundra Shrubs and Submarginal Plants from Barrow, Alaska

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Investigation of plant morphological features, pollen, and habitat have been made for two shrub species from Barrow, Alaska, namely Dryas integrifolia M. Vahl and Salix rotundifolia Trautv., both of which are endemic to the Arctic floristic area. The former species has small lanceolate or plate leaves, whereas the latter has rounded leaves with distinct veins, rich in vitamin C. Both have dwarf and sprawling habits. Pollen studies showed that the pollen grains of the two species are spheroidal to sub-spheroidal or prolate. The type of aperture was tricolporate; pollen size 26.3-31.3 μm; ornamentation finely reticulate under a light microscope (LM) and striate-reticulate under a scanning electron microscope (SEM) for D. integrafolia and finely reticulate under the LM and SEM for S. rotundlfolia. Comparisons were made between the pollen from the same species from Arctic collections with those from China and Japan. Investigation of pollen morphology of tundra plants can provide significant data for comparative studies of fossil pollen and for the reconstruction of paleovegetation and paleoclimate in the Barrow area.

  15. Calibration and Validation of Landsat Tree Cover in the Taiga−Tundra Ecotone

    Directory of Open Access Journals (Sweden)

    Paul Mannix Montesano

    2016-06-01

    Full Text Available Monitoring current forest characteristics in the taiga−tundra ecotone (TTE at multiple scales is critical for understanding its vulnerability to structural changes. A 30 m spatial resolution Landsat-based tree canopy cover map has been calibrated and validated in the TTE with reference tree cover data from airborne LiDAR and high resolution spaceborne images across the full range of boreal forest tree cover. This domain-specific calibration model used estimates of forest height to determine reference forest cover that best matched Landsat estimates. The model removed the systematic under-estimation of tree canopy cover >80% and indicated that Landsat estimates of tree canopy cover more closely matched canopies at least 2 m in height rather than 5 m. The validation improved estimates of uncertainty in tree canopy cover in discontinuous TTE forests for three temporal epochs (2000, 2005, and 2010 by reducing systematic errors, leading to increases in tree canopy cover uncertainty. Average pixel-level uncertainties in tree canopy cover were 29.0%, 27.1% and 31.1% for the 2000, 2005 and 2010 epochs, respectively. Maps from these calibrated data improve the uncertainty associated with Landsat tree canopy cover estimates in the discontinuous forests of the circumpolar TTE.

  16. Pentecostals and Charismatic Protestants in the Republic of Komi and Nenets Tundra

    Directory of Open Access Journals (Sweden)

    Art Leete

    2015-09-01

    Full Text Available Between 2010 and 2012, an extended team of scholars studied contemporary Protestant groups in Russia. The project was labelled Center for the Study of Pentecostal and Charismatic Movements in Russia1 (CSPCMR and was led by Aleksandr Panchenko from the European University in Saint Petersburg and Patrick Plattet from the University of Alaska Fairbanks. Besides Russia and the USA, scholars from Ireland, the United Kingdom, France, and Estonia were involved in this collaborative research effort. The host institution of the project was the European University in St. Petersburg. The aim of the project was to analyse the Protestant-charismatic (P/c Christianity in various regions of post-Soviet Russia. The project proceeded from the notions concerned with global effects of the rapid extension of P/c Christianity in the contemporary world. In the anthropology of Pentecostalism, problems of continuity and change, globalisation and indigenisation, preservation of pre-Pentecostal ontologies, creating the new morality and approaches to economy and politics have been discussed (Coleman 2000; Robbins 2004a, 2004b. The Estonian team’s specific task was to analyse contemporary Protestant missions and churches in the north-eastern corner of European Russia, in the Republic of Komi and the European Nenets tundra.

  17. Estimated change in tundra ecosystem function near Barrow, Alaska between 1972 and 2010

    International Nuclear Information System (INIS)

    How the greening of Arctic landscapes manifests as a change in ecosystem structure and function remains largely unknown. This study investigates the likely implications of plant community change on ecosystem function in tundra near Barrow, Alaska. We use structural data from marked plots, established in 1972 and resampled in 1999, 2008 and 2010 to assess plant community change. Ecosystem functional studies were made close to peak growing season in 2008 and 2010 on destructive plots adjacent to marked plots and included measurement of land–atmosphere CH4 and CO2 exchange, hyperspectral reflectance, albedo, water table height, soil moisture, and plant species cover and abundance. Species cover and abundance data from marked and destructive plots were analyzed together using non-metric multi-dimensional scaling (NMS) ordination. NMS axis scores from destructive plots were used to krig ecosystem function variables in ordination space and produce surface plots from which time series of functional attributes for resampled plots were derived. Generally, the greatest functional change was found in aquatic and wet plant communities, where productivity varied and soil moisture increased, increasing methane efflux. Functional change was minimal in moist and dry communities, which experienced a general decrease in soil moisture availability and appeared overall to be functionally more stable through time. Findings suggest that the Barrow landscape could have become less productive and less responsive to change and disturbance over the past few decades. This study is a contribution to the International Polar Year-Back to the Future Project (512). (letter)

  18. Old soil carbon losses increase with ecosystem respiration in experimentally thawed tundra

    Science.gov (United States)

    Hicks Pries, Caitlin E.; Schuur, Edward A. G.; Natali, Susan M.; Crummer, K. Grace

    2016-02-01

    Old soil carbon (C) respired to the atmosphere as a result of permafrost thaw has the potential to become a large positive feedback to climate change. As permafrost thaws, quantifying old soil contributions to ecosystem respiration (Reco) and understanding how these contributions change with warming is necessary to estimate the size of this positive feedback. We used naturally occurring C isotopes (δ13C and Δ14C) to partition Reco into plant, young soil and old soil sources in a subarctic air and soil warming experiment over three years. We found that old soil contributions to Reco increased with soil temperature and Reco flux. However, the increase in the soil warming treatment was smaller than expected because experimentally warming the soils increased plant contributions to Reco by 30%. On the basis of these data, an increase in mean annual temperature from -5 to 0 °C will increase old soil C losses from moist acidic tundra by 35-55 g C m-2 during the growing season. The largest losses will probably occur where the plant response to warming is minimal.

  19. The Contribution of Moss to Plot-Based Spectral Signals in Moist Acidic Low Arctic Tundra

    Science.gov (United States)

    May, J. L.; Beamish, A. L.

    2015-12-01

    To determine the contribution of moss to peak season normalized difference index (NDVI) field measurement of intact vegetation communities were compared to communities with individual species and litter successively removed until only the moss layer remained. Spectral measurements (n=3) were collected using a field radiometer in five upland and five lowland plots in a moist acidic tundra ecosystem at the Imnaviat Creek Watershed, North Slope Alaska. After spectral measurements were taken individual species were removed in the same order in each plot by clipping them at the moss layer. As individual species were removed NDVI values decreased. Decreases were greatest when dwarf shrub species Salix richardsonii sb. pulchra and Betula nana were removed. Notable increases in NDVI were observed once standing litter was removed. The NDVI values of the moss layer were comparable to intact vegetation communities depending on the bryophyte species composition. This suggests that the NDVI signal of moss is largely masked by vascular species but represents a significant factor missing from overall, large-scale NDVI signals. The results of this study corroborate recent data that points to the mismatch between ground based NDVI and aerial and satellite derived NDVI. This preliminary case study provides a strong basis for better characterization of the contribution of moss to NDVI for improved correction of air and space borne imagery.

  20. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

    Energy Technology Data Exchange (ETDEWEB)

    Lipson, David A.; Raab, Theodore K.; Parker , Melanie; Kelley , Scott T.; Brislawn, Colin J.; Jansson, Janet K.

    2015-07-21

    This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska, and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography, but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes, dominated by fermenters (Bacteroidetes and Firmicutes).

  1. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

    Energy Technology Data Exchange (ETDEWEB)

    Lipson, David A.; Raab, Theodore K.; Parker , Melanie; Kelley , Scott T.; Brislawn, Colin J.; Jansson, Janet K.

    2015-08-01

    Summary This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes,

  2. Heterogeneity of carbon loss and its temperature sensitivity in East-European subarctic tundra soils.

    Science.gov (United States)

    Diáková, Kateřina; Čapek, Petr; Kohoutová, Iva; Mpamah, Promise A; Bárta, Jiří; Biasi, Christina; Martikainen, Pertti J; Šantrůčková, Hana

    2016-09-01

    Arctic peatlands store large stocks of organic carbon which are vulnerable to the climate change but their fate is uncertain. There is increasing evidence that a part of it will be lost as a result of faster microbial mineralization. We studied the vulnerability of 3500-5900 years old bare peat uplifted from permafrost layers by cryogenic processes to the surface of an arctic peat plateau. We aimed to find biotic and abiotic drivers of CLOSS from old peat and compare them with those of adjacent, young vegetated soils of the peat plateau and mineral tundra. The soils were incubated in laboratory at three temperatures (4°C, 12°C and 20°C) and two oxygen levels (aerobic, anaerobic). CLOSS was monitored and soil parameters (organic carbon quality, nutrient availability, microbial activity, biomass and stoichiometry, and extracellular oxidative and hydrolytic enzyme pools) were determined. We found that CLOSS from the old peat was constrained by low microbial biomass representing only 0.22% of organic carbon. CLOSS was only slightly reduced by the absence of oxygen and exponentially increased with temperature, showing the same temperature sensitivity under both aerobic and anaerobic conditions. We conclude that carbon in the old bare peat is stabilized by a combination of physical, chemical and biological controls including soil compaction, organic carbon quality, low microbial biomass and the absence of plants. PMID:27316560

  3. Potential of Immobilized Whole-Cell Methylocella tundrae as a Biocatalyst for Methanol Production from Methane.

    Science.gov (United States)

    Mardina, Primata; Li, Jinglin; Patel, Sanjay K S; Kim, In-Won; Lee, Jung-Kul; Selvaraj, Chandrabose

    2016-07-28

    Methanol is a versatile compound that can be biologically synthesized from methane (CH4) by methanotrophs using a low energy-consuming and environment-friendly process. Methylocella tundrae is a type II methanotroph that can utilize CH4 as a carbon and energy source. Methanol is produced in the first step of the metabolic pathway of methanotrophs and is further oxidized into formaldehyde. Several parameters must be optimized to achieve high methanol production. In this study, we optimized the production conditions and process parameters for methanol production. The optimum incubation time, substrate, pH, agitation rate, temperature, phosphate buffer and sodium formate concentration, and cell concentration were determined to be 24 h, 50% CH4, pH 7, 150 rpm, 30°C, 100 mM and 50 mM, and 18 mg/ml, respectively. The optimization of these parameters significantly improved methanol production from 0.66 to 5.18 mM. The use of alginate-encapsulated cells resulted in enhanced methanol production stability and reusability of cells after five cycles of reuse under batch culture conditions. PMID:27012239

  4. Evolutionary diversification of cryophilic Grylloblatta species (Grylloblattodea: Grylloblattidae in alpine habitats of California

    Directory of Open Access Journals (Sweden)

    Roderick George K

    2010-06-01

    Full Text Available Abstract Background Climate in alpine habitats has undergone extreme variation during Pliocene and Pleistocene epochs, resulting in repeated expansion and contraction of alpine glaciers. Many cold-adapted alpine species have responded to these climatic changes with long-distance range shifts. These species typically exhibit shallow genetic differentiation over a large geographical area. In contrast, poorly dispersing organisms often form species complexes within mountain ranges, such as the California endemic ice-crawlers (Grylloblattodea: Grylloblattidae: Grylloblatta. The diversification pattern of poorly dispersing species might provide more information on the localized effects of historical climate change, the importance of particular climatic events, as well as the history of dispersal. Here we use multi-locus genetic data to examine the phylogenetic relationships and geographic pattern of diversification in California Grylloblatta. Results Our analysis reveals a pattern of deep genetic subdivision among geographically isolated populations of Grylloblatta in California. Alpine populations diverged from low elevation populations and subsequently diversified. Using a Bayesian relaxed clock model and both uncalibrated and calibrated measurements of time to most recent common ancestor, we reconstruct the temporal diversification of alpine Grylloblatta populations. Based on calibrated relaxed clock estimates, evolutionary diversification of Grylloblatta occurred during the Pliocene-Pleistocene epochs, with an initial dispersal into California during the Pliocene and species diversification in alpine clades during the middle Pleistocene epoch. Conclusions Grylloblatta species exhibit a high degree of genetic subdivision in California with well defined geographic structure. Distinct glacial refugia can be inferred within the Sierra Nevada, corresponding to major, glaciated drainage basins. Low elevation populations are sister to alpine populations

  5. Alpine ice cores and ground penetrating radar: combined investigations for glaciological and climatic interpretations of a cold Alpine ice body

    Energy Technology Data Exchange (ETDEWEB)

    Eisen, Olaf; Nixdorf, Uwe [Alfred-Wegener-Inst. fuer Polar- und Meeresforschung, Bremerhaven (Germany); Keck, Lothar; Wagenbach, Dietmar [Univ. Heidelberg (Germany). Inst. fuer Umweltphysik

    2003-11-01

    Accurate interpretation of ice cores as climate archives requires detailed knowledge of their past and present geophysical environment. Different techniques facilitate the determination and reconstruction of glaciological settings surrounding the drilling location. During the ALPCLIM1 project, two ice cores containing long-term climate information were retrieved from Colle Gnifetti, Swiss-Italian Alps. Here, we investigate the potential of ground penetrating radar (GPR) surveys, in conjunction with ice core data, to obtain information about the internal structure of the cold Alpine ice body to improve climatic interpretations. Three drill sites are connected by GPR profiles, running parallel and perpendicular to the flow line, thus yielding a three-dimensional picture of the subsurface and enabling the tracking of internal reflection horizons between the locations. As the observed reflections are of isochronic origin, they permit the transfer of age-depth relations between the ice cores. The accuracy of the GPR results is estimated by comparison of transferred timescales with original core datings, independent information from an older ice core, and, based on glaciological surface data, findings from flow modeling. Our study demonstrates that GPR is a mandatory tool for Alpine ice core studies, as it permits mapping of major transitions in physical-chemical properties, transfer of age-depth relations between sites, correlate signals in core records for interpretation, and establish a detailed picture of the flow regime surrounding the climate archive.

  6. Alpine Windharvest: development of information base regarding potentials and the necessary technical, legal and socio-economic conditions for expanding wind energy in the Alpine Space - Alpine Space wind map - Modeling approach

    Energy Technology Data Exchange (ETDEWEB)

    Schaffner, B.; Remund, J. [Meteotest, Berne (Switzerland)

    2005-07-01

    This report presents describes the development work carried out by the Swiss meteorology specialists of the company METEOTEST as part of a project carried out together with the Swiss wind-energy organisation 'Suisse Eole'. The framework for the project is the EU Interreg IIIB Alpine Space Programme, a European Community Initiative Programme funded by the European Regional Development Fund. The project investigated the use of digital relief-analysis. The series of reports describes the development and use of a basic information system to aid the investigation of the technical, legal and socio-economical conditions for the use of wind energy in the alpine area. This report discusses two modelling approaches investigated for use in the definition of a wind map for the alpine area. The method chosen and its application are discussed. The various sources of information for input to the model are listed and discussed.

  7. Crossing thresholds: Analysis of hazardous tipping points in alpine catchments

    Science.gov (United States)

    Lutzmann, Silke; Sass, Oliver

    2016-04-01

    Steep mountain channels or torrents in small alpine catchments are characterized by high geomorphic activity with sediment dynamics being inherently nonlinear and threshold-mediated. Localized, high intensity rainstorms can drive torrential systems past a tipping point resulting in a sudden onset of hazardous events like (flash-) flooding, heavy bedload transport or debris flows. Such responses exhibit an abrupt switch in the fluvial system's mode (e.g. transport / supply limited). Changes in functional connectivity may persist beyond the tipping point. Torrential hazards cause costly damage in the densely populated Alpine Region. Thus, there is a rising interest in potential effects of climate change on torrential sediment dynamics. Understanding critical conditions close to tipping points is important to reduce uncertainty in predicting sediment fluxes. In this study we aim at (i) establishing threshold precipitation characteristics for the Eastern Alps of Austria. Precipitation is hypothesized to be the main forcing factor of torrential events. (ii) How do thresholds vary in space and time? (iii) The effect of external triggers is strongly mediated by the internal disposition of catchments to respond. Which internal conditions are critical for susceptibility? (iv) Is there a change in magnitude or frequency in the recent past and what can be expected for the future? The 71 km2 catchment of the river Schöttlbach in the East Alpine Region of Styria (Austria) is monitored since a heavy precipitation event resulted in a catastrophic flood in July 2011. Sediment mobilization from slopes as well as within-channel storage and bedload transport are regularly measured using photogrammetric methods and sediment impact sensors. Thus, detailed knowledge exists on magnitude and spatial propagation of sediment waves through the catchment. The associated hydro-meteorological (pre-) conditions can be inferred from a dense station network. Changing bedload transport rates and

  8. Mechanical instability in alpine forest stands: causes and possible remediations

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available The mechanical instability of alpine forests is usually related to critical meteorological events, such as heavy snowfalls and strong winds, causing single trees or groups of trees to fall, particularly in even-aged stands. In the present work, the instability of forest stands in the "dolomiti bellunesi" national park (Eastern Alps is analysed. In this case, falling of trees is caused by "normal" meteorological events and single trees, as opposed to groups, are affected. At risk are especially large beech trees and high Norway spruce trees naturally widespread in beech stands. The main cause for such mechanical instability is soil shallowness, frequent on steep mountain slopes, which does not allow trees to anchor properly. Silvicultural options to reduced such risk and improve stand stability are suggested.

  9. South Scandinavian joints and Alpine/Atlantic-ridge tectonics

    Directory of Open Access Journals (Sweden)

    A. E. Scheidegger

    2000-06-01

    Full Text Available Field observations and studies of the joints and dykes in an area shed light on its younger tectonic development; thus, joint orientations measured in Southern Sweden and in Norway have been statistically studied and compared regarding their tectonic significance with studies from Europe and the mid-Atlantic ridge. The present investigation indicates that the surface joint systems in Sweden agree with those in Europe; they are the result of the intracratonic stress field and the mechanical response associated with the Alpine orogeny. The stress systems in Southern Norway, on the other hand, are the result of the ongoing extensional or wrench-fault tectonism in the Atlantic crust associated with the stresses near the mid-Atlantic ridge, which act normally to the contiguous coastlines from Scandinavia to France, Portugal and North Africa.

  10. Goats on alpine grazing: study on metabolic and hematologic profiles

    Directory of Open Access Journals (Sweden)

    A. Gaviraghi

    2011-03-01

    Full Text Available Summering on alpine pastures from June to October has long been the traditional management of goat flocks in the mountain areas of Lombardy. At present most of the 50.000 goats farmed in Lombardy are still summered, even though only a few thousands - belonging to local breed - are regularly milked. For these goats summering appears to be fundamental not only to allow milk production but also to restore body reserves. The increasing interest in commercial goat milk production in Lombardy involves mainly intensive farming with zero or minimum grazing. However, semi-extensive goat milk production, including summering, could respond to social and environmental goals (Citterio et al., 2002 being able to exploit some economic opportunities...

  11. Agriculture causes nitrate fertilization of remote alpine lakes

    Science.gov (United States)

    Hundey, E. J.; Russell, S. D.; Longstaffe, F. J.; Moser, K. A.

    2016-02-01

    Humans have altered Earth's nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use Δ17O, δ18O and δ15N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic and arrive via the atmosphere. Moreover, agricultural activities, specifically nitrate- and ammonium-based fertilizer use, are contributing most (~60%) Nr, and data from other North American alpine lakes suggest this is a widespread phenomenon. Our findings offer a pathway towards more effective mitigation, but point to challenges in balancing food production with protection of important water resources.

  12. Decadal changes of weather types in the alpine region

    Energy Technology Data Exchange (ETDEWEB)

    Stefanicki, G.; Talkner, P.; Weber, R.O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The annual occurrence of different weather types of Schuepp`s synoptic classification in the Alpine region has changed since the beginning of its recording 1945. The annual frequency (number of days) of convective types has increased and that of advective types has decreased. In parallel the number of long-lasting convective episodes rose and the number of long-lasting advective episodes lessened. Most of the change took place in winter. The frequencies of different weather types and the annual mean of certain meteorological parameters are significantly correlated. Moreover, there is a strong interdependence between the subclass of high pressure types and the North Atlantic Oscillation (NAO) index. (author) 3 figs., 3 refs.

  13. Experimental Evidence that Fungi are Dominant Microbes in Carbon Content and Growth Response to Added Soluble Organic Carbon in Moss-rich Tundra Soil.

    Science.gov (United States)

    Anderson, O Roger; Lee, Jee Min; McGuire, Krista

    2016-05-01

    Global warming significantly affects Arctic tundra, including permafrost thaw and soluble C release that may differentially affect tundra microbial growth. Using laboratory experiments, we report some of the first evidence for the effects of soluble glucose-C enrichment on tundra soil prokaryotes (bacteria and archaea) and fungi, with comparisons to microbial eukaryotes. Fungal increase in C-biomass was equivalent to 10% (w/w) of the added glucose-C, and for prokaryote biomass 2% (w/w), the latter comparable to prior published results. The C-gain after 14 d was 1.3 mg/g soil for fungi, and ~200 μg/g for prokaryotes.

  14. Flood Change Assessment and Attribution in Austrian alpine Basins

    Science.gov (United States)

    Claps, Pierluigi; Allamano, Paola; Como, Anastasia; Viglione, Alberto

    2016-04-01

    The present paper aims to investigate the sensitivity of flood peaks to global warming in the Austrian alpine basins. A group of 97 Austrian watersheds, with areas ranging from 14 to 6000 km2 and with average elevation ranging from 1000 to 2900 m a.s.l. have been considered. Annual maximum floods are available for the basins from 1890 to 2007 with two densities of observation. In a first period, until 1950, an average of 42 records of flood peaks are available. From 1951 to 2007 the density of observation increases to an average amount of contemporary peaks of 85. This information is very important with reference to the statistical tools used for the empirical assessment of change over time, that is linear quantile regressions. Application of this tool to the data set unveils trends in extreme events, confirmed by statistical testing, for the 0.75 and 0.95 empirical quantiles. All applications are made with specific (discharges/area) values . Similarly of what done in a previous approach, multiple quantile regressions have also been applied, confirming the presence of trends even when the possible interference of the specific discharge and morphoclimatic parameters (i.e. mean elevation and catchment area). Application of a geomorphoclimatic model by Allamano et al (2009) can allow to mimic to which extent the empirically available increase in air temperature and annual rainfall can justify the attribution of change derived by the empirical statistical tools. An comparison with data from Swiss alpine basins treated in a previous paper is finally undertaken.

  15. GLORIA Alpine Plant Monitoring in the White Mountains

    Science.gov (United States)

    Jayko, A.; Powell, F. L.; Smiley, J. T.; Pritchett, D. W.; Dennis, A.; Millar, C. I.

    2005-12-01

    In collaboration with the USDA Forest Service Pacific Southwest Research Station and the California Native Plant Society, the University of California White Mountain Research Station established new GLORIA monitoring sites on three summits in the White Mountains of Eastern California in summer 2005. The GLORIA protocol has now been implemented on seven summits in the White Mountains in the past two summers. The GLORIA (Global Observation Research Initiative in Alpine Environments: www.gloria.ac.at/) project is a worldwide initiative for long-term monitoring of climate effects on alpine peaks. This year the protocol was used on summits composed primarily of carbonate (limestone and dolomite) rocks, which ranged from 3478 m to 3735 m in elevation. These suumits contrast with those sampled last year which were composed of granitic and metavolcanic rock. For each summit we followed the GLORIA sampling design and recorded plant species composition, cover, and frequency. We installed dataloggers to measure soil temperature, and researchers from the University of California Merced took soil samples for analysis of soil composition and micro-biota. We had multiple botanists make cover estimates of the same Summit Area Section to assess repeatability of such estimates and we expanded the protocol to include delineation of fixed area (10 m x 10 m) plots within the standard GLORIA Summit Area Sections. Cover and species composition were measured in the fixed area plots as well as in the full Summit Area Sections. This addition to the protocol greatly facilitated calibration of ocular cover estimates for the irregularly-shaped sometimes-very-large Summit Area Sections and will also facilitate comparisons of data among different sites if it is implemented elsewhere. A butterfly census was conducted for the first time in conjunction with sampling. Next year we hope to expand monitoring to gather data on small mammals and focus on sampling at (current) upper elevation limits of

  16. Micrometeorological processes driving snow ablation in an Alpine catchment

    Directory of Open Access Journals (Sweden)

    R. Mott

    2011-08-01

    Full Text Available Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micrometeorological processes driving snow ablation in an Alpine catchment. For this purpose we combine a meteorological model (ARPS with a fully distributed energy balance model (Alpine3D. Turbulent fluxes above melting snow are further investigated by using data from eddy-correlation systems. We compare modelled snow ablation to measured ablation rates as obtained from a series of Terrestrial Laser Scanning campaigns covering a complete ablation season. The measured ablation rates indicate that the advection of sensible heat causes locally increased ablation rates at the upwind edges of the snow patches. The effect, however, appears to be active over rather short distances except for very strong wind conditions. Neglecting this effect, the model is able to capture the mean ablation rates for early ablation periods but strongly overestimates snow ablation once the fraction of snow coverage is below a critical value. While radiation dominates snow ablation early in the season, the turbulent flux contribution becomes important late in the season. Simulation results indicate that the air temperatures appear to overestimate the local air temperature above snow patches once the snow coverage is below a critical value. Measured turbulent fluxes support these findings by suggesting a stable internal boundary layer close to the snow surface causing a strong decrease of the sensible heat flux towards the snow cover. Thus, the existence of a stable internal boundary layer above a patchy snow cover exerts a dominant control on the timing and magnitude of snow ablation for patchy snow covers.

  17. Land use and surface process domains on alpine hillslopes

    Science.gov (United States)

    Kuhn, Nikolaus J.; Caviezel, Chatrina; Hunziker, Matthias

    2015-04-01

    Shrubs and trees are generally considered to protect hillslopes from erosion. As a consequence, shrub encroachment on mountain pastures after abandoning grazing is not considered a threat to soils. However, the abandonment of mown or grazed grasslands causes a shift in vegetation composition and thus a change in landscape ecology and geomorphology. On many alpine slopes, current changes in land use and vegetation cover are accompanied by climate change, potentially generating a new geomorphic regime. Most of the debate focuses on the effect of land abandonment on water erosion rates. Generally, an established perennial vegetation cover improves the mechanical anchoring of the soil and the regulation of the soil water budget, including runoff generation and erosion. However, changing vegetation composition affects many other above- and below-ground properties like root density, -diversity and -geometry, soil structure, pore volume and acidity. Each combination of these properties can lead to a distinct scenario of dominating surface processes, often not reflected by common erosion risk assessment procedures. The study of soil properties along a chronosequence of green alder (alnusviridis) encroachment on the Unteralptal in central Switzerland reveals that shrub encroachment changes soil and vegetation properties towards an increase of resistance to run-off related erosion processes, but a decrease of slope stability against shallow landslides. The latter are a particular threat because of the currently increasing frequency of slide-triggering high magnitude rainfalls. The potential change of process domain on alpine pastures highlights the need for a careful use of erosion models when assessing future land use and climate scenarios. In mountains, but also other intensively managed agricultural landscapes, risk assessment without the appropriate reflection on the shifting relevance of surface processes carries the risk of missing future threats to environmental

  18. Close-Range Sensing Techniques in Alpine Terrain

    Science.gov (United States)

    Rutzinger, M.; Höfle, B.; Lindenbergh, R.; Oude Elberink, S.; Pirotti, F.; Sailer, R.; Scaioni, M.; Stötter, J.; Wujanz, D.

    2016-06-01

    Early career researchers such as PhD students are a main driving force of scientific research and are for a large part responsible for research innovation. They work on specialized topics within focused research groups that have a limited number of members, but might also have limited capacity in terms of lab equipment. This poses a serious challenge for educating such students as it is difficult to group a sufficient number of them to enable efficient knowledge transfer. To overcome this problem, the Innsbruck Summer School of Alpine Research 2015 on close-range sensing techniques in Alpine terrain was organized in Obergurgl, Austria, by an international team from several universities and research centres. Of the applicants a group of 40 early career researchers were selected with interest in about ten types of specialized surveying tools, i.e. laser scanners, a remotely piloted aircraft system, a thermal camera, a backpack mobile mapping system and different grade photogrammetric equipment. During the one-week summer school, students were grouped according to their personal preference to work with one such type of equipment under guidance of an expert lecturer. All students were required to capture and process field data on a mountain-related theme like landslides or rock glaciers. The work on the assignments lasted the whole week but was interspersed with lectures on selected topics by invited experts. The final task of the summer school participants was to present and defend their results to their peers, lecturers and other colleagues in a symposium-like setting. Here we present the framework and content of this summer school which brought together scientists from close-range sensing and environmental and geosciences.

  19. Is snow sublimation important in the alpine water balance?

    Directory of Open Access Journals (Sweden)

    U. Strasser

    2007-09-01

    Full Text Available In alpine terrain, snow sublimation as a component of the winter moisture budget represents a proportion of precipitation which does not contribute to melt. To quantify its amount we analyze the spatial pattern of snow sublimation at the ground, from a canopy and from turbulent suspension during wind-induced snow transport for a high alpine area in the Berchtesgaden National Park (Germany, and we discuss the efficiency of these processes with respect to seasonal snowfall. Therefore, we utilized hourly meteorological recordings from a network of automatic stations, and a distributed simulation framework comprising validated, physically based models. Meteorological data records were spatially distributed over the simulation domain by means of a quasi-physically based interpolation scheme that accounts for topographic influences on the distributed fields. The applied simulation tools were: a detailed model for shortwave and longwave radiative fluxes, a mass and energy balance model for the ground snow cover, a model for the microclimatic conditions within a forest canopy and related snow-vegetation interactions including snow sublimation from the surface of the trees, and a model for the simulation of wind-induced snow transport and related sublimation from suspended snow particles. For each of the sublimation processes, mass rates were quantified and aggregated over an entire winter season. Sublimation from the ground and from most canopy types are spatially relatively homogeneous and sum up to about 100 mm of snow water equivalent (SWE over the winter period. Accumulated seasonal sublimation due to turbulent suspension is small in the valley areas, but can locally, at very wind-exposed mountain ridges, add up to more than 1000 mm of SWE. The fraction of these sublimation losses of winter snowfall is between 10 and 90%.

  20. Mass balance investigation of alpine glaciers through LANDSAT TM data

    Science.gov (United States)

    Bayr, Klaus J.

    1989-01-01

    An analysis of LANDSAT Thematic Mapper (TM) data of the Pasterze Glacier and the Kleines Fleisskees in the Austrian Alps was undertaken and compared with meteorological data of nearby weather stations. Alpine or valley glaciers can be used to study regional and worldwide climate changes. Alpine glaciers respond relatively fast to a warming or cooling trend in temperature through an advance or a retreat of the terminus. In addition, the mass balance of the glacier is being affected. Last year two TM scenes of the Pasterze Glacier of Aug. 1984 and Aug. 1986 were used to study the difference in reflectance. This year, in addition to the scenes from last year, one MSS scene of Aug. 1976 and a TM scene from 1988 were examined for both the Pasterze Glacier and the Kleines Fleisskees. During the overpass of the LANDSAT on 6 Aug. 1988 ground truthing on the Pasterze Glacier was undertaken. The results indicate that there was considerable more reflectance in 1976 and 1984 than in 1986 and 1988. The climatological data of the weather stations Sonnblick and Rudolfshuette were examined and compared with the results found through the LANDSAT data. There were relations between the meteorological and LANDSAT data: the average temperature over the last 100 years showed an increase of .4 C, the snowfall was declining during the same time period but the overall precipitation did not reveal any significant change over the same period. With the use of an interactive image analysis computer, the LANDSAT scenes were studied. The terminus of the Pasterze Glacier retreated 348 m and the terminus of the Kleines Fleisskees 121 m since 1965. This approach using LANDSAT MSS and TM digital data in conjunction with meteorological data can be effectively used to monitor regional and worldwide climate changes.

  1. Statistical Downscaling Of Local Climate In The Alpine Region

    Science.gov (United States)

    Kaspar, Severin; Philipp, Andreas; Jacobeit, Jucundus

    2016-04-01

    The impact of climate change on the alpine region was disproportional strong in the past decades compared to the surrounding areas, which becomes manifest in a higher increase in surface air temperature. Beside the thermal changes also implications for the hydrological cycle may be expected, acting as a very important factor not only for the ecosystem but also for mankind, in the form of water security or considering economical aspects like winter tourism etc. Therefore, in climate impact studies, it is necessary to focus on variables with high influence on the hydrological cycle, for example temperature, precipitation, wind, humidity and radiation. The aim of this study is to build statistical downscaling models which are able to reproduce temperature and precipitation at the mountainous alpine weather stations Zugspitze and Sonnblick and to further project these models into the future to identify possible changes in the behavior of these climate variables and with that in the hydrological cycle. Beside facing a in general very complex terrain in this high elevated regions, we have the advantage of a more direct atmospheric influence on the meteorology of the exposed weather stations from the large scale circulation. Two nonlinear statistical methods are developed to model the station-data series on a daily basis: On the one hand a conditional classification approach was used and on the other hand a model based on artificial neural networks (ANNs) was built. The latter is in focus of this presentation. One of the important steps of developing a new model approach is to find a reliable predictor setup with e.g. informative predictor variables or adequate location and size of the spatial domain. The question is: Can we include synoptic background knowledge to identify an optimal domain for an ANN approach? The yet developed ANN setups and configurations show promising results in downscaling both, temperature (up to 80 % of explained variance) and precipitation (up

  2. Afro-alpine forest cover change on Mt. Guna (Ethiopia)

    Science.gov (United States)

    Birhanu, Adugnaw; Frankl, Amaury; Jacob, Miro; Lanckriet, Sil; Hendrickx, Hanne; Nyssen, Jan

    2016-04-01

    High mountain forests, such as the afro-alpine Erica arborea L. forests in Ethiopia, are very important for the livelihood of local communities, in relation to their impacts on the water balance of mountain ecosystems and surrounding agricultural areas. On volcanoes, the dominance of volcanic tuffs on the slopes, as well as that of gelifracts near the top further enhances infiltration, making it recharge areas. Earlier forest cover change studies in the Ethiopian highlands mainly deal with the lower vegetation belts. In this study, 3.37 km² on the western slopes of Mount Guna (one of the dozens of Miocene shield volcanoes that exist on top of the Ethiopian plateau) was mapped. The slope has an elevation between 3200 at its base and 4113 m a.s.l. at the peak. The present forest cover was recorded from high-resolution georeferenced satellite imagery from Google Maps and field data (2015), while historical forest cover was studied from georeferenced aerial photographs of 1982. In addition, key informant interviews were conducted to identify the trend of forest cover change and management practices. Whereas burning of the Erica forest for sake of land clearance (a typical practice on all Ethiopian mountains until the 1980s) most strikingly took place for three consecutive days in 1975, large-scale deforestation resulting from agricultural expansion and livestock pressure continued thereafter. However, between 2000 and 2014, due to active involvement of local and governmental institutions there was a slight regeneration of the vegetation and the Erica forest. Protection and regeneration of the forest was particularly efficient after it was given into custody of an orthodox church established in 1999 at the lower side of the forest. Overall, the study revealed that human and livestock pressures are the strongest drivers of deforestation. Furthermore, the study indicated that integrating the actions of local and governmental institutions is key for the protection of the

  3. Mapping Alpine Vegetation Location Properties by Dense Matching

    Science.gov (United States)

    Niederheiser, Robert; Rutzinger, Martin; Lamprecht, Andrea; Steinbauer, Klaus; Winkler, Manuela; Pauli, Harald

    2016-06-01

    Highly accurate 3D micro topographic mapping in mountain research demands for light equipment and low cost solutions. Recent developments in structure from motion and dense matching techniques provide promising tools for such applications. In the following, the feasibility of terrestrial photogrammetry for mapping topographic location properties of sparsely vegetated areas in selected European mountain regions is investigated. Changes in species composition at alpine vegetation locations are indicators of climate change consequences, such as the pronounced rise of average temperatures in mountains compared to the global average. Better understanding of climate change effects on plants demand for investigations on a micro-topographic scale. We use professional and consumer grade digital single-lens reflex cameras mapping 288 plots each 3 x 3 m on 18 summits in the Alps and Mediterranean Mountains within the GLORIA (GLobal Observation Research Initiative in Alpine environments) network. Image matching tests result in accuracies that are in the order of millimetres in the XY-plane and below 0.5 mm in Z-direction at the second image pyramid level. Reconstructing vegetation proves to be a challenge due to its fine and small structured architecture and its permanent movement by wind during image acquisition, which is omnipresent on mountain summits. The produced 3D point clouds are gridded to 6 mm resolution from which topographic parameters such as slope, aspect and roughness are derived. At a later project stage these parameters will be statistically linked to botanical reference data in order to conclude on relations between specific location properties and species compositions.

  4. Alpine treeline and timberline dynamics during the Holocene in the Northern Romanian Carpathians

    Directory of Open Access Journals (Sweden)

    Anca GEANTĂ

    2014-11-01

    Full Text Available High altitude environments (treeline and alpine communities are particularly sensitive to climate changes, disturbances and land-use changes due to their limited tolerance and adaptability range, habitat fragmentation and habitat restriction. The current and future climate warming is anticipated to shift the tree- and timberlines upwards thus affecting alpine plant communities and causing land-cover change and fragmentation of alpine habitats. An upslope movement of some trees, shrubs and cold adapted alpine herbs as a response to the current climate warming has already been noted in many montane and subalpine regions.Four Holocene peat and lacustrine sediment sequences located between 1670 and 1918 m a.s.l. (Fig.1, in the Rodna Mountains (Northern Romania, Eastern Carpathians are used with the aim to determine: i the sensitivity of high mountain habitats to climate, fire and land use changes; ii tree- and timberline shifts: and iii the influence of landscape topography on trees and shrubs.

  5. EXPLORING THE POTENTIAL OF AERIAL PHOTOGRAMMETRY FOR 3D MODELLING OF HIGH-ALPINE ENVIRONMENTS

    Directory of Open Access Journals (Sweden)

    K. Legat

    2016-03-01

    Based on the very promising results, some general recommendations for aerial photogrammetry processing in high-alpine areas are made to achieve best possible accuracy of the final 3D-, 2.5D- and 2D products.

  6. Assessing the spatial variability in peak season CO2 exchange characteristics across the Arctic tundra using a light response curve parameterization

    Directory of Open Access Journals (Sweden)

    H. N. Mbufong

    2014-05-01

    Full Text Available This paper aims to assess the functional and spatial variability in the response of CO2 exchange to irradiance across the Arctic tundra during peak season using light response curve (LRC parameters. This investigation allows us to better understand the future response of Arctic tundra under climatic change. Data was collected using the micrometeorological eddy covariance technique from 12 circumpolar Arctic tundra sites, in the range of 64–74° N. The LRCs were generated for 14 days with peak net ecosystem exchange (NEE using an NEE -irradiance model. Parameters from LRCs represent site specific traits and characteristics describing: (a NEE at light saturation (Fcsat, (b dark respiration (Rd, (c light use efficiency (α, (d NEE when light is at 1000 μmol m−2 s−1 (Fc1000, (e potential photosynthesis at light saturation (Psat and (f the light compensation point (LCP. Parameterization of LRCs was successful in predicting CO2 flux dynamics across the Arctic tundra. Yet we did not find any trends in LRC parameters across the whole Arctic tundra but there were indications for temperature and latitudinal differences within sub-regions like Russia and Greenland. Together, LAI and July temperature had a high explanatory power of the variance in assimilation parameters (Fcsat, Fc1000 and Psat, thus illustrating the potential for upscaling CO2 exchange for the whole Arctic tundra. Dark respiration was more variable and less correlated to environmental drivers than was assimilation parameters. Thus, indicating the inherent need to include other parameters such as nutrient availability, substrate quantity and quality in flux monitoring activities.

  7. Response of Tundra Ecosystems to Elevated Atmospheric CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, Walter C.

    1990-09-05

    OAK B188 Response of Tundra Ecosystems to Elevated Atmospheric CO{sub 2}. Atmospheric CO{sub 2} is expected to double by the end of the next century. Global mean increases in surface air temperature of 1.5-4.5 C are anticipated with larger increases towards the poles predicted. Changes in CO{sub 2} levels and temperature could have major impacts on ecosystem functioning, including primary productivity, species composition, plant-animal interactions, and carbon storage. Until recently, there has been little direct information on the impact of changes in CO{sub 2} and temperature on native ecosystems. The study described here was undertaken to evaluate the effects of a 50 and 100% increase in atmospheric CO{sub 2}, and a 100% increase in atmospheric CO{sub 2} coupled with a 4 C summer air temperature rise on the structure and function of an arctic tussock tundra ecosystem. The arctic contains large stores of carbon as soil organic matter, much frozen in permafrost and currently not reactive or available for oxidation and release into the atmosphere. About 10-27% of the world's terrestrial carbon occurs in arctic and boreal regions, and carbon is accumulating in these regions at the rate of 0.19 GT y{sup -1}. Mean temperature increases of 11 C and summer temperature increases of 4 C have been suggested. Mean July temperatures on the arctic coastal plain and arctic foothills regions are 4-12 C, and mean annual temperatures are -7 to -13 C (Haugen, 1982). The projected temperature increases represent a substantial elevation above current temperatures which will have major impacts on physical processes such as permafrost development and development of the active layer, and on biological and ecosystem processes such as primary productivity, carbon storage, and species composition. Extreme nutrient and temperature limitation of this ecosystem raised questions of the responsiveness of arctic systems to elevated CO{sub 2}. Complex ecosystem interactions with the effects

  8. Generic Regional Development Strategies from Local Stakeholders' Scenarios - an Alpine Village Experience

    OpenAIRE

    Ariane Walz; Wolfgang Loibl

    2010-01-01

    The article discusses the participatory elaboration of strategies for sustainable regional development in an Alpine tourist region in Austria to cope with global change effects evolving locally, considering climate change, economic change as well as (local) societal change. Local stakeholders in an Alpine village in the Montafon region contributed in workshops to achieve the final results: participant teams conducted system analyses of the regional system to explore key elements of the region...

  9. The effect of experimental warming on insect herbivory in an alpine plant community

    OpenAIRE

    Hasle, Toril Elisabet

    2013-01-01

    Climate warming is predicted to affect species and trophic interactions worldwide, and alpine ecosystems are expected to be especially sensitive to changes. There are few studies on how insect herbivory respond to warming. Therefore, the aim of this study was to examine if experimental warming had an effect on herbivory by leaf-chewing insects in an alpine plant community. To manipulate the climate I used open-top chambers (OTCs) from an ongoing long-term experiment at Finse, N...

  10. Differences in Sensation Seeking Between Alpine Skiers, Snowboarders and Ski Tourers

    OpenAIRE

    Martin Kopp, Mirjam Wolf, Gerhard Ruedl, Martin Burtscher

    2016-01-01

    Despite different injury rates and injury patterns previous personality related research in the field of downhill winter sports did not subdivide between different alpine slope users. In this study, we tried to find out whether the personality trait sensation seeking differs between skiers, snowboarders and ski tourers. In a cross-sectional survey 1185 persons (726 alpine skiers, 321 snowboarders and 138 ski tourers comparable in age and sex) were electronically questioned with the sensation ...

  11. Characterisation of the surface morphology of an alpine alluvial fan using airborne LiDAR

    OpenAIRE

    M. Cavalli; L. Marchi

    2008-01-01

    International audience Alluvial fans of alpine torrents are both natural deposition areas for sediment discharged by floods and debris flows, and preferred sites for agriculture and settlements. Hazard assessment on alluvial fans depends on proper identification of flow processes and their potential intensity. This study used LiDAR data to examine the morphology of the alluvial fan of a small alpine stream (Moscardo Torrent, Eastern Italian Alps). A high-resolution DTM from LiDAR data was ...

  12. Modeling Blister Rust Incidence in Whitebark Pine at Northern Rocky Mountain Alpine Treelines: A Geospatial Approach

    OpenAIRE

    Smith, Emily Katherine

    2009-01-01

    The status of whitebark pine (Pinus albicaulis), a foundation and keystone species and a pioneer establisher at alpine treeline, is threatened by the invasive and exotic fungal pathogen (Cronartium ribicola) that causes white pine blister rust in five-needled pines. Originally thought to be limited to moderate environments, the disease is now found extensively throughout colder and dryer regions east of the Continental Divide, including alpine treeline. My research objective was to determine ...

  13. Ecological dynamics of two remote alpine lakes during ice-free season

    OpenAIRE

    Rocco Tiberti; Sabino Metta; Martina Austoni; Cristiana Callieri; Morabito Giuseppe; Marchetto Aldo; Michela Rogora; Gabriele A. TARTARI; Jost Von Hardenberg; Antonello Provenzale

    2013-01-01

    We studied hydrochemistry and plankton dynamics in two remote alpine lakes: lake Nivolet superiore (2530 m asl) and lake Trebecchi superiore (2729 m asl) in the Gran Paradiso National Park (Western Italian Alps) in summer 2009. The aim of this study was to enhance the understanding of natural ecological dynamics in the pelagic habitat of alpine lakes by enlarging the number of biotic and abiotic variables usually considered to this end and by increasing the frequency of samplings, generally l...

  14. Effects of climate change on alpine plant species at Finse, Southern Norway

    OpenAIRE

    Molovcakova, Ivana

    2012-01-01

    The issue of climate change is one of the most discussed topics on Earth. The Earth is warming up and that is expected to continue in future. Alpine vegetation has already been affected by climate warming and has already shown responses. This study examined the effects of elevated temperature on individual functional traits. Because the temperature seems to be a crucial indicator of future existence and diversity of alpine plant community, I assessed how the functional traits of 10 selected p...

  15. Geomorphological and geochemistry changes in permafrost after the 2002 tundra wildfire in Kougarok, Seward Peninsula, Alaska

    Science.gov (United States)

    Iwahana, Go; Harada, Koichiro; Uchida, Masao; Tsuyuzaki, Shiro; Saito, Kazuyuki; Narita, Kenji; Kushida, Keiji; Hinzman, Larry D.

    2016-09-01

    Geomorphological and thermohydrological changes to tundra, caused by a wildfire in 2002 on the central Seward Peninsula of Alaska, were investigated as a case study for understanding the response from ice-rich permafrost terrain to surface disturbance. Frozen and unfrozen soil samples were collected at burned and unburned areas, and then water isotope geochemistry and cryostratigraphy of the active layer and near-surface permafrost were analyzed to investigate past hydrological and freeze/thaw conditions and how this information could be recorded within the permafrost. The development of thermokarst subsidence due to ice wedge melting after the fire was clear from analyses of historical submeter-resolution remote sensing imagery, long-term monitoring of thermohydrological conditions within the active layer, in situ surveys of microrelief, and geochemical signals recorded in the near-surface permafrost. The resulting polygonal relief coincided with depression lines along an underground ice wedge network, and cumulative subsidence to 2013 was estimated as at least 10.1 to 12.1 cm (0.9-1.1 cm/year 11 year average). Profiles of water geochemistry in the ground indicated mixing or replenishment of older permafrost water with newer meteoric water, as a consequence of the increase in active layer thickness due to wildfire or past thaw event. Our geocryological analysis of cores suggests that permafrost could be used to reconstruct the permafrost degradation history for the study site. Distinct hydrogen and oxygen isotopic compositions above the Global Meteoric Water Line were found for water from these sites where permafrost degradation with geomorphological change and prolonged surface inundation were suggested.

  16. Plant response to climate change along the forest-tundra ecotone in northeastern Siberia.

    Science.gov (United States)

    Berner, Logan T; Beck, Pieter S A; Bunn, Andrew G; Goetz, Scott J

    2013-11-01

    Russia's boreal (taiga) biome will likely contract sharply and shift northward in response to 21st century climatic change, yet few studies have examined plant response to climatic variability along the northern margin. We quantified climate dynamics, trends in plant growth, and growth-climate relationships across the tundra shrublands and Cajander larch (Larix cajanderi Mayr.) woodlands of the Kolyma river basin (657 000 km(2) ) in northeastern Siberia using satellite-derived normalized difference vegetation indices (NDVI), tree ring-width measurements, and climate data. Mean summer temperatures (Ts ) increased 1.0 °C from 1938 to 2009, though there was no trend (P > 0.05) in growing year precipitation or climate moisture index (CMIgy ). Mean summer NDVI (NDVIs ) increased significantly from 1982 to 2010 across 20% of the watershed, primarily in cold, shrub-dominated areas. NDVIs positively correlated (P watershed (r = 0.52 ± 0.09, mean ± SD), principally in cold areas, and with CMIgy across 9% of the watershed (r = 0.45 ± 0.06), largely in warm areas. Larch ring-width measurements from nine sites revealed that year-to-year (i.e., high-frequency) variation in growth positively correlated (P  0.05), which significantly correlated with NDVIs (r = 0.44, P < 0.05, 1982-2007). Both satellite and tree-ring analyses indicated that plant growth was constrained by both low temperatures and limited moisture availability and, furthermore, that warming enhanced growth. Impacts of future climatic change on forests near treeline in Arctic Russia will likely be influenced by shifts in both temperature and moisture, which implies that projections of future forest distribution and productivity in this area should take into account the interactions of energy and moisture limitations. PMID:23813896

  17. Permafrost collapse alters soil carbon stocks, respiration, CH4 , and N2O in upland tundra.

    Science.gov (United States)

    Abbott, Benjamin W; Jones, Jeremy B

    2015-12-01

    Release of greenhouse gases from thawing permafrost is potentially the largest terrestrial feedback to climate change and one of the most likely to occur; however, estimates of its strength vary by a factor of thirty. Some of this uncertainty stems from abrupt thaw processes known as thermokarst (permafrost collapse due to ground ice melt), which alter controls on carbon and nitrogen cycling and expose organic matter from meters below the surface. Thermokarst may affect 20-50% of tundra uplands by the end of the century; however, little is known about the effect of different thermokarst morphologies on carbon and nitrogen release. We measured soil organic matter displacement, ecosystem respiration, and soil gas concentrations at 26 upland thermokarst features on the North Slope of Alaska. Features included the three most common upland thermokarst morphologies: active-layer detachment slides, thermo-erosion gullies, and retrogressive thaw slumps. We found that thermokarst morphology interacted with landscape parameters to determine both the initial displacement of organic matter and subsequent carbon and nitrogen cycling. The large proportion of ecosystem carbon exported off-site by slumps and slides resulted in decreased ecosystem respiration postfailure, while gullies removed a smaller portion of ecosystem carbon but strongly increased respiration and N2 O concentration. Elevated N2 O in gully soils persisted through most of the growing season, indicating sustained nitrification and denitrification in disturbed soils, representing a potential noncarbon permafrost climate feedback. While upland thermokarst formation did not substantially alter redox conditions within features, it redistributed organic matter into both oxic and anoxic environments. Across morphologies, residual organic matter cover, and predisturbance respiration explained 83% of the variation in respiration response. Consistent differences between upland thermokarst types may contribute to the

  18. Inter-annual Variability in Tundra Phenology Captured with Digital Photography

    Science.gov (United States)

    Melendez, M.; Vargas, S. A.; Tweedie, C. E.

    2012-12-01

    The need to improve multi-scale phenological monitoring of arctic terrestrial ecosystems has been a persistent research challenge. Although there has been a range of advances in remote sensing capacities over the past decade, these present costly, and sometimes logistically challenging and technically demanding solutions for arctic terrestrial ecosystems. In this poster and undergraduate research project, we demonstrate how seasonal and inter-annual variability in landscape phenology can be derived for multiple tundra ecosystems using a low-cost and low-tech kite aerial photography (KAP) system that has been developed as a contribution to the US Arctic Observing Network. Seasonal landscape phenology was observed over the Networked Info-Mechanical Systems (NIMS) grids (2 x 50 meters) located in Barrow and Atqasuk, Alaska using imagery acquired with KAP and analyzed for a range of greenness indices. Preliminary results showed that the 2G-RB greenness index correlated the best with NDVI values calculated from ground based hyperspectral reflectance measurements. 2012 had the highest 2G-RB greenness index values for both Barrow and Atqasuk sites, which correlated well with NDVI values acquired from ground-based hyperspectral reflectance measurements. Wet vegetation types showed the most interannual variability at the Atqasuk site based on the 2G-RB greenness index while in Barrow the moist vegetation types showed the most interannual variability. These results show that vegetation indices similar to those acquired from hyperspectral remote sensing platforms can be derived using low-cost and low-tech techniques. Further analysis using these same techniques is required in order to link relatively small scale vegetation dynamics measured with KAP with those documented at large scales using satellite imagery.

  19. Organic matter composition and stabilization in a polygonal tundra soil of the Lena-Delta

    Directory of Open Access Journals (Sweden)

    S. Höfle

    2012-09-01

    Full Text Available This study investigated soil organic matter (OM composition of differently stabilized soil OM fractions in the active layer of a polygonal tundra soil in the Lena-Delta, Russia by applying density and particle-size fractionation combined with qualitative OM analysis using solid state 13C nuclear magnetic resonance spectroscopy, and lipid analysis combined with 14C analysis. Bulk soil OM was mainly composed of plant-derived, little decomposed material with surprisingly low and strongly increasing apparent 14C ages with active layer depth suggesting slow microbial OM transformation in cold climate. Most soil organic carbon was stored in clay and fine silt fractions (< 6.3 μm, which were composed of little decomposed plant material indicated by the dominance of long n-alkane and n-fatty acid compounds and low alkyl/O-alkyl C ratios. Organo-mineral associations, which are suggested to be a key mechanism of OM stabilization in temperate soils, seem to be less important in the active layer as the mainly plant-derived clay and fine silt sized OM was surprisingly "young" with 14C contents similar to the bulk soil values. Furthermore these fractions contained less organic carbon compared to density fractionated OM occluded in soil aggregates – a further important OM stabilization mechanism in temperate soils restricting accessibility of microorganisms. This process seems to be important at greater active layer depth where particulate OM, occluded in soil aggregates, was "older" than free particulate OM.

  20. Response of tundra ecosystems to elevated atmospheric carbon dioxide. [Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.; Grulke, N.E.

    1988-12-31

    Our past research shows that arctic tussock tundra responds to elevated atmospheric CO{sub 2} with marked increases in net ecosystem carbon flux and photosynthetic rates. However, at ambient temperatures and nutrient availabilities, homeostatic adjustments result in net ecosystem flux rates dropping to those found a contemporary CO{sub 2} levels within three years. Evidence for ecosystem-level acclimation in the first season of elevated CO{sub 2} exposure was found in 1987. Photosynthetic rates of Eriophorum vaginatum, the dominant species, adjusts to elevated CO{sub 2} within three weeks. Past research also indicates other changes potentially important to ecosystem structure and function. Elevated CO{sub 2} treatment apparently delays senescence and increases the period of positive photosynthetic activity. Recent results from the 1987 field season verify the results obtained in the 1983--1986 field seasons: Elevated CO{sub 2} resulted in increased ecosystem-level flux rates. Regressions fitted to the seasonal flux rates indicate an apparent 10 d extension of positive CO{sub 2} uptake reflecting a delay of the onset of plant dormancy. This delay in senescence could increase the frost sensitivity of the system. Major end points proposed for this research include the effects of elevated CO{sub 2} and the interaction of elevated atmospheric CO{sub 2} with elevated soil temperature and increased nutrient availability on: (1) Net ecosystem CO{sub 2} flux; (2) Net photosynthetic rates; (3) Patterns and resource controls on homeostatic adjustment in the above processes to elevated CO{sub 2}; (4) Plant-nutrient status, litter quality, and forage quality; (5) Soil-nutrient status; (6) Plant-growth pattern and shoot demography.

  1. Spaceborne potential for examining taiga-tundra ecotone form and vulnerability

    Science.gov (United States)

    Montesano, Paul M.; Sun, Guoqing; Dubayah, Ralph O.; Ranson, K. Jon

    2016-07-01

    In the taiga-tundra ecotone (TTE), site-dependent forest structure characteristics can influence the subtle and heterogeneous structural changes that occur across the broad circumpolar extent. Such changes may be related to ecotone form, described by the horizontal and vertical patterns of forest structure (e.g., tree cover, density, and height) within TTE forest patches, driven by local site conditions, and linked to ecotone dynamics. The unique circumstance of subtle, variable, and widespread vegetation change warrants the application of spaceborne data including high-resolution (vertical and horizontal components of ecotone form. We demonstrate the potential of spaceborne data for integrating forest height and density to assess TTE form at the scale of forest patches across the circumpolar biome by (1) mapping forest patches in study sites along the TTE in northern Siberia with a multi-resolution suite of spaceborne data and (2) examining the uncertainty of forest patch height from this suite of data across sites of primarily diffuse TTE forms. Results demonstrate the opportunities for improving patch-scale spaceborne estimates of forest height, the vertical component of TTE form, with HRSI. The distribution of relative maximum height uncertainty based on prediction intervals is centered at ˜ 40 %, constraining the use of height for discerning differences in forest patches. We discuss this uncertainty in light of a conceptual model of general ecotone forms and highlight how the uncertainty of spaceborne estimates of height can contribute to the uncertainty in identifying TTE forms. A focus on reducing the uncertainty of height estimates in forest patches may improve depiction of TTE form, which may help explain variable forest responses in the TTE to climate change and the vulnerability of portions of the TTE to forest structure change.

  2. Recent Declines in Warming and Vegetation Greening Trends over Pan-Arctic Tundra

    Directory of Open Access Journals (Sweden)

    Igor V. Polyakov

    2013-08-01

    Full Text Available Vegetation productivity trends for the Arctic tundra are updated for the 1982–2011 period and examined in the context of land surface temperatures and coastal sea ice. Understanding mechanistic links between vegetation and climate parameters contributes to model advancements that are necessary for improving climate projections. This study employs remote sensing data: Global Inventory Modeling and Mapping Studies (GIMMS Maximum Normalized Difference Vegetation Index (MaxNDVI, Special Sensor Microwave Imager (SSM/I sea-ice concentrations, and Advanced Very High Resolution Radiometer (AVHRR radiometric surface temperatures. Spring sea ice is declining everywhere except in the Bering Sea, while summer open water area is increasing throughout the Arctic. Summer Warmth Index (SWI—sum of degree months above freezing trends from 1982 to 2011 are positive around Beringia but are negative over Eurasia from the Barents to the Laptev Seas and in parts of northern Canada. Eastern North America continues to show increased summer warmth and a corresponding steady increase in MaxNDVI. Positive MaxNDVI trends from 1982 to 2011 are generally weaker compared to trends from 1982–2008. So to better understand the changing trends, break points in the time series were quantified using the Breakfit algorithm. The most notable break points identify declines in SWI since 2003 in Eurasia and 1998 in Western North America. The Time Integrated NDVI (TI-NDVI, sum of the biweekly growing season values of MaxNDVI has declined since 2005 in Eurasia, consistent with SWI declines. Summer (June–August sea level pressure (slp averages from 1999–2011 were compared to those from 1982–1998 to reveal higher slp over Greenland and the western Arctic and generally lower pressure over the continental Arctic in the recent period. This suggests that the large-scale circulation is likely a key contributor to the cooler temperatures over Eurasia through increased summer cloud

  3. Distribution of global fallouts cesium-137 in taiga and tundra catenae at the Ob River basin

    Science.gov (United States)

    Semenkov, I. N.; Usacheva, A. A.; Miroshnikov, A. Yu.

    2015-03-01

    The classification of soil catenae at the Ob River basin is developed and applied. This classification reflects the diverse geochemical conditions that led to the formation of certain soil bodies, their combinations and the migration fields of chemical elements. The soil and geochemical diversity of the Ob River basin catenae was analyzed. The vertical and lateral distribution of global fallouts cesium-137 was studied using the example of the four most common catenae types in Western Siberia tundra and taiga. In landscapes of dwarf birches and dark coniferous forests on gleysols, cryosols, podzols, and cryic-stagnosols, the highest 137Cs activity density and specific activity are characteristic of the upper soil layer of over 30% ash, while the moss-grass-shrub cover is characterized by low 137Cs activity density and specific activity. In landscapes of dwarf birches and pine woods on podzols, the maximum specific activity of cesium-137 is typical for moss-grass-shrub cover, while the maximum reserves are concentrated in the upper soil layer of over 30% ash. Bog landscapes and moss-grass-shrub cover are characterized by a minimum activity of 137Cs, and its reserves in soil generally decrease exponentially with depth. The cesium-137 penetration depth increases in oligotrophic histosols from northern to middle taiga landscapes from 10-15 to 40 cm. 137Cs is accumulated in oligotrophic histosols for increases in pH from 3.3 to 4.0 and in concretionary interlayers of pisoplinthic-cryic-histic-stagnosols. Cryogenic movement, on the one hand, leads to burying organic layers enriched in 137Cs and, on the other hand, to deducing specific activity when mixed with low-active material from lower soil layers.

  4. Permafrost collapse alters soil carbon stocks, respiration, CH4 , and N2O in upland tundra.

    Science.gov (United States)

    Abbott, Benjamin W; Jones, Jeremy B

    2015-12-01

    Release of greenhouse gases from thawing permafrost is potentially the largest terrestrial feedback to climate change and one of the most likely to occur; however, estimates of its strength vary by a factor of thirty. Some of this uncertainty stems from abrupt thaw processes known as thermokarst (permafrost collapse due to ground ice melt), which alter controls on carbon and nitrogen cycling and expose organic matter from meters below the surface. Thermokarst may affect 20-50% of tundra uplands by the end of the century; however, little is known about the effect of different thermokarst morphologies on carbon and nitrogen release. We measured soil organic matter displacement, ecosystem respiration, and soil gas concentrations at 26 upland thermokarst features on the North Slope of Alaska. Features included the three most common upland thermokarst morphologies: active-layer detachment slides, thermo-erosion gullies, and retrogressive thaw slumps. We found that thermokarst morphology interacted with landscape parameters to determine both the initial displacement of organic matter and subsequent carbon and nitrogen cycling. The large proportion of ecosystem carbon exported off-site by slumps and slides resulted in decreased ecosystem respiration postfailure, while gullies removed a smaller portion of ecosystem carbon but strongly increased respiration and N2 O concentration. Elevated N2 O in gully soils persisted through most of the growing season, indicating sustained nitrification and denitrification in disturbed soils, representing a potential noncarbon permafrost climate feedback. While upland thermokarst formation did not substantially alter redox conditions within features, it redistributed organic matter into both oxic and anoxic environments. Across morphologies, residual organic matter cover, and predisturbance respiration explained 83% of the variation in respiration response. Consistent differences between upland thermokarst types may contribute to the

  5. Correlations between different acidity forms in amorphous loamy soils of the tundra and taiga zones

    Science.gov (United States)

    Shamrikova, E. V.; Sokolova, T. A.

    2013-05-01

    Pair correlation coefficients ( r) between the acidity parameters for the main genetic horizons of soddy-podzolic soils (SPSs), typical podzolic soils (TPSs), gley-podzolic soils (GPSs), and tundra surfacegley soils (TSGSs) have been calculated on the basis of a previously developed database. A significant direct linear correlation has been revealed between the pHwater and pHKCl values in the organic and eluvial horizons of each soil, but the degree of correlation decreased when going from the less acidic SPSs to the more acidic soils of other taxons. This could be related to the fact that, under strongly acid conditions, extra Al3+ was dissolved in the KCl solutions from complex compounds in the organic horizons and from Al hydroxide interlayers in the soil chlorites. No significant linear correlation has been found between the exchangeable acidity ( H exch) and the activity of the [H]+ ions in the KCl extract ( a(H+)KCl) calculated per unit of mass in the organic horizons of the SPSs, but it has been revealed in the organic horizons of the other soils because of the presence of the strongest organic acids in their KCl extracts. The high r values between the H exch and a(H+)KCl in all the soils of the taiga zones have been related to the common source and composition of the acidic components. The correlation between the exchangeable and total ( H tot) acidities in the organic horizons of the podzolic soils has been characterized by high r values because of the common source of the acidity: H+ and probably Al3+ ions located on the functional groups of organic acids. High r values between the H exch and a(H+)KCl have been observed in the mineral horizons of all the soils, because the Al3+ hydroxo complexes occurring on the surface and in the interlayer spaces of the clay minerals were sources of both acidity forms.

  6. Invasion of terrestrial enchytraeids into two postglacial tundras: North-eastern Greenland and the Arctic Archipelago of Canada (Enchytraeidae, Oligochaeta)

    DEFF Research Database (Denmark)

    Christensen, Bent; Dózsa-Farkas, Klára

    2006-01-01

    that of potential source regions indicating either strong selection or varied dispersal ability. It appears that the Archipelago is influenced mainly from North America and North-eastern Greenland from Europe while the specialized fauna of the ancient Beringian tundra is of minor importance. The two alternative...... scenarios: (a) survival of a prepleistocene fauna in protected refugia within the area or (b) a postglacial re-invasion from outside are discussed, but the available data do not discriminate between these two possibilities. A total of 24 terrestrial enchytraeid taxa are recorded of which 22 are identified...

  7. Contrasting denitrifier communities relate to contrasting N2O emission patterns from acidic peat soils in arctic tundra

    OpenAIRE

    Palmer, Katharina; Biasi, Christina; Horn, Marcus A.

    2011-01-01

    Cryoturbated peat circles (that is, bare surface soil mixed by frost action; pH 3–4) in the Russian discontinuous permafrost tundra are nitrate-rich ‘hotspots' of nitrous oxide (N2O) emissions in arctic ecosystems, whereas adjacent unturbated peat areas are not. N2O was produced and subsequently consumed at pH 4 in unsupplemented anoxic microcosms with cryoturbated but not in those with unturbated peat soil. Nitrate, nitrite and acetylene stimulated net N2O production of both soils in anoxic ...

  8. Is grazing exclusion effective in restoring vegetation in degraded alpine grasslands in Tibet, China?

    Directory of Open Access Journals (Sweden)

    Yan Yan

    2015-06-01

    Full Text Available Overgrazing is considered one of the key disturbance factors that results in alpine grassland degradation in Tibet. Grazing exclusion by fencing has been widely used as an approach to restore degraded grasslands in Tibet since 2004. Is the grazing exclusion management strategy effective for the vegetation restoration of degraded alpine grasslands? Three alpine grassland types were selected in Tibet to investigate the effect of grazing exclusion on plant community structure and biomass. Our results showed that species biodiversity indicators, including the Pielou evenness index, the Shannon–Wiener diversity index, and the Simpson dominance index, did not significantly change under grazing exclusion conditions. In contrast, the total vegetation cover, the mean vegetation height of the community, and the aboveground biomass were significantly higher in the grazing exclusion grasslands than in the free grazed grasslands. These results indicated that grazing exclusion is an effective measure for maintaining community stability and improving aboveground vegetation growth in alpine grasslands. However, the statistical analysis showed that the growing season precipitation (GSP plays a more important role than grazing exclusion in which influence on vegetation in alpine grasslands. In addition, because the results of the present study come from short term (6–8 years grazing exclusion, it is still uncertain whether these improvements will be continuable if grazing exclusion is continuously implemented. Therefore, the assessments of the ecological effects of the grazing exclusion management strategy on degraded alpine grasslands in Tibet still need long term continued research.

  9. The role of endophytic methane oxidizing bacteria in submerged Sphagnum in determining methane emissions of Northeastern Siberian tundra

    Directory of Open Access Journals (Sweden)

    A. J. Dolman

    2010-11-01

    Full Text Available The behavior of tundra ecosystems is critical in the global carbon cycle due to their wet soils and large stores of carbon. Recently, cooperation was observed between methanotrophic bacteria and submerged Sphagnum, which reduces methane emissions in this type of vegetation and supplies CO2 for photosynthesis to the plant. Although proven in the lab, the differences that exist in methane emissions from inundated vegetation types with or without Sphagnum have not been linked to these bacteria before. To further investigate the importance of these bacteria, chamber flux measurements, microbial analysis and flux modeling were used to show that methane emissions in a submerged Sphagnum/sedge vegetation type were 50% lower compared to an inundated sedge vegetation without Sphagnum. From examining the results of the measurements, incubation experiments and flux modeling, it was found that it is likely that this difference is due to, for a large part, oxidation of methane below the water table by these endophytic bacteria. This result is important when upscaled spatially since oxidation by these bacteria plays a large role in 15% of the net methane emissions, while at the same time they promote photosynthesis of Sphagnum, and thus carbon storage. Future changes in the spread of submerged Sphagnum, in combination with the response of these bacteria to a warmer climate, could be an important factor in predicting future greenhouse gas exchange from tundra.

  10. Spatially explicit fire-climate history of the boreal forest-tundra (Eastern Canada) over the last 2000 years.

    Science.gov (United States)

    Payette, Serge; Filion, Louise; Delwaide, Ann

    2008-07-12

    Across the boreal forest, fire is the main disturbance factor and driver of ecosystem changes. In this study, we reconstructed a long-term, spatially explicit fire history of a forest-tundra region in northeastern Canada. We hypothesized that current occupation of similar topographic and edaphic sites by tundra and forest was the consequence of cumulative regression with time of forest cover due to compounding fire and climate disturbances. All fires were mapped and dated per 100 year intervals over the last 2,000 years using several fire dating techniques. Past fire occurrences and post-fire regeneration at the northern forest limit indicate 70% reduction of forest cover since 1800 yr BP and nearly complete cessation of forest regeneration since 900 yr BP. Regression of forest cover was particularly important between 1500s-1700s and possibly since 900 yr BP. Although fire frequency was very low over the last 100 years, each fire event was followed by drastic removal of spruce cover. Contrary to widespread belief of northward boreal forest expansion due to recent warming, lack of post-fire recovery during the last centuries, in comparison with active tree regeneration more than 1,000 years ago, indicates that the current climate does not favour such expansion.

  11. Micrometeorological processes driving snow ablation in an Alpine catchment

    Directory of Open Access Journals (Sweden)

    R. Mott

    2011-11-01

    Full Text Available Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micro-meteorological processes driving snow ablation in an Alpine catchment. For this purpose we combine a meteorological boundary-layer model (Advanced Regional Prediction System with a fully distributed energy balance model (Alpine3D. Turbulent fluxes above melting snow are further investigated by using data from eddy-correlation systems. We compare modeled snow ablation to measured ablation rates as obtained from a series of Terrestrial Laser Scanning campaigns covering a complete ablation season. The measured ablation rates indicate that the advection of sensible heat causes locally increased ablation rates at the upwind edges of the snow patches. The effect, however, appears to be active over rather short distances of about 4–6 m. Measurements suggest that mean wind velocities of about 5 m s−1 are required for advective heat transport to increase snow ablation over a long fetch distance of about 20 m. Neglecting this effect, the model is able to capture the mean ablation rates for early ablation periods but strongly overestimates snow ablation once the fraction of snow coverage is below a critical value of approximately 0.6. While radiation dominates snow ablation early in the season, the turbulent flux contribution becomes important late in the season. Simulation results indicate that the air temperatures appear to overestimate the local air temperature above snow patches once the snow coverage is low. Measured turbulent fluxes support these findings by suggesting a stable internal boundary layer close to the snow surface causing a strong decrease of the sensible heat flux towards the snow cover. Thus, the existence of a stable internal boundary layer above a patchy snow cover

  12. Drones application on snow and ice surveys in alpine areas

    Science.gov (United States)

    La Rocca, Leonardo; Bonetti, Luigi; Fioletti, Matteo; Peretti, Giovanni

    2015-04-01

    First results from Climate change are now clear in Europe, and in Italy in particular, with the natural disasters that damaged irreparably the territory and the habitat due to extreme meteorological events. The Directive 2007/60/EC highlight that an "effective natural hazards prevention and mitigation that requires coordination between Member States above all on natural hazards prevention" is necessary. A climate change adaptation strategy is identified on the basis of the guidelines of the European Community program 2007-2013. Following the directives provided in the financial instrument for civil protection "Union Civil Protection Mechanism" under Decision No. 1313/2013 / EU of the European Parliament and Council, a cross-cutting approach that takes into account a large number of implementation tools of EU policies is proposed as climate change adaptation strategy. In last 7 years a network of trans-Alpine area's authorities was created between Italy and Switzerland to define an adaptive strategy on climate change effects on natural enviroment based on non structural remedies. The Interreg IT - CH STRADA Project (STRategie di ADAttamento al cambiamento climatico) was born to join all the non structural remedies to climate change effects caused by snow and avalanches, on mountain sources, extreme hydrological events and to manage all transnational hydrological resources, involving all stakeholders from Italy and Switzerland. The STRADA project involved all civil protection authorities and all research centers in charge of snow, hydrology end civil protection. The Snow - meteorological center of the Regional Agency for Environment Protection (CNM of ARPA Lombardia) and the Civil Protection of Lombardy Region created a research team to develop tools for avalanche prediction and to observe and predict snow cover on Alpine area. With this aim a lot of aerial photo using Drone as been performed in unusual landscape. Results of all surveys were really interesting on a

  13. Detection and Segmentation of Small Trees in the Forest-Tundra Ecotone Using Airborne Laser Scanning

    Directory of Open Access Journals (Sweden)

    Marius Hauglin

    2016-05-01

    Full Text Available Due to expected climate change and increased focus on forests as a potential carbon sink, it is of interest to map and monitor even marginal forests where trees exist close to their tolerance limits, such as small pioneer trees in the forest-tundra ecotone. Such small trees might indicate tree line migrations and expansion of the forests into treeless areas. Airborne laser scanning (ALS has been suggested and tested as a tool for this purpose and in the present study a novel procedure for identification and segmentation of small trees is proposed. The study was carried out in the Rollag municipality in southeastern Norway, where ALS data and field measurements of individual trees were acquired. The point density of the ALS data was eight points per m2, and the field tree heights ranged from 0.04 to 6.3 m, with a mean of 1.4 m. The proposed method is based on an allometric model relating field-measured tree height to crown diameter, and another model relating field-measured tree height to ALS-derived height. These models are calibrated with local field data. Using these simple models, every positive above-ground height derived from the ALS data can be related to a crown diameter, and by assuming a circular crown shape, this crown diameter can be extended to a crown segment. Applying this model to all ALS echoes with a positive above-ground height value yields an initial map of possible circular crown segments. The final crown segments were then derived by applying a set of simple rules to this initial “map” of segments. The resulting segments were validated by comparison with field-measured crown segments. Overall, 46% of the field-measured trees were successfully detected. The detection rate increased with tree size. For trees with height >3 m the detection rate was 80%. The relatively large detection errors were partly due to the inherent limitations in the ALS data; a substantial fraction of the smaller trees was hit by no or just a few

  14. Impacts of introduced Rangifer on ecosystem processes of maritime tundra on subarctic islands

    Science.gov (United States)

    Ricca, Mark; Miles, A. Keith; Van Vuren, Dirk H.; Eviner, Valerie T.

    2016-01-01

    Introductions of mammalian herbivores to remote islands without predators provide a natural experiment to ask how temporal and spatial variation in herbivory intensity alter feedbacks between plant and soil processes. We investigated ecosystem effects resulting from introductions of Rangifer tarandus (hereafter “Rangifer”) to native mammalian predator- and herbivore-free islands in the Aleutian archipelago of Alaska. We hypothesized that the maritime tundra of these islands would experience either: (1) accelerated ecosystem processes mediated by positive feedbacks between increased graminoid production and rapid nitrogen cycling; or (2) decelerated processes mediated by herbivory that stimulated shrub domination and lowered soil fertility. We measured summer plant and soil properties across three islands representing a chronosequence of elapsed time post-Rangifer introduction (Atka: ~100 yr; Adak: ~50; Kagalaska: ~0), with distinct stages of irruptive population dynamics of Rangifer nested within each island (Atka: irruption, K-overshoot, decline, K-re-equilibration; Adak: irruption, K-overshoot; Kagalaska: initial introduction). We also measured Rangifer spatial use within islands (indexed by pellet group counts) to determine how ecosystem processes responded to spatial variation in herbivory. Vegetation community response to herbivory varied with temporal and spatial scale. When comparing temporal effects using the island chronosequence, increased time since herbivore introduction led to more graminoids and fewer dwarf-shrubs, lichens, and mosses. Slow-growingCladonia lichens that are highly preferred winter forage were decimated on both long-termRangifer-occupied islands. In addition, linear relations between more concentrated Rangifer spatial use and reductions in graminoid and forb biomass within islands added spatial heterogeneity to long-term patterns identified by the chronosequence. These results support, in part, the hypothesis that

  15. Differences in Sensation Seeking Between Alpine Skiers, Snowboarders and Ski Tourers.

    Science.gov (United States)

    Kopp, Martin; Wolf, Mirjam; Ruedl, Gerhard; Burtscher, Martin

    2016-03-01

    Despite different injury rates and injury patterns previous personality related research in the field of downhill winter sports did not subdivide between different alpine slope users. In this study, we tried to find out whether the personality trait sensation seeking differs between skiers, snowboarders and ski tourers. In a cross-sectional survey 1185 persons (726 alpine skiers, 321 snowboarders and 138 ski tourers comparable in age and sex) were electronically questioned with the sensation seeking scale (SSS-V) comprising the four factors thrill and adventure seeking, experiences seeking, disinhibition and boredom susceptibility. Kruskal-Wallis Tests revealed a significantly higher total score of the SSS-V for snowboarders in comparison to alpine skiers and ski tourers (H(2) = 41.5, p Ski tourers and snowboarders scored significantly higher in the dimensions "thrill- and adventure-seeking" and "experience-seeking" than alpine skiers. Furthermore, snowboarders showed higher scores in "disinhibition" related to alpine skiers and ski tourers and "boredom susceptibility" compared to alpine skiers. Data show differences in the personality trait sensation seeking in people practising different winter sports. As snowboarders showed higher SS-scores compared to alpine skiers and ski tourers prevention and information programs might benefit from a selective approach focusing on special characteristics of the respective group. Key pointsIt is the very first research trying to identify differences between different types of winter sport slope usersObtained results show higher sensation seeking scores in snowboardersThese results might stimulate new approaches in educational campaigns to reduce accident rates in winter sports.

  16. Introgression from domestic goat generated variation at the major histocompatibility complex of Alpine ibex.

    Directory of Open Access Journals (Sweden)

    Christine Grossen

    2014-06-01

    Full Text Available The major histocompatibility complex (MHC is a crucial component of the vertebrate immune system and shows extremely high levels of genetic polymorphism. The extraordinary genetic variation is thought to be ancient polymorphisms maintained by balancing selection. However, introgression from related species was recently proposed as an additional mechanism. Here we provide evidence for introgression at the MHC in Alpine ibex (Capra ibex ibex. At a usually very polymorphic MHC exon involved in pathogen recognition (DRB exon 2, Alpine ibex carried only two alleles. We found that one of these DRB alleles is identical to a DRB allele of domestic goats (Capra aegagrus hircus. We sequenced 2489 bp of the coding and non-coding regions of the DRB gene and found that Alpine ibex homozygous for the goat-type DRB exon 2 allele showed nearly identical sequences (99.8% to a breed of domestic goats. Using Sanger and RAD sequencing, microsatellite and SNP chip data, we show that the chromosomal region containing the goat-type DRB allele has a signature of recent introgression in Alpine ibex. A region of approximately 750 kb including the DRB locus showed high rates of heterozygosity in individuals carrying one copy of the goat-type DRB allele. These individuals shared SNP alleles both with domestic goats and other Alpine ibex. In a survey of four Alpine ibex populations, we found that the region surrounding the DRB allele shows strong linkage disequilibria, strong sequence clustering and low diversity among haplotypes carrying the goat-type allele. Introgression at the MHC is likely adaptive and introgression critically increased MHC DRB diversity in the genetically impoverished Alpine ibex. Our finding contradicts the long-standing view that genetic variability at the MHC is solely a consequence of ancient trans-species polymorphism. Introgression is likely an underappreciated source of genetic diversity at the MHC and other loci under balancing selection.

  17. Is pollen morphology of Salix polaris affected by enhanced UV-B irradiation? Results from a field experiment in High Arctic tundra

    NARCIS (Netherlands)

    D. Yeloff; P. Blokker; P. Boelen; J. Rozema

    2008-01-01

    This study tested the hypothesis that the thickness of the pollen wall will increase in response to enhanced UV-B irradiation, by examining the effect of enhanced UV-B irradiance on the pollen morphology of Salix polaris Wahlem. grown in a field experiment on the Arctic tundra of Svalbard. Measureme

  18. Research on dynamics of tundra ecosystems and their potential response to energy research development. Part II. Progress report, 1 April 1982-31 March 1983

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, W.C.

    1983-02-15

    Processes were studied by which phosphorus is replenished in the tundra soil solution following nutrient uptake, and how phosphorus solution concentration decreases following fertilizer addition. The fellfield and meadow soil represent the extremes of substrate conditions likely to be encountered in interior Alaska in terms of organic matter content.

  19. Plant and microbial uptake and allocation of organic and inorganic nitrogen related to plant growth forms and soil conditions at two subarctic tundra sites in Sweden

    DEFF Research Database (Denmark)

    Sørensen, Pernille Lærkedal; Clemmensen, Karina Engelbrecht; Michelsen, Anders;

    2008-01-01

    In order to follow the uptake and allocation of N in different plant functional types and microbes in two tundra ecosystems differing in nutrient availability, we performed a 15Nlabeling experiment with three N forms and followed the partitioning of 15N label among plants, microorganisms and soil...

  20. Can We Model the Scenic Beauty of an Alpine Landscape?

    Directory of Open Access Journals (Sweden)

    Erich Tasser

    2013-03-01

    Full Text Available During the last decade, agriculture has lost its importance in many European mountain regions and tourism, which benefits from attractive landscapes, has become a major source of income. Changes in landscape patterns and elements might affect scenic beauty and therefore the socio-economic welfare of a region. Our study aimed at modeling scenic beauty by quantifying the influence of landscape elements and patterns in relationship to distance. Focusing on Alpine landscapes in South and North Tyrol, we used a photographic questionnaire showing different landscape compositions. As mountain landscapes offer long vistas, we related scenic beauty to different distance zones. Our results indicate that the near zone contributes by 64% to the valuation of scenic beauty, the middle zone by 22%, and the far zone by 14%. In contrast to artificial elements, naturalness and diversity increased scenic beauty. Significant differences between different social groups (origin, age, gender, cultural background occurred only between the local population and tourists regarding great landscape changes. Changes towards more homogenous landscapes were perceived negatively, thus political decision makers should support the conservation of the cultural landscape.

  1. Alpine treeline growth variability: Simulation using an ecosystem process model

    Energy Technology Data Exchange (ETDEWEB)

    Scuderi, L.A.; Orth, K.U. (Univ. of Boston, MA (United States)); Schaaf, C.B. (Univ. of Boston, MA (United States) Phillips Laboratory, Hanscom AFB, MA (United States)); Band, L.E. (Univ. of Toronto, Ontario (Canada))

    1993-08-01

    Standard approaches in dendroclimatology used to determine climate-tree growth relationships at individual alpine treeline sites have primarily focused on empirically based statistical reconstructions. While such statistical relationships produce highly significant results, it is not possible to explore the underlying biophysiology in the links between climate and forest growth. Use of a deterministic forest ecosystem process model (FOREST-BGC) allows an evaluation of the impact of growing season and prior year meteorological conditions on phenological parameters such as net canopy photosynthesis (PSN) and net carbon gain (NETC). These variables were modeled over the course of a year and were statistically related to tree growth at an upper treeline site in the Sierra Nevada Mountains of California. The predicted growth increments over a 40-yr period exhibit trends similar to the measured variation in increment growth and perform better (R[sup 2][sub adj] = 0.62) than regression models based on monthly/seasonal mean temperature and precipitation totals (R[sup 2][sub adj] = 0.52). The standard principal component based approach, while producing results similar to the components identified in the forest ecosystem (FOREST-BGC) analysis, provided a better reconstruction of increment growth (R[sup 2][sub adj] = 0.79). However, site- and species-specific tuning of the FOREST-BGC model could make this approach a viable alternative to standard response function analysis and potentially a valuable tool for pursuing a theoretically based explanation of treeline processes. 40 refs., 6 figs., 1 tab.

  2. Simulation of Natural Acid Sulfate Weathering in an Alpine Watershed

    Science.gov (United States)

    Bassett, R. L.; Miller, William R.; McHugh, John; Catts, John G.

    1992-09-01

    Streams with acidic sulfate compositions (pH less than 3.5) are naturally generated in the alpine Geneva Creek Basin of the southern Rocky Mountains, an area underlain by Proterozoic metamorphic and igneous rocks that are intruded by Tertiary felsic stocks with associated pyritic alteration. These naturally acidic waters are similar in composition to more familiar man-made acid mine waters or to surface waters acidified by sulfate precipitation. Detailed study of the stream compositions has revealed the principal reactions driving the weathering process and was used to estimate the relative effects of snowpack ionic input versus the solute contribution from acid attack in soil zones and groundwater. In the Geneva Creek Basin, atmospheric sources of solute represent a minor component to the stream water composition, except for chloride, which can be used to determine the fraction of contribution. The weathering process is a balance between oxidation of sulfides, dissolution of silicates, formation of the clay minerals vermiculite, kaolinite, and smectite, carbonate neutralization, and precipitation of ferric and aluminum oxyhydroxides and aluminum sulfate. The chemical analyses of snow samples, multiple samples of water from Geneva Creek and its tributaries, and the composition of primary and secondary minerals identified in the basin serve as input to a mass balance geochemical model, which facilitates the interpretation of the principal geochemical processes.

  3. Freshwater and Alpine ecosystem response to Chernobyl fallout in Norway

    International Nuclear Information System (INIS)

    Environmental and agricultural research programmes were initiated in Norway in June 1986 following the Chernobyl accident. The main fallout in Norway occurred on 28 and 29 April and had an extremely patchy distribution between 60 and 66 deg. C N. In Lake Hoeysjoeen in the county of North Troendelag, high radioactivity was found in the sediment and in all levels of the food chains from vegetation to fish, including phytoplankton, zooplankton, bottom animals, brown trout and Arctic char. Food chains for both wild and domestic animals are studied in the Alpine areas of central Norway. High seasonal variation has been found in the radiocaesium load of reindeer. Such a variation is a result of the high radioactivity (up to more than 100 kBq/kg dry weight) in lichens, the only winter food for reindeer. Also there are indications of increased calf mortality and chromosomal aberrations in the blood cells of the reindeer in nutrient poor areas with heavy fallout. In mountain pastures where sheep and goats graze, a sharp increase in meat and goat milk radiocaesium occurred during the late pasture season in 1988. This was caused by the large number of mushrooms with high levels of radioactivity. Present research in Norway will have to be continued in order to develop further national and international co-operation among scientists and institutions with whom biologists had little or no contact previously. (author). 11 refs, 3 figs

  4. Solar-thermic sewage sludge treatment in extreme alpine environments.

    Science.gov (United States)

    Becker, W; Schoen, M A; Wett, B

    2007-01-01

    In the framework of a program for environmental protection conducted by the German mountaineers' club (DAV) problems emerging from residual solids accumulating in on-site wastewater treatment plants of mountain refuges were investigated. To handle these problems in an ecologically and economically reasonable way two devices for solar-supported treatment of sludge and bio-solids have been developed. These units support gravity-filtration and evaporation of liquid sludge as well as thermal acceleration of composting processes. Two solar sludge dryers were installed and operated without external energy supply at alpine refuges treating primary and secondary sludge, respectively. Batch-filling during the season could increase load capacity and a total solids concentration of up to 40% could be achieved before discharge at the beginning of the next season. The promising results from the solar sludge dryer encouraged for the development of a solar composter. The period of temperature levels suitable for composting biosolids in mountain areas can be extended considerably by application of this technology--measured temperature distribution indicated no freezing at all. PMID:18057635

  5. Microbial diversity in European alpine permafrost and active layers.

    Science.gov (United States)

    Frey, Beat; Rime, Thomas; Phillips, Marcia; Stierli, Beat; Hajdas, Irka; Widmer, Franco; Hartmann, Martin

    2016-03-01

    Permafrost represents a largely understudied genetic resource. Thawing of permafrost with global warming will not only promote microbial carbon turnover with direct feedback on greenhouse gases, but also unlock an unknown microbial diversity. Pioneering metagenomic efforts have shed light on the permafrost microbiome in polar regions, but temperate mountain permafrost is largely understudied. We applied a unique experimental design coupled to high-throughput sequencing of ribosomal markers to characterize the microbiota at the long-term alpine permafrost study site 'Muot-da-Barba-Peider' in eastern Switzerland with an approximate radiocarbon age of 12 000 years. Compared to the active layers, the permafrost community was more diverse and enriched with members of the superphylum Patescibacteria (OD1, TM7, GN02 and OP11). These understudied phyla with no cultured representatives proposedly feature small streamlined genomes with reduced metabolic capabilities, adaptations to anaerobic fermentative metabolisms and potential ectosymbiotic lifestyles. The permafrost microbiota was also enriched with yeasts and lichenized fungi known to harbour various structural and functional adaptation mechanisms to survive under extreme sub-zero conditions. These data yield an unprecedented view on microbial life in temperate mountain permafrost, which is increasingly important for understanding the biological dynamics of permafrost in order to anticipate potential ecological trajectories in a warming world. PMID:26832204

  6. Europe's battery: The making of the Alpine energy landscape, 1870-1955

    Science.gov (United States)

    Landry, Marc D., II

    This study examines the environmental history of hydropower development in the Alps from the mid-nineteenth to the mid-twentieth centuries. Analyzing government archival files, associational journals, conference proceedings, and published contemporary material from several Alpine countries, it seeks to determine how and why Europeans modified the Alpine landscape to generate hydropower, and to explore the consequences of these decisions. I argue that during this time period, Europeans thoroughly transformed the Alpine environment, creating what I call "Europe's Battery": a gigantic system for storing hydropower and distributing it on a continental scale. This study shows how nineteenth-century innovations in energy technology contributed to a dramatic shift in the perception of the Alps as a landscape of "white coal." It demonstrates how at the outset of electrification, Europeans modified Alpine waterways on an unprecedented scale in order to tap into the power of flowing Alpine water. I show how after the turn of the twentieth century, Europeans took advantage of the unique mountain environment to store water, first by converting existing lakes into reservoirs. The practice countered what was perceived to be the greatest disadvantage of white coal: its climate-influenced inconstancy. This study shows the importance of war, and especially the First World War, in the forging of the new Alpine landscape. Finally, this study illustrates how from the interwar period to the aftermath of the Second World War, Europeans put the finishing touches on the new Alpine energy landscape by creating large reservoirs behind dams and feeding Alpine hydroelectricity into a burgeoning European electricity grid. By 1955 the Alps had become one of the most important energy landscapes in Europe. This history of the Alpine energy landscape contributes to a number of historiographical fields. It represents an important chapter in the environmental history of one of the world's most

  7. Changes in chloroplast ultrastructure in some high-alpine plants: adaptation to metabolic demands and climate?

    Science.gov (United States)

    Lütz, C; Engel, L

    2007-01-01

    The cytology of leaf cells from five different high-alpine plants was studied and compared with structures in chloroplasts from the typical high-alpine plant Ranunculus glacialis previously described as having frequent envelope plus stroma protrusions. The plants under investigation ranged from subalpine/alpine Geum montanum through alpine Geum reptans, Poa alpina var. vivipara, and Oxyria digyna to nival Cerastium uniflorum and R. glacialis. The general leaf structure (by light microscopy) and leaf mesophyll cell ultrastructure (by transmission electron microscopy [TEM]) did not show any specialized structures unique to these mountain species. However, chloroplast protrusion formation could be found in G. reptans and, to a greater extent, in O. digyna. The other species exhibited only a low percentage of such chloroplast structural changes. Occurrence of protrusions in samples of G. montanum and O. digyna growing in a mild climate at about 50 m above sea level was drastically reduced. Serial TEM sections of O. digyna cells showed that the protrusions can appear as rather broad and long appendices of plastids, often forming pocketlike structures where mitochondria and microbodies are in close vicinity to the plastid and to each other. It is suggested that some high-alpine plants may form such protrusions to facilitate fast exchange of molecules between cytoplasm and plastid as an adaptation to the short, often unfavorable vegetation period in the Alps, while other species may have developed different types of adaptation that are not expressed in ultrastructural changes of the plastids.

  8. Methane-cycling microorganisms in soils of a high-alpine altitudinal gradient.

    Science.gov (United States)

    Hofmann, Katrin; Pauli, Harald; Praeg, Nadine; Wagner, Andreas O; Illmer, Paul

    2016-03-01

    Methanogens and methanotrophs play unique roles as producers and consumers of the greenhouse gas methane (CH4) in soils, respectively. Here, we aimed to reveal whether and to which extent methane-cyclers occur in high-alpine soils, and to assess their spatial distribution along an altitudinal gradient (2700-3500 m) in the Austrian Alps at sites located within the alpine (2700-2900 m), the alpine-nival (3000-3100 m) and the nival belts (3200-3500 m). Methanococcales and Methanocella spp. were most abundant among all quantified methanogenic guilds, whereas Methanosarcinales were not detected in the studied soil. The detected methanogens seem to be capable of persisting despite a highly oxic low-temperature environment. Methanogenic and methanotrophic activities and abundances of methanotrophs, Methanococcales and Methanocella spp. declined with altitude. Methanogenic and methanotrophic abundances were best explained by mean annual soil temperature and dissolved organic carbon, respectively. Alpine belt soils harbored significantly more methane-cyclers than those of the nival belt, indicating some influence of plant cover. Our results show that methanogens are capable of persisting in high-alpine cold soils and might help to understand future changes of these environments caused by climate warming. PMID:26790465

  9. Ungulate herbivory on alpine willow in the Sangre de Cristo Mountains of Colorado

    Science.gov (United States)

    Zeigenfuss, L.C.; Schoenecker, K.A.; Amburg, L.K.V.

    2011-01-01

    In many areas of the Rocky Mountains, elk (Cervus elaphus) migrate from low-elevation mountain valleys during spring to high-elevation subalpine and alpine areas for the summer. Research has focused on the impacts of elk herbivory on winter-range plant communities, particularly on woody species such as willow and aspen; however, little information is available on the effects of elk herbivory on alpine willows. In the Sangre de Cristo Mountains of south central Colorado, select alpine areas appear to receive high levels of summer elk herbivory, while other areas are nearly unbrowsed. In 2005 and 2008, we measured willow height, cover, and utilization on sites that appeared to be used heavily by elk, as well as on sites that appeared to be used lightly, to determine differences between these communities over time. We found less willow cover and shorter willows at sites that received higher levels of browsing compared to those that had lower levels of browsing. Human recreational use was greater at lightly browsed sites than at highly browsed sites. From 2005 to 2008, willow utilization declined, and willow cover and height increased at sites with heavy browsing, likely owing to ownership change of adjacent valley land which led to (1) removal of grazing competition from, cattle at valley locations and (2) increased human use in alpine areas, which displaced elk. We discuss the implications of increased human use and climate change on elk use of these alpine habitats. ?? 2011.

  10. Seedling recruitment of forb species under experimental microhabitats in alpine grassland

    International Nuclear Information System (INIS)

    Which factors limit plant seedling recruitment in alpine meadow of the Qinghai-Tibetan Plateau (QTP), China? This study examined the relative influence of seed mass and microsites (resulted from grazing disturbance) on field seedling emergence and survival of nineteen alpine herbaceous species with a range of traits in QTP. Seed mass had significant effects on seedling emergence and survival eliminating influence of light and nutrient variances among these species. The larger-seed species had more advantageous than the smaller-seed species in seedling survival, but it was disadvatage for seedling emergence, especially under high nutrient availability and low light intensity conditions. Light had obvious effects on seedling survival, but less effects on seedling emergence for these species. Moreover, nutrient and light treatments altered the regression relationships of seed mass and seedling emergence and survival and the order of significances was L25>L50>L100>L10>L4. These results suggested that seed mass may restrict seedling recruitment processes, however, light and nutrient availability all have significant effects on seedling emergence and survival for these alpine species. Moderate light intensity was propitious to seedling emergence and survival in alpine grassland. This suggests that ecological factors in alpine grassland provide a stochastic influence on different seed-mass species. These trends may help to explain why many small-seeded species of Asteraceae and Gramineae tend to be more abundant in disturbed habitats. (author)

  11. Temperature-driven flower longevity in a high-alpine species of Oxalis influences reproductive assurance.

    Science.gov (United States)

    Arroyo, Mary T K; Dudley, Leah S; Jespersen, Gus; Pacheco, Diego A; Cavieres, Lohengrin A

    2013-12-01

    How high-alpine plants confront stochastic conditions for animal pollination is a critical question. We investigated the effect of temperature on potential flower longevity (FL) measured in pollinator-excluded flowers and actual FL measured in pollinated flowers in self-incompatible Oxalis compacta and evaluated if plastically prolonged potential FL can ameliorate slow pollination under cool conditions. Pollinator-excluded and hand-pollinated flowers were experimentally warmed with open-top chambers (OTCs) on a site at 3470 m above sea level (asl). Flower-specific temperatures, and pollinator-excluded and open-pollination flower life-spans were measured at six alpine sites between 3100 and 3470 m asl. Fruit set was analyzed in relation to inferred pollination time. Warming reduced potential FL. Variable thermal conditions across the alpine landscape predicted potential and actual FL; flower senescence was pollination-regulated. Actual FL and potential FL were coupled. Prolonged potential FL generally increased fruit set under cooler conditions. Plastic responses permit virgin flowers of O. compacta to remain open longer under cooler temperatures, thereby ameliorating slow pollination, and to close earlier when pollination tends to be faster under warmer conditions. Plastic potential FL provides adaptive advantages in the cold, thermally variable alpine habitat, and has important implications for reproductive success in alpine plants in a warming world. PMID:23952472

  12. An interpretation of the metamorphic history of the Alpine Schist, northern Westland

    International Nuclear Information System (INIS)

    This thesis presents results of an investigation into the metamorphism of a section of the Alpine Schist in North Westland, between the Crooked River in the north and Griffin Creek in the south. The Alpine Schist is a narrow belt of dominantly quartzofeldspathic schist that has been rapidly extruded along the Alpine Fault. The schist is at its highest grade (garnet-oligoclase) immediately east of the Alpine Fault and grades to biotite zone facies at a distance of c. 3 km west of the fault in this study. Field mapping, optical microscopy, whole-rock analyses, mineral chemistry and zoning, geothermobarometry, stable isotopes and Sm-Nd age determinations for garnet growth zones have enabled a well constrained metamorphic history to be interpreted. As part of this an estimate for the timing and P-T conditions of the peak of Alpine Schist metamorphism in the study area has also been possible. Large polyphase garnet porphyroclasts sampled from mylonitised Alpine Schist at Macs Creek record up to five zones of garnet growth. Textures within these garnets indicate that at least some garnet growth predated the development of the alpine foliation and that garnet growth occurred at least sporadically through most of the Cenozoic, finishing with garnet rims overgrowing the developing mylonitic foliation. Garnet separates were prepared and sent to VIEPS Radiogenic Isotope Laboratory, La Trobe University, Melbourne, Australia for Sm-Nd garnet growth age determinations. For the core (zone 1), a two pint garnet-whole rock age of 98 ± 8.1 Ma indicates garnet growth in the mid-Cretaceous, during a time of widespread extension with scattered plutonism and volcanism in the New Zealand region, which predates the opening of the Tasman Sea by c. 20 Ma. A second Sm-Nd garnet growth age was obtained from zone 4, just inside the synmylonitic outermost rim (zone 5) and show that Alpine Schist garnet growth occurred in the Late Cenozoic. The broad age of 12 ± 37 M (MSWD = 0.89) for zone 4

  13. Simulated heat waves affected alpine grassland only in combination with drought

    Science.gov (United States)

    De Boeck, Hans J.; Bassin, Seraina; Verlinden, Maya; Zeiter, Michaela; Hiltbrunner, Erika

    2016-04-01

    The Alpine region is warming fast, leading to an increase in the frequency and intensity of climate extremes. Currently, it is unclear whether alpine ecosystems are sensitive or resistant to such extremes. In an experiment carried out in the Swiss Alps, we subjected Swiss alpine grassland communities to heat waves with varying intensity (5-10 °C warming) by transplanting monoliths to four different elevations (2440-660 m a.s.l.) for 17 days. Half of the monoliths were regularly irrigated while the other half were deprived of irrigation to additionally induce a drought at each site. We found that heat waves had no significant short-term impacts on fluorescence (Fv/Fm, a stress indicator), senescence and aboveground productivity if irrigation was provided. However, when heat waves coincided with drought, plants showed clear signs of stress, resulting in vegetation browning and reduced phytomass production. This likely resulted from direct drought effects, but also, as measurements of stomatal conductance and canopy temperatures suggest, from increased high-temperature stress as water scarcity decreased heat mitigation through transpiration. The immediate responses to heat waves (with or without droughts) recorded in these alpine grasslands were similar to those observed in the more extensively studied grasslands from temperate climates. Climate extreme impacts may differ in the longer run, however, because the short growing season in alpine environments likely constrains recovery.

  14. Methane dynamics in the subarctic tundra: combining stable isotope analyses, plot- and ecosystem-scale flux measurements

    Science.gov (United States)

    Marushchak, M. E.; Friborg, T.; Biasi, C.; Herbst, M.; Johansson, T.; Kiepe, I.; Liimatainen, M.; Lind, S. E.; Martikainen, P. J.; Virtanen, T.; Soegaard, H.; Shurpali, N. J.

    2016-02-01

    Methane (CH4) fluxes were investigated in a subarctic Russian tundra site in a multi-approach study combining plot-scale data, ecosystem-scale eddy covariance (EC) measurements, and a fine-resolution land cover classification scheme for regional upscaling. The flux data as measured by the two independent techniques resulted in a seasonal (May-October 2008) cumulative CH4 emission of 2.4 (EC) and 3.7 g CH4 m-2 (manual chambers) for the source area representative of the footprint of the EC instruments. Upon upscaling for the entire study region of 98.6 km2, the chamber measured flux data yielded a regional flux estimate of 6.7 g CH4 m-2 yr-1. Our upscaling efforts accounted for the large spatial variability in the distribution of the various land cover types (LCTs) predominant at our study site. Wetlands with emissions ranging from 34 to 53 g CH4 m-2 yr-1 were the most dominant CH4-emitting surfaces. Emissions from thermokarst lakes were an order of magnitude lower, while the rest of the landscape (mineral tundra) was a weak sink for atmospheric methane. Vascular plant cover was a key factor in explaining the spatial variability of CH4 emissions among wetland types, as indicated by the positive correlation of emissions with the leaf area index (LAI). As elucidated through a stable isotope analysis, the dominant CH4 release pathway from wetlands to the atmosphere was plant-mediated diffusion through aerenchyma, a process that discriminates against 13C-CH4. The CH4 released to the atmosphere was lighter than that in the surface porewater, and δ13C in the emitted CH4 correlated negatively with the vascular plant cover (LAI). The mean value of δ13C obtained here for the emitted CH4, -68.2 ± 2.0 ‰, is within the range of values from other wetlands, thus reinforcing the use of inverse modelling tools to better constrain the CH4 budget. Based on the IPCC A1B emission scenario, a temperature increase of 6.1 °C relative to the present day has been predicted for the

  15. The exchange of carbon dioxide between wet arctic tundra and the atmosphere at the Lena River Delta, Northern Siberia

    Directory of Open Access Journals (Sweden)

    L. Kutzbach

    2007-06-01

    Full Text Available The exchange fluxes of carbon dioxide between wet arctic polygonal tundra and the atmosphere were investigated by the micrometeorological eddy covariance method. The investigation site was situated in the centre of the Lena River Delta in Northern Siberia (72°22' N, 126°30' E. The study region is characterized by a polar and distinctly continental climate, very cold and ice-rich permafrost and its position at the interface between the Eurasian continent and the Arctic Ocean. The soils at the site are characterized by high organic matter content, low nutrient availability and pronounced water logging. The vegetation is dominated by sedges and mosses. The micrometeorological campaigns were performed during the periods July–October 2003 and May–July 2004 which included the period of snow and soil thaw as well as the beginning of soil refreeze. The main CO2 exchange processes, the gross photosynthesis and the ecosystem respiration, were found to be of a generally low intensity. The gross photosynthesis accumulated to –432 g m−2 over the photosynthetically active period (June–September. The contribution of mosses to the gross photosynthesis was estimated to be about 40%. The diurnal trend of the gross photosynthesis was mainly controlled by the incoming photosynthetically active radiation. During midday the photosynthetic apparatus of the canopy was frequently near saturation and represented the limiting factor on gross photosynthesis. The synoptic weather conditions strongly affected the exchange fluxes of CO2 by changes in cloudiness, precipitation and pronounced changes of air temperature. The ecosystem respiration accumulated to +327 g m−2 over the photosynthetically active period, which corresponds to 76% of the CO2 uptake by photosynthesis. However, the ecosystem respiration continued at substantial rates during autumn when photosynthesis had ceased and the soils

  16. The southernmost Andean Mountain soils: a toposequence from Nothofagus Forest to Sub Antarctic Tundra at Ushuaia, Tierra del Fuego

    Science.gov (United States)

    Firme Sá, Mariana M.; Schaefer, Carlos E.; Loureiro, Diego C.; Simas, Felipe N.; Francelino, Marcio R.; Senra, Eduardo O.

    2015-04-01

    Located at the southern tip of the Fuegian Andes Cordilhera, the Martial glacier witnessed a rapid process of retreat in the last century. Up to now little is known about the development and genesis of soils of this region. A toposequence of six soils, ranging from 430-925 m a.s.l, was investigated, with emphasis on genesis, chemical and mineralogical properties. The highest, youngest soil is located just below the Martial Glacier Martial Sur sector, and the lowest soils occur on sloping moraines under Nothofagus pumilio forests. Based on chemical, physical and mineralogical characteristics, the soils were classified according to the Soil taxonomy, being keyed out as Inceptisols and Entisols. Soil parent material of the soil is basically moraines, in which the predominant lithic components dominated by metamorphic rocks, with allochthonous contributions of wind-blown materials (very small fragments of volcanic glass) observed by hand lens in all horizons, except the highest profile under Tundra. In Nothofagus Deciduous Forests at the lowest part of the toposequence, poorly developed Inceptisols occur with Folistic horizons, with mixed "andic" and "spodic" characters, but with a predominance of andosolization (Andic Drystrocryepts). Under Tundra vegetation, Inceptisols are formed under hydromorphism and andosolization processes (Oxiaquic Dystrocrepts and Typic Dystrocrepts). On highland periglacial environments, soils without B horizon with strong evidence of cryoturbation and cryogenesis occur, without present-day permafrost down to 2 meters (Typic Cryorthents and Lithic Haploturbels). The mountain soils of Martial glacier generalize young, stony and rich in organic matter, with the exception of barely vegetated Tundra soils at higher altitudes. The forest soils are more acidic and have higher Al3+activity. All soils are dystrophic, except for the highest profile of the local periglacial environment. The organic carbon amounts are higher in forest soils and

  17. Precipitation observation using microwave backhaul links in the alpine and pre-alpine region of Southern Germany

    Directory of Open Access Journals (Sweden)

    C. Chwala

    2012-01-01

    Full Text Available Measuring rain rates over complex terrain is afflicted with large uncertainties because rain gauges are influenced by orography and weather radars are mostly not able to look into mountain valleys. We apply a new method to estimate near surface rain rates exploiting attenuation data from commercial microwave links in the alpine region of Southern Germany. Received signal level (RSL data is recorded minutely with small data loggers at the towers and then sent to a database server via GSM. Due to the large RSL fluctuations in periods without rain, the determination of attenuation caused by precipitation is not straightforward. To be able to continuously process the RSL data from July 2010 to October 2010, we introduce a new method to detect wet and dry periods using spectral time series analysis. We show the performance and limitations of the method and analyse the derived rain rates compared to rain gauge and weather radar measurements. The resulting correlations differ for different links and reach values of R2 = 0.80 for the link-gauge comparison and R2 = 0.84 for the link-radar comparison.

  18. Dust inputs and bacteria influence dissolved organic matter in clear alpine lakes.

    Science.gov (United States)

    Mladenov, N; Sommaruga, R; Morales-Baquero, R; Laurion, I; Camarero, L; Diéguez, M C; Camacho, A; Delgado, A; Torres, O; Chen, Z; Felip, M; Reche, I

    2011-01-01

    Remote lakes are usually unaffected by direct human influence, yet they receive inputs of atmospheric pollutants, dust, and other aerosols, both inorganic and organic. In remote, alpine lakes, these atmospheric inputs may influence the pool of dissolved organic matter, a critical constituent for the biogeochemical functioning of aquatic ecosystems. Here, to assess this influence, we evaluate factors related to aerosol deposition, climate, catchment properties, and microbial constituents in a global dataset of 86 alpine and polar lakes. We show significant latitudinal trends in dissolved organic matter quantity and quality, and uncover new evidence that this geographic pattern is influenced by dust deposition, flux of incident ultraviolet radiation, and bacterial processing. Our results suggest that changes in land use and climate that result in increasing dust flux, ultraviolet radiation, and air temperature may act to shift the optical quality of dissolved organic matter in clear, alpine lakes.

  19. Monitoring of pests of Coccinea suborder in the collection greenhouses at Polar-Alpine Botanical Garden

    Directory of Open Access Journals (Sweden)

    Rak Natalja

    2014-12-01

    Full Text Available The main field of research carried out in the Polar-Alpine botanical garden-institute is the plant introduction and acclimatization. The problem of particular complexity is the protection of plant introducents from pests. The representatives of the Coccinea suborder are found in the Far North exclusively in greenhouses. Monitoring of a phytosanitary condition of Polar-Alpine Botanical Garden plant collection fund revealed the most stable pest species in relation to local conditions and methods used to fight against species of the Coccinea suborder. Сomposition of forage plants is defined and species of plant-reserves, on which pest population is formed, are selected. List of tropical and subtropical plants populated by Coccinea in the collection of the Polar-Alpine Botanical Garden is compiled (data on the years of 2004-2013

  20. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    Science.gov (United States)

    Osborne, Brooke B.; Baron, Jill S.; Wallenstein, Matthew D.

    2016-03-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many highelevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  1. Alpine meteorology: translations of classic contributions by A. Wagner, E. Ekhart, and F. Defant

    Energy Technology Data Exchange (ETDEWEB)

    Whiteman, C.D.; Dreiseitl, E. (eds.)

    1984-06-01

    The English translations of four classic research papers in Alpine meteorology, originally published in German and French in the 1930s and 1940s are presented in this report. The papers include: A. Wagner's 1938 paper entitled Theory and Observation of Periodic Mountain Winds; E. Ekhart's 1944 paper entitled Contributions to Alpine Meteorology; E. Ekhart's 1948 paper entitled On the Thermal Structure of the Mountain Atmosphere; and F. Defant's 1949 paper entitled A Theory of Slope Winds, Along with Remarks on the Theory of Mountain Winds and Valley Winds. A short introduction to these translations summarizes four recent Alpine meteorology field experients, emphasizing ongoing research that extends the research of Wagner, Ekhart, and Defant. The four experiments include the Innsbruck Slope Wind Experiment of 1978, the MESOKLIP Experiment of 1979, the DISKUS Experiment of 1980, and the ALPEX/MERKUR Experiment of 1982.

  2. Inspection of Alpine glaciers with cosmic-ray muon radiography

    Science.gov (United States)

    Nishiyama, Ryuichi; Ariga, Akitaka; Ariga, Tomoko; Ereditato, Antonio; Lechmann, Alessandro; Mair, David; Scampoli, Paola; Schlunegger, Fritz; Vladymyrov, Mykhailo

    2016-04-01

    Radiography using cosmic-ray muons represents a challenging method for probing the bedrock topography beneath Alpine glaciers. We present the current status of our feasibility study at Eiger glacier, situated on the western flank of the Eiger in the Jungfrau region, Central Swiss Alps. The muon radiography is a technique that has been recently developed to investigate the internal density profiles of geoscientific targets. It is based on the measurement of the absorption of the cosmic-ray muons inside a material. Because the energy spectrum of cosmic-ray muons and the energy dependence of muon range have been studied well during the past years, the attenuation of the muon flux can be used to derive the column density, i.e. the density integrated along the muon trajectories, of geoscientific targets. This technique has recently been applied for non-invasive inspection of volcanoes, nuclear reactors, seismic faults, caves and etc. The greatest advantage of the method in the field of glacier studies is that it yields a unique solution of the density underneath a glacier without any assumption of physical properties inside the target. Large density contrasts, as expected between glacier ice (˜ 1.0g/cm3) and bedrock (˜ 2.5g/cm3), would allow us to elucidate the shape of the bedrock in high resolution. Accordingly, this technology will provide for the first time information on the bedrock surface beneath a steep and non-accessible Alpine glacier, in a complementary way with respect to other exploration methods (drilling, ground penetrating radar, seismic survey, gravity explorations and etc.). Our first aim is to demonstrate the feasibility of the method through a case study at the Eiger glacier, situated in the Central Swiss Alps. The Eiger glacier straddles the western flank of the Eiger between 3700 and 2300 m above sea level (a.s.l.). The glacier has shortened by about 150 m during the past 30 years in response to the ongoing global warming, causing a concern for

  3. Greenhouse gas balance of a subarctic tundra - importance of carbon dioxide, methane and nitrous oxide from different land cover types

    Science.gov (United States)

    Marushchak, M. E.; Biasi, C.; Elsakov, V.; Jokinen, S.; Lind, S. E.; Pitkämäki, A.; Virtanen, T.; Martikainen, P. J.

    2012-04-01

    The strong warming predicted for the Arctic has increased the need to understand how carbon (C) balance in tundra will respond to climate change. The large C reservoir of northern permafrost soils (50% of global belowground soil C pool; Tarnocai et al. 2009) may be threatened by warming and associated thawing of permafrost, which might lead to increased release of carbon dioxide (CO2) and methane (CH4) to the atmosphere. Moreover, the recent findings of high nitrous oxide (N2O) emissions from permafrost soils (Repo et al. 2009, Elberling et al. 2010) show that the large nitrogen pool in permafrost soils cannot be neglected anymore when predicting the atmospheric impact of Arctic tundra in a changing climate. Here we report the annual landscape scale (GHG) balance of subarctic tundra including all the three most important GHGs: CO2, CH4 and N2O. The study was conducted in Northeast European Russia in a heterogeneous landscape consisting of upland tundra, fens, willow wetlands and massive peat plateau complexes spotted by thermokarst lakes. Fluxes of CO2, CH4 and N2O were measured during two growing seasons and the cold season between using different chamber techniques at terrestrial ecosystems, and combination of gas gradient method and bubble collectors in thermokarst lakes. The plot scale results were up scaled to the landscape level using a land cover map based on a high-resolution QuickBird satellite image (Hugelius et al. 2011). The land cover types studied represent 97% of the whole area study area of 98.6 km2. On an annual basis the study area acted as a sink of C, but CH4 and N2O emissions caused it to be a net source of GHGs when considering the global warming potential (GWP; 100-year time horizon) of all three gases. Willow wetlands, fens and thermokarst lakes (16% of the landscape) were significant sources of CH4, while CH4 emissions from the rest of the landscape were negligible. Bare peat surfaces on peat plateaus, peat circles, acted as strong hotspots

  4. Seasonal variation of allochthonous and autochthonous energy inputs in an alpine stream

    Directory of Open Access Journals (Sweden)

    Stefano Fenoglio

    2014-10-01

    Full Text Available Despite the enormous importance of alpine streams, information about many aspects of their ecology is still insufficient. Alpine lotic systems differ in many environmental characteristics from those lower down, for example because above tree line streams drain catchments where terrestrial vegetation is scarce and allochthonous organic input is expected to be small. The main objectives of this study were to examine seasonal variation of autochthonous and allochthonous energetic inputs and their relationship with macroinvertebrate communities in the Po river, an alpine non-glacial stream (NW Italy. For one year, samplings were monthly performed in a homogeneous 100 m stream reach for discharge, autochthonous energy input (benthic chlorophyll a, allochthonous energy input (coarse particulate organic matter, abundance and structure of benthic macroinvertebrate community. Chlorophyll a concentrations were in the range of what reported for other alpine streams, but presented a time-lag with respect to what has been reported for glacial-fed mountain rivers. CPOM amounts were lower than those in lowland, forested streams of the same area but exhibited an intriguing, different seasonal variability, probably reported for the first time, with a maximum in spring and a minimum in winter. We collected 29,950 macroinvertebrates belonging to 13 families and 10 orders. Benthic communities were essentially dominated by Ephemeroptera, Plecoptera and Diptera. Scrapers was the most important FFG, but also Shredders were well represented. Relationships between chlorophyll a concentrations, CPOM availability and macroinvertebrate community characteristics were analysed and discussed considering the existence of different top-down or bottom-up regulation mechanisms. This study confirms that benthic algae constitute an essential resource for macroinvertebrates in alpine streams above the tree line but also underlines the importance of terrestrial organic input, a

  5. A comparison between energy transfer and atmospheric turbulent exchanges over alpine meadow and banana plantation

    Science.gov (United States)

    Ding, Zhangwei; Ma, Yaoming; Wen, Zhiping; Ma, Weiqiang

    2016-04-01

    Banana plantation and alpine meadow ecosystems in southern China and the Tibetan Plateau are unique in the underlying surfaces they exhibit. In this study, we used eddy covariance and a micrometeorological tower to examine the characteristics of land surface energy exchanges over a banana plantation in southern China and an alpine meadow in the Tibetan Plateau from May 2010 to August 2012. The results showed that the diurnal and seasonal variations in upward shortwave radiation flux and surface soil heat flux were larger over the alpine meadow than over the banana plantation surface. Dominant energy partitioning varied with season. Latent heat flux was the main consumer of net radiation flux in the growing season, whereas sensible heat flux was the main consumer during other periods. The Monin-Obukhov similarity theory was employed for comparative purposes, using sonic anemometer observations of flow over the surfaces of banana plantations in the humid southern China monsoon region and the semi-arid areas of the TP, and was found to be applicable. Over banana plantation and alpine meadow areas, the average surface albedo and surface aerodynamic roughness lengths under neutral atmospheric conditions were ~0.128 and 0.47m, and ~0.223 and 0.01m, respectively. During the measuring period, the mean annual bulk transfer coefficients for momentum and sensible heat were 1.47×10-2 and 7.13×10-3, and 2.91×10-3 and 1.96×10-3, for banana plantation and alpine meadow areas, respectively. This is the first time in Asia that long-term open field measurements have been taken with the specific aim of making comparisons between banana plantation and alpine meadow surfaces.

  6. Permanent monitoring of alpine slope instabilities with L1-GPS

    Science.gov (United States)

    Limpach, Philippe; Geiger, Alain; Su, Zhenzhong; Beutel, Jan; Gruber, Stephan

    2013-04-01

    Since winter 2010/2011, a network of permanent GPS stations is being set up in the Matter Valley (Swiss Alps). The aim is to monitor the time variable movement of potentially instable rock glaciers. The network has been established in the framework of the X-Sense project, currently totaling more than 20 stations. X-Sense is an interdisciplinary project for monitoring alpine mass movements at multiple scales, funded by the Swiss federal program Nano-Tera within the Swiss Science Foundation. The X-Sense stations consist of low-cost L1 GPS receivers coupled with inclinometers. A part of the stations allow for on-line data transmission. The data of the X-Sense L1 GPS network is operationally processed on a daily basis with Bernese GPS software, in a fully automated processing chain. In addition, real-time solutions are computed for the on-line stations. The geodetic potential of low-cost GPS receivers for the precise monitoring of slope instabilities in mountain areas was previously investigated in a feasibility study. It is shown that low-cost GPS units are able to provide reliable and continuous time series of surface displacements at cm-level accuracy in harsh environment, using adequate differential processing techniques. Enhanced algorithms were developed to derive accurate time series of surface velocities based on the GPS displacements. It was shown that the low-cost GPS receivers allow to reliably observe surface velocities even below 1 cm/day, as well as to detect small and short-term velocity changes. In addition, the time series of more than 2 years obtained reveal the capability to detect seasonal velocity variations, as well as inter-annual variations of the velocity pattern. By providing continuous observations of surface motion, the GPS-based permanent monitoring contributes to the understanding of processes linked to permafrost-related slope instabilities.

  7. Transfer of radiocesium in pre-alpine forest ecosystems

    International Nuclear Information System (INIS)

    Radiocesium aggregated in forest soils is available for plants. A direct measure for this availability is the aggregated transfer factor, Tag, (specific cesium activity of the plant divided by the total activity inventory of the soil). At spruce stands spread over South-West Germany, Tag varies by a factor of ten for different plants on one site, being highest for fern (up to 0.5 m2/kg) and lowest for blackberry. For one species on different sites, Tag can vary by two orders of magnitude. The quantities kind of humus, thickness and pH-value of the organic horizons are used for a radioecological mapping of pre-alpine forest soils. In accordance with this complex transfer behaviour of radiocesium, and with roe deer specific habits, the surveillance of the contamination of more than 5700 roe deer revealed characteristic regional and seasonal structures. The specific 137Cs activity decreases slowly in time and is superimposed by periodic maxima in autumn which correlate with the mushroom season in forests. Calculated Tag's soil - roe deer follow a log-normal distribution showing a geometric mean of 0.011 m2/kg(fw) and an ecological half-life of 3.5 a. Fertilization of a spruce stand area in 1984 mainly with CaCO3 resulted even in 1995 in a reduction of Tag soil-plant by a factor of 3 to 5. This finding can be understood in terms of increasing pH-value and/or enhanced concentration of competing cations

  8. Spatial distribution of stable water isotopes in alpine snow cover

    Directory of Open Access Journals (Sweden)

    N. Dietermann

    2013-07-01

    Full Text Available The aim of this study was to analyse and predict the mean stable water isotopic composition of the snow cover at specific geographic locations and altitudes. In addition, the dependence of the isotopic composition of the entire snow cover on altitude was analysed. Snow in four Swiss catchments was sampled at the end of the accumulation period in April 2010 and a second time during snowmelt in May 2010 and analysed for stable isotope composition of 2H and 18O. The sampling was conducted at both south-facing and north-facing slopes at elevation differences of 100 m, for a total altitude difference of approximately 1000 m. The observed variability of isotopic composition of the snow cover was analysed with stepwise multiple linear regression models. The analysis indicated that there is only a limited altitude effect on the isotopic composition when considering all samples. This is due to the high variability of the isotopic composition of the precipitation during the winter months and, in particular in the case of south-facing slopes, an enrichment of heavy isotopes due to intermittent melting processes. This enrichment effect could clearly be observed in the samples which were taken later in the year. A small altitudinal gradient of the isotopic composition could only be observed at some north-facing slopes. However, the dependence of snow depth and the day of the year were significant predictor variables in all models. This study indicates the necessity to further study the variability of water isotopes in the snow cover to increase prediction for isotopic composition of snowmelt and hence increase model performance of residence time models for alpine areas in order to better understand the accumulation processes and the sources of water in the snow cover of high mountains.

  9. Ultra-sensitive Alpine lakes and climate change

    Directory of Open Access Journals (Sweden)

    Roland SCHMIDT

    2005-08-01

    Full Text Available Global warming is one of the major issues with which mankind is being confronted, having vital ecological and economic consequences. Ice-cover, snow-cover and water temperatures in alpine catchments are controlled by air temperatures, and so are very susceptible to shifts in climate. Local factors such as wind exposure, shading, and snow patches that persist during cold summers can, however, modify the sensitivities of the relationships to air temperature. Thermistors exposed in 45 mountain lakes of the central Austrian Alps (Niedere Tauern measured water temperatures during 1998 – 2003 at two or four hourly intervals. Degree-day and exponential smoothing models tuned with this data suggest we can anticipate extremely large temperature rises in some of the Niedere Tauern lakes in the coming century. Lakes at around 1500 to 2000 m altitude are found to be ultra-sensitive as they lie in the elevation range where changes in both ice-cover and snow-cover duration will be particularly pronounced. In the more extreme cases, our impact models predict a summer-epilimnion water-temperature rise of over 10 degrees. One example of a lake most at risk to future climate change is Moaralmsee. This lake is located at 1825 m a.s.l. on the northern slopes of the Niedere Tauern; its water temperature is likely to rise by 12 degrees. The projected water discharge, ice-cover duration and water temperature changes for the Tauern catchments in the coming century far exceed the variations experienced at any stage during the last ten thousand years.

  10. A sampling method for tundra swans summering in the Bristol Bay lowlands, northern Alaska Peninsula: A summary of a presentation given at the second Alaska Bird Conference, Juneau, Alaska 3-4 April 1987

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A "census" of tundra swans occurring in the northern Alaska Peninsula was collected over 1984-1985, with supplemental information provided from preliminary surveys...

  11. InSAR Detection and Field Evidence for Thermokarst after a Tundra Wildfire, Using ALOS-PALSAR

    Directory of Open Access Journals (Sweden)

    Go Iwahana

    2016-03-01

    Full Text Available Thermokarst is the process of ground subsidence caused by either the thawing of ice-rich permafrost or the melting of massive ground ice. The consequences of permafrost degradation associated with thermokarst for surface ecology, landscape evolution, and hydrological processes have been of great scientific interest and social concern. Part of a tundra patch affected by wildfire in northern Alaska (27.5 km2 was investigated here, using remote sensing and in situ surveys to quantify and understand permafrost thaw dynamics after surface disturbances. A two-pass differential InSAR technique using L-band ALOS-PALSAR has been shown capable of capturing thermokarst subsidence triggered by a tundra fire at a spatial resolution of tens of meters, with supporting evidence from field data and optical satellite images. We have introduced a calibration procedure, comparing burned and unburned areas for InSAR subsidence signals, to remove the noise due to seasonal surface movement. In the first year after the fire, an average subsidence rate of 6.2 cm/year (vertical was measured. Subsidence in the burned area continued over the following two years, with decreased rates. The mean rate of subsidence observed in our interferograms (from 24 July 2008 to 14 September 2010 was 3.3 cm/year, a value comparable to that estimated from field surveys at two plots on average (2.2 cm/year for the six years after the fire. These results suggest that this InSAR-measured ground subsidence is caused by the development of thermokarst, a thawing process supported by surface change observations from high-resolution optical images and in situ ground level surveys.

  12. Spatial and temporal variation of bulk snow properties in northern boreal and tundra environments based on extensive field measurements

    Science.gov (United States)

    Hannula, Henna-Reetta; Lemmetyinen, Juha; Kontu, Anna; Derksen, Chris; Pulliainen, Jouni

    2016-08-01

    An extensive in situ data set of snow depth, snow water equivalent (SWE), and snow density collected in support of the European Space Agency (ESA) SnowSAR-2 airborne campaigns in northern Finland during the winter of 2011-2012 is presented (ESA Earth Observation Campaigns data 2000-2016). The suitability of the in situ measurement protocol to provide an accurate reference for the simultaneous airborne SAR (synthetic aperture radar) data products over different land cover types was analysed in the context of spatial scale, sample spacing, and uncertainty. The analysis was executed by applying autocorrelation analysis and root mean square difference (RMSD) error estimations. The results showed overall higher variability for all the three bulk snow parameters over tundra, open bogs and lakes (due to wind processes); however, snow depth tended to vary over shorter distances in forests (due to snow-vegetation interactions). Sample spacing/sample size had a statistically significant effect on the mean snow depth over all land cover types. Analysis executed for 50, 100, and 200 m transects revealed that in most cases less than five samples were adequate to describe the snow depth mean with RMSD land cover with high overall variability an indication of increased sample size of 1.5-3 times larger was gained depending on the scale and the desired maximum RMSD. Errors for most of the land cover types reached ˜ 10 % if only three measurements were considered. The collected measurements, which are available via the ESA website upon registration, compose an exceptionally large manually collected snow data set in Scandinavian taiga and tundra environments. This information represents a valuable contribution to the snow research community and can be applied to various snow studies.

  13. Evaluating CO2 and CH4 fluxes in Arctic peatland and tundra using a satellite remote sensing driven biophysical model

    Science.gov (United States)

    Watts, J.; Kimball, J. S.; Parmentier, F. W.; Sachs, T.; Rinne, J.; Zona, D.; Oechel, W. C.; Tagesson, T.

    2013-12-01

    The Arctic terrestrial carbon sink is contingent on the balance between vegetation gross primary productivity (GPP) and emissions of carbon dioxide (CO2) and methane (CH4). With climate change, warming temperatures could increase GPP within high latitude systems but may also accelerate soil decomposition and CO2 loss. Regional wetting may also shift carbon emissions towards greater CH4 release, a greenhouse gas at least 25 times more potent than CO2. However, an effective framework for monitoring changes in the Arctic net ecosystem carbon balance (NECB) is lacking. Here we introduce an integrated terrestrial carbon flux (TCF) model approach to estimate CO2 and CH4 fluxes from northern peatland and tundra ecosystems at a daily time step. The TCF model framework uses a light-use efficiency (LUE) algorithm to estimate GPP according to satellite NDVI inputs and estimated moisture and temperature constraints. Ecosystem respiration is derived using a three-pool soil organic carbon decomposition model regulated by surface (moisture inputs. A TCF-CH4 component simulates gas production according to near-surface temperature, anaerobic soil fractions and labile soil carbon inputs derived during model spin-up. Plant transport, soil diffusion and ebullition pathways are used to regulate CH4 emissions into the atmosphere. The combined TCF CO2 and CH4 model was evaluated against tower eddy covariance (EC) flux datasets from six peatland and tundra sites in North America, Eurasia and Greenland. TCF model simulations driven with site information explained on average > 70% (r^2; p moisture and thermal products to be produced in upcoming satellite remote sensing missions.

  14. Correlations between the Heterogeneity of Permafrost Thaw Depth and Vegetation in Boreal Forests and Arctic Tundra in Alaska.

    Science.gov (United States)

    Uy, K. L. Q.; Natali, S.; Kholodov, A. L.; Loranty, M. M.

    2015-12-01

    Global climate change induces rapid large scale changes in the far Northern regions of the globe, which include the thickening of the active layer of arctic and subarctic soils. Active layer depth, in turn, drives many changes to the hydrology and geochemistry of the soil, making an understanding of this layer essential to boreal forest and arctic tundra ecology. Because the structure of plant communities can affect the thermal attributes of the soil, they may drive variations in active layer depth. For instance, trees and tussocks create shade, which reduces temperatures, but also hold snow, which increases temperature through insulation; these aspects of vegetation can increase or decrease summer thaw. The goal of this project is to investigate correlations between the degree of heterogeneity of active layer depths, organic layer thickness, and aboveground vegetation to determine how these facets of Northern ecosystems interact at the ecosystem scale. Permafrost thaw and organic layer depths were measured along 20m transects in twenty-four boreal forest and tundra sites in Alaska. Aboveground vegetation along these transects was characterized by measuring tree diameter at breast height (DBH), tussock dimensions, and understory biomass. Using the coefficient of variation as a measure of heterogeneity, we found a positive correlation between thaw depth variability and tussock volume variability, but little correlation between the former and tree DBH variability. Soil organic layer depth variability was also positively correlated with thaw depth variability, but weakly correlated with tree and tussock heterogeneity. These data suggest that low vegetation and organic layer control the degree of variability in permafrost thaw at the ecosystem scale. Vegetation can thus affect the microtopography of permafrost and future changes in the plant community that affect vegetation heterogeneity will drive corresponding changes in the variability of the soil.

  15. Pulsed resources at tundra breeding sites affect winter irruptions at temperate latitudes of a top predator, the snowy owl.

    Science.gov (United States)

    Robillard, A; Therrien, J F; Gauthier, G; Clark, K M; Bêty, J

    2016-06-01

    Irruptive migration is mostly observed in species specialized on pulsed resources and is thought to be a response to unpredictable changes in food supply. We assessed two alternative hypotheses to explain the periodic winter irruptions of snowy owls Bubo scandiacus every 3-5 years in temperate North America: (a) the lack-of-food hypothesis, which states that a crash in small mammal abundance on the Arctic breeding grounds forces owls to move out of the tundra massively to search for food in winter; (b) the breeding-success hypothesis, which states that high abundance of tundra small mammals during the summer allows for high production of young, thus increasing the pool of migrants moving south the following winter. We modeled winter irruptions of snowy owls in relation to summer food resources and geographic location. Winter abundance of owls was obtained from citizen-based surveys from 1994 to 2011 and summer abundance of small mammals was collected in summer at two distant sites in Canada: Bylot Island, NU (eastern High Arctic) and Daring Lake, NWT (central Low Arctic). Winter owl abundance was positively related to prey abundance during the previous summer at both sites and tended to decrease from western to eastern temperate North America. Irruptive migration of snowy owls was therefore best explained by the breeding success hypothesis and was apparently caused by large-scale summer variations in food. Our results, combined with previous findings, suggest that the main determinants of irruptive migration may be species specific even in a guild of apparently similar species. PMID:26920901

  16. Cultural Resilience of Nenets Social-Ecological Systems in Arctic Russia: A Focus on Reindeer Nomads of the Tundra

    Science.gov (United States)

    Forbes, B. C.

    2013-12-01

    Empirical data on resilience in social-ecological systems (SESs) are reviewed from local and regional scale case studies among full-time nomads in the neighbouring Nenets and Yamal-Nenets Autonomous Okrugs, Russia. The focus is on critical cultural factors contributing to SES resilience. In particular, this work presents an integrated view of people situated in specific tundra landscapes that face significantly different prospects for adaptation depending on existing or planned infrastructure associated with oil and gas development. Factors contributing to general resilience are compared to those that are adapted to certain spatial and temporal contexts. Environmental factors include ample space and an abundance of resources, such as fish and game (e.g. geese), to augment the diet of not only the migratory herders, but also residents from coastal settlements. In contrast to other regions, such as the Nenets Okrug, Yamal Nenets households consist of intact nuclear families with high retention among youth in the nomadic tundra population. Accepting attitudes toward exogenous drivers such as climate change and industrial development appear to play a significant role in how people react to both extreme weather events and piecemeal confiscation or degradation of territory. Consciousness of their role as responsible stewards of the territories they occupy has likely been a factor in maintaining viable wildlife populations over centuries. Institutions administering reindeer herding have remained flexible, especially on Yamal, and so accommodate decision-making that is sensitive to herders' needs and timetables. This affects factors such as herd demography, mobility and energetics. Resilience is further facilitated within the existing governance regimes by herders' own agency, most recently in the post-Soviet shift to smaller, privately managed herds that can better utilize available pastures in a highly dynamic environment experiencing rapid socio-economic, climate and

  17. Effect of Wet Settlement on Mercury in Alpine Soil in Mercury Mining Area

    Institute of Scientific and Technical Information of China (English)

    HEJIN-LIN; TANHONG

    1995-01-01

    There is abundance of Mercury mine resurces in the Fanjinshan Mountain,Mining mercury has a long history there,The concentration of geseous Hg produced in smelting He reaches 20-50mg/m3 in the tail gas.Because mercury element is an easily transferring microelement,the paper talks about the effect of mercury in Hg mining in Guizhou Province on alpine soil,analyses Hg content in alpine soil at 2000 m of relative elevation in the Hg mining area,and explores for causes of the Hg pollution.

  18. Behavioral patterns of captive alpine musk deer: sex-specific behavior comparisons

    Institute of Scientific and Technical Information of China (English)

    Lin LU; Peishi YAN; Xiuxiang MENG; Jinchao FENG; Hongfa XU; Qisen YANG; Zuojian FENG

    2009-01-01

    The aim of this study was to document the behavior of captive alpine musk deer and to determine if daily behavior patterns varied between females and males. From August 2002 to January 2003, focal sampling was used to observe 32 adult captive alpine musk deer (13 female and 19 male) at Xinglongshan Musk Deer Farm (XMDF), Xinglongshan National Nature Reserve, Gansu Province. Results indicated similar behavior patterns for males and females, with only two out of 12 recorded behaviors showing significant sex differences. In comparison to females, males rested for a longer duration and exhibited tail pasting more frequently. This study also provided the first recording of tail pasting by female musk deer.

  19. Distribution and diversity of Arctic-Alpine species in the Balkans

    DEFF Research Database (Denmark)

    Stevanovic, Vladimir; Vukojicic, Snezana; Sinzar-Sekulic, Jasmina;

    2009-01-01

    The distributions of 77 Arctic-Alpine species in the Balkans are mapped and the centers of their richness and diversity presented. Within the Dinaric Alps these are Mts Vranica, Durmitor, and Prokletije; in the Scardo-Pindhic mountains, Šarplanina-Rudoka-Korab form a continuous chain; in the Rhod......The distributions of 77 Arctic-Alpine species in the Balkans are mapped and the centers of their richness and diversity presented. Within the Dinaric Alps these are Mts Vranica, Durmitor, and Prokletije; in the Scardo-Pindhic mountains, Šarplanina-Rudoka-Korab form a continuous chain...

  20. Winter streamflow analysis in frozen, alpine catchments to quantify groundwater contribution and properties

    Science.gov (United States)

    Stoelzle, Michael; Weiler, Markus

    2016-04-01

    Alpine catchments are often considered as quickly responding systems where streamflow contributions from subsurface storages (groundwater) are mostly negligible due to the steep topography, low permeable bedrock and the absence of well-developed soils. Many studies in high altitude catchments have hence focused on water stored in snowpack and glaciers or on rainfall-runoff processes as the dominant streamflow contributions. Interestingly less effort has been devoted to winter streamflow analysis when melt- or rainfall-driven contributions are switched off due to the frozen state of the catchment. Considering projected changes in the alpine cryosphere (e.g. snow, glacier, permafrost) quantification of groundwater storage and contribution to streamflow is crucial to assess the social and ecological implications for downstream areas (e.g. water temperature, drought propagation). In this study we hypothesize that groundwater is the main streamflow contribution during winter and thus being responsible for the perennial regime of many alpine catchments. The hypothesis is investigated with well-known methods based on recession and breakpoint analysis of the streamflow regimes and temperature data to determine frozen periods. Analyzing nine catchments in Switzerland with mean elevation between 1000 and 2400 m asl, we found that above a mean elevation of 1800 m asl winter recessions are sufficient long and persistent enough to quantify groundwater contribution to streamflow and to characterize the properties of subsurface storage. The results show that groundwater in alpine catchment is the dominant streamflow contribution for nearly half a year and accountable for several hundred millimeter of annual streamflow. In sub-alpine catchments, driven by a mix of snowmelt and rainfall, a clear quantification of groundwater contributions is rather challenging due to discontinuous frozen periods in winter. We found that the inter-annual variability of different streamflow

  1. Potential of cold-adapted microorganisms for bioremediation of oil-polluted Alpine soils

    International Nuclear Information System (INIS)

    The environmental contamination by organic pollutants is a widespread problem in all climates. The most widely distributed pollution can be attributed to oil contamination. Bioremediation methods can provide efficient, inexpensive and environmentally safe cleanup tools. The role of cold-adapted microorganisms for the bioremediation of experimentally and chronically oil-contaminated Alpine soils was evaluated in the studies described. The results demonstrated that there is a considerable potential for oil bioremediation in Alpine soils. Oil biodegradation can be significantly enhanced by biostimulation (inorganic nutrient supply), but a complete oil elimination is not possible by employing biological decontamination alone. (Author)

  2. The consequences of elevated CO² and land use in alpine ecosystems

    OpenAIRE

    Inauen, Nicole

    2014-01-01

    The consequences of elevated CO2 and land use in alpine ecosystems This PhD thesis addresses two main aspects of Global Change and their impacts on alpine vegetation and eco-hydrology, (1) the steadily increasing concentration of CO2 in the atmosphere as well as (2) land use and its current decline across the Alps. Current and future rises of atmospheric CO2 concentration are commonly expected to stimulate photosynthesis and to reduce carbon limitation of plant growth. Whether this hypoth...

  3. Alpine Microbial Community Responses to Climate Change and Atmospheric Nitrogen Deposition in Rocky Mountain National Park

    Science.gov (United States)

    Osborne, B. B.; Baron, J.; Wallenstein, M. D.; Richer, E.

    2010-12-01

    Remote alpine ecosystems of the western US exhibit vulnerability to anthropogenic drivers of change. Atmospheric nitrogen (N) deposition and a changing climate introduce nutrients, alter hydrological processes, and expose soils to modified temperature regimes. We cannot yet predict the interacting effects and far-reaching biogeochemical consequences of this influence. Importantly, long-term data reveal headwater nitrate (NO3-) concentration trends increasing >50% from the 1990s to 2006 along the Colorado Front Range in conjunction with warm summer temperatures. Such a change in nutrient cycling raises concern for eutrophication in nutrient-poor alpine lakes. Increasing stream NO3- suggests terrestrial microbes may be responding to changes in important controls of community development and activity: temperature and ammonium (NH4+) availability. Nitrifying bacteria and archaea strongly influence alpine soil NO3- concentrations. Little is understood about alpine microbes. Our research characterizes nitrifier abundance and activity in alpine substrates by exposing them to experimental NH4+ and temperature treatments. Soil substrates fall along a gradient of succession commonly represented in alpine catchments due to deglaciation. These include well-developed meadow soils, unvegetated talus substrate, and newly-exposed glacial sediments. All three substrate types were collected from the Loch Vale watershed in Rocky Mountain National Park, a long-term research site in the Colorado Front Range known to receive elevated levels of atmospheric N deposition. All soils have been evaluated for initial %C, %N, microbial biomass, NO3-, NH4+, and DOC concentrations, and nitrifier abundance. After temperature and NH4+ treatments, samples will be evaluated for changes in biomass and nitrifier abundance as well as net and gross nitrification. Linking the influence of relative soil temperature and NH4+ concentrations on alpine substrates, at a range of successional stages, will

  4. Hydrological Controls on Ecosystem CO2 and CH4 Exchange in a MIXED Tundra and a FEN within an Arctic Landscape UNDER Current and Future Climates

    Science.gov (United States)

    Grant, R. F.; Humphreys, E.; Lafleur, P.

    2014-12-01

    Variation in CO2 and CH4 exchange in years with contrasting weather is strongly affected by hydrology in landscapes underlain by permafrost. Hypotheses for this variation were incorporated into the ecosystem model ecosys which simulated CO2 and CH4 fluxes along a topographic gradient within an arctic landscape at Daring Lake, NWT, Canada. Fluxes modelled at mixed tundra and fen sites within the gradient were compared with CO2 fluxes measured at eddy covariance towers from 2006 to 2009, and with CH4 fluxes measured with surface chambers in 2008. Slopes and correlation coefficients from regressions of modelled vs. measured CO2 fluxes were 1.0 ± 0.1 and 0.7 - 0.8 for both sites in all years. At the mixed tundra site, rises in net CO2 uptake in warmer years with earlier snowmelt were constrained by midafternoon declines in CO2 influxes when vapor pressure deficits (D) exceeded 1.5 kPa, and by rises in CO2 effluxes with greater active layer depth (ALD). Consequently annual net CO2 uptake at this site rose little with warming. At the fen site, CO2 influxes declined less with D and CO2 effluxes rose less with warming, so that rises in net CO2 uptake in warmer years were greater than those at the mixed tundra site. The greater declines in CO2 influxes with warming at the mixed tundra site were modelled from greater soil-plant-atmosphere water potential gradients that developed in drier soil, and the smaller rises in CO2 effluxes with warming at the fen site were modelled from O2 constraints to heterotrophic and below-ground autotrophic respiration that limited their responses to greater ALD. Modelled and measured CH4 exchange during July and August indicated very small influxes at the mixed tundra site, and larger emissions at the fen site. Emissions of CH4 modelled during soil freezing in October - November contributed about one-third of the annual total, and so should be included in estimates of annual emissions. These contrasting responses to warming under current

  5. Spatial and Temporal Variability of Methane Mole Fractions and Exchanges in and Between Soil, Snow, and the Atmosphere in a Tundra System in Northern Alaska

    Science.gov (United States)

    Agnan, Y.; Obrist, D.; Edwards, G. C.; Moore, C.; Hedge, C.; Helmig, D.; Paxton, D.; Jacques, H.

    2015-12-01

    An important global source of atmospheric methane (CH4) is production in tundra soils (an important global source). To place constraints on the potential role that tundra soils play in global CH4 cycling, we have been continuously measuring mole the air space in soils, snow, and the atmosphere as gradient-based surface-atmosphere fluxes for arctic tundra at Toolik Field Station (68° 38' N) starting in October 2014. We have found that atmospheric CH4 mole fractions were, on average, relatively constant during the first 9 months of sampling (averaging 1.93 µmol mol-1), with pronounced diel patterns starting in May and nighttime exceeding daytime mole fractions. However, gradients measured within the soil profile showed high variability in air withdrawn from different locations of these tundra soils (Typic Aquiturbels), with one soil profile indicating a CH4 sink during fall until January; mole fractions were similar to the atmospheric measurements during winter indicating no source or sink (average 1.89 µmol mol-1). A second soil profile 5 m away showed production of CH4 (average 2.48 µmol mol-1, two-times higher than atmospheric levels), even during mid-winter when soil temperatures were below -10 °C. Measurements of CH4 in interstitial snowpack air also exhibited a similar combination of sources and sinks. We used micrometeorological gradient surface flux measurements to confirm that the area was a net source of CH4 in fall, winter, and spring, with emissions averaging 26.6, 25.2, and 16.8 mg m-2 d-1, respectively. In the summer months, we saw strong diel flux patterns with deposition during day and emission at night, corresponding with observed diel variability in CH4 snowpack mole fractions. Our results indicated a high variability of tundra landscape CH4 fluxes, which locally shift from sources to sinks with high temporal variability. CH4 oxidation by methanotrophic bacteria probably occurs in tundra soils, confirming observations in one soil, snowpack, and

  6. Differences in dissolved organic matter lability between alpine glaciers and alpine rock glaciers of the American West

    Science.gov (United States)

    Hall, E.; Fegel, T. S., II; Baron, J.; Boot, C. M.

    2015-12-01

    While alpine glaciers in montane regions represent the largest flux of dissolved organic matter (DOM) from global ice melt no research has examined the bioavailability of DOM melted out of glacial ice in the western continental United States. Furthermore, rock glaciers are an order of magnitude more abundant than ice glaciers in U.S., yet are not included in budgets for perennial ice carbon stores. Our research aims to understand differences in the bioavailability of carbon from ice glaciers and rock glaciers along the Central Rocky Mountains of Colorado. Identical microbial communities were fed standardized amounts of DOM from four different ice glacier-rock glaciers pairs. Using laboratory incubations, paired with mass spectrometry based metabolomics and 16S gene sequencing; we were able to examine functional definitions of DOM lability in glacial ice. We hypothesized that even though DOM quantities are similar in the outputs of both glacial types in our study area, ice glacial DOM would be more bioavailable than DOM from rock glaciers due to higher proportions of byproducts from microbial metabolism than rock glacier DOM, which has higher amounts of "recalcitrant" plant material. Our results show that DOM from ice glaciers is more labile than DOM from geologically and geographically similar paired rock glaciers. Ice glacier DOM represents an important pool of labile carbon to headwater ecosystems of the Rocky Mountains. Metabolomic analysis shows numerous compounds from varying metabolite pathways, including byproducts of nitrification before and after incubation, meaning that, similar to large maritime glaciers in Alaska and Europe, subglacial environments in the mountain ranges of the United States are hotspots for biological activity and processing of organic carbon.

  7. Epilithonimonas psychrotolerans sp. nov., isolated from alpine permafrost.

    Science.gov (United States)

    Ge, Liang; Zhao, Qi; Sheng, Hongmei; Wu, Jianmin; An, Lizhe

    2015-11-01

    A bacterial strain, designated TSBY 57T, was isolated during a study on the phylogenetic diversity of culturable bacteria from alpine permafrost in Tianshan Mountains, China, and was classified by means of a polyphasic taxonomic approach. The novel strain was found to belong to the genus Epilithonimonas and was distinguished from recognized species of this genus. Strain TSBY 57T grew aerobically, at 0-30 °C, with 0-1.5% (w/v) NaCl and at pH 6-8.Cells were Gram-stain-negative, non-motile, non-spore-forming rods. Compared with the reference strains, the novel strain was psychrotolerant. The predominant fatty acids were summed feature 3 (consisting of C16:1ω7c and/or C16:1ω6c), anteiso-C15:0 and iso-C15:0.The sole respiratory quinone was MK-6.Phosphatidylethanolamine was predominant in the polar lipid profile of strain TSBY 57T. These chemotaxonomic traits were in good agreement with the characteristics of the genus Epilithonimonas. On the basis of 16S rRNA gene sequence similarity, strain TSBY 57T was a member of the genus Epilithonimonas and was closely related to Epilithonimonas tenax DSM 16811T (99.0%), Epilithonimonas ginsengisoli DCY78T (98.6%) and Epilithonimonas lactis H1T (98.5%). However, DNA-DNA reassociation values between strain TSBY 57T and E. tenax DSM 16811T, E. ginsengisoli DCY78T and E. lactis H1T were 39.5 ± 2.6, 37.7 ± 1.0 and 37.3 ± 1.1%, respectively. The G+C content of the DNA was 34.4 ± 0.2  mol%. Based on data from this polyphasic taxonomic study, strain TSBY 57T represents a novel species of the genus Epilithonimonas, for which the name Epilithonimonas psychrotolerans sp. nov. is proposed. The type strain is TSBY 57T ( = NRRL B-51307T=CCTCC AB 207182T). PMID:26233482

  8. Personal UV exposure in high albedo alpine sites

    Directory of Open Access Journals (Sweden)

    A. M. Siani

    2008-07-01

    Full Text Available Mountain sites experience enhanced UV radiation levels due to the concurrent effects of shorter radiation path-length, low aerosol load and high reflectivity of the snow surfaces. This study was encouraged by the possibility to collect original data of personal dose on a specific anatomical site (erythemally effective UV dose on the forehead of two groups of volunteers (ski instructors and skiers in the mountainous areas of Italy (the Alpine site of La Thuile-Les Suches in Valle d'Aosta region. Personal doses were assessed using polysulphone dosimetry. Exposure Ratio (ER, defined as the ratio between the personal dose and the corresponding ambient dose (i.e. erythemally weighted dose received by a horizontal surface during the same exposure period was taken into account. In addition measuring skin colours as biological markers of individual response to UV exposure, was also carried out on the forearm and cheek of each volunteer before and after exposure.

    The median ER, taking into account the whole sample, is 0.60 in winter, with a range of 0.29 to 1.46, and 1.02 in spring, ranging from 0.46 to 1.72. No differences in ERs were found between skiers and instructors in spring while in winter skiers experienced lower values.

    Regarding skin colorimetric parameters the main result was that both skiers and instructors had on average significantly lower values of luminance after exposure i.e.~they became darker. It was found that the use of sunscreen and individual skin photo-type did not produce significant variations in ER across instructor/skier group by day and by seasons (p>0.05. It seems that sunscreen use only at the beginning of the exposure or in a few cases a couple of times during exposure (at difference with the specific instructions sheets, was not sufficient to change significantly skin colorimetric parameters across participants.

    In conclusion UV personal doses on the ski-fields are often

  9. Comparison of subsurface connectivity in Alpine headwater catchments

    Science.gov (United States)

    Zuecco, Giulia; Rinderer, Michael; van Meerveld, Ilja; Penna, Daniele; Borga, Marco

    2016-04-01

    Saturation at the soil-bedrock interface or the rise of shallow groundwater into more permeable soil layers results in subsurface stormflow and can lead to hillslope-stream connectivity. Despite the importance of subsurface connectivity for streamflow and streamwater chemistry, the factors controlling its spatial and temporal variability are still poorly understood. This study takes advantage of networks of spatially-distributed piezometers in five small (piezometers in the 14 and 3.3 ha catchments in the Italian Dolomites, and for four years from spring to fall in 7-8 piezometers in three piezometers (nodes). A node was considered to be connected to the stream when shallow groundwater was observed in the piezometer and it was connected by the edges to the stream. Weights were given to each piezometer based on Thiessen polygons to determine the area of the catchment that was connected to the stream. For the Swiss pre-alpine catchments the duration that nodes were connected to the stream was significantly correlated to the local and upslope site characteristics, such as the topographic wetness index, local slope and curvature. For the dolomitic catchment with the largest riparian zone, the time that nodes were connected to the stream was correlated with downslope site characteristics, such as the vertical distance to the nearest stream. The temporal changes in the area of the catchment that was connected to the stream reflected the streamflow dynamics for all catchments. Subsurface connectivity increased during rainfall events but there was a short delay compared to streamflow, suggesting that other processes (e.g. direct channel precipitation, runoff from near stream saturated areas) contributed to streamflow at the beginning of the event. Groundwater levels declined later and slower than streamflow, resulting in complex but mainly anti-clockwise hysteretic relations between streamflow and the area that was connected to the stream. Threshold-like relations between

  10. Spatial-Temporal NDVI Variation of Different Alpine Grassland Classes and Groups in Northern Tibet from 2000 to 2013

    Directory of Open Access Journals (Sweden)

    Xiaoke Zhang

    2015-08-01

    Full Text Available The Normalized Difference Vegetation Index (NDVI can usually be used as a good proxy for evaluating potential variability in regional ecosystems and under climate change. We used 16-day MODIS-NDVI composite satellite data with 250-m resolution for the period 2000 to 2013 to assess the temporal and spatial variation of the NDVI among different alpine grassland classes and groups in northern Tibet. The annual average NDVI of the whole alpine grassland area in northern Tibet generally increased slightly from 2000 to 2003, and the annual average NDVI values ranged from 0.112 to 0.492 across all alpine grassland groups and years. The NDVI clearly decreased from the southeastern to the northwestern areas, with 22.50% of total grasslands significantly having increased or decreased, while 77.50% presented little change during 2000–2013. Both temperature and precipitation were key factors that controlled the NDVI variations of the entire alpine grassland. However, for different alpine grassland classes and groups, the NDVI displayed different correlation patterns with temperature and precipitation. Our results demonstrate that the NDVI variations of alpine grassland generally increased slightly but differed among different classes and groups. Although temperature and precipitation were the driving forces influencing the NDVI of the entire alpine grassland, it was more difficult to define the driving forces for the individual classes and groups, and more detailed analyses covering prolonged observation periods are still needed.

  11. 75 FR 18235 - Paiute Cutthroat Trout Restoration Project, Alpine County, CA

    Science.gov (United States)

    2010-04-09

    ... California Department of Fish and Game (CDFG, California Environmental Quality Act lead agency) (collectively... Fish and Wildlife Service Paiute Cutthroat Trout Restoration Project, Alpine County, CA AGENCY: Fish... Environmental Impact Statement (EIS)/ Environmental Impact Report (EIR) for public review. We, the Fish...

  12. Generic Regional Development Strategies from Local Stakeholders' Scenarios - an Alpine Village Experience

    Directory of Open Access Journals (Sweden)

    Ariane Walz

    2010-09-01

    Full Text Available The article discusses the participatory elaboration of strategies for sustainable regional development in an Alpine tourist region in Austria to cope with global change effects evolving locally, considering climate change, economic change as well as (local societal change. Local stakeholders in an Alpine village in the Montafon region contributed in workshops to achieve the final results: participant teams conducted system analyses of the regional system to explore key elements of the region. Narrative scenarios described possible positive and negative development trends and indicated the critical issues controlling future development; 3D-images of landscape transition simulations show the consequences of certain development directions. Alternative development directions supported the local stakeholders to elaborate regional development strategies. In the end, the scientist team derived generic strategies for Alpine regions based on the locally developed strategy bundle. The article presents the intention, progress and outcome of the participatory approach and elaborates the potential to derive generic strategies from local ones and discusses the possibly occurring conflicts regarding cross-scale transfers of these local strategies. Overall, tourism was seen as a key element for future regional development, which can on the one hand derogate Alpine regions and is on the other hand threatened by climate change and diminution of landscape attractiveness. The suggested development strategies will help to cope with global change issues mitigating the negative consequences on the local society and environment.

  13. Strategies of coping with stress and the sport results of alpine skiers and tennis players

    OpenAIRE

    Knittel Michał; Guszkowska Monika

    2016-01-01

    Study aim: The aim of the study was to determine the relationship between strategies of coping with stress caused by participating in sport competitions and the results of those competitions, as well as to differentiate the applied coping strategies according to the practiced sport discipline (tennis and alpine skiing).

  14. Relationship between alpine tourism demand and hot summer air temperatures associated with climate change

    Science.gov (United States)

    Rebetez, M.; Serquet, G.

    2010-09-01

    We quantified the impacts of hot summer air temperatures on tourism in the Swiss Alps by analyzing the relationship between temperature and overnight stays in 40 Alpine resorts. Several temperature and insolation thresholds were tested to detect their relationship to summer tourism. Our results reveal significant correlations between the number of nights spent in mountain resorts and hot temperatures at lower elevations. Alpine resorts nearest to cities are most sensitive to hot temperatures. This is probably because reactions to hot episodes take place on a short-term basis as heat waves remain relatively rare. The correlation in June is stronger compared to the other months, probably because school holidays and the peak domestic tourist demand in summer usually takes place in July and August. Our results suggest that alpine tourist resorts could benefit from hotter temperatures at lower elevations under future climates. Tourists already react on a short-term basis to hot days and spend more nights in hotels in mountain resorts. If heat waves become more regular, it seems likely that tourists choose to stay at alpine resorts more frequently and for longer periods.

  15. A deposition record of inorganic ions from a high-alpine glacier

    Energy Technology Data Exchange (ETDEWEB)

    Huber, T. [Bern Univ. (Switzerland); Bruetsch, S.; Gaeggeler, H.W.; Schotterer, U.; Schwikowski, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    The lowest five metres of an ice core from a high-alpine glacier (Colle Gnifetti, Monte Rosa massif, 4450m a.s.l., Switzerland) were analysed for ammonium, calcium, chloride, magnesium, nitrate, potassium, sodium, and sulphate by ion chromatography. (author) 1 fig., 3 refs.

  16. Surface corrosion of an Alpine karren field: recent measures at Innerbergli (Siebenhengste, Switzerland).

    OpenAIRE

    Philipp Häuselmann

    2008-01-01

    29 year old rock paintings in the Alpine karren field of Innerbergli (Siebenhengste, Switzerland) prevented the underlying rock from corrosion, while the surface nearby was corroded. Measurement of the steps indicates an average recent corrosion rate of 0.014 (±0.007) mm/a. This denudation rate is very similar to those observed in other comparable places and with other means.

  17. The effects of long-term fertilization on the temporal stability of alpine meadow communities

    NARCIS (Netherlands)

    Yang, Z.; Ruijven, van J.; Du, G.

    2011-01-01

    The aim of the study was to investigate how plant species’ composition, soil parameters and nutrient concentrations in plant biomass differ between fertilized and control plots 62 years after the last fertilizer application on a sub-alpine grassland. A piece of land called the Grass Garden (GG), fer

  18. Multilocus Analyses Reveal Postglacial Demographic Shrinkage of Juniperus morrisonicola (Cupressaceae), a Dominant Alpine Species in Taiwan

    Science.gov (United States)

    Chiu, Chi-Te; Huang, Chao-Li; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh

    2016-01-01

    Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration. PMID:27561108

  19. Improving Alpine Flood Prediction through Hydrological Process Characterization and Uncertainty Analysis

    OpenAIRE

    Tobin, Cara Christine

    2012-01-01

    Among the many challenges of Alpine flood prediction is describing complex, meteo-hydrological processes in a simplified, robust manner that can be easily integrated into operational forecasting. In this dissertation, improved methods to characterize these processes are developed and integrated into the hydrological modeling component of an operational flood forecasting system used in the Swiss Alps. Detailed studies are conducted to improve hydrologi...

  20. Glacial refugia, recolonization patterns and diversification forces in Alpine-endemic Megabunus harvestmen.

    Science.gov (United States)

    Wachter, Gregor A; Papadopoulou, Anna; Muster, Christoph; Arthofer, Wolfgang; Knowles, L Lacey; Steiner, Florian M; Schlick-Steiner, Birgit C

    2016-06-01

    The Pleistocene climatic fluctuations had a huge impact on all life forms, and various hypotheses regarding the survival of organisms during glacial periods have been postulated. In the European Alps, evidence has been found in support of refugia outside the ice shield (massifs de refuge) acting as sources for postglacial recolonization of inner-Alpine areas. In contrast, evidence for survival on nunataks, ice-free areas above the glacier, remains scarce. Here, we combine multivariate genetic analyses with ecological niche models (ENMs) through multiple timescales to elucidate the history of Alpine Megabunus harvestmen throughout the ice ages, a genus that comprises eight high-altitude endemics. ENMs suggest two types of refugia throughout the last glacial maximum, inner-Alpine survival on nunataks for four species and peripheral refugia for further four species. In some geographic regions, the patterns of genetic variation are consistent with long-distance dispersal out of massifs de refuge, repeatedly coupled with geographic parthenogenesis. In other regions, long-term persistence in nunataks may dominate the patterns of genetic divergence. Overall, our results suggest that glacial cycles contributed to allopatric diversification in Alpine Megabunus, both within and at the margins of the ice shield. These findings exemplify the power of ENM projections coupled with genetic analyses to identify hypotheses about the position and the number of glacial refugia and thus to evaluate the role of Pleistocene glaciations in driving species-specific responses of recolonization or persistence that may have contributed to observed patterns of biodiversity. PMID:27037513

  1. Dynamics of natural prokaryotes, viruses and heterotrophic nanoflagellates in alpine karstic groundwater

    NARCIS (Netherlands)

    I.C. Wilhartilz; A.K.T Krischner; C.P.D. Brussaard; U.R. Fisher; C. Wieltschnig; H. Stadler; A.H. Farnleitner

    2013-01-01

    Seasonal dynamics of naturally occurring prokaryotes, viruses, and heterotrophic nanoflagellates in two hydro-geologically contrasting alpine karst springs were monitored over three annual cycles. To our knowledge, this study is the first to shed light on the occurrence and possible interrelationshi

  2. Impacts of management practices on soil organic carbon in degraded alpine meadows on the Tibetan Plateau

    OpenAIRE

    X. F. Chang; Wang, S.P.; X. X. ZHU; Cui, S. J.; Luo, C. Y.; Zhang, Z. H.; A. Wilkes

    2014-01-01

    Grassland soil organic carbon (SOC) is sensitive to anthropogenic activities. Increased anthropogenic disturbance related to overgrazing has led to widespread alpine grassland degradation on the Tibetan Plateau. The degraded grasslands are considered to have great potential for carbon sequestration after adoption of improved management practices. Here, we calibrated and employed the Century model to investigate the effects of overgrazing and improved managem...

  3. Impacts of management practices on soil organic carbon in degraded alpine meadows on the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    X. F. Chang

    2014-01-01

    Full Text Available Grassland soil organic carbon (SOC is sensitive to anthropogenic activities. Increased anthropogenic disturbance related to overgrazing has led to widespread alpine grassland degradation on the Tibetan Plateau. The degraded grasslands are considered to have great potential for carbon sequestration after adoption of improved management practices. Here, we calibrated and employed the Century model to investigate the effects of overgrazing and improved managements on the SOC dynamics in alpine meadows. We calibrated Century model against plant productivity at Haibei Research Station. SOC stocks for validation were obtained in 2009–2010 from degraded alpine meadows in two communes. We found that Century model can successfully capture grassland SOC changes. Overall, our simulation suggests that degraded alpine meadow SOC significantly increased with the advent of restoration managements from 2011 to 2030. Carbon sequestration rates ranged between 0.04 Mg C ha−1 yr−1 in lightly degraded winter grasslands and 2.0 Mg C ha−1 yr−1 in moderately degraded summer grasslands. Our modeling work also predicts that improve management in Tibetan degraded grasslands will contribute to an annual carbon sink of 0.022–0.059 Pg C yr−1. These results imply that restoration of degraded grasslands in Tibetan Plateau has great potential for soil carbon sequestration to mitigate greenhouse gases.

  4. Impacts of management practices on soil organic carbon in degraded alpine meadows on the Tibetan Plateau

    Science.gov (United States)

    Chang, X. F.; Zhu, X. X.; Wang, S. P.; Cui, S. J.; Luo, C. Y.; Zhang, Z. H.; Wilkes, A.

    2014-07-01

    Grassland soil organic carbon (SOC) is sensitive to anthropogenic activities. Increased anthropogenic disturbance related to overgrazing has led to widespread alpine grassland degradation on the Tibetan Plateau. The degraded grasslands are considered to have great potential for carbon sequestration after adoption of improved management practices. Here, we calibrated and employed the Century model to investigate the effects of overgrazing and improved managements on the SOC dynamics in alpine meadows. We calibrated the Century model against plant productivity at the Haibei Research Station. SOC stocks for validation were obtained in 2009-2010 from degraded alpine meadows in two communes. We found that Century model can successfully capture grassland SOC changes. Overall, our simulation suggests that degraded alpine meadow SOC significantly increased with the advent of restoration management from 2011 to 2030. Carbon sequestration rates ranged between 0.04 Mg C ha-1 yr-1 in lightly degraded winter grazing grasslands and 2.0 Mg C ha-1 yr-1 in moderately degraded summer grazing grasslands. Our modelling work also predicts that improve management in degraded Tibetan grasslands will contribute to an annual carbon sink of 0.022-0.059 Pg C yr-1. These results imply that restoration of degraded grasslands in the Tibetan Plateau has great potential for soil carbon sequestration to mitigate greenhouse gases.

  5. Hydrogeology of an alpine rockfall aquifer system and its role in flood attenuation and maintaining baseflow

    Directory of Open Access Journals (Sweden)

    U. Lauber

    2014-06-01

    Full Text Available The frequency and intensity of extreme hydrological events in alpine regions is projected to increase with climate change. The goal of this study was to better understand the functioning of aquifers composed of complex alluvial and rockfall deposits in alpine valleys and to quantify the role of these natural storage spaces in flood attenuation and baseflow maintenance. Geomorphological and hydrogeological mapping, tracer tests, and continuous flow measurements were conducted in the Reintal valley (German Alps, where runoff from a karst spring infiltrates into a series of postglacial alluvial/rockfall aquifers. During high-flow conditions, groundwater velocities of 30 m h−1 were determined along 500 m; hydrograph analyses revealed short lag times (5 h between discharge peaks upstream and downstream from the aquifer series; the maximum discharge ratio downstream (22 and the peak recession coefficient (0.196 d−1 are low compared with other alpine catchments. During low-flow conditions, the underground flow path length increased to 2 km and groundwater velocities decreased to 13 m h−1. Downstream hydrographs revealed a delayed discharge response after 101 h and peaks dampened by a factor of 1.5. These results indicate that alluvial/rockfall aquifers might play an important role in the flow regime and attenuation of floods in alpine regions.

  6. Alpins and thibos vectorial astigmatism analyses: proposal of a linear regression model between methods

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2013-10-01

    Full Text Available PURPOSE: To determine linear regression models between Alpins descriptive indices and Thibos astigmatic power vectors (APV, assessing the validity and strength of such correlations. METHODS: This case series prospectively assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted among two phacoemulsification groups: one assigned to receive AcrySof®Toric intraocular lens (IOL in both eyes and another assigned to have AcrySof Natural IOL associated with limbal relaxing incisions, also in both eyes. All patients were reevaluated postoperatively at 6 months, when refractive astigmatism analysis was performed using both Alpins and Thibos methods. The ratio between Thibos postoperative APV and preoperative APV (APVratio and its linear regression to Alpins percentage of success of astigmatic surgery, percentage of astigmatism corrected and percentage of astigmatism reduction at the intended axis were assessed. RESULTS: Significant negative correlation between the ratio of post- and preoperative Thibos APVratio and Alpins percentage of success (%Success was found (Spearman's ρ=-0.93; linear regression is given by the following equation: %Success = (-APVratio + 1.00x100. CONCLUSION: The linear regression we found between APVratio and %Success permits a validated mathematical inference concerning the overall success of astigmatic surgery.

  7. Geochemistry and petrography of the MacAlpine Hills lunar meteorites

    Science.gov (United States)

    Lindstrom, Marilyn M.; Mckay, David S.; Wentworth, Susan J.; Martinez, Rene R.; Mittlefehldt, David W.; Wang, Ming-Sheng; Lipschutz, Michael E.

    1991-01-01

    MacAlpine Hills 88104 and 88105, anorthositic lunar meteorites recovered form the same area in Antartica, are characterized. Petrographic studies show that MAC88104/5 is a polymict breccia dominated by impact melt clasts. It is better classified as a fragmental breccia than a regolith breccia. The bulk composition is ferroan and highly aluminous (Al2O3-28 percent).

  8. Socially mediated effects of climate change decrease survival of hibernating Alpine marmots.

    Science.gov (United States)

    Rézouki, Célia; Tafani, Marion; Cohas, Aurélie; Loison, Anne; Gaillard, Jean-Michel; Allainé, Dominique; Bonenfant, Christophe

    2016-05-01

    In the context of global change, an increasing challenge is to understand the interaction between weather variables and life histories. Species-specific life histories should condition the way climate influences population dynamics, particularly those that are associated with environmental constraints, such as lifestyles like hibernation and sociality. However, the influence of lifestyle in the response of organisms to climate change remains poorly understood. Based on a 23-year longitudinal study on Alpine marmots, we investigated how their lifestyle, characterized by a long hibernation and a high degree of sociality, interacts with the ongoing climate change to shape temporal variation in age-specific survival. As generally reported in other hibernating species, we expected survival of Alpine marmots to be affected by the continuous lengthening of the growing season of plants more than by changes in winter conditions. We found, however, that Alpine marmots displayed lower juvenile survival over time. Colder winters associated with a thinner snow layer lowered juvenile survival, which in turn was associated with a decrease in the relative number of helpers in groups the following years, and therefore lowered the chances of over-winter survival of juveniles born in the most recent years. Our results provide evidence that constraints on life-history traits associated with hibernation and sociality caused juvenile survival to decrease over time, which might prevent Alpine marmots coping successfully with climate change. PMID:26920650

  9. Multilocus Analyses Reveal Postglacial Demographic Shrinkage of Juniperus morrisonicola (Cupressaceae), a Dominant Alpine Species in Taiwan.

    Science.gov (United States)

    Huang, Chi-Chun; Hsu, Tsai-Wen; Wang, Hao-Ven; Liu, Zin-Huang; Chen, Yi-Yen; Chiu, Chi-Te; Huang, Chao-Li; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh

    2016-01-01

    Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration. PMID:27561108

  10. Cultural Resilience of Social-ecological Systems in the Nenets and Yamal-Nenets Autonomous Okrugs, Russia: A Focus on Reindeer Nomads of the Tundra

    OpenAIRE

    Forbes, Bruce C.

    2013-01-01

    Empirical data on resilience in social-ecological systems (SESs) are reviewed from local and regional scale case studies among full-time nomads in the neighboring Nenets and Yamal-Nenets Autonomous Okrugs, Russia. The focus is on critical cultural factors contributing to SES resilience. In particular, this work presents an integrated view of people situated in specific tundra landscapes that face significantly different prospects for adaptation depending on existing or planned infrastructure ...

  11. Ecosystem CO2 and CH4 exchange in a mixed tundra and a fen within a hydrologically diverse Arctic landscape: 1. Modeling versus measurements

    Science.gov (United States)

    Grant, R. F.; Humphreys, E. R.; Lafleur, P. M.

    2015-07-01

    CO2 and CH4 exchange are strongly affected by hydrology in landscapes underlain by permafrost. Hypotheses for these effects in the model ecosys were tested by comparing modeled CO2 and CH4 exchange with CO2 fluxes measured by eddy covariance from 2006 to 2009, and with CH4 fluxes measured with surface chambers in 2008, along a topographic gradient at Daring Lake, NWT. In an upland tundra, rises in net CO2 uptake in warmer years were constrained by declines in CO2 influxes when vapor pressure deficits (D) exceeded 1.5 kPa and by rises in CO2 effluxes with greater active layer depth. Consequently, net CO2 uptake rose little with warming. In a lowland fen, CO2 influxes declined less with D and CO2 effluxes rose less with warming, so that rises in net CO2 uptake were greater than those in the tundra. Greater declines in CO2 influxes with warming in the tundra were modeled from greater soil-plant-atmosphere water potential gradients that developed under higher D in drained upland soil, and smaller rises in CO2 effluxes with warming in the fen were modeled from O2 constraints to heterotrophic and belowground autotrophic respiration from a shallow water table in poorly drained lowland soil. CH4 exchange modeled during July and August indicated very small influxes in the tundra and larger effluxes characterized by afternoon emission events caused by degassing of warming soil in the fen. Emissions of CH4 modeled from degassing during soil freezing in October-November contributed about one third of the annual total.

  12. The Tundra is a Net Source of CO2 Measured by Autochambers and Eddy Covariance Techniques During Five Years in a Site With Permafrost Thawing.

    Science.gov (United States)

    Celis, G.; Mauritz, M.; Bracho, R. G.; Salmon, V. G.; Webb, E.; Hutchings, J. A.; Natali, S.; Crummer, K. G.; Schuur, E.; Schaedel, C.

    2015-12-01

    Current and future warming of high latitude tundra ecosystems will play an important role in climate change through feedbacks to the global carbon (C) cycle. Long-term observational and experimental studies are pivotal for detecting and understanding changes in the coming decades. Yet studies of the C feedbacks from observational studies and manipulative experiments made on tundra plant communities often have significantly different conclusions with regards to impacts of warming on the ecosystem. Comparing results from these two study types, however, often involves integrating CO2 flux measurements that were collected on different spatial scales using a variety of methods. The process of data assimilation for landscape level analysis is often complicated by the fact that many projects only utilize one method for measuring CO2 fluxes at a given site. This study compares five years of C dynamics in a moist acidic tundra from control plots in a manipulative warming experiment (CiPEHR - plot-scale) and landscape-level natural permafrost thaw gradient (Gradient - Eddy covariance) observations all within a 1km distance from each other. We found net ecosystem exchange (NEE) to be an annual net source of carbon using both methods (Gradient 12.3 - 125.6 g CO2-C m-2 and CiPEHR warming manipulation 80.2 - 175.8 g CO2-C m-2). The differences between sites were biggest in the first three years of observation, and can be explained by lower growing season gross primary production (GPP - first three years) from the manipulation (CiPEHR), and lower ecosystem respiration (Reco) from CiPEHR in the first year only. Suppressed GPP and Reco could be from the impact of experimental setup (chamber soil collars - root damage), which lowered the plant community's capacity to fix C, but recovered within three years. This warrants caution of making generalization of short-term experiments in the tundra and more research is needed evaluating coupling of belowground and aboveground C dynamics.

  13. The exchange of energy, water and carbon dioxide between wet arctic tundra and the atmosphere at the Lena River Delta, Northern Siberia

    Energy Technology Data Exchange (ETDEWEB)

    Kutzbach, L.

    2006-07-01

    The ecosystem-scale exchange fluxes of energy, water and carbon dioxide between wet arctic tundra and the atmosphere were investigated by the micrometeorological eddy covariance method. The investigation site was the centre of the Lena River Delta in Northern Siberia characterised by a polar and distinctly continental climate, very cold and ice-rich permafrost and its position at the interface between the Eurasian continent and the Arctic Ocean. The measurements were performed on the surface of a Holocene river terrace characterised by wet polygonal tundra. The soils at the site are characterised by high organic matter content, low nutrient availability and pronounced water logging. The vegetation is dominated by sedges and mosses. The fluctuations of the H{sub 2}O and CO{sub 2} concentrations were measured with a closed-path infrared gas analyser. The fast-response eddy covariance measurements were supplemented by a set of slow-response meteorological and soil-meteorological measurements. The combined datasets of the two campaigns 2003 and 2004 were used to characterise the seasonal course of the energy, water and CO{sub 2} fluxes and the underlying processes for the synthetic measurement period May 28..October 21 2004/2003 including the period of snow and soil thawing as well as the beginning of refreezing. The synthetic measurement period 2004/2003 was characterised by a long snow ablation period and a late start of the growing season. On the other hand, the growing season ended also late due to high temperatures and snow-free conditions in September. The cumulative summer energy partitioning was characterised by low net radiation, large ground heat flux, low latent heat flux and very low sensible heat flux compared to other tundra sites. These findings point out the major importance of the very cold permafrost for the summer energy budget of the tundra in Northern Siberia. (orig./SR)

  14. The use of invertebrates as indicators of environmental change in alpine rivers and lakes

    Energy Technology Data Exchange (ETDEWEB)

    Khamis, K.; Hannah, D.M. [School of Geography Earth and Environmental Science, University of Birmingham, Birmingham B15 2TT (United Kingdom); Brown, L.E. [School of Geography/water@leeds, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Tiberti, R. [DSTA, Dipartimento di Scienze della Terra e dell' Ambiente, University of Pavia, Via Ferrata 9, 27100 Pavia (Italy); Alpine Wildlife Research Centre, Gran Paradiso National Park, Degioz 11, I-1101 Valsavarenche, Aosta (Italy); Milner, A.M., E-mail: a.m.milner@bham.ac.uk [School of Geography Earth and Environmental Science, University of Birmingham, Birmingham B15 2TT (United Kingdom); Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775 (United States)

    2014-09-15

    In alpine regions climatic change will alter the balance between water sources (rainfall, ice-melt, snowmelt, and groundwater) for aquatic systems, particularly modifying the relative contributions of meltwater, groundwater and rain to both rivers and lakes. While these changes are expected to have implications for alpine aquatic ecosystems, little is known about potential ecological tipping points and associated indicator taxa. We examined changes in biotic communities along a gradient of glacier influence for two study systems: (1) a stream network in the French Pyrénées; and (2) a network of lakes in the Italian Alps, with the aim of identifying potential indicator taxa (macroinvertebrates and zooplankton) of glacier retreat in these environments. To assess parallels in biotic responses across streams and lakes, both primary data and findings from other publications were synthesised. Using TITAN (Threshold Indicator Taxa ANalysis) changes in community composition of river taxa were identified at thresholds of < 5.1% glacier cover and < 66.6% meltwater contribution. Below these thresholds the loss of cold stenothermic benthic invertebrate taxa, Diamesa spp. and the Pyrenean endemic Rhyacophila angelieri was apparent. Some generalist taxa including Protonemura sp., Perla grandis, Baetis alpinus, Rhithrogena loyolaea and Microspectra sp. increased when glacier cover was < 2.7% and < 52% meltwater. Patterns were not as distinct for the alpine lakes, due to fewer sampling sites; however, Daphnia longispina grp. and the benthic invertebrate groups Plectopera and Planaria were identified as potential indicator taxa. While further work is required to assess potential indicator taxa for alpine lake systems, findings from alpine river systems were consistent between methods for assessing glacier influence (meltwater contribution/glacier cover). Hence, it is clear that TITAN could become a useful management tool, enabling: (i) the identification of taxa particularly

  15. The use of invertebrates as indicators of environmental change in alpine rivers and lakes

    International Nuclear Information System (INIS)

    In alpine regions climatic change will alter the balance between water sources (rainfall, ice-melt, snowmelt, and groundwater) for aquatic systems, particularly modifying the relative contributions of meltwater, groundwater and rain to both rivers and lakes. While these changes are expected to have implications for alpine aquatic ecosystems, little is known about potential ecological tipping points and associated indicator taxa. We examined changes in biotic communities along a gradient of glacier influence for two study systems: (1) a stream network in the French Pyrénées; and (2) a network of lakes in the Italian Alps, with the aim of identifying potential indicator taxa (macroinvertebrates and zooplankton) of glacier retreat in these environments. To assess parallels in biotic responses across streams and lakes, both primary data and findings from other publications were synthesised. Using TITAN (Threshold Indicator Taxa ANalysis) changes in community composition of river taxa were identified at thresholds of < 5.1% glacier cover and < 66.6% meltwater contribution. Below these thresholds the loss of cold stenothermic benthic invertebrate taxa, Diamesa spp. and the Pyrenean endemic Rhyacophila angelieri was apparent. Some generalist taxa including Protonemura sp., Perla grandis, Baetis alpinus, Rhithrogena loyolaea and Microspectra sp. increased when glacier cover was < 2.7% and < 52% meltwater. Patterns were not as distinct for the alpine lakes, due to fewer sampling sites; however, Daphnia longispina grp. and the benthic invertebrate groups Plectopera and Planaria were identified as potential indicator taxa. While further work is required to assess potential indicator taxa for alpine lake systems, findings from alpine river systems were consistent between methods for assessing glacier influence (meltwater contribution/glacier cover). Hence, it is clear that TITAN could become a useful management tool, enabling: (i) the identification of taxa particularly

  16. Exploring the Potential of Aerial Photogrammetry for 3d Modelling of High-Alpine Environments

    Science.gov (United States)

    Legat, K.; Moe, K.; Poli, D.; Bollmannb, E.

    2016-03-01

    High-alpine areas are subject to rapid topographic changes, mainly caused by natural processes like glacial retreat and other geomorphological processes, and also due to anthropogenic interventions like construction of slopes and infrastructure in skiing resorts. Consequently, the demand for highly accurate digital terrain models (DTMs) in alpine environments has arisen. Public administrations often have dedicated resources for the regular monitoring of glaciers and natural hazard processes. In case of glaciers, traditional monitoring encompasses in-situ measurements of area and length and the estimation of volume and mass changes. Next to field measurements, data for such monitoring programs can be derived from DTMs and digital ortho photos (DOPs). Skiing resorts, on the other hand, require DTMs as input for planning and - more recently - for RTK-GNSS supported ski-slope grooming. Although different in scope, the demand of both user groups is similar: high-quality and up-to-date terrain data for extended areas often characterised by difficult accessibility and large elevation ranges. Over the last two decades, airborne laser scanning (ALS) has replaced photogrammetric approaches as state-of-the-art technology for the acquisition of high-resolution DTMs also in alpine environments. Reasons include the higher productivity compared to (manual) stereo-photogrammetric measurements, canopy-penetration capability, and limitations of photo measurements on sparsely textured surfaces like snow or ice. Nevertheless, the last few years have shown strong technological advances in the field of aerial camera technology, image processing and photogrammetric software which led to new possibilities for image-based DTM generation even in alpine terrain. At Vermessung AVT, an Austrian-based surveying company, and its subsidiary Terra Messflug, very promising results have been achieved for various projects in high-alpine environments, using images acquired by large-format digital

  17. Divergence and diversity: lessons from an arctic-alpine distribution (Pardosa saltuaria group, Lycosidae).

    Science.gov (United States)

    Muster, Christoph; Berendonk, Thomas U

    2006-09-01

    The relationship of interpopulation genetic divergence and within-population diversity has been studied for many temperate species in Europe, but not for the cold-adapted fauna. Here we present the first European-wide phylogeographical study of an arctic-alpine distribution in invertebrates, focusing on wolf spiders of the Pardosa saltuaria group. One hundred twenty-seven (127) specimens from 14 populations were examined. Within Europe, these populations were distributed among six high mountain ranges and Scandinavia. We sequenced the whole 921 base pair mitochondrial (mt) ND1 gene. The resulting 55 unique haplotypes form three monophyletic phylogroups of deep divergence: a Pyrenean, a Balkan and a 'northern' clade. Genetic distances (3.6-4.0%) between the major clades indicate that the arctic-alpine range disjunction was initiated by vicariance events, which precede the four major Alpine glaciations. However, low divergence and incomplete lineage sorting within the 'northern clade' suggest a late Pleistocene separation of the Alpine, Scandinavian, Carpathian and Sudetian populations. Thus, we provide evidence for a multiglacial origin of arctic-alpine distributions in Europe, i.e. the current disjunction results from range fragmentation in several glacial cycles. The pattern of genetic diversity within populations seems predominantly determined by historical factors, but is modified by contemporary aspects. Overall, diversity and divergence are negatively correlated. We suggest that low diversity values might result from (i) ancient bottlenecking during warm interglacial periods, as seen in the Pyrenees and Balkans; (ii) recent bottlenecking in small modern areas, as seen in the Giant Mountains and Bohemian Forest; and (iii) dispersal bottlenecking in northern Scandinavia. PMID:16911211

  18. Influence of land cover changes on the physical and chemical properties of alpine meadow soil

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Taking the alpine cold meadow grassland in the southeastern part of the Qinghai-Tibetan Plateau as an example, this research deals with the characteristics of alpine meadow soil property changes, including soil nutrients, soil physical properties and soil moisture content under different land coverage conditions. With the degradation of grassland vegetation and the decline of vegetation coverage, soil compactness reduces, gravel content increases and bulk density increases. The originally dense root-system layer is gradually denuded, making the soil coarse and gravel. The change of the organic matter contents with the vegetation coverage change in the surface soil layer (0-20 cm) has shown an obvious cubic polynomial curve process. The organic matter contents increase rapidly when land coverage is above 60%, contrarily decreases on a large scale when land coverage is below 30%. Between 30%-60% of land coverage the organic matter contents remain stable. The total N and organic matter contents in soil have shown quite similar change regularity. Following this the mathematic equations are derived to describe such change processes. Moisture content in soil changes sharply with the vegetation coverage change. Soil moisture content change with the vegetation coverage change has shown a quadratic parabola process. Results have shown that organic matter content and the total N content of the alpine meadow soil decrease by 14890 kg/hm2 and 5505 kg/hm2 respectively as the vegetation coverage reduces from 90% to less than 30%. The heavy changes of soil physical and chemical properties with grassland degradation have made the recovery of alpine meadow ecological system impossible. The protection of alpine meadow vegetation is of vital importance to the maintenance of the regional soil environment and the regional ecological system.

  19. On the importance of sublimation to an alpine snow mass balance in the Canadian Rocky Mountains

    Directory of Open Access Journals (Sweden)

    M. K. MacDonald

    2010-07-01

    Full Text Available A modelling study was undertaken to evaluate the contribution of sublimation to an alpine snow mass balance in the Canadian Rocky Mountains. Snow redistribution and sublimation by wind, snowpack sublimation and snowmelt were simulated for two winters over an alpine ridge transect located in the Canada Rocky Mountains. The resulting snowcover regimes were compared to those from manual snow surveys. Simulations were performed using physically based blowing snow (PBSM and snowpack ablation (SNOBAL models. A hydrological response unit (HRU-based spatial discretization was used rather than a more computationally expensive fully-distributed one. The HRUs were set up to follow an aerodynamic sequence, whereby eroded snow was transported from windswept, upwind HRUs to drift accumulating, downwind HRUs. That snow redistribution by wind can be adequately simulated in computationally efficient HRUs over this ridge has important implications for representing snow transport in large-scale hydrology models and land surface schemes. Alpine snow sublimation losses, in particular blowing snow sublimation losses, were significant. Snow mass losses to sublimation as a percentage of cumulative snowfall were estimated to be 20–32% with the blowing snow sublimation loss amounting to 17–19% of cumulative snowfall. This estimate is considered to be a conservative estimate of the blowing snow sublimation loss in the Canadian Rocky Mountains because the study transect is located in the low alpine zone where the topography is more moderate than the high alpine zone and windflow separation was not observed. An examination of the suitability of PBSM's sublimation estimates in this environment and of the importance of estimating blowing snow sublimation on the simulated snow accumulation regime was conducted by omitting sublimation calculations. Snow accumulation in HRUs was overestimated by 30% when neglecting blowing snow sublimation calculations.

  20. Alpine Ecosystems of Northwest Yunnan, China: an Initial Assessment for Conservation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Implementing conservation actions on-the-ground is not a straightforward process,especially when faced with high scientific uncertainty due to limited available information. This is especially acute in regions of the world that harbor many unique species that have not been well studied, such as the alpine zone of the Hengduan Mountains of Northwest Yunnan (NWY), a global biodiversity hotspot and site of The Nature Conservancy's Yunnan Great Rivers Project. We conducted a quantitative, but rapid regional-level assessment of the alpine flora across NWY to provide a broad-based understanding of local and regional patterns of the alpine flora, the first large-scale analysis of alpine biodiversity patterns in this region. Multivariate analyses were used to classify the major plant community types and link community patterns to habitat variables. Our analysis indicated that most species had small distributions and/or small population sizes. Strong patterns emerged with higher diversity in the more northern mountains, but beta diversity was high, averaging only 10% among sites. The ordinations indicated that elevation and geographic location were the dominant environmental gradients underlying the differences in the species composition among communities. The high beta diversity across the alpine of these mountains implies that conservation strategies ultimately will require the protection of large numbers of species over a large geographical area. However, prioritization should be given to areas where potential payoffs are greatest. Sites with high species richness also have a greater number of endemic species, and, by focusing efforts on these sites, conservation investments would be maximized by protecting the greatest number of unique species.

  1. Experimental study on soil CO2 emission in the alpine grassland ecosystem on Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Xianzhou; SHI; Peili; LIU; Yunfen; OUYANG; Hua

    2005-01-01

    The Tibetan Plateau, the Roof of the World, is the highest plateau with a mean elevation of 4000 m. It is characterized by high levels of solar radiation, low air temperature and low air pressure compared to other regions around the world. The alpine grassland, a typical ecosystem in the Tibetan Plateau, is distributed across regions over the elevation of 4500 m. Few studies for carbon flux in alpine grassland on the Tibetan Plateau were conducted due to rigorous natural conditions. A study of soil respiration under alpine grassland ecosystem on the Tibetan Plateau from October 1999 to October 2001 was conducted at Pangkog County, Tibetan Plateau (31.23°N, 90.01°E, elevation 4800 m). The measurements were taken using a static closed chamber technique, usually every two weeks during the summer and at other times at monthly intervals. The obvious diurnal variation of CO2 emissions from soil with higher emission during daytime and lower emission during nighttime was discovered. Diurnal CO2 flux fluctuated from minimum at 05:00 to maximum at 14:00 in local time. Seasonal CO2 fluxes increased in summer and decreased in winter, representing a great variation of seasonal soil respiration. The mean soil CO2 fluxes in the alpine grassland ecosystem were 21.39 mgCO2 · m-2 · h-1, with an average annual amount of soil respiration of 187.46 gCO2 · m-2 · a-1. Net ecosystem productivity is also estimated, which indicated that the alpine grassland ecosystem is a carbon sink.

  2. Greening Trends in North American Boreal Forest and Tundra during 2000-2009 from MODIS and in situ Measurements

    Science.gov (United States)

    Wang, D.; Morton, D. C.; Masek, J. G.; McManus, K. M.; Sexton, J. O.

    2010-12-01

    High northern latitudes have experienced the strongest warming trends during the satellite era (1970-present). The response of boreal forest and tundra vegetation to recent and projected warming plays a pivotal role for carbon cycling in these ecosystems and related feedbacks within the Earth system. Long time series of normalized differenced vegetation index (NDVI), calculated from historical Advanced Very High Resolution Radiometer (AVHRR) data, provided the first opportunity to evaluate vegetation dynamics over decadal temporal scales and continental to global spatial scales. However, due to coarse spatial resolution (1-8 km), previous studies of greening in North America with aggregated AVHRR NDVI data were unable to separate the contributions from changes in growing season length and vegetation cover to the greening signal in forest and tundra ecosystems. In this study, we isolated trends in peak growing season vegetation cover using NDVI data from the MODerate resolution Imaging Spectroradiometer (MODIS) during 2000-2009. Our time series analysis compared 500 m NDVI data from the same 16-day composite period during peak growing season months to characterize changes in vegetation abundance during 2000-2009. This approach minimized impacts of phenology, changes in growing season length, and clouds or other data artifacts. For comparison with satellite-based observations, we used measurements of upwelling and downwelling spectral radiances over FLUXNET tower sites to derive broadband NDVI values. Trends in vegetation cover from MODIS NDVI during 2000-2009 differ from previous studies with AVHRR data. Approximately 26% of all vegetated area exhibited significant linear trends in NDVI during 2000-2009 (ptrendfire, insect damage, or harvest, and these trends were captured in both MODIS and broadband NDVI from FLUXNET tower sites. However, greening trends were not observed over mature forests due to saturation of NDVI at MODIS resolution. Therefore, satellite

  3. Soil bacterial community and functional shifts in response to altered snowpack in moist acidic tundra of northern Alaska

    Science.gov (United States)

    Ricketts, Michael P.; Poretsky, Rachel S.; Welker, Jeffrey M.; Gonzalez-Meler, Miquel A.

    2016-09-01

    Soil microbial communities play a central role in the cycling of carbon (C) in Arctic tundra ecosystems, which contain a large portion of the global C pool. Climate change predictions for Arctic regions include increased temperature and precipitation (i.e. more snow), resulting in increased winter soil insulation, increased soil temperature and moisture, and shifting plant community composition. We utilized an 18-year snow fence study site designed to examine the effects of increased winter precipitation on Arctic tundra soil bacterial communities within the context of expected ecosystem response to climate change. Soil was collected from three pre-established treatment zones representing varying degrees of snow accumulation, where deep snow ˜ 100 % and intermediate snow ˜ 50 % increased snowpack relative to the control, and low snow ˜ 25 % decreased snowpack relative to the control. Soil physical properties (temperature, moisture, active layer thaw depth) were measured, and samples were analysed for C concentration, nitrogen (N) concentration, and pH. Soil microbial community DNA was extracted and the 16S rRNA gene was sequenced to reveal phylogenetic community differences between samples and determine how soil bacterial communities might respond (structurally and functionally) to changes in winter precipitation and soil chemistry. We analysed relative abundance changes of the six most abundant phyla (ranging from 82 to 96 % of total detected phyla per sample) and found four (Acidobacteria, Actinobacteria, Verrucomicrobia, and Chloroflexi) responded to deepened snow. All six phyla correlated with at least one of the soil chemical properties (% C, % N, C : N, pH); however, a single predictor was not identified, suggesting that each bacterial phylum responds differently to soil characteristics. Overall, bacterial community structure (beta diversity) was found to be associated with snow accumulation treatment and all soil chemical properties. Bacterial

  4. Modern and fossilized biological communities from sediments of Bolshoy Harbei lake (Bolshezemelskaya tundra, Russia) and their response to climate change

    Science.gov (United States)

    Tumanov, Oleg; Nazarova, Larisa; Fefilova, Elena; Baturina, Maria; Loskutova, Olga; Frolova, Larisa; Palagushkina, Olga

    2013-04-01

    High-altitude regions are subjected to the threats of global warming. During the last decade the depth of seasonal melting of permafrost in Northern Russia, significantly increased. Investigation of lake sediments from polar regions has an extreme importance for understanding of the modern environmental processes and their influence on northern ecosystems and biological diversity of these regions. Invertebrate communities are used for diagnostic of lake ecosystems because they have a great sensitivity to climatic changes (Andronnikova, 1996; Lazareva, 2008; O'Brien et al., 2005). The data can be used as well as a basis for inference models for reconstruction of the paleoclimatic conditions. Chironomid-based, Cladocera-based and diatom models have successfully been developed (Nazarova et al., 2008, 2011; Self et al., 2011) and can be used for precise paleotemperature reconstructions (Kienast et al., 2011). In summer 2012, we investigated complex of Kharbei lakes, located in the interfluve of Korotaiha and Bolshaya Rogovaya rivers in the east side of Bolshezemelskaya tundra, Russia (67°33'22″ N, 62°53'23″ E). Six different lakes were investigated using modern hydrobiological and palaeoecological methods. In total 9 cores were obtained, cut, dated and further investigated using sedimenthological, geochemical, and paleobiological methods. The standard hydrobiological methods have shown that the modern zooplankton communities did not change significantly during the last 40 years. Taxonomic composition and structure of planktonic communities didn't change, except for appearance of crustaceans Polyarthra euryptera and Daphnia cucullata. In planktonic communities of Bolshoy Harbei lake we revealed 39 species and forms of Rotifera, 19 - Cladocera and 11 - Copepoda. In zoobenthic communities we registered 24 taxonomical groups characteristic for large tundra lakes of the North East of Russia. Chironomids and Oligochaeta are dominant groups of invertebrates. 103 taxa of

  5. Topographic control of the depth of ground thaw in a peat covered continuous permafrost site in the Canadian arctic tundra

    Science.gov (United States)

    Endrizzi, Stefano; Marsh, Philip; Quinton, William; Dall'Amico, Matteo

    2010-05-01

    Recent research has suggested an energy-based framework for delineating runoff contributing areas for permafrost dominated, tundra environments, where end of winter snow cover, and turbulent and radiant fluxes of energy and water are affected by topography, and control both snowmelt and the depth of ground thaw. The resulting spatially variable thaw depth, when combined with spatially variable water supply, spatially variable organic soil thickness, and depth variable hydraulic conductivity in organic soils, has a significant impact on the flow of water from uplands to the stream channel. In order to consider the effects of a spatially variable depth of thaw on runoff in a tundra basin, the hydrologic model GEOtop was applied to the Siksik Creek drainage basin located approximately 50 km north of Inuvik, NWT, Canada, characterized by a relatively gentle topography, with elevation ranging from 0 and 80 m a.s.l.. The small surface area of the basin (approximately 1 km2) allows the model to be run at a relatively high resolution. GEOtop is a grid based model with a complete surface energy balance scheme that accounts for variations in both the turbulent fluxes of sensible and latent heat, as well as for variations in radiant fluxes. The model also has a complete subsurface heat and water flux scheme that is able to route water and energy both vertically between a large number of soil layers, and horizontally between grids. Field data for model validation include meteorological data, depth of thaw, and runoff data for a 3 year period between 1992 and 1994, and high resolution DEM and vegetation height data obtained from airborne LiDAR in 2004. The purpose of this work is studying how topography controls the depth of thaw, and, therefore, the effects of a spatially variable snow cover are intentionally neglected. GEOtop was then run in a simple configuration, assuming an initial condition of uniform frost table at the ground surface at the end of snow melt, with snow

  6. Seasonality of Air-sea-ice-land Variables for Arctic Tundra in Northern Eurasia and North America

    Science.gov (United States)

    Bhatt, U. S.; Walker, D. A.; Raynolds, M. K.; Steele, M.; Epstein, H.; Jia, G.; Comiso, J. C.; Pinzon, J. E.; Tucker, C. J.

    2009-12-01

    The strength of tundra productivity trends as measured by the annual maximum Normalized Difference Vegetation Index (MaxNDVI) and time integrated NDVI (TI-NDVI) vary around the Arctic over the 1982-2008 period. Our analysis suggests that the timing of terrestrial vegetation growth is connected to seasonal patterns of sea-ice concentrations, ocean temperatures and land surface temperatures. This study used SSMI estimates of sea ice concentration, based on a bootstrap algorithm and AVHRR radiometric surface temperature. Summer Warmth Index (SWI) was calculated as the sum from May to August of the degree months above freezing of surface temperature at each pixel and is an accepted measure of plant growth potential. The Normalized Difference Vegetation Index (NDVI) represents vegetation greenness and has been used extensively to monitor changes in the Arctic. The albedo of green plants varies with solar radiation wavelength, which is the basis for the NDVI index. The analysis was conducted within 50 km of the Arctic coastline to focus on the region of maximum maritime influence. Time series of regional sea-ice concentration, SWI and NDVI were constructed for the 50-km width domains for the Pan-Arctic, North America, Eurasia and Arctic subregions. Standard climate analysis techniques were applied to the regional time series to investigate the seasonality of sea ice, NDVI and SWI. MaxNDVI has increased in the 50-km land domain contiguous to the Beaufort Sea by 17% since 1982, whereas it has only increased by 3% in the coastal Kara Sea region. Analysis of semimonthly MaxNDVI indicates that the vegetation greens up more rapidly in the spring in the Beaufort than the W. Kara and the Kara has slightly higher NDVI in the fall. The climatological weekly sea ice concentrations in 50-km coastal domain displays an earlier breakup in the Beaufort and a later freeze-up in the Kara Sea area. Regional differences in the seasonal cycle can in part explain the spatially varied trends

  7. Potential NEE Budget and Prediction of Future Emissions under Climate Change in an Arctic Wet Sedge Tundra, Barrow, Alaska .

    Science.gov (United States)

    Kalhori, A. A. M.; Oechel, W. C.; Burba, G. G.; Gioli, B.; Zona, D.; Murphy, P.; Goodrich, J. P.

    2015-12-01

    Arctic ecosystems are critically affected by climate change and also play an important role in the global carbon budget. Presented here is a 14-year study of growing season CO2 fluxes in an Alaskan wet sedge tundra ecosystem -which is about 2 km south of the Arctic Ocean and is adjacent to the NOAA Climate Monitoring & Diagnostic Laboratory (CMDL)- and the key environmental controls on these fluxes. We have measured net ecosystem exchange of CO2 (NEE) using the eddy covariance technique from 1998 to 2014 in order to quantify the long-term seasonal and inter-annual variability in the CO2 budget over this period. The WPL correction and the surface heating correction were applied to all CO2 flux data from the open-path instrument (Burba et al., 2008). Despite several gaps in measurement years, we found that growing season net CO2 uptake has significantly increased since the 2000s and that NEE is sensitive to dry conditions in tundra. Our data suggest this increase in CO2 uptake (larger than -6 μmol m-2 s-1) occurred during the initial thawing period and during the June-August growing season. However, there is a decreasing trend in total summer uptake beginning in 2011, continuing until the end of 2014. The mean diurnal pattern for the summer period over the course of 14 years (Figure below), indicates inter-annual variability associated with the key environmental controls on these CO2 fluxes. Monthly trends in Photosynthetically Active Radiation (PAR), net radiation, relative humidity as well as air temperature and soil temperature have consistently simultaneous effects on the variation in NEE. More significant effect of PAR than temperature on summer NEE had been observed for the first period of this study, however our ANOVA, multiple regression and t-test results showed a stronger effect of temperature than PAR in the recent years assuming that Arctic warming will be greater than average global warming. Also the diurnal pattern shows that the maximum daily carbon

  8. Land-atmosphere fluxes of methane and carbon dioxide at Siberian polygonal tundra - new data from 2009 in comparison to data from 2003/04 and 2006.

    Science.gov (United States)

    Schreiber, Peter; Wille, Christian; Sachs, Torsten; Pfeiffer, Eva-Maria; Kutzbach, Lars

    2010-05-01

    The fluxes of carbon dioxide (CO2) and methane (CH4) between wet arctic polygonal tundra and the atmosphere were investigated by the eddy covariance method and empirical modeling. The study site is situated in the Lena River Delta in Northern Siberia (72° 22' N, 126° 30' E) and is characterized by a polar and distinctly continental climate, very cold and ice-rich permafrost, and its position at the interface between the Eurasian continent and the Arctic Ocean. The soils at the site are characterized by high organic matter content, low nutrient availability and pronounced water logging. The vegetation is dominated by sedges and mosses. Flux measurements were performed during one 'synthetic' growing season consisting of the periods July - October 2003 and May - July 2004, one full growing season in 2006 (June - September), and during July - August in 2009. The main carbon exchange processes - gross photosynthesis, ecosystem respiration, and CH4 emissions - were generally found to be of low intensity. Over the 2004/2003 growing season (June - September), these gas fluxes accumulated to -0.43 kg m-2, +0.33 kg m-2, and +2 g m-2, respectively. CH4 emissions from June - September 2006 were 1.96 g m-2 with highest emissions in July (+0.57 g m-2) and August (+0.64 g m-2). Day-to-day variations of photosynthesis were mainly controlled by radiation and hence by the synoptic weather conditions. Variations of ecosystem respiration were best explained by an exponential function of surface temperature, which indicates that plant respiration plays a major role within the tundra carbon balance. The factors controlling CH4 emissions were found to be soil temperature and near-surface atmospheric turbulence. The influence of atmospheric turbulence was attributed to the high coverage of open water surfaces in the tundra. For the 2003- 2004 period, winter fluxes were modeled based on functional relationships found in the measured data. On an annual basis, CH4 emissions accounted for

  9. Ecohydrological interactions between soil and trees in Alpine apple orchards

    Science.gov (United States)

    Penna, Daniele; Scandellari, Francesca; Zanotelli, Damiano; Michael, Engel; Tagliavini, Massimo; Comiti, Francesco

    2016-04-01

    Tracer-based investigations of water exchanges between soil and trees in natural forested catchments are receiving relevant attention in modern ecohydrology. However, the interactions between tree water use and the hydrological cycle in agricultural environments are still poorly understood. In this work, we use stable isotopes of water (2H and 18O) and electric conductivity as tracers to improve our understanding of the functional interrelations between water generating surface runoff and recharging groundwater, and water taken up by apple trees (Malus domestica, cv. 'Pinova') in an Alpine valley in South Tyrol, Northern Italy. From April to October 2015 we monitored two orchards approximately of the same size (roughly 400 m2) and soil texture (silt loam) located in a flat area at different distance from the Adige/Etsch River (50 m vs. 450 m). We have addressed the following questions: i) at which soil depth do apple trees take up water? ii) do apple trees take up water from shallow groundwater? iii) are there differences in the isotopic composition of the water fluxes between the two sites? Samples for isotopic analysis were taken approximately fortnightly from the river, two groundwater wells close to each field, mobile soil water (from suction cups at 25 cm and 50 cm), open area precipitation, throughfall, irrigation and sap (through a portable pressure bomb). Tightly-bound soil water was also cryogenically extracted from samples taken every 10 cm from 60 cm-long soil cores taken at three locations for each field on one occasion in mid-summer. Ancillary measurements were electrical conductivity of all water sources except for sap. In addition to meteorological and discharge data, soil moisture was continuously measured at 10 cm and 50 cm in three locations, and sap flow on three trees, for each field. Preliminary results show that two water pools with distinct isotopic signature exist: i) river water, groundwater and irrigation water show values relatively

  10. Predictive Analysis of Geochemical Controls in an Alpine Stream

    Science.gov (United States)

    Jochems, A. P.; Sherson, L. R.; Crossey, L. J.; Karlstrom, K. E.

    2010-12-01

    Alpine watersheds are increasingly relied upon for use in the American West, necessitating a more complete understanding of annual hydrologic patterns and geologic influences on water chemistry. The Jemez River is a fifth order stream in central New Mexico that flows from its source in the Jemez Mountains to its confluence with the Rio Grande north of the town of Bernalillo. Designated uses of the Jemez River include domestic water supply, recreation, and agriculture. Geothermal uses are currently being considered as well. The river recharges shallow aquifer waters used by several communities, including tribal lands of the Jemez Pueblo. The hydrogeology of the Jemez system is characterized by geothermal inputs from the Baca hydrothermal system associated with the 1.2Ma Valles caldera, as well as groundwater and surface water interactions. Freshwater input from the Rio Guadalupe and several ephemeral tributaries also influences the water chemistry of the Jemez system. Fifteen sites along a 35 km reach of the river were sampled between 2006 and 2010. Discharge of the Jemez River ranged from 10-876 cfs over the study period. The annual hydrograph is affected by annual snowmelt in the Jemez Mountains as well as surges due to monsoonal rains in July and August. Geochemical data collected over this period include temperature, conductivity, pH, dissolved oxygen (D.O.), major ions, trace elements, and stable isotopes. Continuous records of temperature, conductivity, pH, D.O. and turbidity data were collected from a water quality sonde installed in March 2010. Geochemical modeling and time series analysis were performed using PHREEQC, Geochemist’s Workbench, and MATLAB. Empirical data collected during this study gave rise to several models describing the hydrology and geochemistry of the Jemez system. Our data suggest that springs are the primary contributors to dissolved load, and that solute loading from geothermal inputs is intensified by low flows observed on

  11. Interactions between warming and soil moisture increase overlap in reproductive phenology among species in an alpine meadow.

    Science.gov (United States)

    Zhu, Juntao; Zhang, Yangjian; Wang, Wenfeng

    2016-07-01

    Climate warming strongly influences reproductive phenology of plants in alpine and Arctic ecosystems. Here, we focus on phenological shifts caused by experimental warming in a typical alpine meadow on the Tibetan Plateau. Under soil water stress caused by warming, most plants in the alpine meadow advanced or delayed their reproductive events to be aligned with the timing of peak rainfall. As a result, warming significantly increased the temporal overlap among reproductive stages of early- and late-flowering species. In addition, we found that some species, for example the late-flowering species, were unable to produce flowers and fruits under warming with failed monsoon rains. The potentially warmer- and drier-growing seasons under climate change may similarly shift the phenological patterns and change species composition of these alpine systems. PMID:27405376

  12. Coupled cryoconite ecosystem structure-function relationships are revealed by comparing bacterial communities in alpine and Arctic glaciers

    DEFF Research Database (Denmark)

    Edwards, Arwyn; Mur, Luis A. J.; Girdwood, Susan E.;

    2014-01-01

    Cryoconite holes are known as foci of microbial diversity and activity on polar glacier surfaces, but are virtually unexplored microbial habitats in alpine regions. In addition, whether cryoconite community structure reflects ecosystem functionality is poorly understood. Terminal restriction frag...

  13. Lactation curve in Alpine and crossbred Boer goats at a pasture system production with and without concentrate supplementation

    Directory of Open Access Journals (Sweden)

    Luciana Rodrigues

    2010-01-01

    Full Text Available Fifty goats were used (30 Alpine and 20 ½ Boer + ½ Alpine, primiparous and multiparous, with average body weight of 52.7 ± 1.07 kg, evaluated averaging to 203.9 ± 8.04 lactation days. Were tested two pasture production systems: SP1 - with concentrate supplementation and SP2 - without concentrate supplementation. Animals were kept in pasture established with Panicum maximum cv. Tanzania. Milk control was performed every 14 days, by weighting milk. It was calculated some variables: time to reach peak, production at peak (PP, milk production on t time and persistence (PS. Genotype and pasture production system influenced the lactation curve. Concentrate supplementation of Alpine goats resulted in longer time to reach peak of lactation, higher PP and PS. Alpine goats, on pasture production system should be supplemented with concentrate.

  14. Variation of terpenes in milk and cultured cream from Norwegian alpine rangeland-fed and in-door fed cows.

    Science.gov (United States)

    Borge, Grethe Iren A; Sandberg, Ellen; Øyaas, Jorun; Abrahamsen, Roger K

    2016-05-15

    The terpene content of milk and cream made from milk obtained from cows fed indoors, and by early or late grazing, in alpine rangeland farms in Norway, were analysed for three consecutive years. The main terpenes identified and semi-quantified were the monoterpenes β-pinene, α-pinene, α-thujene, camphene, sabinene, δ-3-carene, d-limonene, γ-terpinene, camphor, β-citronellene, and the sesquiterpene β-caryophyllene. The average total terpene content increased five times during the alpine rangeland feeding period. The terpenes α-thujene, sabinene, γ-terpinene and β-citronellene were only detected in milk and cultured cream from the alpine rangeland feeding period and not in samples from the indoors feeding period. These four terpenes could be used, as indicators, to show that milk and cultured cream originate from the alpine rangeland feeding period. The terpenes did not influence the sensorial quality of the milk or the cultured cream. PMID:26775961

  15. Phylogeographic patterns in Leccinum sect. Scabra and the status of the arctic/alpine species L. rotundifoliae

    NARCIS (Netherlands)

    Bakker, den H.C.; Zuccarello, G.C.; Kuyper, T.W.; Noordeloos, M.E.

    2007-01-01

    We investigated inter- and intraspecific phylogenetic relationships in the ectomycorrhizal fungal genus Leccinum section Scabra. Species of this section are exclusively associated with Betula and occur throughout the Northern Hemisphere. We compared the phylogenetic relationships of arctic, alpine,

  16. Plio-Pleistocene evolution of the north Alpine drainage system: new constraints from detrital thermochronology of foreland deposits

    Science.gov (United States)

    Reiter, Wolfgang; Elfert, Simon; Glotzbach, Christoph; Spiegel, Cornelia

    2015-04-01

    The evolution of drainage systems in and around active orogens may be strongly affected by climatic or tectonic processes. Information on the drainage evolution is stored in the sediments of the foreland depocentres. We investigated the provenance of two key deposits adjacent to the Central Alps, the Pliocene Sundgau gravels and the Pleistocene Höhere Deckenschotter by applying detrital thermochronology. Combined with provenance information from Rhine Graben deposits, we propose a reconstruction of the north Alpine drainage system since the middle Pliocene and discuss potential controlling mechanisms. Our data show that the Rhine Graben received detritus from the Alpine realm already during the Pliocene, indicating two different river systems—the proto-Rhine and the Aare-Doubs—draining the Alpine realm toward the North Sea and Mediterranean Sea. The investigated sediments contain detritus from two central Alpine sources, one showing a regional exhumational equilibrium and the other characterized by increasing exhumation rates. Discharge of the latter source ceased after ~2 Ma, reflecting a northward shift of the main Alpine drainage divide. Between ~2.0 and 1.2 Ma, the drainage system was affected by a major change, which we explain as resulting from a change in the Alpine stress field leading to tectonic exhumation and topography reduction in the area of the southern Aar massif. Generally, it seems that between ~4 and 1.2 Ma, the drainage system was mainly controlled by tectonic processes, despite first glaciations that already affected the north-Alpine foreland by ~2 Ma. The drainage system only seems to have reacted to the late Cenozoic climate changes after ~1.2 Ma, i.e., at the time of the most intense Alpine glaciation. At that time, the course of the Rhine River shifted toward the area of the Hegau volcanics, and the size of the Rhine River catchment became strongly reduced.

  17. Organic Farming and Social-Ecological Resilience: the Alpine Valleys of Sölktäler, Austria

    OpenAIRE

    Sonja K. Hadatsch; Rebecka Milestad

    2003-01-01

    Farming in the Austrian Alps is small in scale and involves a high degree of manual labor. In the face of structural changes in agriculture, alpine farms are finding it increasingly difficult to remain economically viable. Organic farming presents a promising alternative for alpine farmers because it receives considerable financial support under the Common Agricultural Policy of the European Union. Recent years have seen an increase in the number of organic farms in Austria in general, and in...

  18. Microsatellite diversity of the agriculturally important alpine grass Poa alpina in relation to land use and natural environment

    OpenAIRE

    Rudmann-Maurer, K; Weyand, A; Fischer, M.; STÖCKLIN, J.

    2007-01-01

    Background and Aims: The Alpine Meadow Grass Poa alpina is common in subalpine and alpine natural sites and agriculturally used land, where it is an important fodder grass. Natural factors and human land use are supposed to have been shaping its genetic diversity for hundreds of years. The species comprises sexually and vegetatively reproducing plants. The aim of this study was to investigate the effects of agricultural land use, environmental factors and the mode of reproduction on the distr...

  19. The relative age effect and the influence on performance in youth alpine ski racing.

    Science.gov (United States)

    Müller, Lisa; Hildebrandt, Carolin; Raschner, Christian

    2015-03-01

    The relative age effect (RAE), which refers to an over representation of athletes born early in a selection year, recently was proven to be present in alpine skiing. However, it was not made apparent whether the RAE exists as early as at the youngest level of youth ski racing at national level, nor whether the relative age influences racing performance. As a consequence, the purpose of the present study was twofold: first, to examine the extent of the RAE and second, to assess the influence the relative age has on the overall performance at the youngest levels of youth ski racing. The study included the investigation of 1,438 participants of the Austrian Kids Cup and 1,004 participants of the Teenager Cup at the provincial level, as well as 250 finalists of the Kids Cup and 150 finalists of the Teenager Cup at the national level. Chi²-tests revealed a highly significant RAE already at the youngest level of youth ski racing (Kids Cup) at both the provincial and national levels. There are not again favorably selected the relatively older athletes from the first into the second level of youth ski racing (Teenager Cup). Among the athletes of the Kids Cup, the relative age quarter distribution differed highly significantly from the distribution of the total sample with an over representation of relatively older athletes by comparison taking the top three positions. The data revealed that relative age had a highly significant influence on performance. This study demonstrated that the RAE poses a problem as early as the youngest level of youth ski racing, thereby indicating that many young talented kids are discriminated against, diminishing any chance they might have of becoming elite athletes despite their talents and efforts. The RAE influences not only the participation rate in alpine skiing, but also the performances. As a result, changes in the talent development system are imperative. Key pointsThe relative age influences not only the participation in youth ski

  20. Identification and climatology of Alpine pumping from a regional climate simulation

    Science.gov (United States)

    Graf, Maximilian; Kossmann, Meinolf; Trusilova, Kristina; Mühlbacher, Gudrun

    2016-02-01

    The thermally driven circulation between the European Alps and the alpine foreland - named Alpine pumping – occurs regularly under clear and calm weather conditions. While previous studies focused on the impact of Alpine pumping on moist convection and transport of air pollutants, this study was motivated by its ventilation effect for Munich, located about 50 km north of the Alps in undulating and only slightly inclined terrain, where local thermal circulations are weak. Hourly data from a reanalysis driven regional climate simulation with COSMO-CLM model for the period 1989 to 2008 were analysed to identify days with Alpine pumping and to determine the mean diurnal characteristics of this regional thermal circulation. Four literature derived combinations of meteorological criteria were tested to identify days favorable for Alpine pumping from COSMO-CLM results. The first criterion selects days with a daily sum of solar radiation ≥20 MJ/m2 and has been used in an earlier observational study. On average 60 d/y are fulfilling the criterion in the model simulation, which compares well to the 67 d/y determined from observations. The other three criteria combinations consider a maximum wind velocity at 850 hPa, a maximum daily precipitation sum, and/or a maximum mean cloud cover. The mean annual number of selected days is lower for these criteria combinations and ranges between 20 and 52. Diurnal wind reversals occur on 77 to 81% of the selected days, depending on the criteria combination The daily solar radiation sum of 20 MJ/m2 is only exceeded during April to September, while days satisfying the criteria combinations without the radiation threshold occur all year round. In agreement with observations, the simulated regional thermally driven wind field extends up to ~100 km north of the Alps with average near-surface wind speeds of 0.5-1.5 m/s in the Munich area. With increasing distance from the Alps, the diurnal cycle of Alpine pumping is delayed by up to 3

  1. The fluid budget of a continental plate boundary fault: Quantification from the Alpine Fault, New Zealand

    Science.gov (United States)

    Menzies, Catriona D.; Teagle, Damon A. H.; Niedermann, Samuel; Cox, Simon C.; Craw, Dave; Zimmer, Martin; Cooper, Matthew J.; Erzinger, Jörg

    2016-07-01

    Fluids play a key role in modifying the chemical and physical properties of fault zones, which may prime them for repeated rupture by the generation of high pore fluid pressures and precipitation of commonly weak, secondary minerals. Fluid flow paths, sources and fluxes, and the permeability evolution of fault zones throughout their seismic cycles remain poorly constrained, despite their importance to understanding fault zone behaviour. Here we use geochemical tracers of fluid-rock exchange to determine budgets for meteoric, metamorphic and mantle fluids on a major compressional tectonic plate boundary. The Alpine Fault marks the transpressional Pacific-Australian plate boundary through South Island, New Zealand and appears to fail in regular (329 ± 68 yrs) large earthquakes (Mw ∼ 8) with the most recent event in 1717 AD. Significant convergent motion has formed the Southern Alps and elevated geothermal gradients in the hangingwall, which drive crustal fluid flow. Along the Alpine Fault the Alpine Schist of the Pacific Plate is thrust over radiogenic metasedimentary rocks on the Australian plate. The absence of highly radiogenic (87Sr/86Sr > 0.7200) strontium isotope ratios of hangingwall hot springs and hydrothermal minerals formed at a range of depths in the Alpine Fault damage zone indicates that the fluid flow is restricted to the hangingwall by a cross-fault fluid flow barrier throughout the seismogenic crust. Helium isotope ratios measured in hot springs near to the Alpine Fault (0.15-0.81 RA) indicate the fault is a crustal-scale feature that acts as a conduit for fluids from the mantle. Rock-exchanged oxygen, but meteoric water-like hydrogen isotope signatures of hydrothermal veins indicate that partially rock-exchanged meteoric fluids dominate down to the top of the brittle to ductile transition zone at ∼6 km. Geochemical tracer transport modelling suggests only ∼0.02 to 0.05% of total rainfall west of the Main Divide penetrates to depth, yet this

  2. Nitrogen transformation in alpine soils of the Northern Caucasus: effect of nitrogen source and low temperatures

    Science.gov (United States)

    Makarov, Mikhail; Ermak, Anton; Malysheva, Tatiana; Mulyukova, Olga

    2010-05-01

    The alpine landscape supports a variety of plant communities whose distribution corresponds to their topographic position. Topography controls snow accumulation and hence soil winter temperature, length of growing season and soil water availability. The research was conducted at the Teberda Biosphere Reserve (Northern Caucasus, Russia). The study sites were located at Mt. Malaya Khatipara (43°27'N, 41°42'E) between 2700 and 2750 m a.s.l. The investigated toposequence was representative of the soil and plant community associations in the alpine zone of the Teberda Reserve: the wind-exposed ridges and upper slopes are covered by low-productive alpine lichen heaths; intermediate topographic positions are occupied by the most productive grasslands and meadows; the slope bottom is occupied by low-productive snowbed community. Under intensive snow cover accumulation typical for many alpine ecosystems, the temperature of soil within winter makes nearby 0 °C, while in case of absence or thin snow cover, characteristic for a lichen heath, the temperature can fall to -10 °C. The influence of nitrogen source, low temperatures and soil drying on processes of nitrogen mineralization, nitrification and plant/microbial immobilization was studied in the field and laboratory incubation experiments. 15N labeled ammonium, nitrate, glycine and aspartic acid were injected in situ before growth of aboveground biomass into the soil of lichen heath to investigate how the different nitrogen sources was subsequently utilized and cycled in the ecosystem. We analyzed the distribution of 15N between plants, soil microorganisms and different soil nitrogen compounds during all growing season in order to reveal differences for separate nitrogen sources. We concluded that the soil microorganisms were more efficient than plants in nitrogen uptake (especially amino acids) under natural conditions. In the laboratory, fresh and dry-rewetted soils of different alpine ecosystems were incubated at

  3. L’innovation au pluriel des cré-acteurs alpins

    Directory of Open Access Journals (Sweden)

    Andréa Finger-Stich

    2009-06-01

    Full Text Available La capacité d’innovation pour un développement durable des territoires alpins ne peut dépendre uniquement de conditions économiques, légales et politiques définies par les Etats aux échelles nationale et internationale. Elle dépend aussi de conditions locales, qui situent historiquement et géographiquement les acteurs dans une continuité de relations sociales et écologiques. Cette perspective accentue l’importance de la dimension collective, donc organisationnelle, du processus d’innovation, allant de l’imagination, puis au développement, à la réalisation – voire la diffusion – d’une nouvelle pratique. Le point de vue de cet article est qu’une innovation, pour contribuer au développement durable des Alpes, doit changer les relations écologique, politique, sociale et culturelle, qui engagent les acteurs du territoire. Ce changement affecte tant l’objet territoire que le sujet acteur du territoire. C’est pourquoi, innover dans les Alpes revient aussi à innover les Alpes et les acteurs alpins(Cosalp, 2008. Sur la base d’une recherche sur la participation des populations locales dans la gestion de forêts communales alpines, l’article relève l’importance des interactions locales impliquant les acteurs d’occupations, genres, âges et origines divers1.The capacity to innovate for a sustainable development of alpine territories cannot depend only on economic, legal and political conditions defined by the State at national and international levels. It depends also on local conditions that situate historically and geographically the actors in a continuity of social and ecological relationships. This approach highlights the collective - thus organisational - dimensions of the innovation process, including the imagination, the development, the implementation and even the diffusion of a new practice. Our point of view is that for contributing to the sustainable development of the Alps, innovations need to

  4. Alpine Warming induced Nitrogen Export from Green Lakes Valley, Colorado Front Range, USA

    Science.gov (United States)

    Barnes, R. T.; Williams, M. W.; Parman, J.

    2012-12-01

    Alpine ecosystems are particularly susceptible to disturbance due to their short growing seasons, sparse vegetation and thin soils. Atmospheric nitrogen deposition and warming temperatures currently affect Green Lakes Valley (GLV) within the Colorado Front Range. Research conducted within the alpine links chronic nitrogen inputs to a suite of ecological impacts, resulting in increased nitrate export. According to NADP records at the site, the atmospheric flux of nitrogen has decreased by 0.56 kg ha-1 yr-1 since 2000, due to a decrease in precipitation. Concurrent with this decrease, alpine nitrate yields have continued to increase; by 32% relative to the previous decade (1990-1999). In order to determine the source(s) of the sustained nitrate increases we utilized long term datasets to construct a mass balance model for four stream segments (glacier to subalpine) for nitrogen and weathering product constituents. We also compared geochemical fingerprints of various solute sources (glacial meltwater, thawing permafrost, snow, and stream water) to alpine stream water to determine if sources had changed over time. Long term trends indicate that in addition to increases in nitrate; sulfate, calcium, and silica have also increased over the same period. The geochemical composition of thawing permafrost (as indicated by rock glacial meltwater) suggests it is the source of these weathering products. Mass balance results indicate the high ammonium loads within glacial meltwater are rapidly nitrified, contributing approximately 0.45 kg yr-1 to the NO3- flux within the upper reaches of the watershed. The sustained export of these solutes during dry, summer months is likely facilitated by thawing cryosphere providing hydraulic connectivity late into the growing season. In a neighboring catchment, lacking permafrost and glacial features, there were no long term weathering or nitrogen solute trends; providing further evidence that the changes in alpine chemistry in GLV are likely

  5. Morphology and properties of the soils of permafrost peatlands in the southeast of the Bol'shezemel'skaya tundra

    Science.gov (United States)

    Kaverin, D. A.; Pastukhov, A. V.; Lapteva, E. M.; Biasi, C.; Marushchak, M.; Martikainen, P.

    2016-05-01

    The morphology and properties of the soils of permafrost peatlands in the southeast of the Bol'shezemel'skaya tundra are characterized. The soils developing in the areas of barren peat circles differ from oligotrophic permafrost-affected peat soils (Cryic Histosols) of vegetated peat mounds in a number of morphological and physicochemical parameters. The soils of barren circles are characterized by the wellstructured surface horizons, relatively low exchangeable acidity, and higher rates of decomposition and humification of organic matter. It is shown that the development of barren peat circles on tops of peat mounds is favored by the activation of erosional and cryogenic processes in the topsoil. The role of winter wind erosion in the destruction of the upper peat and litter horizons is demonstrated. A comparative analysis of the temperature regime of soils of vegetated peat mounds and barren peat circles is presented. The soil-geocryological complex of peat mounds is a system consisting of three major layers: seasonally thawing layer-upper permafrost-underlying permafrost. The upper permafrost horizons of peat mounds at the depth of 50-90 cm are morphologically similar to the underlying permafrost. However, these layers differ in their physicochemical properties, especially in the composition and properties of their organic matter.

  6. Complete genome sequence of Terriglobus saanensis type strain SP1PR4T, an Acidobacteria from tundra soil

    Energy Technology Data Exchange (ETDEWEB)

    Rawat, Suman R. [Rutgers University; Mannisto, Minna [Finnish Forest Research Institute, Parkano, Finland; Starovoytov, Valentin [Rutgers University; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Davenport, Karen W. [Los Alamos National Laboratory (LANL); Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Haggblom, Max [Rutgers University

    2012-01-01

    Terriglobus saanensis SP1PR4T is a novel species of the genus Terriglobus. T. saanensis is of ecological interest because it is a representative of the phylum Acidobacteria, which are dominant members of bacterial soil microbiota in Arctic ecosystems. T. saanensis is a cold-adapted acidophile and a versatile heterotroph utilizing a suite of simple sugars and complex polysaccharides. The genome contained an abundance of genes assigned to metabolism and transport of carbohydrates including gene modules encoding for carbohydrate-active enzyme (CAZyme) family involved in breakdown, utilization and biosynthesis of diverse structural and storage polysaccharides. T. saanensis SP1PR4T represents the first member of genus Terriglobus with a completed genome sequence, consisting of a single replicon of 5,095,226 base pairs (bp), 54 RNA genes and 4,279 protein-coding genes. We infer that the physiology and metabolic potential of T. saanensis is adapted to allow for resilience to the nutrient-deficient conditions and fluctuating temperatures of Arctic tundra soils.

  7. Spatial and temporal variation of bulk snow properties in northern boreal and tundra environments based on extensive field measurements

    Science.gov (United States)

    Hannula, Henna-Reetta; Lemmetyinen, Juha; Kontu, Anna; Derksen, Chris; Pulliainen, Jouni

    2016-08-01

    An extensive in situ data set of snow depth, snow water equivalent (SWE), and snow density collected in support of the European Space Agency (ESA) SnowSAR-2 airborne campaigns in northern Finland during the winter of 2011-2012 is presented (ESA Earth Observation Campaigns data 2000-2016). The suitability of the in situ measurement protocol to provide an accurate reference for the simultaneous airborne SAR (synthetic aperture radar) data products over different land cover types was analysed in the context of spatial scale, sample spacing, and uncertainty. The analysis was executed by applying autocorrelation analysis and root mean square difference (RMSD) error estimations. The results showed overall higher variability for all the three bulk snow parameters over tundra, open bogs and lakes (due to wind processes); however, snow depth tended to vary over shorter distances in forests (due to snow-vegetation interactions). Sample spacing/sample size had a statistically significant effect on the mean snow depth over all land cover types. Analysis executed for 50, 100, and 200 m transects revealed that in most cases less than five samples were adequate to describe the snow depth mean with RMSD community and can be applied to various snow studies.

  8. Inclusion of Additional Plant Species and Trait Information in Dynamic Vegetation Modeling of Arctic Tundra and Boreal Forest Ecosystem

    Science.gov (United States)

    Euskirchen, E. S.; Patil, V.; Roach, J.; Griffith, B.; McGuire, A. D.

    2015-12-01

    Dynamic vegetation models (DVMs) have been developed to model the ecophysiological characteristics of plant functional types in terrestrial ecosystems. They have frequently been used to answer questions pertaining to processes such as disturbance, plant succession, and community composition under historical and future climate scenarios. While DVMs have proved useful in these types of applications, it has often been questioned if additional detail, such as including plant dynamics at the species-level and/or including species-specific traits would make these models more accurate and/or broadly applicable. A sub-question associated with this issue is, 'How many species, or what degree of functional diversity, should we incorporate to sustain ecosystem function in modeled ecosystems?' Here, we focus on how the inclusion of additional plant species and trait information may strengthen dynamic vegetation modeling in applications pertaining to: (1) forage for caribou in northern Alaska, (2) above- and belowground carbon storage in the boreal forest and lake margin wetlands of interior Alaska, and (3) arctic tundra and boreal forest leaf phenology. While the inclusion of additional information generally proved valuable in these three applications, this additional detail depends on field data that may not always be available and may also result in increased computational complexity. Therefore, it is important to assess these possible limitations against the perceived need for additional plant species and trait information in the development and application of dynamic vegetation models.

  9. A more holistic understanding of soil organic matter pools of alpine and pre-alpine grassland soils in a changing climate

    Science.gov (United States)

    Garcia Franco, Noelia; Wiesmeier, Martin; Kiese, Ralf; Dannenmann, Michael; Wolf, Benjamin; Brandhuber, Robert; Beck, Robert; Kögel-Knabner, Ingrid

    2016-04-01

    In southern Germany, the alpine and pre-alpine grassland systems (> 1 Mio ha) provide an important economic value via fodder used for milk and meat production and grassland soils support environmental key functions (C and N storage, water retention, erosion control and biodiversity hot spot). In addition, these grassland soils constitute important regions for tourism and recreation. However, the different land use and management practices in this area introduce changes which are likely to accelerate due to climate change. The newly launched SUPSALPS project within the BonaRes Initiative of the German Ministry for Education and Research is focused on the development and evaluation of innovative grassland management strategies under climate change with an emphasis on soil functions, which are on the one hand environmental sustainable and on the other hand economically viable. Several field experiments of the project will be initialized in order to evaluate grassland soil functioning for a range of current and climate adapted management practices. A multi-factorial design combines ongoing and new plant-soil meso-/macrocosm and field studies at a multitude of existing long-term research sites along an elevation gradient in Bavaria. One of the specific objectives of the project is to improve our knowledge on the sensitivity of specific soil organic matter (SOM) fractions to climate change. Moreover, the project aims to determine the processes and mechanisms involved in the build-up and stabilization of C and N pools under different management practices. In order to derive sensitive SOM pools, a promising physical fractionation method was developed that enables the separation of five different SOM fractions by density, ultrasonication and sieving separation: fine particulate organic matter (fPOM), occluded particulate organic matter (oPOM>20μm and oPOM 20 μm; medium + fine silt and clay, < 20 μm). Methods to further characterize SOM (NMR, 13C and 15N stable isotopes

  10. PV plants for Alpine huts: Installation and operating experience at seven ENEL plants

    International Nuclear Information System (INIS)

    The problem of supplying electric power to isolated users far from the electricity distribution grid is one of general interest. Such consumers are nowadays generally supplied with electricity produced by small diesel generator-sets, and only recently have photovoltaic arrays and wind-turbines offered an alternative to the internal combustion engine. ENEL, as a State-owned electricity utility, is interested in the development of this particular application of renewable energy sources. Enlarging a low-voltage distribution network to connect consumers whose power requirements are extremely low (about 1000 kWh/year) may, in certain conditions, be uneconomical, both for the utility, which has to absorb most of the expense involved in construction and maintenance, and for the consumer himself. The paper reports the design criteria, the tests and the problems encountered in electrifying seven alpine huts belonging to CAI (Italian Alpine Club)

  11. INTERACT Management planning for arctic and northern alpine stations - Examples of good practices

    DEFF Research Database (Denmark)

    of the cornerstones in the INTERACT project is the exchange of station management practises between INTERACT station managers. Therefore INTERACT partners have identified topics of importance for station management and described good practises and lessons learned. The resulted in a book about management of arctic...... and northern alpine research stations. In this book station managers share their knowledge and experience gained frommanaging a set of very diverse research stations in very different environmental and climatic settings. The book covers issues like management planning, policies, permit issues, handling...... of visitors, outreach, science plans, data management and education. The target audience for the book is mainly managers of research stations in arctic and alpine areas, but it is our hope that it will also be a useful tool for others being involved in science coordination and logistics....

  12. Integrating RapidEye and ancillary data to map alpine habitats in South Tyrol, Italy

    Science.gov (United States)

    Polychronaki, Anastasia; Spindler, Nadine; Schmidt, Alexander; Stoinschek, Barbara; Zebisch, Marc; Renner, Kathrin; Sonnenschein, Ruth; Notarnicola, Claudia

    2015-05-01

    In this paper, we present a two-stage method for mapping habitats using Earth observation (EO) data in three Alpine sites in South Tyrol, Italy. The first stage of the method was the classification of land cover types using multi-temporal RapidEye images and support vector machines (SVMs). The second stage involved reclassification of the land cover types to habitat types following a rule-based spatial kernel. The highest accuracies in land cover classification were 95.1% overall accuracy, 0.94 kappa coefficient and 4.9% overall disagreement. These accuracies were obtained when the combination of images with topographic parameters and homogeneity texture was used. The habitat classification accuracies were rather moderate due to the broadly defined rules and possible inaccuracies in the reference map. Overall, our proposed methodology could be implemented to map cost-effectively alpine habitats over large areas and could be easily adapted to map other types of habitats.

  13. Responses of sequential and hierarchical phenological events to warming and cooling in alpine meadows.

    Science.gov (United States)

    Li, Xine; Jiang, Lili; Meng, Fandong; Wang, Shiping; Niu, Haishan; Iler, Amy M; Duan, Jichuan; Zhang, Zhenhua; Luo, Caiyun; Cui, Shujuan; Zhang, Lirong; Li, Yaoming; Wang, Qi; Zhou, Yang; Bao, Xiaoying; Dorji, Tsechoe; Li, Yingnian; Peñuelas, Josep; Du, Mingyuan; Zhao, Xinquan; Zhao, Liang; Wang, Guojie

    2016-01-01

    Organisms' life cycles consist of hierarchical stages, from a single phenological stage (for example, flowering within a season), to vegetative and reproductive phases, to the total lifespan of the individual. Yet phenological events are typically studied in isolation, limiting our understanding of life history responses to climate change. Here, we reciprocally transfer plant communities along an elevation gradient to investigate plastic changes in the duration of sequential phenological events for six alpine species. We show that prolonged flowering leads to longer reproductive phases and activity periods when plants are moved to warmer locations. In contrast, shorter post-fruiting leaf and flowering stages led to shorter vegetative and reproductive phases, respectively, which resulted in shorter activity periods when plants were moved to cooler conditions. Therefore, phenological responses to warming and cooling do not simply mirror one another in the opposite direction, and low temperature may limit reproductive allocation in the alpine region. PMID:27535205

  14. Impacts of extreme air temperatures on cyanobacteria in five deep peri-Alpine lakes

    OpenAIRE

    Nicole GALLINA; Anneville, Orlane; Beniston, Martin

    2011-01-01

    Cyanobacteria are of major interest in freshwater ecosystems, since they are able to produce toxins with potentially negative impacts on the environment, health and thus on economics and society. It is therefore important for water management authorities to assess the manner in which cyanobacteria may evolve under climate change, especially in the Alpine Region where warming is projected by climate models to be more important than the global average. In this study, air temperature extremes un...

  15. Effects of Climate Change on Habitat Availability and Configuration for an Endemic Coastal Alpine Bird

    OpenAIRE

    Jackson, Michelle M.; Gergel, Sarah E.; Kathy Martin

    2015-01-01

    North America's coastal mountains are particularly vulnerable to climate change, yet harbour a number of endemic species. With little room "at the top" to track shifting climate envelopes, alpine species may be especially negatively affected by climate-induced habitat fragmentation. We ask how climate change will affect the total amount, mean patch size, and number of patches of suitable habitat for Vancouver Island White-tailed Ptarmigan (Lagopus leucura saxatilis; VIWTP), a threatened, ende...

  16. Methanotrophic and Methanogenic Communities in Swiss Alpine Fens Dominated by Carex rostrata and Eriophorum angustifolium

    OpenAIRE

    Cheema, Simrita; Zeyer, Josef; Henneberger, Ruth

    2015-01-01

    Vascular plants play a key role in controlling CH4 emissions from natural wetlands, because they influence CH4 production, oxidation, and transport to the atmosphere. Here we investigated differences in the abundance and composition of methanotrophic and methanogenic communities in three Swiss alpine fens dominated by different vascular plant species under natural conditions. The sampling locations either were situated at geographically distinct sites with different physicochemical properties...

  17. Soil organic carbon storage and soil CO2 flux in the alpine meadow ecosystem

    Institute of Scientific and Technical Information of China (English)

    TAO Zhen; SHEN ChengDe; GAO QuanZhou; SUN YanMin; YI WeiXi; LI YingNian

    2007-01-01

    High-resolution sampling, measurements of organic carbon contents and 14C signatures of selected four soil profiles in the Haibei Station situated on the northeast Tibetan Plateau, and application of 14C tracing technology were conducted in an attempt to investigate the turnover times of soil organic carbon and the soil-CO2 flux in the alpine meadow ecosystem. The results show that the organic carbon stored in the soils varies from 22.12(104 kg C hm-2 to 30.75(104 kg C hm-2 in the alpine meadow ecosystems, with an average of 26.86(104 kg C hm-2. Turnover times of organic carbon pools increase with depth from 45 a to 73 a in the surface soil horizon to hundreds of years or millennia or even longer at the deep soil horizons in the alpine meadow ecosystems. The soil-CO2 flux ranges from 103.24 g C m-2 a-1 to 254.93 gC m-2 a-1, with an average of 191.23 g C m-2 a-1. The CO2 efflux produced from microbial decomposition of organic matter varies from 73.3 g C m-2 a-1 to 181 g C m-2 a-1. More than 30% of total soil organic carbon resides in the active carbon pool and 72.8%-81.23% of total CO2 emitted from organic matter decomposition results from the topsoil horizon (from 0 cm to 10 cm) for the Kobresia meadow. Responding to global warming, the storage, volume of flow and fate of the soil organic carbon in the alpine meadow ecosystem of the Tibetan Plateau will be changed, which needs further research.

  18. Seismic site characterization for the Deep-Fault-Drilling-Project Alpine Fault

    Science.gov (United States)

    Glomb, Vera; Buske, Stefan; Kovacs, Adrienn; Gorman, Andrew

    2013-04-01

    The Alpine Fault in New Zealand (South Island) is one of the largest active plate-bounding continental fault zones on earth with earthquakes of magnitude 7.9 occuring every 200-400 years. Due to the surface exposure and the shallow depth of mechanical and chemical transitions it is a globally significant natural laboratory. Within the ICDP Deep-Fault-Drilling-Project Alpine Fault (DFDP-AF; https://wiki.gns.cri.nz/DFDP) a drill hole shall give insight into the geological structure of the fault zone and its evolution to understand the related deformation and earthquake processes. With the help of advanced seismic imaging techniques the shallow structure of the Alpine Fault is imaged to find the most suitable drill site location. A new seismic reflection profile has been acquired in 2011 by the WhataDUSIE project team consisting of partners from the University of Otago (New Zealand), TU Bergakademie Freiberg (Germany) and the University of Alberta (Canada). The reflection profile, located in the Whataroa river valley, has a total length of about 5 km. Up to 643 geophones with spacings between 4-8 m recorded the approximately 100 shot points along the profile line. Single shot gathers as well as preliminary imaging results will be presented. The high-quality data show various indicators of the Alpine Fault such as strong reflections and distorted first-arrival wavefields which are clearly visible already in single shot gathers. With the help of high resolution seismic images we can study the shallow structures of the subsurface thus gaining information about the location and dip of reflectors. Further detailed processing and intensive interpretative work will enable a seismic site characterization providing important information for the selection of the borehole location. Additionally the high resolution seismic images themselves allow a better understanding of the tectonic and geodynamic settings.

  19. Seasonal Dynamics of Water Use Strategy of Two Salix Shrubs in Alpine Sandy Land, Tibetan Plateau.

    Directory of Open Access Journals (Sweden)

    Yajuan Zhu

    Full Text Available Water is a limiting factor for plant growth and vegetation dynamics in alpine sandy land of the Tibetan Plateau, especially with the increasing frequency of extreme precipitation events and drought caused by climate change. Therefore, a relatively stable water source from either deeper soil profiles or ground water is necessary for plant growth. Understanding the water use strategy of dominant species in the alpine sandy land ecosystem is important for vegetative rehabilitation and ecological restoration. The stable isotope methodology of δD, δ18O, and δ13C was used to determine main water source and long-term water use efficiency of Salix psammophila and S. cheilophila, two dominant shrubs on interdune of alpine sandy land in northeastern Tibetan Plateau. The root systems of two Salix shrubs were investigated to determine their distribution pattern. The results showed that S. psammophila and S. cheilophila absorbed soil water at different soil depths or ground water in different seasons, depending on water availability and water use strategy. Salix psammophila used ground water during the growing season and relied on shallow soil water recharged by rain in summer. Salix cheilophila used ground water in spring and summer, but relied on shallow soil water recharged by rain in spring and deep soil water recharged by ground water in fall. The two shrubs had dimorphic root systems, which is coincident with their water use strategy. Higher biomass of fine roots in S. psammophila and longer fine roots in S. cheilophila facilitated to absorb water in deeper soil layers. The long-term water use efficiency of two Salix shrubs increased during the dry season in spring. The long-term water use efficiency was higher in S. psammophila than in S. cheilophila, as the former species is better adapted to semiarid climate of alpine sandy land.

  20. Seasonal Dynamics of Water Use Strategy of Two Salix Shrubs in Alpine Sandy Land, Tibetan Plateau.

    Science.gov (United States)

    Zhu, Yajuan; Wang, Guojie; Li, Renqiang

    2016-01-01

    Water is a limiting factor for plant growth and vegetation dynamics in alpine sandy land of the Tibetan Plateau, especially with the increasing frequency of extreme precipitation events and drought caused by climate change. Therefore, a relatively stable water source from either deeper soil profiles or ground water is necessary for plant growth. Understanding the water use strategy of dominant species in the alpine sandy land ecosystem is important for vegetative rehabilitation and ecological restoration. The stable isotope methodology of δD, δ18O, and δ13C was used to determine main water source and long-term water use efficiency of Salix psammophila and S. cheilophila, two dominant shrubs on interdune of alpine sandy land in northeastern Tibetan Plateau. The root systems of two Salix shrubs were investigated to determine their distribution pattern. The results showed that S. psammophila and S. cheilophila absorbed soil water at different soil depths or ground water in different seasons, depending on water availability and water use strategy. Salix psammophila used ground water during the growing season and relied on