WorldWideScience

Sample records for climatic conditions vegetation

  1. Global vegetation-fire pattern under different land use and climate conditions

    Science.gov (United States)

    Thonicke, K.; Poulter, B.; Heyder, U.; Gumpenberger, M.; Cramer, W.

    2008-12-01

    Fire is a process of global significance in the Earth System influencing vegetation dynamics, biogeochemical cycling and biophysical feedbacks. Naturally ignited wildfires have long history in the Earth System. Humans have been using fire to shape the landscape for their purposes for many millenia, sometimes influencing the status of the vegetation remarkably as for example in Mediterranean-type ecosystems. Processes and drivers describing fire danger, ignitions, fire spread and effects are relatively well-known for many fire-prone ecosystems. Modeling these has a long tradition in fire-affected regions to predict fire risk and behavior for fire-fighting purposes. On the other hand, the global vegetation community realized the importance of disturbances to be recognized in their global vegetation models with fire being globally most important and so-far best studied. First attempts to simulate fire globally considered a minimal set of drivers, whereas recent developments attempt to consider each fire process separately. The process-based fire model SPITFIRE (SPread and InTensity of FIRE) simulates these processes embedded in the LPJ DGVM. Uncertainties still arise from missing measurements for some parameters in less-studied fire regimes, or from broad PFT classifications which subsume different fire-ecological adaptations and tolerances. Some earth observation data sets as well as fire emission models help to evaluate seasonality and spatial distribution of simulated fire ignitions, area burnt and fire emissions within SPITFIRE. Deforestation fires are a major source of carbon released to the atmosphere in the tropics; in the Amazon basin it is the second-largest contributor to Brazils GHG emissions. How ongoing deforestation affects fire regimes, forest stability and biogeochemical cycling in the Amazon basin under present climate conditions will be presented. Relative importance of fire vs. climate and land use change is analyzed. Emissions resulting from

  2. Changes in climatic conditions, vegetation cover and erosion during the Holocene in southeast Spain

    Energy Technology Data Exchange (ETDEWEB)

    Bellin, N.; Vanacker, V.

    2009-07-01

    The present-day landscape in Southeast Spain is the result of a long occupation history. To have a better understanding of the impact of human societies on soil degradation, we analysed the main shifts in vegetation cover, climate and human occupation for the last 12000 years. Our analyses use recently published information from continental and marine pollen series. The data suggest that climatic factors appear to be important driving factors of vegetation degradation induced by an increased aridity that is already recorded at about 5000 years ago. (Author) 19 refs.

  3. Changes in climatic conditions, vegetation cover and erosion during the Holocene in southeast Spain

    International Nuclear Information System (INIS)

    Bellin, N.; Vanacker, V.

    2009-01-01

    The present-day landscape in Southeast Spain is the result of a long occupation history. To have a better understanding of the impact of human societies on soil degradation, we analysed the main shifts in vegetation cover, climate and human occupation for the last 12000 years. Our analyses use recently published information from continental and marine pollen series. The data suggest that climatic factors appear to be important driving factors of vegetation degradation induced by an increased aridity that is already recorded at about 5000 years ago. (Author) 19 refs.

  4. Simulating the vegetation response in western Europe to abrupt climate changes under glacial background conditions

    Directory of Open Access Journals (Sweden)

    M.-N. Woillez

    2013-03-01

    Full Text Available The last glacial period has been punctuated by two types of abrupt climatic events, the Dansgaard–Oeschger (DO and Heinrich (HE events. These events, recorded in Greenland ice and in marine sediments, involved changes in the Atlantic Meridional Overturning Circulation (AMOC and led to major changes in the terrestrial biosphere. Here we use the dynamical global vegetation model ORCHIDEE to simulate the response of vegetation to abrupt changes in the AMOC strength. We force ORCHIDEE offline with outputs from the IPSL_CM4 general circulation model, in which the AMOC is forced to change by adding freshwater fluxes in the North Atlantic. We investigate the impact of a collapse and recovery of the AMOC, at different rates, and focus on Western Europe, where many pollen records are available for comparison. The impact of an AMOC collapse on the European mean temperatures and precipitations simulated by the GCM is relatively small but sufficient to drive an important regression of forests and expansion of grasses in ORCHIDEE, in qualitative agreement with pollen data for an HE event. On the contrary, a run with a rapid shift of the AMOC to a hyperactive state of 30 Sv, mimicking the warming phase of a DO event, does not exhibit a strong impact on the European vegetation compared to the glacial control state. For our model, simulating the impact of an HE event thus appears easier than simulating the abrupt transition towards the interstadial phase of a DO. For both a collapse or a recovery of the AMOC, the vegetation starts to respond to climatic changes immediately but reaches equilibrium about 200 yr after the climate equilibrates, suggesting a possible bias in the climatic reconstructions based on pollen records, which assume equilibrium between climate and vegetation. However, our study does not take into account vegetation feedbacks on the atmosphere.

  5. Desertification in 1957-2015 Estimated from Vegetation Coverage and Climate Conditions on the Tibetan Plateau

    Science.gov (United States)

    Cuo, L.

    2017-12-01

    Desert is an area that receives less than 25 cm precipitation in cold climate or 50 cm precipitation in hot climate (Miller, 1961). Others defined true desert as a region having no recorded precipitation in 12 consecutive months (McGinnies et al., 1968). According to Koppen-Gieger climate classification system, if mean annual precipitation is less than 50% of the value A calculated by mean annual temperature times 20 plus 280 if 70% or more precipitation falls in April-September, the region has desert climate; if the mean annual precipitation is within 50%-100% of the value A, the region has semi-arid or steppe climate. On the Tibetan Plateau, the above definitions will result in no desert at all or the majority of the region falling into the category of desert which is not consistent with reality based on field exploration. In this study, the fractional vegetation coverage (FPC), precipitation, soil moisture and extreme wind days are used as indices to define areas of various degrees of desertification which produces much more realistic distribution of desert areas on the plateau. The Lund-Potsdam-Jena Dynamic Vegetation model (LPJ) is used to simulate vegetation growth, succession and vegetation properties such as FPC and soil moisture on the Tibetan Plateau. Gridded daily climate data are generated to drive the model and to analyze the status and changes of various deserts including light desert, medium desert, severe desert, extremely severe desert and desert proned area. The study will reveal the status and changes of possible driving factors of desertification, as well as various kinds of desert on the Tibetan Plateau during 1957-2015.

  6. Investigation the Frost Resistance of Vegetative and Reproductive Buds of Pear Cultivars in Mashhad Climate Condition

    Directory of Open Access Journals (Sweden)

    shadan khorshidi

    2017-09-01

    Full Text Available Introduction: Most deciduous trees need low temperature to break flower bud dormancy. One of the most important abiotic stresses is low temperature which limits production of temperate fruits. Pear production has been considerably reduced in recent years. Important pear cultivars show different levels of resistance to cold. Cold compatibility followed by resistance increase is controlled genetically and contains several mechanisms which lead to production of different metabolites such as: polypeptides, amino acids and sugars. The object of this research was to evaluate the frost resistance of different ‘Dare Gazi’ genotypes and other pear cultivars in Mashhad climate condition. Materials and Methods: This study was conducted to investigate the frost resistance of 23 ‘Dare Gazi’ pear genotypes and nine other cultivars include: ‘William’s’, ‘Bell de june’, ‘Spadona’, ‘Koshia’, ‘Domkaj’, ‘Torsh’, ‘Sebri’ and ‘Tabrizi’. Plant material contained vegetative and reproductive buds of one-year-old shoot samples which were collected from 25-year old trees on March 2014, four days after winter cold (-6.6 °C in three directions of trees and sent to the laboratory. Frost damages of vegetative and reproductive buds were investigated based on visual observations (%, electrolyte leakage (EC and proline content. EC was measured with a Metrohm 644 digital conductivity meter and proline content was measured based on Bates et al. (1973 method, using acid ninhydrin. The experiment was performed on completely randomized experimental design with three replications. Statistical analysis was carried out using MSTAT-C and Excel software. Mean values were compared using the least significance difference test (LSD at 1% levels. Cluster analysis was conducted by SPSS 16 program. Results and Discussion: Highest EC of reproductive buds was observed in ‘Dare Gazi’ 10, 19, ‘Tabrizi’ and ‘Torsh’ whereas ‘Dare Gazi’ 8, 18

  7. Burial of downed deadwood is strongly affected by log attributes, forest ground vegetation, edaphic conditions, and climate zones

    Science.gov (United States)

    Jogeir N. Stokland; Christopher W. Woodall; Jonas Fridman; Göran Ståhl

    2016-01-01

    Deadwood can represent a substantial portion of forest ecosystem carbon stocks and is often reported following good practice guidance associated with national greenhouse gas inventories. In high-latitude forest ecosystems, a substantial proportion of downed deadwood is overgrown by ground vegetation and buried in the humus layer. Such burial obfuscates the important...

  8. A contribution to the thermal and aero-dynamical modelling of the urban micro-climate. Analysis of the water and vegetation impact on the comfort conditions in outdoor spaces; Contribution a la modelisation thermo-aeraulique du microclimat urbain. Caracterisation de l'impact de l'eau et de la vegetation sur les conditions de confort en espaces exterieurs

    Energy Technology Data Exchange (ETDEWEB)

    Vinet, J.

    2000-11-01

    In summer, temperatures in cities may rise, thereby inducing the so-called 'urban heat island' and tremendous consequences on outdoor comfort, health risks, pollutant emission and energy consumption. Replacing vegetation and moist surfaces by concrete or asphalt may enhance these problems. Therefore, the aim of this thesis is to quantify the impact of vegetation and water on urban micro-climate and comfort through numerical modelling; In the first part, a scientific literature review considers various topics applied to our problem such as urban micro-climate, simulations, urbanism, urban forestry and outdoor thermal comfort. This information is relevant to define and interpret further numerical modelling. Numerical simulations based on the coupling of the SOLENE. thermal program and the N3S CFD code are proposed to model wind flow, air and surface temperatures. The theoretical principles, hypothesis and coupling methodology are presented here. This set of numerical tools is combined in order to help urban or landscape planners, architects and engineers, to analyse the impacts of different projects on micro-climate and on outdoor thermal comfort, under hot summer conditions. To illustrate this approach, an open space in Montpellier (southern France) called the 'Place du Millenaire' and designed by Ricardo Bofill is studied, considering various cases (no vegetation, actual vegetation and vegetation in 30 years). The comparative results demonstrate improvements of urban form, micro-climate and outdoor thermal comfort. (author)

  9. Atmosphere-vegetation-soil interactions in a climate change context; Impact of changing conditions on engineered transport infrastructure slopes in Europe

    NARCIS (Netherlands)

    Tang, A.M.; Hughes, P.N.; Dijkstra, T.A.; Askarinejad, A.; Brenčič, M.; Cui, Y.J.; Diez, J.J.; Firgi, T.; Gajewska, B.; Gentile, F.; Grossi, G.; Jommi, C.; Kehagia, F.; Koda, E.; Maat, Ter H.W.; Lenart, S.; Lourenco, S.; Oliveira, M.; Osinski, P.; Springman, S.M.; Stirling, R.; Toll, D.G.; Beek, Van V.

    2018-01-01

    In assessing the impact of climate change on infrastructure, it is essential to consider the interactions between the atmosphere, vegetation and the near-surface soil. This paper presents an overview of these processes, focusing on recent advances from the literature and those made by members of

  10. Vegetation index anomaly response to varying lengths of drought across vegetation and climatic gradients in Hawaii

    Science.gov (United States)

    Lucas, M.; Miura, T.; Trauernicht, C.; Frazier, A. G.

    2017-12-01

    A drought which results in prolonged and extended deficit in naturally available water supply and creates multiple stresses across ecosystems is classified as an ecological drought. Detecting and understanding the dynamics and response of such droughts in tropical systems, specifically across various vegetation and climatic gradients is fairly undetermined, yet increasingly important for better understandings of the ecological effects of drought. To understanding the link between what lengths and intensities of known meteorological drought triggers detectable ecological vegetation responses, a landscape scale regression analysis evaluating the response (slope) and relationship strength (R-squared) of several cumulative SPI (standard precipitation index) lengths(1, 3, 6, 12, 18, 24, 36, 48, and 60 month), to various satellite derived monthly vegetation indices anomalies (NDVI, EVI, EVI2, and LSWI) was performed across a matrix of dominant vegetation covers (grassland, shrubland, and forest) and climatic moisture zones (arid, dry, mesic, and wet). The nine different SPI lags across these climactic and vegetation gradients was suggest that stronger relationships and steeper slopes were found in dryer climates (across all vegetation covers) and finer vegetation types (across all moisture zones). Overall NDVI, EVI and EVI2 showed the best utility in these dryer climatic zones across all vegetation types. Within arid and dry areas "best" fits showed increasing lengths of cumulative SPI were with increasing vegetation coarseness respectively. Overall these findings suggest that rainfall driven drought may have a stronger impact on the ecological condition of vegetation in water limited systems with finer vegetation types ecologically responding more rapidly to meteorological drought events than coarser woody vegetation systems. These results suggest that previously and newly documented trends of decreasing rainfall and increasing drought in Hawaiian drylands may have

  11. Plant functional diversity affects climate-vegetation interaction

    Science.gov (United States)

    Groner, Vivienne P.; Raddatz, Thomas; Reick, Christian H.; Claussen, Martin

    2018-04-01

    We present how variations in plant functional diversity affect climate-vegetation interaction towards the end of the African Humid Period (AHP) in coupled land-atmosphere simulations using the Max Planck Institute Earth system model (MPI-ESM). In experiments with AHP boundary conditions, the extent of the green Sahara varies considerably with changes in plant functional diversity. Differences in vegetation cover extent and plant functional type (PFT) composition translate into significantly different land surface parameters, water cycling, and surface energy budgets. These changes have not only regional consequences but considerably alter large-scale atmospheric circulation patterns and the position of the tropical rain belt. Towards the end of the AHP, simulations with the standard PFT set in MPI-ESM depict a gradual decrease of precipitation and vegetation cover over time, while simulations with modified PFT composition show either a sharp decline of both variables or an even slower retreat. Thus, not the quantitative but the qualitative PFT composition determines climate-vegetation interaction and the climate-vegetation system response to external forcing. The sensitivity of simulated system states to changes in PFT composition raises the question how realistically Earth system models can actually represent climate-vegetation interaction, considering the poor representation of plant diversity in the current generation of land surface models.

  12. Past and future effects of climate change on spatially heterogeneous vegetation activity in China

    Science.gov (United States)

    Gao, Jiangbo; Jiao, Kewei; Wu, Shaohong; Ma, Danyang; Zhao, Dongsheng; Yin, Yunhe; Dai, Erfu

    2017-07-01

    Climate change is a major driver of vegetation activity but its complex ecological relationships impede research efforts. In this study, the spatial distribution and dynamic characteristics of climate change effects on vegetation activity in China from the 1980s to the 2010s and from 2021 to 2050 were investigated using a geographically weighted regression (GWR) model. The GWR model was based on combined datasets of satellite vegetation index, climate observation and projection, and future vegetation productivity simulation. Our results revealed that the significantly positive precipitation-vegetation relationship was and will be mostly distributed in North China. However, the regions with temperature-dominated distribution of vegetation activity were and will be mainly located in South China. Due to the varying climate features and vegetation cover, the spatial correlation between vegetation activity and climate change may be altered. There will be different dominant climatic factors for vegetation activity distribution in some regions such as Northwest China, and even opposite correlations in Northeast China. Additionally, the response of vegetation activity to precipitation will move southward in the next three decades. In contrast, although the high warming rate will restrain the vegetation activity, precipitation variability could modify hydrothermal conditions for vegetation activity. This observation is exemplified in the projected future enhancement of vegetation activity in the Tibetan Plateau and weakened vegetation activity in East and Middle China. Furthermore, the vegetation in most parts of North China may adapt to an arid environment, whereas in many southern areas, vegetation will be repressed by water shortage in the future.

  13. Simulations of Vegetation Impacts on Arctic Climate

    Science.gov (United States)

    Bonfils, C.; Phillips, T. J.; Riley, W. J.; Post, W. M.; Torn, M. S.

    2009-12-01

    Because global warming disproportionately influences high-latitude climate, changes in arctic vegetation are in progress. These land-cover changes include redistribution of local vegetation types as well as northward migration of lower-latitude species in response to the increasing warming. The resulting displacement of low-lying tundra vegetation by shrubs and trees darkens the surface, thus accelerating regional warming. As participants in the U.S. Department of Energy IMPACTS Project, we are investigating the potential for abrupt arctic climatic change resulting from such variations in vegetation, among other mechanisms. To estimate the relative magnitudes of effects to be expected from changes in high-latitude land cover, we are conducting several numerical experiments with the Community Climate System Model (CCSM). These experiments include: 1) A “present-day-climate” control experiment with current atmospheric greenhouse-gas concentrations and climatological monthly sea surface temperatures and sea ice extents prescribed, and with “standard” CLM plant functional types (PFTs) specified; 2) A “changed-vegetation-type” experiment that is the same as 1), except that the “standard” PFTs are augmented by additional vegetation types (forbs, sedges, shrubs, mosses, and lichens) that are not presently represented in CLM. This experiment will require information on the location, fractional cover, and physiological parameterizations of these new PFTs. 3) A “changed-vegetation-extent experiment” that is the same as 2), except that the spatial extents of selected PFTs (e.g. shrubs or boreal forest PFTs) are shifted northward from their present locations in the CLM. We will report on the atmospheric climate and land-surface feedbacks associated with these vegetation changes, with emphasis on local and regional surface energy and moisture fluxes and near-surface temperature, humidity, and clouds. Acknowledgments This work was performed under the auspices

  14. Vegetation-climate feedbacks modulate rainfall patterns in Africa under future climate change

    Science.gov (United States)

    Wu, Minchao; Schurgers, Guy; Rummukainen, Markku; Smith, Benjamin; Samuelsson, Patrick; Jansson, Christer; Siltberg, Joe; May, Wilhelm

    2016-07-01

    Africa has been undergoing significant changes in climate and vegetation in recent decades, and continued changes may be expected over this century. Vegetation cover and composition impose important influences on the regional climate in Africa. Climate-driven changes in vegetation structure and the distribution of forests versus savannah and grassland may feed back to climate via shifts in the surface energy balance, hydrological cycle and resultant effects on surface pressure and larger-scale atmospheric circulation. We used a regional Earth system model incorporating interactive vegetation-atmosphere coupling to investigate the potential role of vegetation-mediated biophysical feedbacks on climate dynamics in Africa in an RCP8.5-based future climate scenario. The model was applied at high resolution (0.44 × 0.44°) for the CORDEX-Africa domain with boundary conditions from the CanESM2 general circulation model. We found that increased tree cover and leaf-area index (LAI) associated with a CO2 and climate-driven increase in net primary productivity, particularly over subtropical savannah areas, not only imposed important local effect on the regional climate by altering surface energy fluxes but also resulted in remote effects over central Africa by modulating the land-ocean temperature contrast, Atlantic Walker circulation and moisture inflow feeding the central African tropical rainforest region with precipitation. The vegetation-mediated feedbacks were in general negative with respect to temperature, dampening the warming trend simulated in the absence of feedbacks, and positive with respect to precipitation, enhancing rainfall reduction over the rainforest areas. Our results highlight the importance of accounting for vegetation-atmosphere interactions in climate projections for tropical and subtropical Africa.

  15. Tropical climate and vegetation cover during Heinrich event 1: Simulations with coupled climate vegetation models

    OpenAIRE

    Handiani, Dian Noor

    2012-01-01

    This study focuses on the climate and vegetation responses to abrupt climate change in the Northern Hemisphere during the last glacial period. Two abrupt climate events are explored: the abrupt cooling of the Heinrich event 1 (HE1), followed by the abrupt warming of the Bølling-Allerød interstadial (BA). These two events are simulated by perturbing the freshwater balance of the Atlantic Ocean, with the intention of altering the Atlantic Meridional Overturning Circulation (AMOC) and also of in...

  16. Determining Thermal Specifications for Vegetated GREEN Roofs in Moderate Winter Climats

    NARCIS (Netherlands)

    Dr. Christoph Maria Ravesloot

    2015-01-01

    Because local weather conditions in moderate climates are changing constantly, heat transfer specifications of substrate and vegetation in vegetated green roofs also change accordingly. Nevertheless, it is assumed that vegetated green roofs can have a positive effect on the thermal performance of

  17. Quantifying How Climate Affects Vegetation in the Amazon Rainforest

    Science.gov (United States)

    Das, K.; Kodali, A.; Szubert, M.; Ganguly, S.; Bongard, J.

    2016-12-01

    Amazon droughts in 2005 and 2010 have raised serious concern about the future of the rainforest. Amazon forests are crucial because of their role as the largest carbon sink in the world which would effect the global warming phenomena with decreased photosynthesis activity. Especially, after a decline in plant growth in 1.68 million km2 forest area during the once-in-a-century severe drought in 2010, it is of primary importance to understand the relationship between different climatic variables and vegetation. In an earlier study, we have shown that non-linear models are better at capturing the relation dynamics of vegetation and climate variables such as temperature and precipitation, compared to linear models. In this research, we learn precise models between vegetation and climatic variables (temperature, precipitation) for normal conditions in the Amazon region using genetic programming based symbolic regression. This is done by removing high elevation and drought affected areas and also considering the slope of the region as one of the important factors while building the model. The model learned reveals new and interesting ways historical and current climate variables affect the vegetation at any location. MAIAC data has been used as a vegetation surrogate in our study. For temperature and precipitation, we have used TRMM and MODIS Land Surface Temperature data sets while learning the non-linear regression model. However, to generalize the model to make it independent of the data source, we perform transfer learning where we regress a regularized least squares to learn the parameters of the non-linear model using other data sources such as the precipitation and temperature from the Climatic Research Center (CRU). This new model is very similar in structure and performance compared to the original learned model and verifies the same claims about the nature of dependency between these climate variables and the vegetation in the Amazon region. As a result of this

  18. Last Glacial vegetation and climate change in the southern Levant

    Science.gov (United States)

    Miebach, Andrea; Chen, Chunzhu; Litt, Thomas

    2015-04-01

    Reconstructing past climatic and environmental conditions is a key task for understanding the history of modern mankind. The interaction between environmental change and migration processes of the modern Homo sapiens from its source area in Africa into Europe is still poorly understood. The principal corridor of the first human dispersal into Europe and also later migration dynamics crossed the Middle East. Therefore, the southern Levant is a key area to investigate the paleoenvironment during times of human migration. In this sense, the Last Glacial (MIS 4-2) is particularly interesting to investigate for two reasons. Firstly, secondary expansions of the modern Homo sapiens are expected to occur during this period. Secondly, there are ongoing discussions on the environmental conditions causing the prominent lake level high stand of Lake Lisan, the precursor of the Dead Sea. This high stand even culminated in the merging of Lake Lisan and Lake Kinneret (Sea of Galilee). To provide an independent proxy for paleoenvironmental reconstructions in the southern Levant during the Last Glacial, we investigated pollen assemblages of the Dead Sea/Lake Lisan and Lake Kinneret. Located at the Dead Sea Transform, the freshwater Lake Kinneret is nowadays connected via the Jordan with the hypersaline Dead Sea, which occupies Earth's lowest elevation on land. The southern Levant is a transition area of three different vegetation types. Therefore, also small changes in the climate conditions effect the vegetation and can be registered in the pollen assemblage. In contrast to the Holocene, our preliminary results suggest another vegetation pattern during the Last Glacial. The vegetation belt of the fragile Mediterranean biome did no longer exist in the vicinity of Lake Kinneret. Moreover, the vegetation was rather similar in the whole study area. A steppe vegetation with dwarf shrubs, herbs, and grasses predominated. Thermophilous elements like oaks occurred in limited amounts. The

  19. Climate contributions to vegetation variations in Central Asian drylands

    DEFF Research Database (Denmark)

    Zhou, Yu; Zhang, Li; Fensholt, Rasmus

    2015-01-01

    Central Asia comprises a large fraction of the world's drylands, known to be vulnerable to climate change. We analyzed the inter-annual trends and the impact of climate variability in the vegetation greenness for Central Asia from 1982 to 2011 using GIMMS3g normalized difference vegetation index...

  20. Broad-Scale Environmental Conditions Responsible for Post-Fire Vegetation Dynamics

    Directory of Open Access Journals (Sweden)

    Stuart E. Marsh

    2010-11-01

    Full Text Available Ecosystem response to disturbance is influenced by environmental conditions at a number of scales. Changes in climate have altered fire regimes across the western United States, and have also likely altered spatio-temporal patterns of post-fire vegetation regeneration. Fire occurrence data and a vegetation index (NDVI derived from the NOAA Advanced Very High Resolution Radiometer (AVHRR were used to monitor post-fire vegetation from 1989 to 2007. We first investigated differences in post-fire rates of vegetation regeneration between ecoregions. We then related precipitation, temperature, and elevation records at four temporal scales to rates of post-fire vegetation regeneration to ascertain the influence of climate on post-fire vegetation dynamics. We found that broad-scale climate factors are an important influence on post-fire vegetation regeneration. Most notably, higher rates of post-fire regeneration occurred with warmer minimum temperatures. Increases in precipitation also resulted in higher rates of post-fire vegetation growth. While explanatory power was slight, multiple statistical approaches provided evidence for real ecological drivers of post-fire regeneration that should be investigated further at finer scales. The sensitivity of post-disturbance vegetation dynamics to climatic drivers has important ramifications for the management of ecosystems under changing climatic conditions. Shifts in temperature and precipitation regimes are likely to result in changes in post-disturbance dynamics, which could represent important feedbacks into the global climate system.

  1. Simulating vegetation dynamics in Chile from 21ka BP to present: Effects of climate change on vegetation functions and cover

    Science.gov (United States)

    Werner, Christian; Liakka, Johan; Schmid, Manuel; Fuentes, Juan-Pablo; Ehlers, Todd A.; Hickler, Thomas

    2017-04-01

    Vegetation composition and establishment is strongly dependent on climate conditions but also a result of vegetation dynamics (competition for light, water and nutrients). In addition, vegetation exerts control over the development of landscapes as it mediates the climatic and hydrological forces shaping the terrain via hillslope and fluvial processes. At the same time, topography as well as soil texture and soil depth affect the microclimate, soil water storage and rooting space that is defining the environmental envelope for vegetation development. Within the EarthShape research program (www.earthshape.net) we evaluate these interactions by simulating the co-evolution of landscape and vegetation with a dynamic vegetation model (LPJ-GUESS) and a landscape evolution model (LandLab). LPJ-GUESS is a mechanistic model driven by daily or monthly weather data and explicitly simulates vegetation physiology, succession, competition and water and nutrient cycling. Here we present the results of first transient vegetation simulations from 21kyr BP to present-day using the TraCE-21ka climate dataset for four focus sites along the coastal cordillera of Chile that are exposed to a substantial meridional climate gradient (ranging from hyper-arid to humid-temperate conditions). We show that the warming occurring in the region from LGM to present, in addition to the increase of atmospheric CO2 concentrations, led to a shift in vegetation composition and surface cover. Future work will show how these changes resonate in the dynamics of hillslope and fluvial erosion and ultimately bi-directional feedback mechanisms of vegetation development and landscape evolution/ soil formation (see also companion presentation by Schmid et al., this session).

  2. Integrated analysis of climate, soil, topography and vegetative growth in Iberian viticultural regions.

    Directory of Open Access Journals (Sweden)

    Helder Fraga

    Full Text Available The Iberian viticultural regions are convened according to the Denomination of Origin (DO and present different climates, soils, topography and management practices. All these elements influence the vegetative growth of different varieties throughout the peninsula, and are tied to grape quality and wine type. In the current study, an integrated analysis of climate, soil, topography and vegetative growth was performed for the Iberian DO regions, using state-of-the-art datasets. For climatic assessment, a categorized index, accounting for phenological/thermal development, water availability and grape ripening conditions was computed. Soil textural classes were established to distinguish soil types. Elevation and aspect (orientation were also taken into account, as the leading topographic elements. A spectral vegetation index was used to assess grapevine vegetative growth and an integrated analysis of all variables was performed. The results showed that the integrated climate-soil-topography influence on vine performance is evident. Most Iberian vineyards are grown in temperate dry climates with loamy soils, presenting low vegetative growth. Vineyards in temperate humid conditions tend to show higher vegetative growth. Conversely, in cooler/warmer climates, lower vigour vineyards prevail and other factors, such as soil type and precipitation acquire more important roles in driving vigour. Vines in prevailing loamy soils are grown over a wide climatic diversity, suggesting that precipitation is the primary factor influencing vigour. The present assessment of terroir characteristics allows direct comparison among wine regions and may have great value to viticulturists, particularly under a changing climate.

  3. Integrated analysis of climate, soil, topography and vegetative growth in Iberian viticultural regions.

    Science.gov (United States)

    Fraga, Helder; Malheiro, Aureliano C; Moutinho-Pereira, José; Cardoso, Rita M; Soares, Pedro M M; Cancela, Javier J; Pinto, Joaquim G; Santos, João A

    2014-01-01

    The Iberian viticultural regions are convened according to the Denomination of Origin (DO) and present different climates, soils, topography and management practices. All these elements influence the vegetative growth of different varieties throughout the peninsula, and are tied to grape quality and wine type. In the current study, an integrated analysis of climate, soil, topography and vegetative growth was performed for the Iberian DO regions, using state-of-the-art datasets. For climatic assessment, a categorized index, accounting for phenological/thermal development, water availability and grape ripening conditions was computed. Soil textural classes were established to distinguish soil types. Elevation and aspect (orientation) were also taken into account, as the leading topographic elements. A spectral vegetation index was used to assess grapevine vegetative growth and an integrated analysis of all variables was performed. The results showed that the integrated climate-soil-topography influence on vine performance is evident. Most Iberian vineyards are grown in temperate dry climates with loamy soils, presenting low vegetative growth. Vineyards in temperate humid conditions tend to show higher vegetative growth. Conversely, in cooler/warmer climates, lower vigour vineyards prevail and other factors, such as soil type and precipitation acquire more important roles in driving vigour. Vines in prevailing loamy soils are grown over a wide climatic diversity, suggesting that precipitation is the primary factor influencing vigour. The present assessment of terroir characteristics allows direct comparison among wine regions and may have great value to viticulturists, particularly under a changing climate.

  4. Comparative Climates of the Trappist-1 Planetary System: Results from a Simple Climate-vegetation Model

    International Nuclear Information System (INIS)

    Alberti, Tommaso; Carbone, Vincenzo; Lepreti, Fabio; Vecchio, Antonio

    2017-01-01

    The recent discovery of the planetary system hosted by the ultracool dwarf star TRAPPIST-1 could open new paths for investigations of the planetary climates of Earth-sized exoplanets, their atmospheres, and their possible habitability. In this paper, we use a simple climate-vegetation energy-balance model to study the climate of the seven TRAPPIST-1 planets and the climate dependence on various factors: the global albedo, the fraction of vegetation that could cover their surfaces, and the different greenhouse conditions. The model allows us to investigate whether liquid water could be maintained on the planetary surfaces (i.e., by defining a “surface water zone (SWZ)”) in different planetary conditions, with or without the presence of a greenhouse effect. It is shown that planet TRAPPIST-1d seems to be the most stable from an Earth-like perspective, since it resides in the SWZ for a wide range of reasonable values of the model parameters. Moreover, according to the model, outer planets (f, g, and h) cannot host liquid water on their surfaces, even with Earth-like conditions, entering a snowball state. Although very simple, the model allows us to extract the main features of the TRAPPIST-1 planetary climates.

  5. Comparative Climates of the Trappist-1 Planetary System: Results from a Simple Climate-vegetation Model

    Energy Technology Data Exchange (ETDEWEB)

    Alberti, Tommaso; Carbone, Vincenzo; Lepreti, Fabio [Dipartimento di Fisica, Università della Calabria, Ponte P. Bucci, Cubo 31C, I-87036, Rende (CS) (Italy); Vecchio, Antonio, E-mail: tommaso.alberti@unical.it, E-mail: tommasoalberti89@gmail.com [LESIA—Observatoire de Paris, PSL Research University, 5 place Jules Janssen, F-92190, Meudon (France)

    2017-07-20

    The recent discovery of the planetary system hosted by the ultracool dwarf star TRAPPIST-1 could open new paths for investigations of the planetary climates of Earth-sized exoplanets, their atmospheres, and their possible habitability. In this paper, we use a simple climate-vegetation energy-balance model to study the climate of the seven TRAPPIST-1 planets and the climate dependence on various factors: the global albedo, the fraction of vegetation that could cover their surfaces, and the different greenhouse conditions. The model allows us to investigate whether liquid water could be maintained on the planetary surfaces (i.e., by defining a “surface water zone (SWZ)”) in different planetary conditions, with or without the presence of a greenhouse effect. It is shown that planet TRAPPIST-1d seems to be the most stable from an Earth-like perspective, since it resides in the SWZ for a wide range of reasonable values of the model parameters. Moreover, according to the model, outer planets (f, g, and h) cannot host liquid water on their surfaces, even with Earth-like conditions, entering a snowball state. Although very simple, the model allows us to extract the main features of the TRAPPIST-1 planetary climates.

  6. Climatic drivers of vegetation based on wavelet analysis

    Science.gov (United States)

    Claessen, Jeroen; Martens, Brecht; Verhoest, Niko E. C.; Molini, Annalisa; Miralles, Diego

    2017-04-01

    Vegetation dynamics are driven by climate, and at the same time they play a key role in forcing the different bio-geochemical cycles. As climate change leads to an increase in frequency and intensity of hydro-meteorological extremes, vegetation is expected to respond to these changes, and subsequently feed back on their occurrence. This response can be analysed using time series of different vegetation diagnostics observed from space, in the optical (e.g. Normalised Difference Vegetation Index (NDVI), Solar Induced Fluorescence (SIF)) and microwave (Vegetation Optical Depth (VOD)) domains. In this contribution, we compare the climatic drivers of different vegetation diagnostics, based on a monthly global data-cube of 24 years at a 0.25° resolution. To do so, we calculate the wavelet coherence between each vegetation-related observation and observations of air temperature, precipitation and incoming radiation. The use of wavelet coherence allows unveiling the scale-by-scale response and sensitivity of the diverse vegetation indices to their climatic drivers. Our preliminary results show that the wavelet-based statistics prove to be a suitable tool for extracting information from different vegetation indices. Going beyond traditional methods based on linear correlations, the application of wavelet coherence provides information about: (a) the specific periods at which the correspondence between climate and vegetation dynamics is larger, (b) the frequencies at which this correspondence occurs (e.g. monthly or seasonal scales), and (c) the time lag in the response of vegetation to their climate drivers, and vice versa. As expected, areas of high rainfall volumes are characterised by a strong control of radiation and temperature over vegetation. Furthermore, precipitation is the most important driver of vegetation variability over short terms in most regions of the world - which can be explained by the rapid response of leaf development towards available water content

  7. Climate and Vegetation Effects on Temperate Mountain Forest ...

    Science.gov (United States)

    Current forest composition may be resilient to typical climatic variability; however, climate trends, combined with projected changes in species composition, may increase tree vulnerability to water stress. A shift in forest composition toward tree species with higher water use has implications for biogenic emissions and deposition of reactive nitrogen and carbon compounds. Forest evapotranspiration (ET) can vary greatly at daily and seasonal time scales, but compared to carbon fluxes, often exhibits relatively consistent inter-annual behavior. The processes controlling ET involve the combined effects of physical and biological factors. Atmospheric conditions that promote high ET, consisting of high radiation and vapor pressure deficit (D), are often characterized by rainless periods when soil water supply to vegetation may be limiting and plant stomata may close to prevent excessive water loss. In contrast, periods of high ecosystem water availability require frequent precipitation and are characterized by low D. Thus, the combination of these contrasting conditions throughout a growing season may explain some of the consistency in ET. Additionally, vegetation composition is also an important factor in determining ET. In mixed species forests, physiological differences in water use strategies (e.g. isohydric/anisohydric species) can produce conservative water use throughout wet and dry phases of the growing season. Furthermore, transpiration by evergreen specie

  8. Oscillations in a simple climate-vegetation model

    Science.gov (United States)

    Rombouts, J.; Ghil, M.

    2015-05-01

    We formulate and analyze a simple dynamical systems model for climate-vegetation interaction. The planet we consider consists of a large ocean and a land surface on which vegetation can grow. The temperature affects vegetation growth on land and the amount of sea ice on the ocean. Conversely, vegetation and sea ice change the albedo of the planet, which in turn changes its energy balance and hence the temperature evolution. Our highly idealized, conceptual model is governed by two nonlinear, coupled ordinary differential equations, one for global temperature, the other for vegetation cover. The model exhibits either bistability between a vegetated and a desert state or oscillatory behavior. The oscillations arise through a Hopf bifurcation off the vegetated state, when the death rate of vegetation is low enough. These oscillations are anharmonic and exhibit a sawtooth shape that is characteristic of relaxation oscillations, as well as suggestive of the sharp deglaciations of the Quaternary. Our model's behavior can be compared, on the one hand, with the bistability of even simpler, Daisyworld-style climate-vegetation models. On the other hand, it can be integrated into the hierarchy of models trying to simulate and explain oscillatory behavior in the climate system. Rigorous mathematical results are obtained that link the nature of the feedbacks with the nature and the stability of the solutions. The relevance of model results to climate variability on various timescales is discussed.

  9. Effects of climate change on forest vegetation in the Northern Rockies Region [Chapter 6

    Science.gov (United States)

    Keane, Robert E.; Mahalovich, Mary Frances; Bollenbacher, Barry L.; Manning, Mary E.; Loehman, Rachel A.; Jain, Terrie B.; Holsinger, Lisa M.; Larson, Andrew J.; Webster, Meredith M.

    2018-01-01

    The projected rapid changes in climate will affect the unique vegetation assemblages of the Northern Rockies region in myriad ways, both directly through shifts in vegetation growth, mortality, and regeneration, and indirectly through changes in disturbance regimes and interactions with changes in other ecosystem processes, such as hydrology, snow dynamics, and exotic invasions (Bonan 2008; Hansen and Phillips 2015; Hansen et al. 2001; Notaro et al. 2007). These impacts, taken collectively, could change the way vegetation is managed by public land agencies in this area. Some species may be in danger of rapid decreases in abundance, while others may undergo range expansion (Landhäusser et al. 2010). New vegetation communities may form, while historical vegetation complexes may simply shift to other areas of the landscape or become rare. Juxtaposed with climate change concerns are the consequences of other land management policies and past activities, such as fire exclusion, fuels treatments, and grazing. A thorough assessment of the responses of vegetation to projected climate change is needed, along with an evaluation of the vulnerability of important species, communities, and vegetation-related resources that may be influenced by the effects, both direct and indirect, of climate change. This assessment must also account for past management actions and current vegetation conditions and their interactions with future climates.

  10. Relationships between vegetation and climate change in Transbaikalia, Siberia

    Energy Technology Data Exchange (ETDEWEB)

    Tchebakova, N.M.; Parfenova, E.I. [V.N. Sukachev Inst. of Forest, Russian Academy of Sciences, Siberian Branch, Akademgorodok, Krasnoyarsk (Russian Federation)

    2002-10-01

    This paper demonstrated how vegetation of the Lake Baikal basin may respond to climate change at a mountain biome (an orobiome over the entire basin) and a stand in a locality. An orobiome vegetation model was developed along with a higher resolution stand model based on climatic parameters. Regional climates were modeled based on physiology and site climates based on topography. Bioclimatic multiple regression models were then developed to predict regional vegetation and forest stand characteristics distribution over a mountain range in Central Transbaikalia under current and future climate scenarios. Bioclimatic models were combined with climatic layers of different resolutions. Tree species composition and wood volume was predicted based on 2 climate indices - temperature sums (base 5 degrees C) and the dryness index. Results indicate that lowland vegetation will shift 250 m upslope and highland vegetation will shift 450 m upslope. This will significantly reduce the tundra and light-needled taiga, and will expand the forest-steppe. Results also indicate that the total phytomass within the entire basin will not change much. Stand phytomass across the basin will, however, increase. The model used in this study does not include climate-forcing factors such as wind, snow and permafrost. The model is open to new development to include a dynamic components that would inject vitality into the model. 13 refs., 2 tabs., 3 figs.

  11. Greenhouse design for vegetable production in subtropical climate in Taiwan

    NARCIS (Netherlands)

    Hemming, S.; Speetjens, S.L.; Wang, D.; Tsay, J.R.

    2014-01-01

    In Taiwan open field vegetable production is threatened by subtropical climatic disasters, such as high wind speeds and heavy rainfall, which can cause the destruction of whole crops. Next to that vegetable production is threatened by pests and diseases resulting a high need for pesticides.

  12. Broad-Scale Environmental Conditions Responsible for Post-Fire Vegetation Dynamics

    OpenAIRE

    Casady, Grant M.; Marsh, Stuart E.

    2010-01-01

    Ecosystem response to disturbance is influenced by environmental conditions at a number of scales. Changes in climate have altered fire regimes across the western United States, and have also likely altered spatio-temporal patterns of post-fire vegetation regeneration. Fire occurrence data and a vegetation index (NDVI) derived from the NOAA Advanced Very High Resolution Radiometer (AVHRR) were used to monitor post-fire vegetation from 1989 to 2007. We first investigated differences in post-fi...

  13. [Correlation analysis on normalized difference vegetation index (NDVI) of different vegetations and climatic factors in Southwest China].

    Science.gov (United States)

    Zhang, Yuan-Dong; Zhang, Xiao-He; Liu, Shi-Rong

    2011-02-01

    Based on the 1982-2006 NDVI remote sensing data and meteorological data of Southwest China, and by using GIS technology, this paper interpolated and extracted the mean annual temperature, annual precipitation, and drought index in the region, and analyzed the correlations of the annual variation of NDVI in different vegetation types (marsh, shrub, bush, grassland, meadow, coniferous forest, broad-leaved forest, alpine vegetation, and cultural vegetation) with corresponding climatic factors. In 1982-2006, the NDVI, mean annual temperature, and annual precipitation had an overall increasing trend, and the drought index decreased. Particularly, the upward trend of mean annual temperature was statistically significant. Among the nine vegetation types, the NDVI of bush and mash decreased, and the downward trend was significant for bush. The NDVI of the other seven vegetation types increased, and the upward trend was significant for coniferous forest, meadow, and alpine vegetation, and extremely significant for shrub. The mean annual temperature in the areas with all the nine vegetation types increased significantly, while the annual precipitation had no significant change. The drought index in the areas with marsh, bush, and cultural vegetation presented an increasing trend, that in the areas with meadow and alpine vegetation decreased significantly, and this index in the areas with other four vegetation types had an unobvious decreasing trend. The NDVI of shrub and coniferous forest had a significantly positive correlation with mean annual temperature, and that of shrub and meadow had significantly negative correlation with drought index. Under the conditions of the other two climatic factors unchanged, the NDVI of coniferous forest, broad-leaved forest, and alpine vegetation showed the strongest correlation with mean annual temperature, that of grass showed the strongest correlation with annual precipitation, and the NDVI of mash, shrub, grass, meadow, and cultural

  14. Microbiological parameters and maturity degree during composting of Posidonia oceanica residues mixed with vegetable wastes in semi-arid pedo-climatic condition.

    Science.gov (United States)

    Saidi, Neyla; Kouki, Soulwene; M'hiri, Fadhel; Jedidi, Naceur; Mahrouk, Meriam; Hassen, Abdennaceur; Ouzari, Hadda

    2009-01-01

    The aim of this study was to characterize the biological stability and maturity degree of compost during a controlled pile-composting trial of mixed vegetable residues (VR) collected from markets of Tunis City with residues of Posidonia oceanica (PoR), collected from Tunis beaches. The accumulation in beaches (as well as their removal) constitutes a serious environmental problem in all Mediterranean countries particularly in Tunisia. Aerobic-thermophilic composting is the most reasonable way to profit highly-valuable content of organic matter in these wastes for agricultural purposes. The physical, chemical, and biological parameters were monitored during composting over 150 d. The most appropriate parameters were selected to establish the maturity degree. The main result of this research was the deduction of the following maturity criterion: (a) C/N ratio 80%. These five parameters, considered jointly are indicative of a high maturity degree and thus of a high-quality organic amendment which employed in a rational way, may improve soil fertility and soil quality. The mature compost was relatively rich in N (13.0 g/kg), P (4.74 g/kg) and MgO (15.80 g/kg). Thus composting definitively constitutes the most optimal option to exploit these wastes.

  15. Semi-arid vegetation response to antecedent climate and water balance windows

    Science.gov (United States)

    Thoma, David P.; Munson, Seth M.; Irvine, Kathryn M.; Witwicki, Dana L.; Bunting, Erin

    2016-01-01

    Questions Can we improve understanding of vegetation response to water availability on monthly time scales in semi-arid environments using remote sensing methods? What climatic or water balance variables and antecedent windows of time associated with these variables best relate to the condition of vegetation? Can we develop credible near-term forecasts from climate data that can be used to prepare for future climate change effects on vegetation? Location Semi-arid grasslands in Capitol Reef National Park, Utah, USA. Methods We built vegetation response models by relating the normalized difference vegetation index (NDVI) from MODIS imagery in Mar–Nov 2000–2013 to antecedent climate and water balance variables preceding the monthly NDVI observations. We compared how climate and water balance variables explained vegetation greenness and then used a multi-model ensemble of climate and water balance models to forecast monthly NDVI for three holdout years. Results Water balance variables explained vegetation greenness to a greater degree than climate variables for most growing season months. Seasonally important variables included measures of antecedent water input and storage in spring, switching to indicators of drought, input or use in summer, followed by antecedent moisture availability in autumn. In spite of similar climates, there was evidence the grazed grassland showed a response to drying conditions 1 mo sooner than the ungrazed grassland. Lead times were generally short early in the growing season and antecedent window durations increased from 3 mo early in the growing season to 1 yr or more as the growing season progressed. Forecast accuracy for three holdout years using a multi-model ensemble of climate and water balance variables outperformed forecasts made with a naïve NDVI climatology. Conclusions We determined the influence of climate and water balance on vegetation at a fine temporal scale, which presents an opportunity to forecast vegetation

  16. A method for climate and vegetation reconstruction through the inversion of a dynamic vegetation model

    Energy Technology Data Exchange (ETDEWEB)

    Garreta, Vincent; Guiot, Joel; Hely, Christelle [CEREGE, UMR 6635, CNRS, Universite Aix-Marseille, Europole de l' Arbois, Aix-en-Provence (France); Miller, Paul A.; Sykes, Martin T. [Lund University, Department of Physical Geography and Ecosystems Analysis, Geobiosphere Science Centre, Lund (Sweden); Brewer, Simon [Universite de Liege, Institut d' Astrophysique et de Geophysique, Liege (Belgium); Litt, Thomas [University of Bonn, Paleontological Institute, Bonn (Germany)

    2010-08-15

    Climate reconstructions from data sensitive to past climates provide estimates of what these climates were like. Comparing these reconstructions with simulations from climate models allows to validate the models used for future climate prediction. It has been shown that for fossil pollen data, gaining estimates by inverting a vegetation model allows inclusion of past changes in carbon dioxide values. As a new generation of dynamic vegetation model is available we have developed an inversion method for one model, LPJ-GUESS. When this novel method is used with high-resolution sediment it allows us to bypass the classic assumptions of (1) climate and pollen independence between samples and (2) equilibrium between the vegetation, represented as pollen, and climate. Our dynamic inversion method is based on a statistical model to describe the links among climate, simulated vegetation and pollen samples. The inversion is realised thanks to a particle filter algorithm. We perform a validation on 30 modern European sites and then apply the method to the sediment core of Meerfelder Maar (Germany), which covers the Holocene at a temporal resolution of approximately one sample per 30 years. We demonstrate that reconstructed temperatures are constrained. The reconstructed precipitation is less well constrained, due to the dimension considered (one precipitation by season), and the low sensitivity of LPJ-GUESS to precipitation changes. (orig.)

  17. Decision-Support System for Urban Air Pollution under Future Climate Conditions

    OpenAIRE

    Jensen , Steen ,; Brandt , Jørgen; Hvidberg , Martin; Ketzel , Matthias; Hedegaard , Gitte ,; Christensen , Jens ,

    2011-01-01

    Part 6: Climate Services and Environmental Tools for Urban Planning and Climate Change Applications and Services; International audience; Climate change is expected to influence urban living conditions and challenge the ability of cities to adapt to and mitigate climate change. Urban climates will be faced with elevated temperatures and future climate conditions are expected to cause higher ozone concentrations, increased biogenic emissions from vegetation, changes in the chemistry of the atm...

  18. Does urban vegetation mitigate air pollution in northern conditions?

    International Nuclear Information System (INIS)

    Setälä, Heikki; Viippola, Viljami; Rantalainen, Anna-Lea; Pennanen, Arto; Yli-Pelkonen, Vesa

    2013-01-01

    It is generally accepted that urban vegetation improves air quality and thereby enhances the well-being of citizens. However, empirical evidence on the potential of urban trees to mitigate air pollution is meager, particularly in northern climates with a short growing season. We studied the ability of urban park/forest vegetation to remove air pollutants (NO 2 , anthropogenic VOCs and particle deposition) using passive samplers in two Finnish cities. Concentrations of each pollutant in August (summer; leaf-period) and March (winter, leaf-free period) were slightly but often insignificantly lower under tree canopies than in adjacent open areas, suggesting that the role of foliage in removing air pollutants is insignificant. Furthermore, vegetation-related environmental variables (canopy closure, number and size of trees, density of understorey vegetation) did not explain the variation in pollution concentrations. Our results suggest that the ability of urban vegetation to remove air pollutants is minor in northern climates. -- Highlights: ► The ability of northern urban vegetation to remove air pollutants is minor. ► Vegetation-related environmental variables had no effect on air pollution levels. ► The ability of vegetation to clean air did not differ between summer and winter. ► Dry deposition passive samplers proved applicable in urban air pollution study. -- The ability of urban vegetation to remove air pollutants seems to be minor in northern climates

  19. Climate change and spatial distribution of vegetation in Colombia

    Directory of Open Access Journals (Sweden)

    Juan Carlos Alarcon Hincapie

    2013-12-01

    Full Text Available Vegetation change under two climate change scenarios in different periods of the 21st Century are modeled for Colombia. Vegetation for the years 1970 to 2000 was reproduced using the Holdridge model with climate data with a spatial resolution of 900 meters. The vegetation types that occupied the most territory were sub-humid tropical forest, tropical dry forest and Andean wet forest. These results were validated by comparing with the Colombian ecosystem map (SINA, 2007, which confirmed a high degree of similarity between the modeled spatial vegetation patterns and modern ecosystem distributions. Future vegetation maps were simulated using data generated by a regional climate model under two scenarios (A2 and B2; IPCC, 2007 for the periods 2011-2040 and 2070-2100. Based on our predictions high altitude vegetation will convert to that of lower altitudes and drier provinces with the most dramatic change occurring in the A2 scenario from 2070-2100. The most affected areas are the páramo and other high Andean vegetation types, which in the timeframe of the explored scenarios will disappear by the middle of the 21st Century.

  20. The influence of vegetation dynamics on anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    U. Port

    2012-11-01

    Full Text Available In this study, vegetation–climate and vegetation–carbon cycle interactions during anthropogenic climate change are assessed by using the Earth System Model of the Max Planck Institute for Meteorology (MPI ESM that includes vegetation dynamics and an interactive carbon cycle. We assume anthropogenic CO2 emissions according to the RCP 8.5 scenario in the time period from 1850 to 2120. For the time after 2120, we assume zero emissions to evaluate the response of the stabilising Earth System by 2300.

    Our results suggest that vegetation dynamics have a considerable influence on the changing global and regional climate. In the simulations, global mean tree cover extends by 2300 due to increased atmospheric CO2 concentration and global warming. Thus, land carbon uptake is higher and atmospheric CO2 concentration is lower by about 40 ppm when considering dynamic vegetation compared to the static pre-industrial vegetation cover. The reduced atmospheric CO2 concentration is equivalent to a lower global mean temperature. Moreover, biogeophysical effects of vegetation cover shifts influence the climate on a regional scale. Expanded tree cover in the northern high latitudes results in a reduced albedo and additional warming. In the Amazon region, declined tree cover causes a regional warming due to reduced evapotranspiration. As a net effect, vegetation dynamics have a slight attenuating effect on global climate change as the global climate cools by 0.22 K due to natural vegetation cover shifts in 2300.

  1. Updated vegetation information in high resolution regional climate simulations using WRF

    DEFF Research Database (Denmark)

    Nielsen, Joakim Refslund; Dellwik, Ebba; Hahmann, Andrea N.

    Climate studies show that the frequency of heat wave events and above-average high temperatures during the summer months over Europe will increase in the coming decades. Such climatic changes and long-term meteorological conditions will impact the seasonal development of vegetation and ultimately...... modify the energy distribution at the land surface. In weather and climate models it is important to represent the vegetation variability accurately to obtain reliable results. The weather research and forecasting (WRF) model uses a green vegetation fraction (GVF) climatology to represent the seasonal...... or changes in management practice since it is derived more than twenty years ago. In this study, a new high resolution, high quality GVF product is applied in a WRF climate simulation over Denmark during the 2006 heat wave year. The new GVF product reflects the year 2006 and it was previously tested...

  2. Ecosystem Evapotranspiration as a Response to Climate and Vegetation Coverage Changes in Northwest Yunnan, China.

    Science.gov (United States)

    Yang, Hao; Luo, Peng; Wang, Jun; Mou, Chengxiang; Mo, Li; Wang, Zhiyuan; Fu, Yao; Lin, Honghui; Yang, Yongping; Bhatta, Laxmi Dutt

    2015-01-01

    Climate and human-driven changes play an important role in regional droughts. Northwest Yunnan Province is a key region for biodiversity conservation in China, and it has experienced severe droughts since the beginning of this century; however, the extent of the contributions from climate and human-driven changes remains unclear. We calculated the ecosystem evapotranspiration (ET) and water yield (WY) of northwest Yunnan Province, China from 2001 to 2013 using meteorological and remote sensing observation data and a Surface Energy Balance System (SEBS) model. Multivariate regression analyses were used to differentiate the contribution of climate and vegetation coverage to ET. The results showed that the annual average vegetation coverage significantly increased over time with a mean of 0.69 in spite of the precipitation fluctuation. Afforestation/reforestation and other management efforts attributed to vegetation coverage increase in NW Yunnan. Both ET and WY considerably fluctuated with the climate factors, which ranged from 623.29 mm to 893.8 mm and -51.88 mm to 384.40 mm over the time period. Spatially, ET in the southeast of NW Yunnan (mainly in Lijiang) increased significantly, which was in line with the spatial trend of vegetation coverage. Multivariate linear regression analysis indicated that climatic factors accounted for 85.18% of the ET variation, while vegetation coverage explained 14.82%. On the other hand, precipitation accounted for 67.5% of the WY. We conclude that the continuous droughts in northwest Yunnan were primarily climatically driven; however, man-made land cover and vegetation changes also increased the vulnerability of local populations to drought. Because of the high proportion of the water yield consumed for subsistence and poor infrastructure for water management, local populations have been highly vulnerable to climate drought conditions. We suggest that conservation of native vegetation and development of water

  3. Ecosystem Evapotranspiration as a Response to Climate and Vegetation Coverage Changes in Northwest Yunnan, China.

    Directory of Open Access Journals (Sweden)

    Hao Yang

    Full Text Available Climate and human-driven changes play an important role in regional droughts. Northwest Yunnan Province is a key region for biodiversity conservation in China, and it has experienced severe droughts since the beginning of this century; however, the extent of the contributions from climate and human-driven changes remains unclear. We calculated the ecosystem evapotranspiration (ET and water yield (WY of northwest Yunnan Province, China from 2001 to 2013 using meteorological and remote sensing observation data and a Surface Energy Balance System (SEBS model. Multivariate regression analyses were used to differentiate the contribution of climate and vegetation coverage to ET. The results showed that the annual average vegetation coverage significantly increased over time with a mean of 0.69 in spite of the precipitation fluctuation. Afforestation/reforestation and other management efforts attributed to vegetation coverage increase in NW Yunnan. Both ET and WY considerably fluctuated with the climate factors, which ranged from 623.29 mm to 893.8 mm and -51.88 mm to 384.40 mm over the time period. Spatially, ET in the southeast of NW Yunnan (mainly in Lijiang increased significantly, which was in line with the spatial trend of vegetation coverage. Multivariate linear regression analysis indicated that climatic factors accounted for 85.18% of the ET variation, while vegetation coverage explained 14.82%. On the other hand, precipitation accounted for 67.5% of the WY. We conclude that the continuous droughts in northwest Yunnan were primarily climatically driven; however, man-made land cover and vegetation changes also increased the vulnerability of local populations to drought. Because of the high proportion of the water yield consumed for subsistence and poor infrastructure for water management, local populations have been highly vulnerable to climate drought conditions. We suggest that conservation of native vegetation and development of water

  4. Spatiotemporal analysis of the effect of climate change on vegetation health in the Drakensberg Mountain Region of South Africa.

    Science.gov (United States)

    Mukwada, Geoffrey; Manatsa, Desmond

    2018-05-24

    The impact of climate change on mountain ecosystems has been in the spotlight for the past three decades. Climate change is generally considered to be a threat to ecosystem health in mountain regions. Vegetation indices can be used to detect shifts in ecosystem phenology and climate change in mountain regions while satellite imagery can play an important role in this process. However, what has remained problematic is determining the extent to which ecosystem phenology is affected by climate change under increasingly warming conditions. In this paper, we use climate and vegetation indices that were derived from satellite data to investigate the link between ecosystem phenology and climate change in the Namahadi Catchment Area of the Drakensberg Mountain Region of South Africa. The time series for climate indices as well as those for gridded precipitation and temperature data were analyzed in order to determine climate shifts, and concomitant changes in vegetation health were assessed in the resultant epochs using vegetation indices. The results indicate that vegetation indices should only be used to assess trends in climate change under relatively pristine conditions, where human influence is limited. This knowledge is important for designing climate change monitoring strategies that are based on ecosystem phenology and vegetation health.

  5. Improvement of greenhouse design and climate control in mediterranean conditions

    NARCIS (Netherlands)

    Tuzel, Yuksel; Zwart, de Feije; Sapounas, A.; Hemming, Silke; Stanghellini, Cecilia

    2017-01-01

    The Mediterranean Region is one of the most important areas of the world in terms of protected cultivation. Turkey, with its increasing greenhouse area, is one of the representative countries of the region. Thanks to the mild winter climatic conditions, cultivation of vegetables under simple

  6. Trends in global vegetation activity and climatic drivers indicate a decoupled response to climate change

    DEFF Research Database (Denmark)

    Schut, Antonius G T; Ivits, Eva; Conijn, Jacob G.

    2015-01-01

    Detailed understanding of a possible decoupling between climatic drivers of plant productivity and the response of ecosystems vegetation is required. We compared trends in six NDVI metrics (1982-2010) derived from the GIMMS3g dataset with modelled biomass productivity and assessed uncertainty...... in trend estimates. Annual total biomass weight (TBW) was calculated with the LINPAC model. Trends were determined using a simple linear regression, a Thiel-Sen medium slope and a piecewise regression (PWR) with two segments. Values of NDVI metrics were related to Net Primary Production (MODIS......-NPP) and TBWper biome and land-use type. The simple linear and Thiel-Sen trends did not differ much whereas PWR increased the fraction of explained variation, depending on the NDVI metric considered. A positive trend in TBW indicating more favorable climatic conditions was found for 24% of pixels on land...

  7. Productive vegetation: relationships between net primary productivity, vegetation types and climate change in the Wet Tropics bioregion

    International Nuclear Information System (INIS)

    Ramirez, Vanessa Valdez; Williams, Stephen E.; VanDerWal, Jeremy

    2007-01-01

    Full text: Full text: There is now ample evidence demonstrating the impacts of climate change on biodiversity and human society (Walther ef a/. 2002). Numerous studies have shown climate change is one of the most significant threats to tropical forests, such as the Wet Tropics Heritage Area, due to their high biodiversity and endemism (Pounds ef al. 1999; Hughes 2000; Parmesan and Yohe 2003). Williams ef al. (2003) suggested that small shifts in net primary productivity (NPP) as a result of climate change could lead to potentially massive follow-on effects for the extremely diverse and vulnerable rainforest flora and fauna. It is therefore crucial to explore the relationships between NPP and local biodiversity, especially to create models for different climate change scenarios. Nevertheless, NPP in the Wet Tropics has yet to be estimated. This is the first study to provide a general NPP estimate for the Wet Tropics bioregion using climate surrogates (Schuur 2003). This technique estimates NPP in an accurate, repeatable, and cost-effective way. NPP values were linked to vegetation types and examined under various climatic and environmental conditions. Results show a significant difference in productivity according to vegetation types and climatic variables, with temperature and rainfall seasonality as the most important determining variables. Additionally, lowland and upland vegetations showed a significant difference in productivity patterns throughout the year. Vegetation types located above 1000 metres in altitude had the lowest values of mean annual productivity due to their high rainfall and low temperatures; vegetation types located below 600 metres showed increased productivity values during the wet season (December-March). Net primary productivity will certainly be impacted by changes in temperature and rainfall, due to climate change. Although an increase in NPP values can be predicted for upland areas, the more widely distributed lowlands will drastically

  8. Climate change-induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands.

    Science.gov (United States)

    Tietjen, Britta; Schlaepfer, Daniel R; Bradford, John B; Lauenroth, William K; Hall, Sonia A; Duniway, Michael C; Hochstrasser, Tamara; Jia, Gensuo; Munson, Seth M; Pyke, David A; Wilson, Scott D

    2017-07-01

    Drylands occur worldwide and are particularly vulnerable to climate change because dryland ecosystems depend directly on soil water availability that may become increasingly limited as temperatures rise. Climate change will both directly impact soil water availability and change plant biomass, with resulting indirect feedbacks on soil moisture. Thus, the net impact of direct and indirect climate change effects on soil moisture requires better understanding. We used the ecohydrological simulation model SOILWAT at sites from temperate dryland ecosystems around the globe to disentangle the contributions of direct climate change effects and of additional indirect, climate change-induced changes in vegetation on soil water availability. We simulated current and future climate conditions projected by 16 GCMs under RCP 4.5 and RCP 8.5 for the end of the century. We determined shifts in water availability due to climate change alone and due to combined changes of climate and the growth form and biomass of vegetation. Vegetation change will mostly exacerbate low soil water availability in regions already expected to suffer from negative direct impacts of climate change (with the two RCP scenarios giving us qualitatively similar effects). By contrast, in regions that will likely experience increased water availability due to climate change alone, vegetation changes will counteract these increases due to increased water losses by interception. In only a small minority of locations, climate change-induced vegetation changes may lead to a net increase in water availability. These results suggest that changes in vegetation in response to climate change may exacerbate drought conditions and may dampen the effects of increased precipitation, that is, leading to more ecological droughts despite higher precipitation in some regions. Our results underscore the value of considering indirect effects of climate change on vegetation when assessing future soil moisture conditions in water

  9. Climate change-induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands

    Science.gov (United States)

    Tietjen, Britta; Schlaepfer, Daniel R.; Bradford, John B.; Laurenroth, William K.; Hall, Sonia A.; Duniway, Michael C.; Hochstrasser, Tamara; Jia, Gensuo; Munson, Seth M.; Pyke, David A.; Wilson, Scott D.

    2017-01-01

    Drylands occur world-wide and are particularly vulnerable to climate change since dryland ecosystems depend directly on soil water availability that may become increasingly limited as temperatures rise. Climate change will both directly impact soil water availability, and also change plant biomass, with resulting indirect feedbacks on soil moisture. Thus, the net impact of direct and indirect climate change effects on soil moisture requires better understanding.We used the ecohydrological simulation model SOILWAT at sites from temperate dryland ecosystems around the globe to disentangle the contributions of direct climate change effects and of additional indirect, climate change-induced changes in vegetation on soil water availability. We simulated current and future climate conditions projected by 16 GCMs under RCP 4.5 and RCP 8.5 for the end of the century. We determined shifts in water availability due to climate change alone and due to combined changes of climate and the growth form and biomass of vegetation.Vegetation change will mostly exacerbate low soil water availability in regions already expected to suffer from negative direct impacts of climate change (with the two RCP scenarios giving us qualitatively similar effects). By contrast, in regions that will likely experience increased water availability due to climate change alone, vegetation changes will counteract these increases due to increased water losses by interception. In only a small minority of locations, climate change induced vegetation changes may lead to a net increase in water availability. These results suggest that changes in vegetation in response to climate change may exacerbate drought conditions and may dampen the effects of increased precipitation, i.e. leading to more ecological droughts despite higher precipitation in some regions. Our results underscore the value of considering indirect effects of climate change on vegetation when assessing future soil moisture conditions in water

  10. Holocene vegetation and climate history of the northern Bighorn Basin, southern Montana

    Science.gov (United States)

    Lyford, M.E.; Betancourt, J.L.; Jackson, S.T.

    2002-01-01

    Records of Holocene vegetation and climate change at low elevations (treeline indicates wetter conditions between 4400 and 2700 14C yr B.P. Increased aridity after 2700 14C yr B.P. initiated expansion of J. osteosperma from the east to west side of the Pryor Mountains. ?? 2002 University of Washington.

  11. INFORMATION-ANALYTICAL SYSTEM OF FORECAST VEGETATION FIRES IN NATURAL CONDITIONS

    Directory of Open Access Journals (Sweden)

    R. M. Kogan

    2015-01-01

    Full Text Available A system for spatial prediction for fire danger as function of weather and pyrological vegetation characteristics was constructed. The method of calculating the time conducted vegetable combustible materials in fire condition of each month of the season was suggested. Calculate the probability of fires and danger periods of plant formations in a monsoon climate. The geographic information system was developed, it was tested in the Middle Amur region in the Russian Far East.

  12. Impacts of 21st century climate changes on flora and vegetation in Denmark

    Science.gov (United States)

    Skov, Flemming; Nygaard, Bettina; Wind, Peter; Borchsenius, Finn; Normand, Signe; Balslev, Henrik; Fløjgaard, Camilla; Svenning, Jens-Christian

    2009-11-01

    In this paper we examined the potential impacts of predicted climatic changes on the flora and vegetation in Denmark using data from a digital database on the natural vegetation of Europe. Climate scenarios A2 and B2 were used to find regions with present climatic conditions similar to Denmark's climate in the year 2100. The potential natural vegetation of Denmark today is predominantly deciduous forest that would cover more than 90% of the landscape. Swamps, bogs, and wet forest would be found under moist or wet conditions. Dwarf shrub heaths would be naturally occurring on poor soils along the coast together with dune systems and salt-marsh vegetation. When comparing the natural vegetation of Denmark to the vegetation of five future-climate analogue areas, the most obvious trend is a shift from deciduous to thermophilous broadleaved forest currently found in Southern and Eastern Europe. A total of 983 taxa were recorded for this study of which 539 were found in Denmark. The Sørensen index was used to measure the floristic similarity between Denmark and the five subregions. Deciduous forest, dwarf shrub heath, and coastal vegetation were treated in more detail, focusing on potential new immigrant species to Denmark. Finally, implications for management were discussed. The floristic similarity between Denmark and regions in Europe with a climate similar to what is expected for Denmark in year 2100 was found to vary between 48-78%, decreasing from North to South. Hence, it seems inevitable that climate changes of the magnitudes foreseen will alter the distribution of individual species and the composition of natural vegetation units. Changes, however, will not be immediate. Historic evidence shows a considerable lag in response to climatic change under natural conditions, but little is known about the effects of human land-use and pollution on this process. Facing such uncertainties we suggested that a dynamic strategy based on modeling, monitoring and adaptive

  13. Impacts of 21st century climate changes on flora and vegetation in Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Skov, Flemming; Nygaard, Bettina; Wind, Peter; Floejgaard, Camilla [Department of Wildlife Ecology and Biodiversity, National Environmental Research Institute, Aarhus University, Grenaavej 14, DK-8410 Roende (Denmark); Borchsenius, Finn; Normand, Signe; Balslev, Henrik; Svenning, Jens-Christian, E-mail: fs@dmu.d [Department of Biological Sciences, Aarhus University, Ny Munkegade 114, DK-8000 Aarhus C (Denmark)

    2009-11-01

    In this paper we examined the potential impacts of predicted climatic changes on the flora and vegetation in Denmark using data from a digital database on the natural vegetation of Europe. Climate scenarios A2 and B2 were used to find regions with present climatic conditions similar to Denmark's climate in the year 2100. The potential natural vegetation of Denmark today is predominantly deciduous forest that would cover more than 90% of the landscape. Swamps, bogs, and wet forest would be found under moist or wet conditions. Dwarf shrub heaths would be naturally occurring on poor soils along the coast together with dune systems and salt-marsh vegetation. When comparing the natural vegetation of Denmark to the vegetation of five future-climate analogue areas, the most obvious trend is a shift from deciduous to thermophilous broadleaved forest currently found in Southern and Eastern Europe. A total of 983 taxa were recorded for this study of which 539 were found in Denmark. The Soerensen index was used to measure the floristic similarity between Denmark and the five subregions. Deciduous forest, dwarf shrub heath, and coastal vegetation were treated in more detail, focusing on potential new immigrant species to Denmark. Finally, implications for management were discussed. The floristic similarity between Denmark and regions in Europe with a climate similar to what is expected for Denmark in year 2100 was found to vary between 48-78%, decreasing from North to South. Hence, it seems inevitable that climate changes of the magnitudes foreseen will alter the distribution of individual species and the composition of natural vegetation units. Changes, however, will not be immediate. Historic evidence shows a considerable lag in response to climatic change under natural conditions, but little is known about the effects of human land-use and pollution on this process. Facing such uncertainties we suggested that a dynamic strategy based on modeling, monitoring and

  14. Impacts of 21st century climate changes on flora and vegetation in Denmark

    International Nuclear Information System (INIS)

    Skov, Flemming; Nygaard, Bettina; Wind, Peter; Floejgaard, Camilla; Borchsenius, Finn; Normand, Signe; Balslev, Henrik; Svenning, Jens-Christian

    2009-01-01

    In this paper we examined the potential impacts of predicted climatic changes on the flora and vegetation in Denmark using data from a digital database on the natural vegetation of Europe. Climate scenarios A2 and B2 were used to find regions with present climatic conditions similar to Denmark's climate in the year 2100. The potential natural vegetation of Denmark today is predominantly deciduous forest that would cover more than 90% of the landscape. Swamps, bogs, and wet forest would be found under moist or wet conditions. Dwarf shrub heaths would be naturally occurring on poor soils along the coast together with dune systems and salt-marsh vegetation. When comparing the natural vegetation of Denmark to the vegetation of five future-climate analogue areas, the most obvious trend is a shift from deciduous to thermophilous broadleaved forest currently found in Southern and Eastern Europe. A total of 983 taxa were recorded for this study of which 539 were found in Denmark. The Soerensen index was used to measure the floristic similarity between Denmark and the five subregions. Deciduous forest, dwarf shrub heath, and coastal vegetation were treated in more detail, focusing on potential new immigrant species to Denmark. Finally, implications for management were discussed. The floristic similarity between Denmark and regions in Europe with a climate similar to what is expected for Denmark in year 2100 was found to vary between 48-78%, decreasing from North to South. Hence, it seems inevitable that climate changes of the magnitudes foreseen will alter the distribution of individual species and the composition of natural vegetation units. Changes, however, will not be immediate. Historic evidence shows a considerable lag in response to climatic change under natural conditions, but little is known about the effects of human land-use and pollution on this process. Facing such uncertainties we suggested that a dynamic strategy based on modeling, monitoring and adaptive

  15. 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...

  16. Urbanization, urban climate and influence of vegetation

    DEFF Research Database (Denmark)

    Feyisa, Gudina Legese

    and consequent problems. Through these papers, the project contributes to: 1) the science of remote sensing and Geographic Information System (GIS) by introducing methods that improve LULC classification accuracies, and an improved method of spatial thermal climate analyses, 2) better understanding of urban......, contributes to the research gaps by considering examples from two cities in Ethiopia, namely Addis Ababa and Adama. The major sources of data used in this study were remotely sensed multi-temporal digital imagery from Landsat TM and ETM+ sensors, ground surveying of LULC, measurements of air temperature...... and humidity, and questionnaire surveying. Remote sensing and GIS techniques were applied to analyze urbanization-induced dynamics of LULC and associated urban warming in five-year intervals between 1985 and 2010. LULC dynamics were analyzed applying post-classification change analysis using the Landsat...

  17. Homogenization of vegetation structure across residential neighborhoods: effects of climate, urban morphology, and socio-economics

    Science.gov (United States)

    Climate is a key driver regulating vegetation structure across rural ecosystems. In urban ecosystems, multiple interactions between humans and the environment can have homogenizing influences, confounding the relationship between vegetation structure and climate. In fact, vegetat...

  18. Changes in vegetation phenology on the Mongolian Plateau and their climatic determinants.

    Directory of Open Access Journals (Sweden)

    Lijuan Miao

    Full Text Available Climate change affects the timing of phenological events, such as the start, end, and length of the growing season of vegetation. A better understanding of how the phenology responded to climatic determinants is important in order to better anticipate future climate-ecosystem interactions. We examined the changes of three phenological events for the Mongolian Plateau and their climatic determinants. To do so, we derived three phenological metrics from remotely sensed vegetation indices and associated these with climate data for the period of 1982 to 2011. The results suggested that the start of the growing season advanced by 0.10 days yr-1, the end was delayed by 0.11 days yr-1, and the length of the growing season expanded by 6.3 days during the period from 1982 to 2011. The delayed end and extended length of the growing season were observed consistently in grassland, forest, and shrubland, while the earlier start was only observed in grassland. Partial correlation analysis between the phenological events and the climate variables revealed that higher temperature was associated with an earlier start of the growing season, and both temperature and precipitation contributed to the later ending. Overall, our findings suggest that climate change will substantially alter the vegetation phenology in the grasslands of the Mongolian Plateau, and likely also in biomes with similar environmental conditions, such as other semi-arid steppe regions.

  19. Changes in vegetation phenology on the Mongolian Plateau and their climatic determinants.

    Science.gov (United States)

    Miao, Lijuan; Müller, Daniel; Cui, Xuefeng; Ma, Meihong

    2017-01-01

    Climate change affects the timing of phenological events, such as the start, end, and length of the growing season of vegetation. A better understanding of how the phenology responded to climatic determinants is important in order to better anticipate future climate-ecosystem interactions. We examined the changes of three phenological events for the Mongolian Plateau and their climatic determinants. To do so, we derived three phenological metrics from remotely sensed vegetation indices and associated these with climate data for the period of 1982 to 2011. The results suggested that the start of the growing season advanced by 0.10 days yr-1, the end was delayed by 0.11 days yr-1, and the length of the growing season expanded by 6.3 days during the period from 1982 to 2011. The delayed end and extended length of the growing season were observed consistently in grassland, forest, and shrubland, while the earlier start was only observed in grassland. Partial correlation analysis between the phenological events and the climate variables revealed that higher temperature was associated with an earlier start of the growing season, and both temperature and precipitation contributed to the later ending. Overall, our findings suggest that climate change will substantially alter the vegetation phenology in the grasslands of the Mongolian Plateau, and likely also in biomes with similar environmental conditions, such as other semi-arid steppe regions.

  20. Simulating sub-Milankovitch climate variations associated with vegetation dynamics

    Directory of Open Access Journals (Sweden)

    E. Tuenter

    2007-01-01

    Full Text Available Climate variability at sub-Milankovitch periods (between 2 and 15 kyr is studied in a set of transient simulations with a coupled atmosphere/ocean/vegetation model of intermediate complexity (CLIMBER-2. Focus is on the region influenced by the African and Asian summer monsoon. Pronounced variations at periods of about 10 kyr (Asia and Africa and about 5 kyr (Asia are found in the monsoonal runoff in response to the precessional forcing. In the model this is due to the following mechanism. For low summer insolation (precession maximum precipitation is low and desert expands at the expense of grass, while for high insolation (precession minimum precipitation is high and the tree fraction increases also reducing the grass fraction. This induces sub-Milankovitch variations in the grass fraction and associated variations in the water holding capacity of the soil. The runoff does not exhibit sub-Milankovitch variability when vegetation is kept fixed. High-latitude vegetation also exhibits sub-Milankovitch variability under both obliquity and precessional forcing. We thus hypothesize that sub-Milankovitch variability can occur due to the dynamic response of the vegetation. However, this mechanism should be further tested with more sophisticated climate/vegetation models.

  1. Vegetation response to climate change : implications for Canada's conservation lands

    International Nuclear Information System (INIS)

    Scott, D.; Lemieux, C.

    2003-01-01

    Studies have shown that Canada's national parks are vulnerable to the impacts of climate change. A wide range of biophysical climate change impacts could affect the integrity of conservation lands in each region of Canada. This report examines the potential impact of climate change on landscape alterations and vegetation distribution in Canada's wide network of conservation lands. It also presents several ways to integrate climate change into existing conservation policy and adaptation strategies. Canada's conservation lands include provincial parks, migratory bird sanctuaries, national wildlife areas and wildlife protected areas. This is the first study to examine biome changes by applying an equilibrium Global Vegetation Model (GVM) to Canada's network of national park systems. Some of the policy and planning challenges posed by changes in landscape level vegetation were also addressed. The report indicates that in terms of potential changes to the biome classification of Canada's national forests, more northern biomes are projected to decrease. These northern biomes include the tundra, taiga and boreal conifer forests. 56 refs., 8 tabs., 6 figs

  2. African climate and vegetation at the roots of humankind during the Pliocene

    Science.gov (United States)

    Contoux, Camille; Ramstein, Gilles; Banks, Will; Sepulchre, Pierre; Schuster, Mathieu; Zhang, Zhongshi

    2017-04-01

    This study is devoted to the intricate links between climate, vegetation and hominin population distribution during Pliocene, during which peculiar combinations of climate and vegetation conditions have favored the development of hominin species. The aridification of North Africa from the Late Oligocene to the Tortonian has been recently linked to the Tethys shrinkage and associated changes in monsoon patterns. Since the Tortonian the response to orbital forcing has drastically increased accompanied by the onset of the Sahara desert [Zhang et al , Nature 2014] . Therefore, the context of the emergence and development of hominins is marked by a succession of wet and dry periods driven by orbital forcing factors. We focus here on the Pliocene period during which fossils have been discovered West and East of the African Rift (in the Chad basin and Rift Valley respectively). In order to better understand the climate and vegetation relationships during this period allowing populations to live both West and East of the Rift, we simulated the climate of the Pliocene for different orbital configurations with the coupled model IPSL-CM5A (OAGCM). We then use these simulated climates to carry out an equilibrium vegetation model, BIOME4, for 4 different orbital configurations with high eccentricity. We found that australopithecines occur in areas were primary productivity and precipitation are low, suggesting they were adapted to semi-arid environments.

  3. High potential for weathering and climate effects of non-vascular vegetation in the Late Ordovician

    Science.gov (United States)

    Porada, Philipp; Lenton, Tim; Pohl, Alexandre; Weber, Bettina; Mander, Luke; Donnadieu, Yannick; Beer, Christian; Pöschl, Ulrich; Kleidon, Axel

    2017-04-01

    Early non-vascular vegetation in the Late Ordovician may have strongly increased chemical weathering rates of surface rocks at the global scale. This could have led to a drawdown of atmospheric CO2 and, consequently, a decrease in global temperature and an interval of glaciations. Under current climatic conditions, usually field or laboratory experiments are used to quantify enhancement of chemical weathering rates by non-vascular vegetation. However, these experiments are constrained to a small spatial scale and a limited number of species. This complicates the extrapolation to the global scale, even more so for the geological past, where physiological properties of non-vascular vegetation may have differed from current species. Here we present a spatially explicit modelling approach to simulate large-scale chemical weathering by non-vascular vegetation in the Late Ordovician. For this purpose, we use a process-based model of lichens and bryophytes, since these organisms are probably the closest living analogue to Late Ordovician vegetation. The model explicitly represents multiple physiological strategies, which enables the simulated vegetation to adapt to Ordovician climatic conditions. We estimate productivity of Ordovician vegetation with the model, and relate it to chemical weathering by assuming that the organisms dissolve rocks to extract phosphorus for the production of new biomass. Thereby we account for limits on weathering due to reduced supply of unweathered rock material in shallow regions, as well as decreased transport capacity of runoff for dissolved weathered material in dry areas. We simulate a potential global weathering flux of 2.8 km3 (rock) per year, which we define as volume of primary minerals affected by chemical transformation. Our estimate is around 3 times larger than today's global chemical weathering flux. Furthermore, chemical weathering rates simulated by our model are highly sensitive to atmospheric CO2 concentration, which implies

  4. Dynamic Response of Satellite-Derived Vegetation Growth to Climate Change in the Three North Shelter Forest Region in China

    Directory of Open Access Journals (Sweden)

    Bin He

    2015-08-01

    Full Text Available Since the late 1970s, the Chinese government has initiated ecological restoration programs in the Three North Shelter Forest System Project (TNSFSP area. Whether accelerated climate change will help or hinder these efforts is still poorly understood. Using the updated and extended AVHRR NDVI3g dataset from 1982 to 2011 and corresponding climatic data, we investigated vegetation variations in response to climate change. The results showed that the overall state of vegetation in the study region has improved over the past three decades. Vegetation cover significantly decreased in 23.1% and significantly increased in 21.8% of the study area. An increase in all three main vegetation types (forest, grassland, and cropland was observed, but the trend was only statistically significant in cropland. In addition, bare and sparsely vegetated areas, mainly located in the western part of the study area, have significantly expanded since the early 2000s. A moisture condition analysis indicated that the study area experienced significant climate variations, with warm-wet conditions in the western region and warm-dry conditions in the eastern region. Correlation analysis showed that variations in the Normalized Difference Vegetation Index (NDVI were positively correlated with precipitation and negatively correlated with temperature. Ultimately, climate change influenced vegetation growth by controlling the availability of soil moisture. Further investigation suggested that the positive impacts of precipitation on NDVI have weakened in the study region, whereas the negative impacts from temperature have been enhanced in the eastern study area. However, over recent years, the negative temperature impacts have been converted to positive impacts in the western region. Considering the variations in the relationship between NDVI and climatic variables, the warm–dry climate in the eastern region is likely harmful to vegetation growth, whereas the warm

  5. Ocean climate and seal condition

    Directory of Open Access Journals (Sweden)

    Crocker Daniel E

    2005-03-01

    Full Text Available Abstract Background The condition of many marine mammals varies with fluctuations in productivity and food supply in the ocean basin where they forage. Prey is impacted by physical environmental variables such as cyclic warming trends. The weaning weight of northern elephant seal pups, Mirounga angustirostris, being closely linked to maternal condition, indirectly reflects prey availability and foraging success of pregnant females in deep waters of the northeastern Pacific. The aim of this study was to examine the effect of ocean climate on foraging success in this deep-diving marine mammal over the course of three decades, using cohort weaning weight as the principal metric of successful resource accrual. Results The mean annual weaning weight of pups declined from 1975 to the late 1990s, a period characterized by a large-scale, basin-wide warm decadal regime that included multiple strong or long-duration El Niños; and increased with a return to a cool decadal regime from about 1999 to 2004. Increased foraging effort and decreased mass gain of adult females, indicative of reduced foraging success and nutritional stress, were associated with high ocean temperatures. Conclusion Despite ranging widely and foraging deeply in cold waters beyond coastal thermoclines in the northeastern Pacific, elephant seals are impacted significantly by ocean thermal dynamics. Ocean warming redistributes prey decreasing foraging success of females, which in turn leads to lower weaning mass of pups. Annual fluctuations in weaning mass, in turn, reflect the foraging success of females during the year prior to giving birth and signals changes in ocean temperature cycles.

  6. Dynamics of climatic characteristics influencing vegetation in Siberia

    International Nuclear Information System (INIS)

    Shulgina, Tamara M; Genina, Elena Yu; Gordov, Evgeny P

    2011-01-01

    The spatiotemporal pattern of the dynamics of surface air temperature and precipitation and those bioclimatic indices that are based upon factors which control vegetation cover are investigated. Surface air temperature and precipitation data are retrieved from the ECMWF ERA Interim reanalysis and APHRODITE JMA datasets, respectively, which were found to be the closest to the observational data. We created an archive of bioclimatic indices for further detailed studies of interrelations between local climate and vegetation cover changes, which include carbon uptake changes related to changes of vegetation types and amount, as well as with spatial shifts of vegetation zones. Meanwhile, analysis reveals significant positive trends of the growing season length accompanied by a statistically significant increase of the sums of the growing degree days and precipitation over the south of West Siberia. The trends hint at a tendency for an increase of vegetation ecosystems' productivity across the south of West Siberia (55°–60°N, 59°–84°E) in the past several decades and (if sustained) may lead to a future increase of vegetation productivity in this region.

  7. Postglacial fire history and interactions with vegetation and climate in southwestern Yunnan Province of China

    Science.gov (United States)

    Xiao, Xiayun; Haberle, Simon G.; Shen, Ji; Xue, Bin; Burrows, Mark; Wang, Sumin

    2017-06-01

    A high-resolution, continuous 18.5 kyr (1 kyr = 1000 cal yr BP) macroscopic charcoal record from Qinghai Lake in southwestern Yunnan Province, China, reveals postglacial fire frequency and variability history. The results show that three periods with high-frequency and high-severity fires occurred during the periods 18.5-15.0, 13.0-11.5, and 4.3-0.8 ka, respectively. This record was compared with major pollen taxa and pollen diversity indices from the same core, and tentatively related to the regional climate proxy records with the aim to separate climate- from human-induced fire activity, and discuss vegetation-fire-climate interactions. The results suggest that fire was mainly controlled by climate before 4.3 ka and by the combined actions of climate and humans after 4.3 ka. Before 4.3 ka, high fire activity corresponded to cold and dry climatic conditions, while warm and humid climatic conditions brought infrequent and weak fires. Fire was an important disturbance factor and played an important role in forest dynamics around the study area. Vegetation responses to fire after 4.3 ka are not consistent with those before 4.3 ka, suggesting that human influence on vegetation and fire regimes may have become more prevalent after 4.3 ka. The comparisons between fire activity and vegetation reveal that evergreen oaks are flammable plants and fire-tolerant taxa. Alnus is a fire-adapted taxon and a nonflammable plant, but density of Alnus forest is a key factor to decide its fire resistance. The forests dominated by Lithocarpus/Castanopsis and/or tropical trees and shrubs are not easy to ignite, but Lithocarpus/Castanopsis and tropical trees and shrubs are fire-sensitive taxa. Fire appears to be unfavourable to plant diversity in the study area.

  8. The ACCENT-VOCBAS field campaign on biosphere-atmosphere interactions in a Mediterranean ecosystem of Castelporziano (Rome: site characteristics, climatic and meteorological conditions, and eco-physiology of vegetation

    Directory of Open Access Journals (Sweden)

    S. Fares

    2009-06-01

    Full Text Available Biosphere-atmosphere interactions were investigated on a sandy dune Mediterranean ecosystem in a field campaign held in 2007 within the frame of the European Projects ACCENT and VOCBAS. The campaign was carried out in the Presidential estate of Castelporziano, a peri-urban park close to Rome. Former campaigns (e.g. BEMA performed in Castelporziano investigated the emission of biogenic volatile organic compounds (BVOC. These campaigns focused on pseudosteppe and evergreen oak groves whereas the contribution of the largely biodiverse dune vegetation, a prominent component of the Mediterranean ecosystem, was overlooked. While specific aspects of the campaign will be discussed in companion papers, the general climatic and physiological aspects are presented here, together with information regarding BVOC emission from the most common plant species of the dune ecosystem. During the campaign regular air movements were observed, dominated by moderate nocturnal land breeze and diurnal sea breeze. A regular daily increase of ozone concentration in the air was also observed, but daily peaks of ozone were lower than those measured in summer on the same site. The site was ideal as a natural photochemical reactor to observe reaction, transport and deposition processes occurring in the Mediterranean basin, since the sea-land breeze circulation allowed a strong mixing between biogenic and anthropogenic emissions and secondary pollutants. Measurements were run in May, when plant physiological conditions were optimal, in absence of severe drought and heat stress. Foliar rates of photosynthesis and transpiration were as high as generally recorded in unstressed Mediterranean sclerophyllous plants. Most of the plant species emitted high level of monoterpenes, despite measurements being made in a period in which emissions of volatile isoprenoids could be restrained by developmental and environmental factors, such as leaf age and relatively low air temperature

  9. Combining super-ensembles and statistical emulation to improve a regional climate and vegetation model

    Science.gov (United States)

    Hawkins, L. R.; Rupp, D. E.; Li, S.; Sarah, S.; McNeall, D. J.; Mote, P.; Betts, R. A.; Wallom, D.

    2017-12-01

    Changing regional patterns of surface temperature, precipitation, and humidity may cause ecosystem-scale changes in vegetation, altering the distribution of trees, shrubs, and grasses. A changing vegetation distribution, in turn, alters the albedo, latent heat flux, and carbon exchanged with the atmosphere with resulting feedbacks onto the regional climate. However, a wide range of earth-system processes that affect the carbon, energy, and hydrologic cycles occur at sub grid scales in climate models and must be parameterized. The appropriate parameter values in such parameterizations are often poorly constrained, leading to uncertainty in predictions of how the ecosystem will respond to changes in forcing. To better understand the sensitivity of regional climate to parameter selection and to improve regional climate and vegetation simulations, we used a large perturbed physics ensemble and a suite of statistical emulators. We dynamically downscaled a super-ensemble (multiple parameter sets and multiple initial conditions) of global climate simulations using a 25-km resolution regional climate model HadRM3p with the land-surface scheme MOSES2 and dynamic vegetation module TRIFFID. We simultaneously perturbed land surface parameters relating to the exchange of carbon, water, and energy between the land surface and atmosphere in a large super-ensemble of regional climate simulations over the western US. Statistical emulation was used as a computationally cost-effective tool to explore uncertainties in interactions. Regions of parameter space that did not satisfy observational constraints were eliminated and an ensemble of parameter sets that reduce regional biases and span a range of plausible interactions among earth system processes were selected. This study demonstrated that by combining super-ensemble simulations with statistical emulation, simulations of regional climate could be improved while simultaneously accounting for a range of plausible land

  10. Vegetation and climate history during the last millennium derived from Anggertu Lake, Tengger Desert

    Science.gov (United States)

    Duan, F.; An, C.; Zhao, Y.; Wang, W.; Cao, Z.

    2017-12-01

    Studying the climate changes during the last millennium can help us to understand current relationship between human-social activities and natural environment changes, and improve projections of future climate. Pollen assemblages, loss-on-ignition (LOIorg at 550 °C) and grain size data collected from sediment core (AGE15A) from the center of Anggertu lake (eastern Tengger Desert, Inner Mongolia) are presented to reconstruct regional vegetation and climate history during the last millennium. Results show that: 1) desert or desert steppe dominated by Artemisia and Amaranthaceae expanded around this region during the period of 988 1437 A.D., indicating a generally dry climate condition with two short humid periods (1003 1082 A.D. and 1388 1437 A.D). These two wet periods are characterized by relatively high vegetation cover and bio-productivity, reflected by high pollen concentrations and LOIorg. Increase in the steppe or meadow vegetation communities (Poaceae, Cyperaceae) and vegetation cover during the period of 1437 2015 A.D. suggest a wetting trend, as also indicated by gradually finer grain size. The relatively high LOI indicate a high bio-productivity during this interval. And then unstable lacustrine environment was found with frequent fluctuations in pollen concentration and grain size since 1842 A.D.. 2) This study recorded a relatively dry Medieval Warm Period (MWP; 1082 1388 A.D.) and a wet Little Ice Age (LIA; 1437 1842 A.D.), which is generally consistent with climate characteristics in arid central Asia (ACA). 3) Increased Amaranthaceae and high abundance of Poaceae were related to overgrazing and agricultural activities at that time to some extent. Thus vegetation evolution of the lake region was influenced by human activities and climate changes.

  11. Climate, people, fire and vegetation: new insights into vegetation dynamics in the Eastern Mediterranean since the 1st century AD

    Directory of Open Access Journals (Sweden)

    J. Bakker

    2013-01-01

    Full Text Available Anatolia forms a bridge between Europe, Africa and Asia and is influenced by all three continents in terms of climate, vegetation and human civilisation. Unfortunately, well-dated palynological records focussing on the period from the end of the classical Roman period until subrecent times are rare for Anatolia and completely absent for southwest Turkey, resulting in a lacuna in knowledge concerning the interactions of climatic change, human impact, and environmental change in this important region. Two well-dated palaeoecological records from the Western Taurus Mountains, Turkey, provide a first relatively detailed record of vegetation dynamics from late Roman times until the present in SW Turkey. Combining pollen, non-pollen palynomorphs, charcoal, sedimentological, archaeological data, and newly developed multivariate numerical analyses allows for the disentangling of climatic and anthropogenic influences on vegetation change. Results show changes in both the regional pollen signal as well as local soil sediment characteristics match shifts in regional climatic conditions. Both climatic as well as anthropogenic change had a strong influence on vegetation dynamics and land use. A moist environmental trend during the late-3rd century caused an increase in marshes and wetlands in the moister valley floors, limiting possibilities for intensive crop cultivation at such locations. A mid-7th century shift to pastoralism coincided with a climatic deterioration as well as the start of Arab incursions into the region, the former driving the way in which the vegetation developed afterwards. Resurgence in agriculture was observed in the study during the mid-10th century AD, coinciding with the Medieval Climate Anomaly. An abrupt mid-12th century decrease in agriculture is linked to socio-political change, rather than the onset of the Little Ice Age. Similarly, gradual deforestation occurring from the 16th century onwards has been linked to changes in

  12. Interactions of Vegetation and Climate: Remote Observations, Earth System Models, and the Amazon Forest

    Science.gov (United States)

    Quetin, Gregory R.

    The natural composition of terrestrial ecosystems can be shaped by climate to take advantage of local environmental conditions. Ecosystem functioning, e.g. interaction between photosynthesis and temperature, can also acclimate to different climatological states. The combination of these two factors thus determines ecological-climate interactions. The ecosystem functioning also plays a key role in predicting the carbon cycle, hydrological cycle, terrestrial surface energy balance, and the feedbacks in the climate system. Predicting the response of the Earth's biosphere to global warming requires the ability to mechanistically represent the processes controlling ecosystem functioning through photosynthesis, respiration, and water use. The physical environment in a place shapes the vegetation there, but vegetation also has the potential to shape the environment, e.g. increased photosynthesis and transpiration moisten the atmosphere. These two-way ecoclimate interactions create the potential for feedbacks between vegetation at the physical environment that depend on the vegetation and the climate of a place, and can change throughout the year. In Chapter 1, we derive a global empirical map of the sensitivity of vegetation to climate using the response of satellite-observed greenness to interannual variations in temperature and precipitation. We infer mechanisms constraining ecosystem functioning by analyzing how the sensitivity of vegetation to climate varies across climate space. Our analysis yields empirical evidence for multiple physical and biological mediators of the sensitivity of vegetation to climate at large spatial scales. In hot and wet locations, vegetation is greener in warmer years despite temperatures likely exceeding thermally optimum conditions. However, sunlight generally increases during warmer years, suggesting that the increased stress from higher atmospheric water demand is offset by higher rates of photosynthesis. The sensitivity of vegetation

  13. Water–Soil–Vegetation Dynamic Interactions in Changing Climate

    Directory of Open Access Journals (Sweden)

    Xixi Wang

    2017-09-01

    Full Text Available Previous studies of land degradation, topsoil erosion, and hydrologic alteration typically focus on these subjects individually, missing important interrelationships among these important aspects of the Earth’s system. However, an understanding of water–soil–vegetation dynamic interactions is needed to develop practical and effective solutions to sustain the globe’s eco-environment and grassland agriculture, which depends on grasses, legumes, and other fodder or soil-building crops. This special issue is intended to be a platform for a discussion of the relevant scientific findings based on experimental and/or modeling studies. Its 12 peer-reviewed articles present data, novel analysis/modeling approaches, and convincing results of water–soil–vegetation interactions under historical and future climates. Two of the articles examine how lake/pond water quality is related to human activity and climate. Overall, these articles can serve as important references for future studies to further advance our understanding of how water, soil, and vegetation interactively affect the health and productivity of the Earth’s ecosystem.

  14. IN11B-1621: Quantifying How Climate Affects Vegetation in the Amazon Rainforest

    Science.gov (United States)

    Das, Kamalika; Kodali, Anuradha; Szubert, Marcin; Ganguly, Sangram; Bongard, Joshua

    2016-01-01

    Amazon droughts in 2005 and 2010 have raised serious concern about the future of the rainforest. Amazon forests are crucial because of their role as the largest carbon sink in the world which would effect the global warming phenomena with decreased photosynthesis activity. Especially, after a decline in plant growth in 1.68 million km2 forest area during the once-in-a-century severe drought in 2010, it is of primary importance to understand the relationship between different climatic variables and vegetation. In an earlier study, we have shown that non-linear models are better at capturing the relation dynamics of vegetation and climate variables such as temperature and precipitation, compared to linear models. In this research, we learn precise models between vegetation and climatic variables (temperature, precipitation) for normal conditions in the Amazon region using genetic programming based symbolic regression. This is done by removing high elevation and drought affected areas and also considering the slope of the region as one of the important factors while building the model. The model learned reveals new and interesting ways historical and current climate variables affect the vegetation at any location. MAIAC data has been used as a vegetation surrogate in our study. For temperature and precipitation, we have used TRMM and MODIS Land Surface Temperature data sets while learning the non-linear regression model. However, to generalize the model to make it independent of the data source, we perform transfer learning where we regress a regularized least squares to learn the parameters of the non-linear model using other data sources such as the precipitation and temperature from the Climatic Research Center (CRU). This new model is very similar in structure and performance compared to the original learned model and verifies the same claims about the nature of dependency between these climate variables and the vegetation in the Amazon region. As a result of this

  15. Trends in Global Vegetation Activity and Climatic Drivers Indicate a Decoupled Response to Climate Change.

    Directory of Open Access Journals (Sweden)

    Antonius G T Schut

    Full Text Available Detailed understanding of a possible decoupling between climatic drivers of plant productivity and the response of ecosystems vegetation is required. We compared trends in six NDVI metrics (1982-2010 derived from the GIMMS3g dataset with modelled biomass productivity and assessed uncertainty in trend estimates. Annual total biomass weight (TBW was calculated with the LINPAC model. Trends were determined using a simple linear regression, a Thiel-Sen medium slope and a piecewise regression (PWR with two segments. Values of NDVI metrics were related to Net Primary Production (MODIS-NPP and TBW per biome and land-use type. The simple linear and Thiel-Sen trends did not differ much whereas PWR increased the fraction of explained variation, depending on the NDVI metric considered. A positive trend in TBW indicating more favorable climatic conditions was found for 24% of pixels on land, and for 5% a negative trend. A decoupled trend, indicating positive TBW trends and monotonic negative or segmented and negative NDVI trends, was observed for 17-36% of all productive areas depending on the NDVI metric used. For only 1-2% of all pixels in productive areas, a diverging and greening trend was found despite a strong negative trend in TBW. The choice of NDVI metric used strongly affected outcomes on regional scales and differences in the fraction of explained variation in MODIS-NPP between biomes were large, and a combination of NDVI metrics is recommended for global studies. We have found an increasing difference between trends in climatic drivers and observed NDVI for large parts of the globe. Our findings suggest that future scenarios must consider impacts of constraints on plant growth such as extremes in weather and nutrient availability to predict changes in NPP and CO2 sequestration capacity.

  16. Satellite-based hybrid drought monitoring tool for prediction of vegetation condition in Eastern Africa: A case study for Ethiopia

    Science.gov (United States)

    Tadesse, Tsegaye; Demisse, Getachew Berhan; Zaitchik, Ben; Dinku, Tufa

    2014-03-01

    An experimental drought monitoring tool has been developed that predicts the vegetation condition (Vegetation Outlook) using a regression-tree technique at a monthly time step during the growing season in Eastern Africa. This prediction tool (VegOut-Ethiopia) is demonstrated for Ethiopia as a case study. VegOut-Ethiopia predicts the standardized values of the Normalized Difference Vegetation Index (NDVI) at multiple time steps (weeks to months into the future) based on analysis of "historical patterns" of satellite, climate, and oceanic data over historical records. The model underlying VegOut-Ethiopia capitalizes on historical climate-vegetation interactions and ocean-climate teleconnections (such as El Niño and the Southern Oscillation (ENSO)) expressed over the 24 year data record and also considers several environmental characteristics (e.g., land cover and elevation) that influence vegetation's response to weather conditions to produce 8 km maps that depict future general vegetation conditions. VegOut-Ethiopia could provide vegetation monitoring capabilities at local, national, and regional levels that can complement more traditional remote sensing-based approaches that monitor "current" vegetation conditions. The preliminary results of this case study showed that the models were able to predict the vegetation stress (both spatial extent and severity) in drought years 1-3 months ahead during the growing season in Ethiopia. The correlation coefficients between the predicted and satellite-observed vegetation condition range from 0.50 to 0.90. Based on the lessons learned from past research activities and emerging experimental forecast models, future studies are recommended that could help Eastern Africa in advancing knowledge of climate, remote sensing, hydrology, and water resources.

  17. Effects of late Holocene climate variability and anthropogenic stressors on the vegetation of the Maya highlands

    Science.gov (United States)

    Franco-Gaviria, F.; Correa-Metrio, A.; Cordero-Oviedo, C.; López-Pérez, M.; Cárdenes-Sandí, G. M.; Romero, F. M.

    2018-06-01

    Climate variability and human activities have shaped the vegetation communities of the Maya region of southern Mexico and Central America on centennial to millennial timescales. Most research efforts in the region have focused on the lowlands, with relatively little known about the environmental history of the regional highlands. Here we present data from two sediment sequences collected from lakes in the highlands of Chiapas, Mexico. Our aim was to disentangle the relative contributions of climate and human activities in the development of regional vegetation during the late Holocene. The records reveal a long-term trend towards drier conditions with superimposed centennial-scale droughts. A declining moisture trend from 3400 to 1500 cal yr BP is consistent with previously reported southward displacement of the Intertropical Convergence Zone, whereas periodic droughts were probably a consequence of drivers such as El Niño. These conditions, together with dense human occupation, converted the vegetation from forest to more open systems. According to the paleoecological records, cultural abandonment of the area occurred ca. 1500 cal yr BP, favoring forest recovery that was somewhat limited by low moisture availability. About 600 cal yr BP, wetter conditions promoted the establishment of modern montane cloud forests, which consist of a diverse mixture of temperate and tropical elements. The vegetation types that occupied the study area during the last few millennia have remained within the envelope defined by the modern vegetation mosaic. This finding highlights the importance of microhabitats in the maintenance biodiversity through time, even under scenarios of high climate variability and anthropogenic pressure.

  18. Mediterranean biomes: Evolution of their vegetation, floras and climate

    Science.gov (United States)

    Rundel, Philip W.; Arroyo, Mary T.K.; Cowling, R.M.; Keeley, J. E.; Lamont, B.B.; Vargas, Pablo

    2016-01-01

    Mediterranean-type ecosystems (MTEs) possess the highest levels of plant species richness in the world outside of the wet tropics. Sclerophyll vegetation similar to today’s mediterranean-type shrublands was already present on oligotrophic soils in the wet and humid climate of the Cretaceous, with fire-adapted Paleogene lineages in southwestern Australia and the Cape Region. The novel MTC seasonality present since the mid-Miocene has allowed colonization of MTEs from a regional species pool with associated diversification. Fire persistence has been a primary driving factor for speciation in four of the five regions. Understanding the regional patterns of plant species diversity among the MTEs involves complex interactions of geologic and climatic histories for each region as well as ecological factors that have promoted diversification in the Neogene and Quaternary. A critical element of species richness for many MTE lineages has been their ability to speciate and persist at fine spatial scales, with low rates of extinction.

  19. Vegetation coupling to global climate: Trajectories of vegetation change and phenology modeling from satellite observations

    Science.gov (United States)

    Fisher, Jeremy Isaac

    Important systematic shifts in ecosystem function are often masked by natural variability. The rich legacy of over two decades of continuous satellite observations provides an important database for distinguishing climatological and anthropogenic ecosystem changes. Examples from semi-arid Sudanian West Africa and New England (USA) illustrate the response of vegetation to climate and land-use. In Burkina Faso, West Africa, pastoral and agricultural practices compete for land area, while degradation may follow intensification. The Nouhao Valley is a natural experiment in which pastoral and agricultural land uses were allocated separate, coherent reserves. Trajectories of annual net primary productivity were derived from 18 years of coarse-grain (AVHRR) satellite data. Trends suggested that pastoral lands had responded rigorously to increasing rainfall after the 1980's droughts. A detailed analysis at Landsat resolution (30m) indicated that the increased vegetative cover was concentrated in the river basins of the pastoral region, implying a riparian wood expansion. In comparison, riparian cover was reduced in agricultural regions. We suggest that broad-scale patterns of increasing semi-arid West African greenness may be indicative of climate variability, whereas local losses may be anthropogenic in nature. The contiguous deciduous forests, ocean proximity, topography, and dense urban developments of New England provide an ideal landscape to examine influences of climate variability and the impact of urban development vegetation response. Spatial and temporal patterns of interannual climate variability were examined via green leaf phenology. Phenology, or seasonal growth and senescence, is driven by deficits of light, temperature, and water. In temperate environments, phenology variability is driven by interannual temperature and precipitation shifts. Average and interannual phenology analyses across southern New England were conducted at resolutions of 30m (Landsat

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

    Science.gov (United States)

    Sarah C. Elmendorf; Gregory H.R. Henry; Robert D. Hollister; Robert G. Björk; Anne D. Bjorkman; Terry V. Callaghan; [and others] NO-VALUE; William Gould; Joel Mercado

    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...

  1. [Variation trends of natural vegetation net primary productivity in China under climate change scenario].

    Science.gov (United States)

    Zhao, Dong-sheng; Wu, Shao-hong; Yin, Yun-he

    2011-04-01

    Based on the widely used Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ) for climate change study, and according to the features of natural environment in China, the operation mechanism of the model was adjusted, and the parameters were modified. With the modified LPJ model and taking 1961-1990 as baseline period, the responses of natural vegetation net primary productivity (NPP) in China to climate change in 1991-2080 were simulated under the Special Report on Emissions Scenarios (SRES) B2 scenario. In 1961-1990, the total NPP of natural vegetation in China was about 3.06 Pg C a(-1); in 1961-2080, the total NPP showed a fluctuant decreasing trend, with an accelerated decreasing rate. Under the condition of slight precipitation change, the increase of mean air temperature would have definite adverse impact on the NPP. Spatially, the NPP decreased from southeast coast to northwest inland, and this pattern would have less variation under climate change. In eastern China with higher NPP, especially in Northeast China, east of North China, and Loess Plateau, the NPP would mainly have a decreasing trend; while in western China with lower NPP, especially in the Tibetan Plateau and Tarim Basin, the NPP would be increased. With the intensive climate change, such a variation trend of NPP would be more obvious.

  2. How will climate change affect the vegetation cycle over France? A generic modeling approach

    Directory of Open Access Journals (Sweden)

    Nabil Laanaia

    2016-01-01

    Full Text Available The implementation of adaptation strategies of agriculture and forestry to climate change is conditioned by the knowledge of the impacts of climate change on the vegetation cycle and of the associated uncertainties. Using the same generic Land Surface Model (LSM to simulate the response of various vegetation types is more straightforward than using several specialized crop and forestry models, as model implementation differences are difficult to assess. The objective of this study is to investigate the potential of a LSM to address this issue. Using the SURFEX (“Surface Externalisée” modeling platform, we produced and analyzed 150-yr (1950–2100 simulations of the biomass of four vegetation types (rainfed straw cereals, rainfed grasslands, broadleaf and needleleaf forests and of the soil water content associated to each of these vegetation types over France. Statistical methods were used to quantify the impact of climate change on simulated phenological dates. The duration of soil moisture stress periods increases everywhere in France, especially for grasslands with, on average, an increase of 9 days per year in near-future (NF conditions and 36 days per year in distant-future (DF conditions. For all the vegetation types, leaf onset and the annual maximum LAI occur earlier. For straw cereals in the Languedoc-Provence-Corsica area, NF leaf onset occurs 18 days earlier and 37 days earlier in DF conditions, on average. On the other hand, local discrepancies are simulated for the senescence period (e.g. earlier in western and southern France for broadleaf forests, slightly later in mountainous areas of eastern France for both NF and DF. Changes in phenological dates are more uncertain in DF than in NF conditions in relation to differences in climate models, especially for forests. Finally, it is shown that while changes in leaf onset are mainly driven by air temperature, longer soil moisture stress periods trigger earlier leaf senescence

  3. Vegetation physiology controls continental water cycle responses to climate change

    Science.gov (United States)

    Lemordant, L. A.; Swann, A. L. S.; Cook, B.; Scheff, J.; Gentine, P.

    2017-12-01

    Abstract per se:Predicting how climate change will affect the hydrologic cycle is of utmost importance for ecological systems and for human life and activities. A typical perspective is that global warming will cause an intensification of the mean state, the so-called "dry gets drier, wet gets wetter" paradigm. While this result is robust over the oceans, recent works suggest it may be less appropriate for terrestrial regions. Using Earth System Models (ESMs) with decoupled surface (vegetation physiology, PHYS) and atmospheric (radiative, ATMO) CO2 responses, we show that the CO2 physiological response dominates the change in the continental hydrologic cycle compared to radiative and precipitation changes due to increased atmospheric CO2, counter to previous assumptions. Using multiple linear regression analysis, we estimate the individual contribution of each of the three main drivers, precipitation, radiation and physiological CO2 forcing (see attached figure). Our analysis reveals that physiological effects dominate changes for 3 key indicators of dryness and/or vegetation stress (namely LAI, P-ET and EF) over the largest fraction of the globe, except for soil moisture which exhibits a more complex response. This highlights the key role of vegetation in controlling future terrestrial hydrologic response.Legend of the Figure attached:Decomposition along the three main drivers of LAI (a), P-ET (b), EF (c) in the control run. Green quantifies the effect of the vegetation physiology based on the run PHYS; red and blue quantify the contribution of, respectively, net radiation and precipitation, based on multiple linear regression in ATMO. Pie charts show for each variable the fraction (labelled in %) of land under the main influence (more than 50% of the changes is attributed to this driver) of one the three main drivers (green for grid points dominated by vegetation physiology, red for grid points dominated by net radiation, and blue for grid points dominated by the

  4. Insights into Penultimate Interglacial-Glacial Climate Change on Vegetation History at Lake Van, Turkey

    Science.gov (United States)

    Pickarski, N.; Litt, T.

    2017-12-01

    A new detailed pollen and oxygen isotope record of the penultimate interglacial-glacial cycle (ca. 250-129 ka; MIS 7-6), has been generated from the sediment core at Lake Van, Turkey. The integration of all available proxies (pollen, microscopic charcoal, δ18Obulk, and XRF) shows three temperate intervals of high effective soil moisture availability. This is evidenced by the predominance of oak steppe-forested landscapes similar to the present interglacial vegetation in this sensitive semiarid region. The wettest/warmest stage, as indicated by highest temperate tree percentages, can be broadly correlated with MIS 7c, while the amplitude of the tree population maximum during the oldest penultimate interglacial (MIS 7e) appears to be reduced due to warm but drier climatic conditions. A detailed comparison of the penultimate interglacial complex (MIS 7) to the last interglacial (MIS 5e) and the current interglacial (MIS 1) provides a vivid illustration of possible differences in the successive climatic cycles. Intervening periods of treeless vegetation (MIS 7d, 7a) were predominated by steppe elements. The occurrence of Artemisia and Chenopodiaceae during MIS 7d indicates very dry and cold climatic conditions, while higher temperate tree percentages (mainly deciduous Quercus) points to relatively humid and mild conditions throughout MIS 7b. Despite the general dominance of dry and cold desert-steppe vegetation during the penultimate glacial (MIS 6), this period can be divided into two parts: an early stage (ca. 193-157 ka) with higher oscillations in tree percentages and a later stage (ca. 157-131 ka) with lower tree percentages and subdued oscillations. Furthermore, we are able to identify the MIS 6e event (ca. 179-159 ka), which reveals clear climate variability due to rapid alternation in the vegetation cover. In comparison with long European pollen archives, speleothem isotope records from the Near East, and global climate parameters, the new high

  5. Response of spatial vegetation distribution in China to climate changes since the Last Glacial Maximum (LGM)

    Science.gov (United States)

    Wang, Siyang; Xu, Xiaoting; Shrestha, Nawal; Zimmermann, Niklaus E.; Tang, Zhiyao; Wang, Zhiheng

    2017-01-01

    Analyzing how climate change affects vegetation distribution is one of the central issues of global change ecology as this has important implications for the carbon budget of terrestrial vegetation. Mapping vegetation distribution under historical climate scenarios is essential for understanding the response of vegetation distribution to future climatic changes. The reconstructions of palaeovegetation based on pollen data provide a useful method to understand the relationship between climate and vegetation distribution. However, this method is limited in time and space. Here, using species distribution model (SDM) approaches, we explored the climatic determinants of contemporary vegetation distribution and reconstructed the distribution of Chinese vegetation during the Last Glacial Maximum (LGM, 18,000 14C yr BP) and Middle-Holocene (MH, 6000 14C yr BP). The dynamics of vegetation distribution since the LGM reconstructed by SDMs were largely consistent with those based on pollen data, suggesting that the SDM approach is a useful tool for studying historical vegetation dynamics and its response to climate change across time and space. Comparison between the modeled contemporary potential natural vegetation distribution and the observed contemporary distribution suggests that temperate deciduous forests, subtropical evergreen broadleaf forests, temperate deciduous shrublands and temperate steppe have low range fillings and are strongly influenced by human activities. In general, the Tibetan Plateau, North and Northeast China, and the areas near the 30°N in Central and Southeast China appeared to have experienced the highest turnover in vegetation due to climate change from the LGM to the present. PMID:28426780

  6. Exploring Connections between Global Climate Indices and African Vegetation Phenology

    Science.gov (United States)

    Brown, Molly E.; deBeurs, Kirsten; Vrieling, Anton

    2009-01-01

    Variations in agricultural production due to rainfall and temperature fluctuations are a primary cause of food insecurity on the continent in Africa. Agriculturally destructive droughts and floods are monitored from space using satellite remote sensing by organizations seeking to provide quantitative and predictive information about food security crises. Better knowledge on the relation between climate indices and food production may increase the use of these indices in famine early warning systems and climate outlook forums on the continent. Here we explore the relationship between phenology metrics derived from the 26 year AVHRR NDVI record and the North Atlantic Oscillation index (NAO), the Indian Ocean Dipole (IOD), the Pacific Decadal Oscillation (PDO), the Multivariate ENSO Index (MEI) and the Southern Oscillation Index (SOI). We explore spatial relationships between growing conditions as measured by the NDVI and the five climate indices in Eastern, Western and Southern Africa to determine the regions and periods when they have a significant impact. The focus is to provide a clear indication as to which climate index has the most impact on the three regions during the past quarter century. We found that the start of season and cumulative NDVI were significantly affected by variations in the climate indices. The particular climate index and the timing showing highest correlation depended heavily on the region examined. The research shows that climate indices can contribute to understanding growing season variability in Eastern, Western and Southern Africa.

  7. The effects of climate, permafrost and fire on vegetation change in Siberia in a changing climate

    Energy Technology Data Exchange (ETDEWEB)

    Tchebakova, N M; Parfenova, E [V N Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Sciences, Academgorodok, Krasnoyarsk, 660036 (Russian Federation); Soja, A J, E-mail: ncheby@forest.akadem.r, E-mail: Amber.J.Soja@nasa.go [National Institute of Aerospace (NIA), NASA Langley Research Center, Climate Sciences, 21 Langley Boulevard, Mail Stop 420, Hampton, VA 23681-2199 (United States)

    2009-10-15

    Observations and general circulation model projections suggest significant temperature increases in Siberia this century that are expected to have profound effects on Siberian vegetation. Potential vegetation change across Siberia was modeled, coupling our Siberian BioClimatic Model with several Hadley Centre climate change scenarios for 2020, 2050 and 2080, with explicit consideration of permafrost and fire activity. In the warmer and drier climate projected by these scenarios, Siberian forests are predicted to decrease and shift northwards and forest-steppe and steppe ecosystems are predicted to dominate over half of Siberia due to the dryer climate by 2080. Despite the large predicted increases in warming, permafrost is not predicted to thaw deep enough to sustain dark (Pinus sibirica, Abies sibirica, and Picea obovata) taiga. Over eastern Siberia, larch (Larix dahurica) taiga is predicted to continue to be the dominant zonobiome because of its ability to withstand continuous permafrost. The model also predicts new temperate broadleaf forest and forest-steppe habitats by 2080. Potential fire danger evaluated with the annual number of high fire danger days (Nesterov index is 4000-10 000) is predicted to increase by 2080, especially in southern Siberia and central Yakutia. In a warming climate, fuel load accumulated due to replacement of forest by steppe together with frequent fire weather promotes high risks of large fires in southern Siberia and central Yakutia, where wild fires would create habitats for grasslands because the drier climate would no longer be suitable for forests.

  8. Empirical methods for estimating future climatic conditions

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    Applying the empirical approach permits the derivation of estimates of the future climate that are nearly independent of conclusions based on theoretical (model) estimates. This creates an opportunity to compare these results with those derived from the model simulations of the forthcoming changes in climate, thus increasing confidence in areas of agreement and focusing research attention on areas of disagreements. The premise underlying this approach for predicting anthropogenic climate change is based on associating the conditions of the climatic optimums of the Holocene, Eemian, and Pliocene with corresponding stages of the projected increase of mean global surface air temperature. Provided that certain assumptions are fulfilled in matching the value of the increased mean temperature for a certain epoch with the model-projected change in global mean temperature in the future, the empirical approach suggests that relationships leading to the regional variations in air temperature and other meteorological elements could be deduced and interpreted based on use of empirical data describing climatic conditions for past warm epochs. Considerable care must be taken, of course, in making use of these spatial relationships, especially in accounting for possible large-scale differences that might, in some cases, result from different factors contributing to past climate changes than future changes and, in other cases, might result from the possible influences of changes in orography and geography on regional climatic conditions over time

  9. Biocrust spectral response as affected by changing climatic conditions

    Science.gov (United States)

    Rodriguez-Caballero, Emilio; Guirado, Emilio; Escribano, Paula; Reyes, Andres; Weber, Bettina

    2017-04-01

    Drylands are characterized by scarce vegetation coverage and low rates of biological activity, both constrained by water scarcity. Under these conditions, biocrusts form key players of ecosystem functioning. They comprise complex poikilohydric communities of cyanobacteria, algae, lichens and bryophytes together with heterotrophic bacteria, archaea and fungi, which cover the uppermost soil layer. Biocrusts can cope with prolonged phases of drought, being rapidly re-activated when water becomes available again. Upon reactivation, biocrusts almost immediately turn green, fixing atmospheric carbon and nitrogen and increasing ecosystem productivity. However, due to their inconspicuous growth they have only rarely been analysed and spatially and temporally continuous information on their response to water pulses is missing. These data are particularly important under changing climatic conditions predicting an increase in aridity and variations in precipitation patterns within most of the dryland regions. In the present study, we used multi-temporal series of NDVI obtained from LANDSAT images to analyze biocrust and vegetation response to water pulses within the South African Succulent Karoo and we predicted their future response under different climate change scenarios. The results showed that biocrust and vegetation greenness are controlled by aridity, solar radiation and soil water content, showing similar annual patterns, with minimum values during dry periods that increased within the rainy season and decreased again after the onset of drought. However, biocrusts responded faster to water availability and turned green almost immediately after small rains, producing a small NDVI peak only few days after rainfall, whereas more time was needed for vegetation to grow new green tissue. However, once the photosynthetic tissue of vegetation was restored, it caused the highest increase of NDVI values after the rain. Predicted changes in precipitation patterns and aridity

  10. Climatic growing conditions of Jatropha curcas L.

    Energy Technology Data Exchange (ETDEWEB)

    Maes, W.H.; Achten, W.M.J.; Muys, B. [Katholieke Universiteit Leuven, Division Forest, Nature and Landscape, Celestijnenlaan 200 E Box 2411, BE-3001 Leuven (Belgium); Trabucco, A. [Katholieke Universiteit Leuven, Division Forest, Nature and Landscape, Celestijnenlaan 200 E Box 2411, BE-3001 Leuven (Belgium); International Water Management Institute (IWMI), P.O. Box 2075, Colombo (Sri Lanka)

    2009-10-15

    The massive investment in new jatropha plantations worldwide is not sufficiently based on a profound scientific knowledge of its ecology. In this article, we define the climatic conditions in its area of natural distribution by combining the locations of herbarium specimens with corresponding climatic information, and compare these conditions with those in 83 jatropha plantations worldwide. Most specimens (87%) were found in tropical savannah and monsoon climates (A{sub m}, A{sub w}) and in temperate climates without dry season and with hot summer (C{sub fa}), while very few were found in semi-arid (B{sub S}) and none in arid climates (B{sub W}). Ninety-five percent of the specimens grew in areas with a mean annual rainfall above 944 mm year{sup -1} and an average minimum temperature of the coldest month (T{sub min}) above 10.5 C. The mean annual temperature range was 19.3-27.2 C. The climatic conditions at the plantations were different from those of the natural distribution specimens for all studied climatic variables, except average maximum temperature in the warmest month. Roughly 40% of the plantations were situated in regions with a drier climate than in 95% of the area of the herbarium specimens, and 28% of the plantations were situated in areas with T{sub min} below 10.5 C. The observed precipitation preferences indicate that jatropha is not common in regions with arid and semi-arid climates. Plantations in arid and semi-arid areas hold the risk of low productivity or irrigation requirement. Plantations in regions with frost risk hold the risk of damage due to frost. (author)

  11. Seasonal Differences in Climatic Controls of Vegetation Growth in the Beijing-Tianjin Sand Source Region of China.

    Science.gov (United States)

    Wang, H.

    2017-12-01

    Seasonal differences in climatic controls of vegetation growth in the Beijing-Tianjin Sand Source Region of China Bin He1 , Haiyan Wan11 State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China Corresponding author: Bin He, email addresses: hebin@bnu.edu.cnPhone:+861058806506, Address: Beijing Normal University, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China. Email addresses of co-authors: wanghaiyan@mail.bnu.edu.cnABSTRACTLaunched in 2000, the Beiing-Tainjin Sand Source Controlling Project (BTSSCP) is an ecological restoration project intended to prevent desertification in China. Evidence from multiple sources has confirmed increases in vegetation growth in the BTSSCP region since the initiation of the project. Precipitation and related soil moisture conditions typically are considered to be the main drivers of vegetation growth in this arid region. However, by investigating the relationships between vegetation growth and corresponding climatic factors, we identified seasonal variation in the climatic constraints of vegetation growth. In spring, vegetation growth is stimulated mainly by elevated temperature, whereas precipitation is the lead driver of summer greening. In autumn, positive effects of both temperature and precipitation on vegetation growth were observed. Furthermore, strong biosphere-atmosphere interactions were observed in this region. Spring warming promotes vegetation growth, but also reduces soil moisture. Summer greening has a strong cooling effect on land surface temperature. These results indicate that 1) precipitation-based projections of vegetation growth may be misleading; and 2) the ecological and environment consequences of ecological projects should be comprehensively evaluated. KEYWORDS: vegetation growth, climatic drivers, seasonal variation, BTSSCP

  12. Climate conditions in Sweden in a 100,000-year time perspective

    Energy Technology Data Exchange (ETDEWEB)

    Kjellstroem, Erik; Strandberg, Gustav (Rossby Centre, SMHI, Norrkoeping (Sweden)); Brandefelt, Jenny (Dept. of Mechanics, Royal Inst. of Technology, Stockholm (Sweden)); Naeslund, Jens-Ove (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Smith, Ben (Dept of Physical Geography and Ecosystems Analysis, Lund Univ., Lund (Sweden)); Wohlfarth, Barbara (Dept. of Geology and Geochemistry, Stockholm Univ., Stockholm (Sweden))

    2009-04-15

    This report presents results from a project devoted to describing the climatic extremes within which the climate in Fennoscandia may vary over a 100,000 year time span. Based on forcing conditions which have yielded extreme conditions during the last glacial-interglacial cycle, as well as possible future conditions following continued anthropogenic emissions, projections of climate conditions have been made with climate models. Three different periods have been studied; i) a stadial within Marine Isotope Stage 3 (MIS 3) during the last glacial cycle, representing a cold period with a relatively small ice sheet covering parts of Fennoscandia, ii) the Last Glacial Maximum (LGM), with an extensive ice sheet covering large parts of northern Europe and iii) a possible future period in a climate warmer than today. The future case is characterised by high greenhouse gas concentrations in the atmosphere and a complete loss of the Greenland ice sheet. The climate modelling involved the use of a global climate model (GCM) for producing boundary conditions that were used by a regional climate model (RCM). The regional model produced detailed information on climate variables like near-surface air temperature and precipitation over Europe. These climate variables were subsequently used to force a vegetation model that produced a vegetation cover over Europe, consistent with the simulated regional climate. In a final step, the new vegetation cover from the vegetation model was used in the regional climate model to produce the final regional climate. For the studied periods, data on relevant climate parameters have been extracted from the regional model for the Forsmark and Oskarshamn areas on the Swedish east coast and the Olkiluoto region on the west coast of Finland. Due to computational constraints, the modelling efforts include only one forcing scenario per time period. As there is a large degree of uncertainty in the choice of an appropriate forcing scenario, we perform

  13. Climate conditions in Sweden in a 100,000-year time perspective

    International Nuclear Information System (INIS)

    Kjellstroem, Erik; Strandberg, Gustav; Brandefelt, Jenny; Naeslund, Jens-Ove; Smith, Ben; Wohlfarth, Barbara

    2009-04-01

    This report presents results from a project devoted to describing the climatic extremes within which the climate in Fennoscandia may vary over a 100,000 year time span. Based on forcing conditions which have yielded extreme conditions during the last glacial-interglacial cycle, as well as possible future conditions following continued anthropogenic emissions, projections of climate conditions have been made with climate models. Three different periods have been studied; i) a stadial within Marine Isotope Stage 3 (MIS 3) during the last glacial cycle, representing a cold period with a relatively small ice sheet covering parts of Fennoscandia, ii) the Last Glacial Maximum (LGM), with an extensive ice sheet covering large parts of northern Europe and iii) a possible future period in a climate warmer than today. The future case is characterised by high greenhouse gas concentrations in the atmosphere and a complete loss of the Greenland ice sheet. The climate modelling involved the use of a global climate model (GCM) for producing boundary conditions that were used by a regional climate model (RCM). The regional model produced detailed information on climate variables like near-surface air temperature and precipitation over Europe. These climate variables were subsequently used to force a vegetation model that produced a vegetation cover over Europe, consistent with the simulated regional climate. In a final step, the new vegetation cover from the vegetation model was used in the regional climate model to produce the final regional climate. For the studied periods, data on relevant climate parameters have been extracted from the regional model for the Forsmark and Oskarshamn areas on the Swedish east coast and the Olkiluoto region on the west coast of Finland. Due to computational constraints, the modelling efforts include only one forcing scenario per time period. As there is a large degree of uncertainty in the choice of an appropriate forcing scenario, we perform

  14. Community responses to extreme climatic conditions

    Directory of Open Access Journals (Sweden)

    Frédéric JIGUET, Lluis BROTONS, Vincent DEVICTOR

    2011-06-01

    Full Text Available Species assemblages and natural communities are increasingly impacted by changes in the frequency and severity of extreme climatic events. Here we propose a brief overview of expected and demonstrated direct and indirect impacts of extreme events on animal communities. We show that differential impacts on basic biological parameters of individual species can lead to strong changes in community composition and structure with the potential to considerably modify the functional traits of the community. Sudden disequilibria have even been shown to induce irreversible shifts in marine ecosystems, while cascade effects on various taxonomic groups have been highlighted in Mediterranean forests. Indirect effects of extreme climatic events are expected when event-induced habitat changes (e.g. soil stability, vegetation composition, water flows altered by droughts, floods or hurricanes have differential consequences on species assembled within the communities. Moreover, in increasing the amplitude of trophic mismatches, extreme events are likely to turn many systems into ecological traps under climate change. Finally, we propose a focus on the potential impacts of an extreme heat wave on local assemblages as an empirical case study, analysing monitoring data on breeding birds collected in France. In this example, we show that despite specific populations were differently affected by local temperature anomalies, communities seem to be unaffected by a sudden heat wave. These results suggest that communities are tracking climate change at the highest possible rate [Current Zoology 57 (3: 406–413, 2011].

  15. Carbon isotopes and charcoal in soils, vegetation changes and climate inferences in the southeastern Brazil

    International Nuclear Information System (INIS)

    Pessenda, L.C.R.; Gouveia, S.E.M; Aravena, R; Boulet, R; Bendassolli, J.A

    2001-01-01

    The use of carbon isotopes in studies of soil organic matter (SOM) dynamics have been applied to infer information about vegetation and climate changes during the late Quaternary (Schwartz et al., 1986; Pessenda et al., 1996). This approach had also been used in different areas in Brazil to document vegetation changes during the Holocene (Desjardins et al., 1996; Gouveia et al., 1997; Pessenda et al., 1998a, b, 2001) and late Pleistocene/Holocene (Freitas et al., 2001). The application of carbon isotopes is based on the different 13 C composition of C 3 and C 4 plants and its preservation in SOM. 13 C values of C 3 plant species range from approximately -32% o to -20% o PDB, with a mean of -27% o . In contrast, δ 13 C of C 4 species range from -17% o to -9% o with mean of -13% o . Thus, C 3 and C 4 plant species have distinct δ 13 C values and differ from each other by approximately 14% o (Boutton, 1991). The study of charcoal fragments found in sediments and soils also supplies information about climatic conditions. Charcoal distribution in the soil profiles can provide information about the occurrence of paleofires (Pessenda et al., 1996), possibly associated with drier climate periods and/or human disturbance. In this paper we report δ 13 C data of soil and 14 C dates on charcoal from five soil profiles collected under natural vegetation in the Parana and Sao Paulo states, southeastern Brazil. Carbon isotopes are used to evaluate vegetation changes during the late Pleistocene and Holocene. Charcoal distribution in the soil and its dating are used to infer linkage between forest fires and climate changes and to establish the chronology (au)

  16. Addressing climate change in the Forest Vegetation Simulator to assess impacts on landscape forest dynamics

    Science.gov (United States)

    Nicholas L. Crookston; Gerald E. Rehfeldt; Gary E. Dixon; Aaron R. Weiskittel

    2010-01-01

    To simulate stand-level impacts of climate change, predictors in the widely used Forest Vegetation Simulator (FVS) were adjusted to account for expected climate effects. This was accomplished by: (1) adding functions that link mortality and regeneration of species to climate variables expressing climatic suitability, (2) constructing a function linking site index to...

  17. Implications of climate variability for the detection of multiple equilibria and for rapid transitions in the atmosphere-vegetation system

    Energy Technology Data Exchange (ETDEWEB)

    Bathiany, S. [Max Planck Institute for Meteorology, Hamburg (Germany); Claussen, M. [Max Planck Institute for Meteorology, Hamburg (Germany); Universitaet Hamburg, Meteorologisches Institut, Hamburg (Germany); Fraedrich, K. [Universitaet Hamburg, Meteorologisches Institut, Hamburg (Germany)

    2012-05-15

    Paleoclimatic records indicate a decline of vegetation cover in the Western Sahara at the end of the African Humid Period (about 5,500 years before present). Modelling studies have shown that this phenomenon may be interpreted as a critical transition that results from a bifurcation in the atmosphere-vegetation system. However, the stability properties of this system are closely linked to climate variability and depend on the climate model and the methods of analysis. By coupling the Planet Simulator (PlaSim), an atmosphere model of intermediate complexity, with the simple dynamic vegetation model VECODE, we assess previous methods for the detection of multiple equilibria, and demonstrate their limitations. In particular, a stability diagram can yield misleading results because of spatial interactions, and the system's steady state and its dependency on initial conditions are affected by atmospheric variability and nonlinearities. In addition, we analyse the implications of climate variability for the abruptness of a vegetation decline. We find that a vegetation collapse can happen at different locations at different times. These collapses are possible despite large and uncorrelated climate variability. Because of the nonlinear relation between vegetation dynamics and precipitation the green state is initially stabilised by the high variability. When precipitation falls below a critical threshold, the desert state is stabilised as variability is then also decreased. (orig.)

  18. Detection of the Coupling between Vegetation Leaf Area and Climate in a Multifunctional Watershed, Northwestern China

    Science.gov (United States)

    Lu Hao; Cen Pan; Peilong Liu; Decheng Zhou; Liangxia Zhang; Zhe Xiong; Yongqiang Liu; Ge Sun

    2016-01-01

    Accurate detection and quantification of vegetation dynamics and drivers of observed climatic and anthropogenic change in space and time is fundamental for our understanding of the atmosphere–biosphere interactions at local and global scales. This case study examined the coupled spatial patterns of vegetation dynamics and climatic variabilities during the past...

  19. Hydraulic and Vegetative Models of Historic Environmental Conditions Isolate the Role of Riparian Vegetation in Inducing Channel Change

    Science.gov (United States)

    Manners, R.; Schmidt, J. C.; Wheaton, J. M.

    2011-12-01

    An enduring question in geomorphology is the role of riparian vegetation in inducing or exacerbating channel narrowing. It is typically difficult to isolate the role of vegetation in causing channel narrowing, because narrowing typically occurs where there are changes in stream flow, sediment supply, the invasion of non-native vegetation, and sometimes climate change. Therefore, linkages between changes in vegetation communities and changes in channel form are often difficult to identify. We took a mechanistic approach to isolate the role of the invasive riparian shrub tamarisk (Tamarix spp) in influencing channel narrowing in the Colorado River basin. Detailed geomorphic reconstructions of two sites on the Yampa and Green Rivers, respectively, in Dinosaur National Monument show that channel narrowing has been progressive and that tamarisk encroachment has also occurred; at the same time, dams have been constructed, diversions increased, and spring snowmelt runoff has been occurring earlier in spring. We simulated hydraulic and sediment transport conditions during the two largest floods of record -- 1984 and 2011. Two-dimensional hydraulic models were built to reflect these conditions and allowed us to perform sensitivity tests to determine the dominant determinants of the observed patterns of erosion and deposition. Channel and floodplain topography were constrained through detailed stratigraphic analysis, including precise dating of deposits based on dating of buried tamarisk plants in a series of floodplain trenches and pits. We also used historical air photos to establish past channel topography. To parameterize the influence of riparian vegetation, we developed a model that links detailed terrestrial laser scan (TLS) measurements of stand structure and its corresponding hydraulic roughness at the patch scale to reach-scale riparian vegetation patterns determined from airborne LiDaR (ALS). This model, in conjunction with maps of the ages and establishment

  20. Climate conditions in bedded confinement buildings

    Science.gov (United States)

    Confinement buildings are utilized for finishing cattle to allow more efficient collection of animal waste and to buffer animals against adverse climatic conditions. Environmental data were obtained from a 29 m wide x 318 m long bedded confinement building with the long axis oriented east to west. T...

  1. Quantifying the effects of land use and climate on Holocene vegetation in Europe

    Science.gov (United States)

    Marquer, Laurent; Gaillard, Marie-José; Sugita, Shinya; Poska, Anneli; Trondman, Anna-Kari; Mazier, Florence; Nielsen, Anne Birgitte; Fyfe, Ralph M.; Jönsson, Anna Maria; Smith, Benjamin; Kaplan, Jed O.; Alenius, Teija; Birks, H. John B.; Bjune, Anne E.; Christiansen, Jörg; Dodson, John; Edwards, Kevin J.; Giesecke, Thomas; Herzschuh, Ulrike; Kangur, Mihkel; Koff, Tiiu; Latałowa, Małgorzata; Lechterbeck, Jutta; Olofsson, Jörgen; Seppä, Heikki

    2017-09-01

    Early agriculture can be detected in palaeovegetation records, but quantification of the relative importance of climate and land use in influencing regional vegetation composition since the onset of agriculture is a topic that is rarely addressed. We present a novel approach that combines pollen-based REVEALS estimates of plant cover with climate, anthropogenic land-cover and dynamic vegetation modelling results. This is used to quantify the relative impacts of land use and climate on Holocene vegetation at a sub-continental scale, i.e. northern and western Europe north of the Alps. We use redundancy analysis and variation partitioning to quantify the percentage of variation in vegetation composition explained by the climate and land-use variables, and Monte Carlo permutation tests to assess the statistical significance of each variable. We further use a similarity index to combine pollen-based REVEALS estimates with climate-driven dynamic vegetation modelling results. The overall results indicate that climate is the major driver of vegetation when the Holocene is considered as a whole and at the sub-continental scale, although land use is important regionally. Four critical phases of land-use effects on vegetation are identified. The first phase (from 7000 to 6500 BP) corresponds to the early impacts on vegetation of farming and Neolithic forest clearance and to the dominance of climate as a driver of vegetation change. During the second phase (from 4500 to 4000 BP), land use becomes a major control of vegetation. Climate is still the principal driver, although its influence decreases gradually. The third phase (from 2000 to 1500 BP) is characterised by the continued role of climate on vegetation as a consequence of late-Holocene climate shifts and specific climate events that influence vegetation as well as land use. The last phase (from 500 to 350 BP) shows an acceleration of vegetation changes, in particular during the last century, caused by new farming

  2. Observational Quantification of Climatic and Human Influences on Vegetation Greening in China

    Directory of Open Access Journals (Sweden)

    Wenjian Hua

    2017-04-01

    Full Text Available This study attempts to quantify the relative contributions of vegetation greening in China due to climatic and human influences from multiple observational datasets. Satellite measured vegetation greenness, Normalized Difference Vegetation Index (NDVI, and relevant climate, land cover, and socioeconomic data since 1982 are analyzed using a multiple linear regression (MLR method. A statistically significant positive trend of average growing-season (April–October NDVI is found over more than 34% of the vegetated areas, mainly in North China, while significant decreases in NDVI are only seen in less than 5% of the areas. The relationships between vegetation and climate (temperature, precipitation, and radiation vary by geographical location and vegetation type. We estimate the NDVI changes in association with the non-climatic effects by removing the climatic effects from the original NDVI time series using the MLR analysis. Our results indicate that land use change is the dominant factor driving the long-term changes in vegetation greenness. The significant greening in North China is due to the increase in crops, grasslands, and forests. The socioeconomic datasets provide consistent and supportive results for the non-climatic effects at the provincial level that afforestation and reduced fire events generally have a major contribution. This study provides a basis for quantifying the non-climatic effects due to possible human influences on the vegetation greening in China.

  3. Georgian climate change under global warming conditions

    Directory of Open Access Journals (Sweden)

    Mariam Elizbarashvili

    2017-03-01

    Full Text Available Georgian Climate change has been considered comprehensively, taking into account World Meteorological Organization recommendations and recent observation data. On the basis of mean temperature and precipitation decadal trend geo-information maps for 1936–2012 years period, Georgian territory zoning has been carried out and for each areas climate indices main trends have been studied, that best characterize climate change - cold and hot days, tropical nights, vegetation period duration, diurnal maximum precipitation, maximum five-day total precipitation, precipitation intensity simple index, precipitation days number of at least 10 mm, 20 mm and 50 mm, rainy and rainless periods duration. Trends of temperature indices are statistically significant. On the Black Sea coastline and Colchis lowland at high confidence level cold and hot days and tropical nights number changes are statistically significant. On eastern Georgia plains at high level of statistical significance, the change of all considered temperature indices has been fixed except for the number of hot days. In mountainous areas only hot day number increasing is significant. Trends of most moisture indices are statistically insignificant. While keeping Georgian climate change current trends, precipitation amount on the Black Sea coastline and Colchis lowland, as well as in some parts of Western Caucasus to the end of the century will increase by 50% and amounts to 3000 and 6000 mm, respectively this will strengthen humidity of those areas. Besides increasing of rainy period duration may constitute the risk for flooding and high waters. On eastern Georgia plains, in particular Kvemo Kartli, annual precipitation amount will decrease by 50% or more, and will be only 150–200 mm and the precipitation daily maximum will decrease by about 20 mm and be only 10–15 mm, which of course will increase the intensity of desertification of steppe and semi-desert landscapes.

  4. Global warming and climate change in Amazonia: Climate-vegetation feedback and impacts on water resources

    Science.gov (United States)

    Marengo, José; Nobre, Carlos A.; Betts, Richard A.; Cox, Peter M.; Sampaio, Gilvan; Salazar, Luis

    This chapter constitutes an updated review of long-term climate variability and change in the Amazon region, based on observational data spanning more than 50 years of records and on climate-change modeling studies. We start with the early experiments on Amazon deforestation in the late 1970s, and the evolution of these experiments to the latest studies on greenhouse gases emission scenarios and land use changes until the end of the twenty-first century. The "Amazon dieback" simulated by the HadCM3 model occurs after a "tipping point" of CO2 concentration and warming. Experiments on Amazon deforestation and change of climate suggest that once a critical deforestation threshold (or tipping point) of 40-50% forest loss is reached in eastern Amazonia, climate would change in a way which is dangerous for the remaining forest. This may favor a collapse of the tropical forest, with a substitution of the forest by savanna-type vegetation. The concept of "dangerous climate change," as a climate change, which induces positive feedback, which accelerate the change, is strongly linked to the occurrence of tipping points, and it can be explained as the presence of feedback between climate change and the carbon cycle, particularly involving a weakening of the current terrestrial carbon sink and a possible reversal from a sink (as in present climate) to a source by the year 2050. We must, therefore, currently consider the drying simulated by the Hadley Centre model(s) as having a finite probability under global warming, with a potentially enormous impact, but with some degree of uncertainty.

  5. Lateral variations in vegetation in the Himalaya since the Miocene and implications for climate evolution

    Science.gov (United States)

    Vögeli, Natalie; Najman, Yani; van der Beek, Peter; Huyghe, Pascale; Wynn, Peter M.; Govin, Gwladys; van der Veen, Iris; Sachse, Dirk

    2017-08-01

    The Himalaya has a major influence on global and regional climate, in particular on the Asian monsoon system. The foreland basin of the Himalaya contains a record of tectonics and paleoclimate since the Miocene. Previous work on the evolution of vegetation and climate has focused on the central and western Himalaya, where a shift from C3 to C4 vegetation has been observed at ∼7 Ma and linked to increased seasonality, but the climatic evolution of the eastern part of the orogen is less well understood. In order to track vegetation as a marker of monsoon intensity and seasonality, we analyzed δ13 C and δ18 O values of soil carbonate and associated δ13 C values of bulk organic carbon from previously dated sedimentary sections exposing the syn-orogenic detrital Dharamsala and Siwalik Groups in the west, and, for the first time, the Siwalik Group in the east of the Himalayan foreland basin. Sedimentary records span from 20 to 1 Myr in the west (Joginder Nagar, Jawalamukhi, and Haripur Kolar sections) and from 13 to 1 Myr in the east (Kameng section), respectively. The presence of soil carbonate in the west and its absence in the east is a first indication of long-term lateral climatic variation, as soil carbonate requires seasonally arid conditions to develop. δ13 C values in soil carbonate show a shift from around -10‰ to -2‰ at ∼7 Ma in the west, which is confirmed by δ13 C analyses on bulk organic carbon that show a shift from around -23‰ to -19‰ at the same time. Such a shift in isotopic values is likely to be associated with a change from C3 to C4 vegetation. In contrast, δ13 C values of bulk organic carbon remain at ∼ - 23 ‰ in the east. Thus, our data show that the current east-west variation in climate was established at 7 Ma. We propose that the regional change towards a more seasonal climate in the west is linked to a decrease of the influence of the Westerlies, delivering less winter precipitation to the western Himalaya, while the east

  6. Increasing of Urban Radiation due to Climate Change and Reduction Strategy using Vegetation

    Science.gov (United States)

    Park, C.; Lee, D.; Heo, H. K.; Ahn, S.

    2017-12-01

    Urban Heat Island (UHI) which means urban air temperature is higher than suburban area is one of the most important environmental issues in Urban. High density of buildings and high ratio of impervious surfaces increases the radiation fluxes in urban canopy. Furthermore, climate change is expected to make UHI even more seriously in the future. Increased irradiation and air temperature cause high amount of short wave and long wave radiation, respectively. This increases net radiation negatively affects heat condition of pedestrian. UHI threatens citizen's health by increasing violence and heat related diseases. For this reason, understanding how much urban radiation will increase in the future, and exploring radiation reduction strategies is important for reducing UHI. In this research, we aim to reveal how the radiation flux in the urban canyon will change as the climate change and determine how much of urban vegetation will be needed to cover this degradation. The study area is a commercial district in Seoul where highly populated area. Due to the high density of buildings and lack of urban vegetation, this area has a poor thermal condition in summer. In this research, we simulate the radiation flux on the ground using multi-layer urban canopy model. Unlike conventionally used urban canopy model to simulate radiation transfer using vertically single layer, the multi-layer model we used here, enables to consider the vertical heterogeneous of buildings and urban vegetation. As a result, net radiation of urban ground will be increase 2.1 W/m² in the 2050s and 2.7 W/m² in the 2100s. And to prevent the increase of radiation, it is revealed that the urban vegetation should by increased by 10%. This research will be valuable in establishing greening planning as a strategy to reduce UHI effect.

  7. Phenological Characterization of Desert Sky Island Vegetation Communities with Remotely Sensed and Climate Time Series Data

    Directory of Open Access Journals (Sweden)

    Stuart E. Marsh

    2010-01-01

    Full Text Available Climate change and variability are expected to impact the synchronicity and interactions between the Sonoran Desert and the forested sky islands which represent steep biological and environmental gradients. The main objectives were to examine how well satellite greenness time series data and derived phenological metrics (e.g., season start, peak greenness can characterize specific vegetation communities across an elevation gradient, and to examine the interactions between climate and phenological metrics for each vegetation community. We found that representative vegetation types (11, varying between desert scrub, mesquite, grassland, mixed oak, juniper and pine, often had unique seasonal and interannual phenological trajectories and spatial patterns. Satellite derived land surface phenometrics (11 for each of the vegetation communities along the cline showed numerous distinct significant relationships in response to temperature (4 and precipitation (7 metrics. Satellite-derived sky island vegetation phenology can help assess and monitor vegetation dynamics and provide unique indicators of climate variability and patterns of change.

  8. Notable shifting in the responses of vegetation activity to climate change in China

    Science.gov (United States)

    Chen, Aifang; He, Bin; Wang, Honglin; Huang, Ling; Zhu, Yunhua; Lv, Aifeng

    The weakening relationship between inter-annual temperature variability and vegetation activity in the Northern Hemisphere over the last three decades has been reported by a recent study. However, how and to what extent vegetation activity responds to climate change in China is still unclear. We applied the Pearson correlation and partial correlation methods with a moving 15-y window to the GIMMS NDVI dataset from NOAA/AVHRR and observed climate data to examine the variation in the relationships between vegetation activity and climate variables. Results showed that there was an expanding negative response of vegetation growth to climate warming and a positive role of precipitation. The change patterns between NDVI and climate variables over vegetation types during the past three decades pointed an expending negative correlation between NDVI and temperature and a positive role of precipitation over most of the vegetation types (meadow, grassland, shrub, desert, cropland, and forest). Specifically, correlation between NDVI and temperature (PNDVI-T) have shifted from positive to negative in most of the station of temperature-limited areas with evergreen broadleaf forests, whereas precipitation-limited temperate grassland and desert were characterized by a positive PNDVI-P. This study contributes to ongoing investigations of the effects of climate change on vegetation activity. It is also of great importance for designing forest management strategies to cope with climate change.

  9. Evaluating the sensitivity of Eurasian forest biomass to climate change using a dynamic vegetation model

    International Nuclear Information System (INIS)

    Shuman, J K; Shugart, H H

    2009-01-01

    Climate warming could strongly influence the structure and composition of the Eurasian boreal forest. Temperature related changes have occurred, including shifts in treelines and changes in regeneration. Dynamic vegetation models are well suited to the further exploration of the impacts that climate change may have on boreal forests. Using the individual-based gap model FAREAST, forest composition and biomass are simulated at over 2000 sites across Eurasia. Biomass output is compared to detailed forest data from a representative sample of Russian forests and a sensitivity analysis is performed to evaluate the impact that elevated temperatures and modified precipitation will have on forest biomass and composition in Eurasia. Correlations between model and forest inventory biomass are strong for several boreal tree species. A significant relationship is shown between altered precipitation and biomass. This analysis showed that a modest increase in temperature of 2 deg. C across 200 years had no significant effect on biomass; however further exploration with increased warming reflective of values measured within Siberia, or at an increased rate, are warranted. Overall, FAREAST accurately simulates forest biomass and composition at sites throughout a large geographic area with widely varying climatic conditions and produces reasonable biomass responses to simulated climatic shifts. These results indicate that this model is robust and useful in making predictions regarding the effect of future climate change on boreal forest structure across Eurasia.

  10. Climate, vegetation, distribution of taxa and diversity: A synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Nazrul-Islam, A K.M. [Ecology Laboratory, Department of Botany, University of Dhaka, Dhaka (Bangladesh); Abdus Salam International Centre for Theoretical Physics, Trieste (Italy)

    2005-07-15

    An attempt has been made to investigate from a range of viewpoints the principle of the climatic control of plant distribution. The accumulated plant weight (w) is related to the incoming solar radiation (S) and is dependent on leaf area index, the incoming solar radiation and the efficiency of solar radiation to dry matter conversion. A review is presented and a model is discussed in order to stimulate interest and knowledge in this crucial and central theme of ecology. The aim is to develop a model based on eco-physiological principles to predict the major vegetational zones of the globe. Predictions were based on various plant responses, such as low temperature survival and evapo-transpiration. Taxonomic diversity declined in a poleward direction; for both the northern and southern hemispheres family diversity is greatest near the equator, declined markedly from latitude 30 deg. to 90 deg. Strong correlation between family diversity and absolute minimum temperature exists and a regression line suggests a decrease of 3.3 families per deg. C reductions in minimum temperature. Analysis of the islands ecology differing in areas at various altitudes of the present and past has been most productive in providing means of investigating dispersal and migration and vertical diversity. Experimental studies have been attempted in herbaceous vegetation at different latitudes (tundra and British Isles) by clearing the native species (Carex bigelowii, Eriphorum vaginatum) of the area and by introducing exotic species such as Lolium perenne. The cover of the exotic species subsequently declined and ultimately became extinct and was covered by the native species. In order to investigate the climatic control of the distribution of taxa it becomes necessary to split the life (life cycles) of a plant into a number of stages, each of which is a link in the chain of survival and each of which can dominate the control of distribution. When a stage of life cycle is broken then

  11. Climate, vegetation, distribution of taxa and diversity: A synthesis

    International Nuclear Information System (INIS)

    Nazrul-Islam, A.K.M.

    2005-07-01

    An attempt has been made to investigate from a range of viewpoints the principle of the climatic control of plant distribution. The accumulated plant weight (w) is related to the incoming solar radiation (S) and is dependent on leaf area index, the incoming solar radiation and the efficiency of solar radiation to dry matter conversion. A review is presented and a model is discussed in order to stimulate interest and knowledge in this crucial and central theme of ecology. The aim is to develop a model based on eco-physiological principles to predict the major vegetational zones of the globe. Predictions were based on various plant responses, such as low temperature survival and evapo-transpiration. Taxonomic diversity declined in a poleward direction; for both the northern and southern hemispheres family diversity is greatest near the equator, declined markedly from latitude 30 deg. to 90 deg. Strong correlation between family diversity and absolute minimum temperature exists and a regression line suggests a decrease of 3.3 families per deg. C reductions in minimum temperature. Analysis of the islands ecology differing in areas at various altitudes of the present and past has been most productive in providing means of investigating dispersal and migration and vertical diversity. Experimental studies have been attempted in herbaceous vegetation at different latitudes (tundra and British Isles) by clearing the native species (Carex bigelowii, Eriphorum vaginatum) of the area and by introducing exotic species such as Lolium perenne. The cover of the exotic species subsequently declined and ultimately became extinct and was covered by the native species. In order to investigate the climatic control of the distribution of taxa it becomes necessary to split the life (life cycles) of a plant into a number of stages, each of which is a link in the chain of survival and each of which can dominate the control of distribution. When a stage of life cycle is broken then

  12. Empirically Derived and Simulated Sensitivity of Vegetation to Climate Across Global Gradients of Temperature and Precipitation

    Science.gov (United States)

    Quetin, G. R.; Swann, A. L. S.

    2017-12-01

    Successfully predicting the state of vegetation in a novel environment is dependent on our process level understanding of the ecosystem and its interactions with the environment. We derive a global empirical map of the sensitivity of vegetation to climate using the response of satellite-observed greenness and leaf area to interannual variations in temperature and precipitation. Our analysis provides observations of ecosystem functioning; the vegetation interactions with the physical environment, across a wide range of climates and provide a functional constraint for hypotheses engendered in process-based models. We infer mechanisms constraining ecosystem functioning by contrasting how the observed and simulated sensitivity of vegetation to climate varies across climate space. Our analysis yields empirical evidence for multiple physical and biological mediators of the sensitivity of vegetation to climate as a systematic change across climate space. Our comparison of remote sensing-based vegetation sensitivity with modeled estimates provides evidence for which physiological mechanisms - photosynthetic efficiency, respiration, water supply, atmospheric water demand, and sunlight availability - dominate the ecosystem functioning in places with different climates. Earth system models are generally successful in reproducing the broad sign and shape of ecosystem functioning across climate space. However, this general agreement breaks down in hot wet climates where models simulate less leaf area during a warmer year, while observations show a mixed response but overall more leaf area during warmer years. In addition, simulated ecosystem interaction with temperature is generally larger and changes more rapidly across a gradient of temperature than is observed. We hypothesize that the amplified interaction and change are both due to a lack of adaptation and acclimation in simulations. This discrepancy with observations suggests that simulated responses of vegetation to

  13. Parameterization of a bucket model for soil-vegetation-atmosphere modeling under seasonal climatic regimes

    Directory of Open Access Journals (Sweden)

    N. Romano

    2011-12-01

    Full Text Available We investigate the potential impact of accounting for seasonal variations in the climatic forcing and using different methods to parameterize the soil water content at field capacity on the water balance components computed by a bucket model (BM. The single-layer BM of Guswa et al. (2002 is employed, whereas the Richards equation (RE based Soil Water Atmosphere Plant (SWAP model is used as a benchmark model. The results are analyzed for two differently-textured soils and for some synthetic runs under real-like seasonal weather conditions, using stochastically-generated daily rainfall data for a period of 100 years. Since transient soil-moisture dynamics and climatic seasonality play a key role in certain zones of the World, such as in Mediterranean land areas, a specific feature of this study is to test the prediction capability of the bucket model under a condition where seasonal variations in rainfall are not in phase with the variations in plant transpiration. Reference is made to a hydrologic year in which we have a rainy period (starting 1 November and lasting 151 days where vegetation is basically assumed in a dormant stage, followed by a drier and rainless period with a vegetation regrowth phase. Better agreement between BM and RE-SWAP intercomparison results are obtained when BM is parameterized by a field capacity value determined through the drainage method proposed by Romano and Santini (2002. Depending on the vegetation regrowth or dormant seasons, rainfall variability within a season results in transpiration regimes and soil moisture fluctuations with distinctive features. During the vegetation regrowth season, transpiration exerts a key control on soil water budget with respect to rainfall. During the dormant season of vegetation, the precipitation regime becomes an important climate forcing. Simulations also highlight the occurrence of bimodality in the probability distribution of soil moisture during the season when plants are

  14. Change in Vegetation Growth and Its Feedback to Climate in the Tibet Plateau

    Science.gov (United States)

    Piao, S.

    2015-12-01

    Vegetation growth is strongly influenced by climate and climate change and can affect the climate system through a number of bio-physical processes. As a result, monitoring, understanding and predicting the response of vegetation growth to global change has been a central activity in Earth system science during the past two decades. The Tibetan Plateau (TP) has experienced a pronounced warming over recent decades. The warming rate of the TP over the period 1960-2009 was about twice the global average warming rate, yet with heterogeneous patterns. In this study, we use satellite derived NDVI data to investigate spatio-temporal change in vegetation growth over the last three decades.

  15. Global terrestrial isoprene emission models: sensitivity to variability in climate and vegetation

    Directory of Open Access Journals (Sweden)

    A. Arneth

    2011-08-01

    Full Text Available Due to its effects on the atmospheric lifetime of methane, the burdens of tropospheric ozone and growth of secondary organic aerosol, isoprene is central among the biogenic compounds that need to be taken into account for assessment of anthropogenic air pollution-climate change interactions. Lack of process-understanding regarding leaf isoprene production as well as of suitable observations to constrain and evaluate regional or global simulation results add large uncertainties to past, present and future emissions estimates. Focusing on contemporary climate conditions, we compare three global isoprene models that differ in their representation of vegetation and isoprene emission algorithm. We specifically aim to investigate the between- and within model variation that is introduced by varying some of the models' main features, and to determine which spatial and/or temporal features are robust between models and different experimental set-ups. In their individual standard configurations, the models broadly agree with respect to the chief isoprene sources and emission seasonality, with maximum monthly emission rates around 20–25 Tg C, when averaged by 30-degree latitudinal bands. They also indicate relatively small (approximately 5 to 10 % around the mean interannual variability of total global emissions. The models are sensitive to changes in one or more of their main model components and drivers (e.g., underlying vegetation fields, climate input which can yield increases or decreases in total annual emissions of cumulatively by more than 30 %. Varying drivers also strongly alters the seasonal emission pattern. The variable response needs to be interpreted in view of the vegetation emission capacities, as well as diverging absolute and regional distribution of light, radiation and temperature, but the direction of the simulated emission changes was not as uniform as anticipated. Our results highlight the need for modellers to evaluate their

  16. Groundwater dynamics in mountain peatlands with contrasting climate, vegetation, and hydrogeological setting

    Science.gov (United States)

    Millar, David J.; Cooper, David J.; Ronayne, Michael J.

    2018-06-01

    Hydrological dynamics act as a primary control on ecosystem function in mountain peatlands, serving as an important regulator of carbon fluxes. In western North America, mountain peatlands exist in different hydrogeological settings, across a range climatic conditions, and vary in floristic composition. The sustainability of these ecosystems, particularly those at the low end of their known elevation range, is susceptible to a changing climate via changes in the water cycle. We conducted a hydrological investigation of two mountain peatlands, with differing vegetation, hydrogeological setting (sloping vs basin), and climate (strong vs weak monsoon influence). Growing season saturated zone water budgets were modeled on a daily basis, and subsurface flow characterizations were performed during multiple field campaigns at each site. The sloping peatland expectedly showed a strong lateral groundwater potential gradient throughout the growing season. Alternatively, the basin peatland had low lateral gradients but more pronounced vertical gradients. A zero-flux plane was apparent at a depth of approximately 50 cm below the peat surface at the basin peatland; shallow groundwater above this depth moved upward towards the surface via evapotranspiration. The differences in groundwater flow dynamics between the two sites also influenced water budgets. Higher groundwater inflow at the sloping peatland offset higher rates of evapotranspiration losses from the saturated zone, which were apparently driven by differences in vegetative cover. This research revealed that although sloping peatlands cover relatively small portions of mountain watersheds, they provide unique settings where vegetation directly utilizes groundwater for transpiration, which were several-fold higher than typically reported for surrounding uplands.

  17. A strategy for assessing potential future changes in climate, hydrology, and vegetation in the Western United States

    Science.gov (United States)

    Thompson, Robert Stephen; Hostetler, Steven W.; Bartlein, Patrick J.; Anderson, Katherine H.

    1998-01-01

    Historical and geological data indicate that significant changes can occur in the Earth's climate on time scales ranging from years to millennia. In addition to natural climatic change, climatic changes may occur in the near future due to increased concentrations of carbon dioxide and other trace gases in the atmosphere that are the result of human activities. International research efforts using atmospheric general circulation models (AGCM's) to assess potential climatic conditions under atmospheric carbon dioxide concentrations of twice the pre-industrial level (a '2 X CO2' atmosphere) conclude that climate would warm on a global basis. However, it is difficult to assess how the projected warmer climatic conditions would be distributed on a regional scale and what the effects of such warming would be on the landscape, especially for temperate mountainous regions such as the Western United States. In this report, we present a strategy to assess the regional sensitivity to global climatic change. The strategy makes use of a hierarchy of models ranging from an AGCM, to a regional climate model, to landscape-scale process models of hydrology and vegetation. A 2 X CO2 global climate simulation conducted with the National Center for Atmospheric Research (NCAR) GENESIS AGCM on a grid of approximately 4.5o of latitude by 7.5o of longitude was used to drive the NCAR regional climate model (RegCM) over the Western United States on a grid of 60 km by 60 km. The output from the RegCM is used directly (for hydrologic models) or interpolated onto a 15-km grid (for vegetation models) to quantify possible future environmental conditions on a spatial scale relevant to policy makers and land managers.

  18. Wind energy under cold climate conditions

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B.

    1999-03-01

    There is an increasing interest in wind energy production under different climatic conditions, among them cold climate and icing conditions. More and more wind turbines are being installed in cold climates and even adapted technology has been developed for that environment. Various national activities are going on in at least Finland, Canada, Italy, Sweden, etc. and international collaboration has been carried out within the European Union's Non-nuclear energy programme. Wind turbine operation is affected by both the cold temperatures and the formation of ice on the blades and the supporting structure. Cold temperatures can be handled by material selections known in other technical fields but to prevent icing, new techniques have to be - and have been - developed. Icing affects the reliability of anemometers, which concerns both turbine control and resource estimation, and changes the aerodynamics of the blades, which eventually stops the turbine. In addition, occasional icing events can locally affect public safety. The development of applied technology has entered some different paths and different solutions are tried out. As the applications are entering a commercial phase, these is a request to gather the experiences and monitor the reliability in a form that can be utilised by developers, manufactureres, consultants and other tenderers. The Topical Experts Meeting will focus on site classification, operational experiences, modelling and mesurements of ice induced loads and safety aspects. (EHS)

  19. The yield of eggplant depending on climate conditions and mulching

    Directory of Open Access Journals (Sweden)

    Adamczewska-Sowińska Katarzyna

    2016-06-01

    Full Text Available The field production of eggplant in moderate climates is difficult as it depends heavily on thermal conditions. Eggplant is a species that is sensitive to low temperatures, and temperatures below 16°C constrain the growth of young plants. Other disadvantageous factors include: temperatures that are too high, water shortage and excessive soil humidity. The growth conditions for eggplant can be improved by using mulches. The purpose of the experiment was the assessment of eggplant cropping while using synthetic mulches of polyethylene foil and polypropylene textile. The research took five years (2008-2012 and on the basis of the obtained results it was possible to determine the influence of weather conditions on the yielding of this species. It was proven that eggplant cropping significantly depended on the air temperature and the amount of rainfall during the vegetation period. The highest yield was observed when the average air temperature was high and at the same time rainfall was evenly distributed throughout the vegetation season. It also turned out that the agro-technical procedure which significantly increased eggplant fruit cropping was mulching the soil with polyethylene black foil, or transparent foil, previously having applied a herbicide.

  20. The responses of net primary production (NPP) and total carbon storage for the continental United States to changes in atmospheric CO{sub 2}, climate, and vegetation

    Energy Technology Data Exchange (ETDEWEB)

    McGuire, D.A. [Marine Biological Lab., Woods Hole, MA (United States)

    1995-06-01

    We extrapolated 3 biogeochemistry models (BIOME-BGC, CENTURY, and TEM) across the continental US with the vegetation distributions of 3 biogeography models (BIOME2, DOLY, and MAPSS) for contemporary climate at 355 ppmv CO{sub 2} and each of 3 GCM climate scenarios at 710 ppmv. For contemporary conditions, continental NPP ranges from 3132 to 3854 TgC/yr and total carbon storage ranges from 109 to 125 PgC. The responses of NPP range from no response (BIOME-BGC with DOLY or MAPSS vegetations for UKMO climate) to increases of 53% and 56% (TEM with BIOME2 vegetations for GFDL and OSU climates). The responses of total carbon storage vary from a decrease of 39% (BIOME-BGC with MAPSS vegetation for UKMO climate) to increases of 52% and 56% (TEM with BIOME2 vegetations for OSU and GFDL climates). The UKMO responses of BIOME-BGC with MAPSS vegetation are caused by both decreased forest area (from 44% to 38%) and photosynthetic water stress. The OSU and GFDL responses of TEM with BIOME2 vegetations are caused by forest expansion (from 46% to 67% for OSU and to 75% for GFDL) and increased nitrogen cycling.

  1. NOAA Climate Data Record (CDR) of Normalized Difference Vegetation Index (NDVI), Version 4

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains gridded daily Normalized Difference Vegetation Index (NDVI) derived from the NOAA Climate Data Record (CDR) of Advanced Very High Resolution...

  2. Understanding climate impacts on vegetation using a spatiotemporal non-linear Granger causality framework

    Science.gov (United States)

    Papagiannopoulou, Christina; Decubber, Stijn; Miralles, Diego; Demuzere, Matthias; Dorigo, Wouter; Verhoest, Niko; Waegeman, Willem

    2017-04-01

    Satellite data provide an abundance of information about crucial climatic and environmental variables. These data - consisting of global records, spanning up to 35 years and having the form of multivariate time series with different spatial and temporal resolutions - enable the study of key climate-vegetation interactions. Although methods which are based on correlations and linear models are typically used for this purpose, their assumptions for linearity about the climate-vegetation relationships are too simplistic. Therefore, we adopt a recently proposed non-linear Granger causality analysis [1], in which we incorporate spatial information, concatenating data from neighboring pixels and training a joint model on the combined data. Experimental results based on global data sets show that considering non-linear relationships leads to a higher explained variance of past vegetation dynamics, compared to simple linear models. Our approach consists of several steps. First, we compile an extensive database [1], which includes multiple data sets for land surface temperature, near-surface air temperature, surface radiation, precipitation, snow water equivalents and surface soil moisture. Based on this database, high-level features are constructed and considered as predictors in our machine-learning framework. These high-level features include (de-trended) seasonal anomalies, lagged variables, past cumulative variables, and extreme indices, all calculated based on the raw climatic data. Second, we apply a spatiotemporal non-linear Granger causality framework - in which the linear predictive model is substituted for a non-linear machine learning algorithm - in order to assess which of these predictor variables Granger-cause vegetation dynamics at each 1° pixel. We use the de-trended anomalies of Normalized Difference Vegetation Index (NDVI) to characterize vegetation, being the target variable of our framework. Experimental results indicate that climate strongly (Granger

  3. Vegetation-climate feedback causes reduced precipitation in CMIP5 regional Earth system model simulation over Africa

    Science.gov (United States)

    Wu, Minchao; Smith, Benjamin; Schurgers, Guy; Lindström, Joe; Rummukainen, Markku; Samuelsson, Patrick

    2013-04-01

    Terrestrial ecosystems have been demonstrated to play a significant role within the climate system, amplifying or dampening climate change via biogeophysical and biogeochemical exchange with the atmosphere and vice versa (Cox et al. 2000; Betts et al. 2004). Africa is particularly vulnerable to climate change and studies of vegetation-climate feedback mechanisms on Africa are still limited. Our study is the first application of A coupled Earth system model at regional scale and resolution over Africa. We applied a coupled regional climate-vegetation model, RCA-GUESS (Smith et al. 2011), over the CORDEX Africa domain, forced by boundary conditions from a CanESM2 CMIP5 simulation under the RCP8.5 future climate scenario. The simulations were from 1961 to 2100 and covered the African continent at a horizontal grid spacing of 0.44°. RCA-GUESS simulates changes in the phenology, productivity, relative cover and population structure of up to eight plant function types (PFTs) in response to forcing from the climate part of the model. These vegetation changes feedback to simulated climate through dynamic adjustments in surface energy fluxes and surface properties. Changes in the net ecosystem-atmosphere carbon flux and its components net primary production (NPP), heterotrophic respiration and emissions from biomass burning were also simulated but do not feedback to climate in our model. Constant land cover was assumed. We compared simulations with and without vegetation feedback switched "on" to assess the influence of vegetation-climate feedback on simulated climate, vegetation and ecosystem carbon cycling. Both positive and negative warming feedbacks were identified in different parts of Africa. In the Sahel savannah zone near 15°N, reduced vegetation cover and productivity, and mortality caused by a deterioration of soil water conditions led to a positive warming feedback mediated by decreased evapotranspiration and increased sensible heat flux between vegetation and

  4. Decomposing the uncertainty in climate impact projections of Dynamic Vegetation Models: a test with the forest models LANDCLIM and FORCLIM

    Science.gov (United States)

    Cailleret, Maxime; Snell, Rebecca; von Waldow, Harald; Kotlarski, Sven; Bugmann, Harald

    2015-04-01

    not so much at medium elevations. (ii) Considering climate change, the variability that is due to the GCM-RCM chains is much greater than the variability induced by the uncertainty in the initial climatic conditions. (iii) The uncertainties caused by the intrinsic stochasticity in the DVMs and by the random generation of the climate time-series are negligible. Overall, our results indicate that DVMs are quite sensitive to the climate data, highlighting particularly (1) the limitations of using one single multi-model average climate change scenario in climate impact studies and (2) the need to better consider the uncertainty in climate model outputs for projecting future vegetation changes.

  5. Uncovering effects of climate variables on global vegetation

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this project is to understand the causal relationships of how ecosystem dynamics, mostly characterized by vegetation changes, in different...

  6. Future vegetation ecosystem response to warming climate over the Tibetan Plateau

    Science.gov (United States)

    Bao, Y.; Gao, Y.; Wang, Y.

    2017-12-01

    The amplified vegetation response to climate variability has been found over the Tibetan Plateau (TP) in recent decades. In this study, the potential impacts of 21st century climate change on the vegetation ecosystem over the TP are assessed based on the dynamic vegetation outputs of models from Coupled Model Intercomparison Project Phase 5 (CMIP5), and the sensitivity of the TP vegetation in response to warming climate was investigated. Models project a continuous and accelerating greening in future, especially in the eastern TP, which closely associates with the plant type upgrade due to the pronouncing warming in growing season.Vegetation leaf area index (LAI) increase well follows the global warming, suggesting the warming climate instead of co2 fertilization controlls the future TP plant growth. The warming spring may advance the start of green-up day and extend the growing season length. More carbon accumulation in vegetation and soil will intensify the TP carbon cycle and will keep it as a carbon sink in future. Keywords: Leaf Area Index (LAI), Climate Change, Global Dynamic Vegetation Models (DGVMs), CMIP5, Tibetan Plateau (TP)

  7. The fire-vegetation-climate system: how ecology can contribute to earth system science

    CSIR Research Space (South Africa)

    Archibald, S

    2013-05-01

    Full Text Available and future state of global vegetation. A key complexity that is currently not well captured by Earth System models is that vegetation is not always deterministically responsive to climate and soils. Feedbacks within the Earth System, top-down controls...

  8. Effects of submerged vegetation on water clarity across climates

    NARCIS (Netherlands)

    Kosten, S.; Lacerot, G.; Jeppesen, E.; Motta Marques, D.M.L.; Nes, van E.H.; Mazzeo, N.; Scheffer, M.

    2009-01-01

    A positive feedback between submerged vegetation and water clarity forms the backbone of the alternative state theory in shallow lakes. The water clearing effect of aquatic vegetation may be caused by different physical, chemical, and biological mechanisms and has been studied mainly in temperate

  9. Climate and Vegetation Effects on Temperate Mountain Forest Evapotranspiration

    Science.gov (United States)

    Current forest composition may be resilient to typical climatic variability; however, climate trends, combined with projected changes in species composition, may increase tree vulnerability to water stress. A shift in forest composition toward tree species with higher water use h...

  10. Vegetation

    DEFF Research Database (Denmark)

    Epstein, H.E.; Walker, D.A.; Bhatt, U.S.

    2012-01-01

    increased 20-26%. • Increasing shrub growth and range extension throughout the Low Arctic are related to winter and early growing season temperature increases. Growth of other tundra plant types, including graminoids and forbs, is increasing, while growth of mosses and lichens is decreasing. • Increases...... in vegetation (including shrub tundra expansion) and thunderstorm activity, each a result of Arctic warming, have created conditions that favor a more active Arctic fire regime....

  11. Forest restoration as a strategy to mitigate climate impacts on wildfire, vegetation, and water in semiarid forests.

    Science.gov (United States)

    O'Donnell, Frances C; Flatley, William T; Springer, Abraham E; Fulé, Peter Z

    2018-06-25

    Climate change and wildfire are interacting to drive vegetation change and potentially reduce water quantity and quality in the southwestern United States, Forest restoration is a management approach that could mitigate some of these negative outcomes. However, little information exists on how restoration combined with climate change might influence hydrology across large forest landscapes that incorporate multiple vegetation types and complex fire regimes. We combined spatially explicit vegetation and fire modeling with statistical water and sediment yield models for a large forested landscape (335,000 ha) on the Kaibab Plateau in northern Arizona, USA. Our objective was to assess the impacts of climate change and forest restoration on the future fire regime, forest vegetation, and watershed outputs. Our model results predict that the combination of climate change and high-severity fire will drive forest turnover, biomass declines, and compositional change in future forests. Restoration treatments may reduce the area burned in high-severity fires and reduce conversions from forested to non-forested conditions. Even though mid-elevation forests are the targets of restoration, the treatments are expected to delay the decline of high-elevation spruce-fir, aspen, and mixed conifer forests by reducing the occurrence of high-severity fires that may spread across ecoregions. We estimate that climate-induced vegetation changes will result in annual runoff declines of up to 10%, while restoration reduced or reversed this decline. The hydrologic model suggests that mid-elevation forests, which are the targets of restoration treatments, provide around 80% of runoff in this system and the conservation of mid- to high-elevation forests types provides the greatest benefit in terms of water conservation. We also predict that restoration treatments will conserve water quality by reducing patches of high-severity fire that are associated with high sediment yield. Restoration

  12. Global patterns of NDVI-indicated vegetation extremes and their sensitivity to climate extremes

    International Nuclear Information System (INIS)

    Liu Guo; Liu Hongyan; Yin Yi

    2013-01-01

    Extremes in climate have significant impacts on ecosystems and are expected to increase under future climate change. Extremes in vegetation could capture such impacts and indicate the vulnerability of ecosystems, but currently have not received a global long-term assessment. In this study, a robust method has been developed to detect significant extremes (low values) in biweekly time series of global normalized difference vegetation index (NDVI) from 1982 to 2006 and thus to acquire a global pattern of vegetation extreme frequency. This pattern coincides with vegetation vulnerability patterns suggested by earlier studies using different methods over different time spans, indicating a consistent mechanism of regulation. Vegetation extremes were found to aggregate in Amazonia and in the semi-arid and semi-humid regions in low and middle latitudes, while they seldom occurred in high latitudes. Among the environmental variables studied, extreme low precipitation has the highest slope against extreme vegetation. For the eight biomes analyzed, these slopes are highest in temperate broadleaf forest and temperate grassland, suggesting a higher sensitivity in these environments. The results presented here contradict the hypothesis that vegetation in water-limited semi-arid and semi-humid regions might be adapted to drought and suggest that vegetation in these regions (especially temperate broadleaf forest and temperate grassland) is highly prone to vegetation extreme events under more severe precipitation extremes. It is also suggested here that more attention be paid to precipitation-induced vegetation changes than to temperature-induced events. (letter)

  13. Remotely Sensed Northern Vegetation Response to Changing Climate: Growing Season and Productivity Perspective

    Science.gov (United States)

    Ganguly, S.; Park, Taejin; Choi, Sungho; Bi, Jian; Knyazikhin, Yuri; Myneni, Ranga

    2016-01-01

    Vegetation growing season and maximum photosynthetic state determine spatiotemporal variability of seasonal total gross primary productivity of vegetation. Recent warming induced impacts accelerate shifts on growing season and physiological status over Northern vegetated land. Thus, understanding and quantifying these changes are very important. Here, we first investigate how vegetation growing season and maximum photosynthesis state are evolved and how such components contribute on inter-annual variation of seasonal total gross primary productivity. Furthermore, seasonally different response of northern vegetation to changing temperature and water availability is also investigated. We utilized both long-term remotely sensed data to extract larger scale growing season metrics (growing season start, end and duration) and productivity (i.e., growing season summed vegetation index, GSSVI) for answering these questions. We find that regionally diverged growing season shift and maximum photosynthetic state contribute differently characterized productivity inter-annual variability and trend. Also seasonally different response of vegetation gives different view of spatially varying interaction between vegetation and climate. These results highlight spatially and temporally varying vegetation dynamics and are reflective of biome-specific responses of northern vegetation to changing climate.

  14. Effects of future climate change, CO2 enrichment, and vegetation structure variation on hydrological processes in China

    Science.gov (United States)

    Zhu, Qiuan; Jiang, Hong; Peng, Changhui; Liu, Jinxun; Fang, Xiuqin; Wei, Xiaohua; Liu, Shirong; Zhou, Guomo

    2012-01-01

    Investigating the relationship between factors (climate change, atmospheric CO2 concentrations enrichment, and vegetation structure) and hydrological processes is important for understanding and predicting the interaction between the hydrosphere and biosphere. The Integrated Biosphere Simulator (IBIS) was used to evaluate the effects of climate change, rising CO2, and vegetation structure on hydrological processes in China at the end of the 21st century. Seven simulations were implemented using the assemblage of the IPCC climate and CO2 concentration scenarios, SRES A2 and SRES B1. Analysis results suggest that (1) climate change will have increasing effects on runoff, evapotranspiration (ET), transpiration (T), and transpiration ratio (transpiration/evapotranspiration, T/E) in most hydrological regions of China except in the southernmost regions; (2) elevated CO2 concentrations will have increasing effects on runoff at the national scale, but at the hydrological region scale, the physiology effects induced by elevated CO2 concentration will depend on the vegetation types, climate conditions, and geographical background information with noticeable decreasing effects shown in the arid Inland region of China; (3) leaf area index (LAI) compensation effect and stomatal closure effect are the dominant factors on runoff in the arid Inland region and southern moist hydrological regions, respectively; (4) the magnitudes of climate change (especially the changing precipitation pattern) effects on the water cycle are much larger than those of the elevated CO2 concentration effects; however, increasing CO2 concentration will be one of the most important modifiers to the water cycle; (5) the water resource condition will be improved in northern China but depressed in southernmost China under the IPCC climate change scenarios, SRES A2 and SRES B1.

  15. Assessments of Drought Impacts on Vegetation in China with the Optimal Time Scales of the Climatic Drought Index

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2015-07-01

    Full Text Available Drought is expected to increase in frequency and severity due to global warming, and its impacts on vegetation are typically extensively evaluated with climatic drought indices, such as multi-scalar Standardized Precipitation Evapotranspiration Index (SPEI. We analyzed the covariation between the SPEIs of various time scales and the anomalies of the normalized difference vegetation index (NDVI, from which the vegetation type-related optimal time scales were retrieved. The results indicated that the optimal time scales of needle-leaved forest, broadleaf forest and shrubland were between 10 and 12 months, which were considerably longer than the grassland, meadow and cultivated vegetation ones (2 to 4 months. When the optimal vegetation type-related time scales were used, the SPEI could better reflect the vegetation’s responses to water conditions, with the correlation coefficients between SPEIs and NDVI anomalies increased by 5.88% to 28.4%. We investigated the spatio-temporal characteristics of drought and quantified the different responses of vegetation growth to drought during the growing season (April–October. The results revealed that the frequency of drought has increased in the 21st century with the drying trend occurring in most of China. These results are useful for ecological assessments and adapting management steps to mitigate the impact of drought on vegetation. They are helpful to employ water resources more efficiently and reduce potential damage to human health caused by water shortages.

  16. Late Holocene vegetation changes in relation with climate fluctuations and human activities in Languedoc (Southern France)

    OpenAIRE

    J. Azuara; N. Combourieu-Nebout; V. Lebreton; F. Mazier; S. D. Müller; L. Dezileau

    2015-01-01

    Holocene climate fluctuations and human activities since the Neolithic have shaped present-day Mediterranean environments. Separating anthropogenic effects from climatic impacts to reconstruct Mediterranean paleoenvironments over the last millennia remains a challenging issue. High resolution pollen analyses were undertaken on two cores from the Palavasian lagoon system (Hérault, southern France). These records allow reconstruction of vegetation dynamics ove...

  17. Climate change and California: potential implications for vegetation, carbon, and fire.

    Science.gov (United States)

    Jonathan. Thompson

    2005-01-01

    Nineteen scientists from leading research institutes in the United States collaborated to estimate how California’s environment and economy would respond to global climate change. A scientist from the PNW Research Station led efforts to estimate effects on vegetation, carbon, and fire.To quantify the range of the possible effects of climate change over the...

  18. Microscale vegetation-soil feedback boosts hysteresis in a regional vegetation-climate system

    NARCIS (Netherlands)

    Janssen, R.H.H.; Meinders, M.B.J.; Nes, van E.H.; Scheffer, M.

    2008-01-01

    It has been hypothesized that a positive feedback between vegetation cover and monsoon circulation may lead to the existence of two alternative stable states in the Sahara region: a vegetated state with moderate precipitation and a desert state with low precipitation. This could explain the sudden

  19. [Responses of vegetation changes to climatic variations in Panxi area based on the MODIS multispectral data].

    Science.gov (United States)

    Shao, Huai-Yong; Wu, Jin-Hui; Liu, Meng; Yang, Wu-Nian

    2014-01-01

    It is an important research area to quantitatively studying the relationship between global climatic change and vegetation change based on the remote sensing technology. Panxi area is the ecological barrier of the upper reaches of the Yangtze River, and it is essential for the stability of the ecological environment of Sichuan as well as that of the whole China. The present article analyzes the vegetation change in 2001-2008 and the relationship between vegetation change and climatic variations of Panxi area, based on MODIS multispectral data and meteorological data. The results indicate that NDVI is positively correlated with temperature and precipitation. The precipitation is the major factor that affects the change of vegetation in the Panxi region and the trend of NDVI is similar with autumn precipitation; while at the same time the influence of climate has a one-month-time-lag.

  20. Climate and vegetation changes around the Atlantic Ocean resulting from changes in the meridional overturning circulation during deglaciation

    Science.gov (United States)

    Handiani, D.; Paul, A.; Dupont, L.

    2012-07-01

    The Bølling-Allerød (BA, starting ~ 14.5 ka BP) is one of the most pronounced abrupt warming periods recorded in ice and pollen proxies. The leading explanation of the cause of this warming is a sudden increase in the rate of deepwater formation in the North Atlantic Ocean and the resulting effect on the heat transport by the Atlantic Meridional Overturning Circulation (AMOC). In this study, we used the University of Victoria (UVic) Earth System-Climate Model (ESCM) to run simulations, in which a freshwater perturbation initiated a BA-like warming period. We found that under present climate conditions, the AMOC intensified when freshwater was added to the Southern Ocean. However, under Heinrich event 1 (HE1, ~ 16 ka BP) climate conditions, the AMOC only intensified when freshwater was extracted from the North Atlantic Ocean, possibly corresponding to an increase in evaporation or a decrease in precipitation in this region. The intensified AMOC led to a warming in the North Atlantic Ocean and a cooling in the South Atlantic Ocean, resembling the bipolar seesaw pattern typical of the last glacial period. In addition to the physical response, we also studied the simulated vegetation response around the Atlantic Ocean region. Corresponding with the bipolar seesaw hypothesis, the rainbelt associated with the Intertropical Convergence Zone (ITCZ) shifted northward and affected the vegetation pattern in the tropics. The most sensitive vegetation area was found in tropical Africa, where grass cover increased and tree cover decreased under dry climate conditions. An equal but opposite response to the collapse and recovery of the AMOC implied that the change in vegetation cover was transient and robust to an abrupt climate change such as during the BA period, which is also supported by paleovegetation data. The results are in agreement with paleovegetation records from Western tropical Africa, which also show a reduction in forest cover during this time period. Further

  1. The need of data harmonization to derive robust empirical relationships between soil conditions and vegetation.

    NARCIS (Netherlands)

    Bartholomeus, R.P.; Witte, J.P.M.; van Bodegom, P.M.; Aerts, R.

    2008-01-01

    Question: Is it possible to improve the general applicability and significance of empirical relationships between abiotic conditions and vegetation by harmonization of temporal data? Location: The Netherlands. Methods: Three datasets of vegetation, recorded after periods with different

  2. Optimizing cloud removal from satellite remotely sensed data for monitoring vegetation dynamics in humid tropical climate

    International Nuclear Information System (INIS)

    Hashim, M; Pour, A B; Onn, C H

    2014-01-01

    Remote sensing technology is an important tool to analyze vegetation dynamics, quantifying vegetation fraction of Earth's agricultural and natural vegetation. In optical remote sensing analysis removing atmospheric interferences, particularly distribution of cloud contaminations, are always a critical task in the tropical climate. This paper suggests a fast and alternative approach to remove cloud and shadow contaminations for Landsat Enhanced Thematic Mapper + (ETM + ) multi temporal datasets. Band 3 and Band 4 from all the Landsat ETM + dataset are two main spectral bands that are very crucial in this study for cloud removal technique. The Normalise difference vegetation index (NDVI) and the normalised difference soil index (NDSI) are two main derivatives derived from the datasets. Change vector analysis is used in this study to seek the vegetation dynamics. The approach developed in this study for cloud optimizing can be broadly applicable for optical remote sensing satellite data, which are seriously obscured with heavy cloud contamination in the tropical climate

  3. NDVI-Based Analysis on the Influence of Climate Change and Human Activities on Vegetation Restoration in the Shaanxi-Gansu-Ningxia Region, Central China

    Directory of Open Access Journals (Sweden)

    Shuangshuang Li

    2015-08-01

    Full Text Available In recent decades, climate change has affected vegetation growth in terrestrial ecosystems. We investigated spatial and temporal patterns of vegetation cover on the Loess Plateau’s Shaanxi-Gansu-Ningxia region in central China using MODIS-NDVI data for 2000–2014. We examined the roles of regional climate change and human activities in vegetation restoration, particularly from 1999 when conversion of sloping farmland to forestland or grassland began under the national Grain-for-Green program. Our results indicated a general upward trend in average NDVI values in the study area. The region’s annual growth rate greatly exceeded those of the Three-North Shelter Forest, the upper reaches of the Yellow River, the Qinling–Daba Mountains, and the Three-River Headwater region. The green vegetation zone has been annually extending from the southeast toward the northwest, with about 97.4% of the region evidencing an upward trend in vegetation cover. The NDVI trend and fluctuation characteristics indicate the occurrence of vegetation restoration in the study region, with gradual vegetation stabilization associated with 15 years of ecological engineering projects. Under favorable climatic conditions, increasing local vegetation cover is primarily attributable to ecosystem reconstruction projects. However, our findings indicate a growing risk of vegetation degradation in the northern part of Shaanxi Province as a result of energy production facilities and chemical industry infrastructure, and increasing exploitation of mineral resources.

  4. Climatic Changes Effects On Spectral Vegetation Indices For Forested Areas Analysis From Satellite Data

    International Nuclear Information System (INIS)

    Zoran, M.; Stefan, S.

    2007-01-01

    Climate-induced changes at the land surface may in turn feed back on the climate itself through changes in soil moisture, vegetation, radiative characteristics, and surface-atmosphere exchanges of water vapor. Thresholding based on biophysical variables derived from time trajectories of satellite data is a new approach to classifying forest land cover via remote . sensing .The input data are composite values of the Normalized Difference Vegetation Index (NDVI). Classification accuracies are function of the class, comparison method and season of the year. The aim of the paper is forest biomass assessment and land-cover changes analysis due to climatic effects

  5. Climatic factors driving vegetation declines in the 2005 and 2010 Amazon droughts.

    Directory of Open Access Journals (Sweden)

    Wenqian Zhao

    Full Text Available Along with global climate change, the occurrence of extreme droughts in recent years has had a serious impact on the Amazon region. Current studies on the driving factors of the 2005 and 2010 Amazon droughts has focused on the influence of precipitation, whereas the impacts of temperature and radiation have received less attention. This study aims to explore the climate-driven factors of Amazonian vegetation decline during the extreme droughts using vegetation index, precipitation, temperature and radiation datasets. First, time-lag effects of Amazonian vegetation responses to precipitation, radiation and temperature were analyzed. Then, a multiple linear regression model was established to estimate the contributions of climatic factors to vegetation greenness, from which the dominant climate-driving factors were determined. Finally, the climate-driven factors of Amazonian vegetation greenness decline during the 2005 and 2010 extreme droughts were explored. The results showed that (i in the Amazon vegetation greenness responded to precipitation, radiation and temperature, with apparent time lags for most averaging interval periods associated with vegetation index responses of 0-4, 0-9 and 0-6 months, respectively; (ii on average, the three climatic factors without time lags explained 27.28±21.73% (mean±1 SD of vegetation index variation in the Amazon basin, and this value increased by 12.22% and reached 39.50±27.85% when time lags were considered; (iii vegetation greenness in this region in non-drought years was primarily affected by precipitation and shortwave radiation, and these two factors altogether accounted for 93.47% of the total explanation; and (iv in the common epicenter of the two droughts, pixels with a significant variation in precipitation, radiation and temperature accounted for 36.68%, 40.07% and 10.40%, respectively, of all pixels showing a significant decrease in vegetation index in 2005, and 15.69%, 2.01% and 45.25% in

  6. Fire and climate suitability for woody vegetation communities in the south central United States

    Science.gov (United States)

    Stroh, Esther; Struckhoff, Matthew; Stambaugh, Michael C.; Guyette, Richard P.

    2018-01-01

    Climate and fire are primary drivers of plant species distributions. Long-term management of south central United States woody vegetation communities can benefit from information on potential changes in climate and fire frequencies, and how these changes might affect plant communities. We used historical (1900 to 1929) and future (2040 to 2069 and 2070 to 2099) projected climate data for the conterminous US to estimate reference and future fire probabilities

  7. Disentangling Modern Fire-Climate-Vegetation Relationships across the Boreal Forest Biome

    Science.gov (United States)

    Young, A. M.; Boschetti, L.; Duffy, P.; Hu, F.; Higuera, P.

    2015-12-01

    Fire regimes differ between Eurasian and North American boreal forests, due in part to differences in climate and the dominant forest types. While North American boreal forests are dominated by stand-replacing fires, much of the Eurasian boreal forest is characterized by lower intensity surface fires. These different fire regimes have important consequences for continental-scale biogeochemical cycling and surface-energy fluxes1. Here, we use generalized linear models (GLM) and boosted regression trees (BRT) to explore the relative importance of vegetation, annual climatic factors, and their interactions in determining annual fire occurrence across Eurasian and North American boreal forests. We use remotely sensed burned area (MCD64A1), land cover (MCD12Q1), and observed climate data (CRU) from 2002-2012 at 0.25° spatial resolution to quantify these relationships at annual temporal scales and continental spatial scales. The spatial distribution of boreal fire occurrence was well explained with climate and vegetation variables, with similarities and differences in fire-climate-vegetation relationships between Eurasia and North America. For example, while GLMs indicate vegetation is a significant factor determining fire occurrence in both continents, the effect of climate differed. Spring temperature and precipitation are significant factors explaining fire occurrence in Eurasia, but no climate variables were significant for explaining fire occurrence in North America. BRTs complement this analysis, highlighting climatic thresholds to fire occurrence in both continents. The nature of these thresholds can vary among vegetation types, even within each continent, further implying regional sensitivity to climate-induced shifts in wildfire activity. To build on these results and better understand regional sensitivity of northern-high latitude fire regimes, future work will explore these relationships in forest-tundra and arctic tundra ecosystems, and apply historical

  8. Late Holocene Vegetation and Climate at the Mid Altitudes of the Western Himalaya

    Science.gov (United States)

    ROY, I.; Ranhotra, P. S.; Shekhar, M.; Bhattacharyya, A.; Agrawal, S.; Kumar, P.; Patil, S. K.; Pal, A. K.

    2017-12-01

    The palynological, stable carbon isotope and magnetic susceptibility studies of a 42 cm deep sedimentary core collected from palaeolacustrine deposit at the Nachiketa area ( 2,400 m amsl) near Uttarkashi of Western Himalaya provides the late Holocene vegetation and climatic scenario of the area. Between 3200 to 1650 cal yrs BP, the high susceptibility (χlf) values along with the good frequency of fern spores might indicate the prevailing moist conditions due to high summer monsoon with good influx of the sediments. However, the low pollen concentration between 3200 to 2680 cal years BP might be due to less ground vegetation cover or poor pollen preservation in the sediments. The well represented fern spores along with the other ground vegetation taxa in the period from 1650 cal yrs BP to 600 cal yrs BP also indicates the continuous prevalence of moist conditions that can be related with the globally known medieval warm period (MWP), supported by the δ13C values around -24‰ during this time and the high χLF values. Moreover, the good representation of Cyperaceae pollen suggests the in-filling of the lake followed by the invasion of ground vegetation viz. Cheno/Ams, Apiaceae, Poaceae etc. The good pollen frequency of broadleaved taxa viz. Quercus and Alnus also supports the moist conditions. Since 600 cal years BP the lowered χLF values signifies reduced input from the surrounding suggesting the filling of the lake. The marked increase in the pollen frequency of Cheno/Ams with low values of fern spores suggest less moist conditions with reduced summer monsoon that can be related to Little Ice Age (LIA) episode. Also the low negative δ13C values (around -21‰) indicates the less ground moisture supporting the C4 taxa. The Quercus and Alnus also reduced in their pollen presence. Whereas the Pinus pollen increased gradually since nearly before 410 cal years BP till recent showing the increased invasion of this taxa to near proximity of the area. The

  9. Automatically Maintain Climatic Conditions inside Agricultural Greenhouses

    Directory of Open Access Journals (Sweden)

    Ali Jasim Ramadhan

    2016-11-01

    Full Text Available In this work, a novel system is designed to remote monitor / automatic control of the temperature, humidity and soil moisture of the agricultural greenhouses. In the proposed system, the author used the mentioned sensors for monitoring the climatic conditions of the agricultural greenhouses; and the system makes a controlling process to fix the required parameters for plant growth by running / stopping the fan, air exchanger and irrigation devices when any changes happened in these parameters. The presented system is based on XBee protocol in the implemented wireless sensor star topology network (WSN to monitor the agricultural greenhouses in real time, and used the GSM and Internet technologies to monitor the agricultural greenhouses from anywhere.

  10. Vegetation-climate feedback causes reduced precipitation and tropical rainforest cover in CMIP5 regional Earth system model simulation over Africa

    Science.gov (United States)

    Wu, M.; Smith, B.; Samuelsson, P.; Rummukainen, M.; Schurgers, G.

    2012-12-01

    We applied a coupled regional climate-vegetation model, RCA-GUESS (Smith et al. 2011), over the CORDEX Africa domain, forced by boundary conditions from a CanESM2 CMIP5 simulation under the RCP8.5 future climate scenario. The simulations were from 1961 to 2100 and covered the African continent at a horizontal grid spacing of 0.44°. RCA-GUESS simulates changes in the phenology, productivity, relative cover and population structure of up to eight plant function types (PFTs) in response to forcing from the climate part of the model. These vegetation changes feed back to simulated climate through dynamic adjustments in surface energy fluxes and surface properties. Changes in the net ecosystem-atmosphere carbon flux and its components net primary production (NPP), heterotrophic respiration and emissions from biomass burning were also simulated but do not feed back to climate in our model. Constant land cover was assumed. We compared simulations with and without vegetation feedback switched "on" to assess the influence of vegetation-climate feedback on simulated climate, vegetation and ecosystem carbon cycling. Both positive and negative warming feedbacks were identified in different parts of Africa. In the Sahel savannah zone near 15°N, reduced vegetation cover and productivity, and mortality caused by a deterioration of soil water conditions led to a positive warming feedback mediated by decreased evapotranspiration and increased sensible heat flux between vegetation and the atmosphere. In the equatorial rainforest stronghold region of central Africa, a feedback syndrome characterised by reduced plant production and LAI, a dominance shift from tropical trees to grasses, reduced soil water and reduced rainfall was identified. The likely underlying mechanism was a decline in evaporative water recycling associated with sparser vegetation cover, reminiscent of Earth system model studies in which a similar feedback mechanism was simulated to force dieback of tropical

  11. Slarti: A boundary condition editor for a coupled climate model

    Science.gov (United States)

    Mickelson, S. A.; Jacob, R. L.; Pierrehumbert, R.

    2006-12-01

    One of the largest barriers to making climate models more flexible is the difficulty in creating new boundary conditions, especially for "deep time" paleoclimate cases where continents are in different positions. Climate models consist of several mutually-interacting component models and the boundary conditions must be consistent between them. We have developed a program called Slarti which uses a Graphical User Interface and a set of consistency rules to aid researchers in creating new, consistent, boundary condition files for the Fast Ocean Atmosphere Model (FOAM). Users can start from existing mask, topography, or bathymetry data or can build a "world" entirely from scratch (e.g. a single island continent). Once a case has been started, users can modify mask, vegetation, bathymetry, topography, and river flow fields by drawing new data through a "paint" interface. Users activate a synchronization button which goes through the fields to eliminate inconsistencies. When the changes are complete and save is selected, Slarti creates all the necessary files for an initial run of FOAM. The data is edited at the highest resolution (the ocean-land surface in FOAM) and then interpolated to the atmosphere resolution. Slarti was implemented in Java to maintain portability across platforms. We also relied heavily on Java Swing components to create the interface. This allowed us to create an object-oriented interface that could be used on many different systems. Since Slarti allows users to visualize their changes, they are able to see areas that may cause problems when the model is ran. Some examples would be lakes from the river flow field and narrow trenches within the bathymetry. Through different checks and options available through its interface, Slarti makes the process of creating new boundary conditions for FOAM easier and faster while reducing the chance for user errors.

  12. Arsenic uptake and speciation in vegetables grown under greenhouse conditions.

    Science.gov (United States)

    Smith, E; Juhasz, A L; Weber, J

    2009-04-01

    The accumulation of arsenic (As) by vegetables is a potential human exposure pathway. The speciation of As in vegetables is an important consideration due to the varying toxicity of different As species. In this study, common Australian garden vegetables were hydroponically grown with As-contaminated irrigation water to determine the uptake and species of As present in vegetable tissue. The highest concentrations of total As were observed in the roots of all vegetables and declined in the aerial portions of the plants. Total As accumulation in the edible portions of the vegetables decreased in the order radish > mung bean > lettuce = chard. Arsenic was present in the roots of radish, chard, and lettuce as arsenate (As(V)) and comprised between 77 and 92% of the total As present, whereas in mung beans, arsenite (As(III)) comprised 90% of the total As present. In aerial portions of the vegetables, As was distributed equally between both As(V) and As(III) in radish and chard but was present mainly as As(V) in lettuce. The presence of elevated As in vegetable roots suggests that As species may be complexed by phytochelatins, which limits As translocation to aerial portions of the plant.

  13. Potential influence of climate-induced vegetation shifts on future land use and associated land carbon fluxes in Northern Eurasia

    International Nuclear Information System (INIS)

    Kicklighter, D W; Melillo, J M; Lu, X; Cai, Y; Paltsev, S; Sokolov, A P; Reilly, J M; Zhuang, Q; Parfenova, E I; Tchebakova, N M

    2014-01-01

    Climate change will alter ecosystem metabolism and may lead to a redistribution of vegetation and changes in fire regimes in Northern Eurasia over the 21st century. Land management decisions will interact with these climate-driven changes to reshape the region’s landscape. Here we present an assessment of the potential consequences of climate change on land use and associated land carbon sink activity for Northern Eurasia in the context of climate-induced vegetation shifts. Under a ‘business-as-usual’ scenario, climate-induced vegetation shifts allow expansion of areas devoted to food crop production (15%) and pastures (39%) over the 21st century. Under a climate stabilization scenario, climate-induced vegetation shifts permit expansion of areas devoted to cellulosic biofuel production (25%) and pastures (21%), but reduce the expansion of areas devoted to food crop production by 10%. In both climate scenarios, vegetation shifts further reduce the areas devoted to timber production by 6–8% over this same time period. Fire associated with climate-induced vegetation shifts causes the region to become more of a carbon source than if no vegetation shifts occur. Consideration of the interactions between climate-induced vegetation shifts and human activities through a modeling framework has provided clues to how humans may be able to adapt to a changing world and identified the trade-offs, including unintended consequences, associated with proposed climate/energy policies. (paper)

  14. Disentangling the Role of Climate, Topography and Vegetation in Species Richness Gradients.

    Directory of Open Access Journals (Sweden)

    Mario R Moura

    Full Text Available Environmental gradients (EG related to climate, topography and vegetation are among the most important drivers of broad scale patterns of species richness. However, these different EG do not necessarily drive species richness in similar ways, potentially presenting synergistic associations when driving species richness. Understanding the synergism among EG allows us to address key questions arising from the effects of global climate and land use changes on biodiversity. Herein, we use variation partitioning (also know as commonality analysis to disentangle unique and shared contributions of different EG in explaining species richness of Neotropical vertebrates. We use three broad sets of predictors to represent the environmental variability in (i climate (annual mean temperature, temperature annual range, annual precipitation and precipitation range, (ii topography (mean elevation, range and coefficient of variation of elevation, and (iii vegetation (land cover diversity, standard deviation and range of forest canopy height. The shared contribution between two types of EG is used to quantify synergistic processes operating among EG, offering new perspectives on the causal relationships driving species richness. To account for spatially structured processes, we use Spatial EigenVector Mapping models. We perform analyses across groups with distinct dispersal abilities (amphibians, non-volant mammals, bats and birds and discuss the influence of vagility on the partitioning results. Our findings indicate that broad scale patterns of vertebrate richness are mainly affected by the synergism between climate and vegetation, followed by the unique contribution of climate. Climatic factors were relatively more important in explaining species richness of good dispersers. Most of the variation in vegetation that explains vertebrate richness is climatically structured, supporting the productivity hypothesis. Further, the weak synergism between topography and

  15. Influence of dynamic vegetation on climate change and terrestrial carbon storage in the Last Glacial Maximum

    Science.gov (United States)

    O'ishi, R.; Abe-Ouchi, A.

    2013-07-01

    When the climate is reconstructed from paleoevidence, it shows that the Last Glacial Maximum (LGM, ca. 21 000 yr ago) is cold and dry compared to the present-day. Reconstruction also shows that compared to today, the vegetation of the LGM is less active and the distribution of vegetation was drastically different, due to cold temperature, dryness, and a lower level of atmospheric CO2 concentration (185 ppm compared to a preindustrial level of 285 ppm). In the present paper, we investigate the influence of vegetation change on the climate of the LGM by using a coupled atmosphere-ocean-vegetation general circulation model (AOVGCM, the MIROC-LPJ). The MIROC-LPJ is different from earlier studies in the introduction of a bias correction method in individual running GCM experiments. We examined four GCM experiments (LGM and preindustrial, with and without vegetation feedback) and quantified the strength of the vegetation feedback during the LGM. The result shows that global-averaged cooling during the LGM is amplified by +13.5 % due to the introduction of vegetation feedback. This is mainly caused by the increase of land surface albedo due to the expansion of tundra in northern high latitudes and the desertification in northern middle latitudes around 30° N to 60° N. We also investigated how this change in climate affected the total terrestrial carbon storage by using offline Lund-Potsdam-Jena dynamic global vegetation model (LPJ-DGVM). Our result shows that the total terrestrial carbon storage was reduced by 597 PgC during the LGM, which corresponds to the emission of 282 ppm atmospheric CO2. In the LGM experiments, the global carbon distribution is generally the same whether the vegetation feedback to the atmosphere is included or not. However, the inclusion of vegetation feedback causes substantial terrestrial carbon storage change, especially in explaining the lowering of atmospheric CO2 during the LGM.

  16. Influence of dynamic vegetation on climate change and terrestrial carbon storage in the Last Glacial Maximum

    Directory of Open Access Journals (Sweden)

    R. O'ishi

    2013-07-01

    Full Text Available When the climate is reconstructed from paleoevidence, it shows that the Last Glacial Maximum (LGM, ca. 21 000 yr ago is cold and dry compared to the present-day. Reconstruction also shows that compared to today, the vegetation of the LGM is less active and the distribution of vegetation was drastically different, due to cold temperature, dryness, and a lower level of atmospheric CO2 concentration (185 ppm compared to a preindustrial level of 285 ppm. In the present paper, we investigate the influence of vegetation change on the climate of the LGM by using a coupled atmosphere-ocean-vegetation general circulation model (AOVGCM, the MIROC-LPJ. The MIROC-LPJ is different from earlier studies in the introduction of a bias correction method in individual running GCM experiments. We examined four GCM experiments (LGM and preindustrial, with and without vegetation feedback and quantified the strength of the vegetation feedback during the LGM. The result shows that global-averaged cooling during the LGM is amplified by +13.5 % due to the introduction of vegetation feedback. This is mainly caused by the increase of land surface albedo due to the expansion of tundra in northern high latitudes and the desertification in northern middle latitudes around 30° N to 60° N. We also investigated how this change in climate affected the total terrestrial carbon storage by using offline Lund-Potsdam-Jena dynamic global vegetation model (LPJ-DGVM. Our result shows that the total terrestrial carbon storage was reduced by 597 PgC during the LGM, which corresponds to the emission of 282 ppm atmospheric CO2. In the LGM experiments, the global carbon distribution is generally the same whether the vegetation feedback to the atmosphere is included or not. However, the inclusion of vegetation feedback causes substantial terrestrial carbon storage change, especially in explaining the lowering of atmospheric CO2 during the LGM.

  17. Response of Vegetation to Climate Change in the Drylands of East Asia

    International Nuclear Information System (INIS)

    Dai, L; Wang, K; Wang, R L; Zhang, L

    2014-01-01

    Over the past 25 years, global climate and environmental changes have caused an unprecedented rate of vegetation change, as exemplified in the drylands of East Asia. In this study, we investigated the spatio-temporal changes of vegetation in this region and analysed their relationship with climate data. Our results show that vegetation productivity significantly increased from 1982 to 2006. This increasing trend was observed for most of the region, particularly for northwest Mongolia and central Inner Mongolia. Grasslands, croplands, forests, and shrublands, all exhibited this trend. The annual growth rate of the grasslands determined using the Normalized Difference Vegetation Index (NDVI) was the largest observed change; reaching 0.07% p.a, followed by shrublands (0.06%), croplands (0.03%), and forests (0.02%). In the different geographic regions, the roles of temperature and precipitation on vegetation growth were shown to be different. Temperature was the dominant factor for the observed NDVI increase in northwest Mongolia and the centre of Inner Mongolia. The combined influences of temperature and precipitation changes have resulted in the promotion of vegetation growth, as seen in eastern GanSu. Temperature change is the primary factor for initiating vegetation growth in spring and autumn because warmer temperatures increase the length of the growing season, and are thus evaluated as an increased NDVI value. Increased precipitation has been shown to play a positive role on vegetation growth during summer

  18. Evaluation and attribution of vegetation contribution to seasonal climate predictability

    Science.gov (United States)

    Catalano, Franco; Alessandri, Andrea; De Felice, Matteo

    2015-04-01

    The land surface model of EC-Earth has been modified to include dependence of vegetation densities on the Leaf Area Index (LAI), based on the Lambert-Beer formulation. Effective vegetation fractional coverage can now vary at seasonal and interannual time-scales and therefore affect biophysical parameters such as the surface roughness, albedo and soil field capacity. The modified model is used to perform a real predictability seasonal hindcast experiment. LAI is prescribed using a recent observational dataset based on the third generation GIMMS and MODIS satellite data. Hindcast setup is: 7 months forecast length, 2 start dates (1st May and 1st November), 10 members, 28 years (1982-2009). The effect of the realistic LAI prescribed from observation is evaluated with respect to a control experiment where LAI does not vary. Hindcast results demonstrate that a realistic representation of vegetation significantly improves the forecasts of temperature and precipitation. The sensitivity is particularly large for temperature during boreal winter over central North America and Central Asia. This may be attributed in particular to the effect of the high vegetation component on the snow cover. Summer forecasts are improved in particular for precipitation over Europe, Sahel, North America, West Russia and Nordeste. Correlation improvements depends on the links between targets (temperature and precipitation) and drivers (surface heat fluxes, albedo, soil moisture, evapotranspiration, moisture divergence) which varies from region to region.

  19. Contribution of Dynamic Vegetation Phenology to Decadal Climate Predictability

    NARCIS (Netherlands)

    Weiss, M.; Miller, P.A.; Hurk, van den B.J.J.M.; Noije, van T.; Stefanescu, S.; Haarsma, R.; Ulft, van L.H.; Hazeleger, W.; Sager, Le P.; Smith, B.; Schurgers, G.

    2014-01-01

    In this study, the impact of coupling and initializing the leaf area index from the dynamic vegetation model Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS) is analyzed on skill of decadal predictions in the fully coupled atmosphere-land-ocean-sea ice model, the European Consortium Earth

  20. Simulating vegetation response to climate change in the Blue Mountains with MC2 dynamic global vegetation model

    Directory of Open Access Journals (Sweden)

    John B. Kim

    2018-04-01

    Full Text Available Warming temperatures are projected to greatly alter many forests in the Pacific Northwest. MC2 is a dynamic global vegetation model, a climate-aware, process-based, and gridded vegetation model. We calibrated and ran MC2 simulations for the Blue Mountains Ecoregion, Oregon, USA, at 30 arc-second spatial resolution. We calibrated MC2 using the best available spatial datasets from land managers. We ran future simulations using climate projections from four global circulation models (GCM under representative concentration pathway 8.5. Under this scenario, forest productivity is projected to increase as the growing season lengthens, and fire occurrence is projected to increase steeply throughout the century, with burned area peaking early- to mid-century. Subalpine forests are projected to disappear, and the coniferous forests to contract by 32.8%. Large portions of the dry and mesic forests are projected to convert to woodlands, unless precipitation were to increase. Low levels of change are projected for the Umatilla National Forest consistently across the four GCM’s. For the Wallowa-Whitman and the Malheur National Forest, forest conversions are projected to vary more across the four GCM-based simulations, reflecting high levels of uncertainty arising from climate. For simulations based on three of the four GCMs, sharply increased fire activity results in decreases in forest carbon stocks by the mid-century, and the fire activity catalyzes widespread biome shift across the study area. We document the full cycle of a structured approach to calibrating and running MC2 for transparency and to serve as a template for applications of MC2. Keywords: Climate change, Regional change, Simulation, Calibration, Forests, Fire, Dynamic global vegetation model

  1. Impacts of Climate Change Induced Vegetation Responses on BVOC Emissions from Subarctic Heath Ecosystems

    DEFF Research Database (Denmark)

    Valolahti, Hanna Maritta

    The role of biogenic volatile organic compounds (BVOCs) affecting Earths’ climate system is one of the greatest uncertainties when modelling the global climate change. BVOCs presence in the atmosphere can have both positive and negative climate feedback mechanisms when they involve atmospheric...... chemistry and physics. Vegetation is the main source of BVOCs. Their production is directly linked to temperature and the foliar biomass. On global scale, vegetation in subarctic and arctic regions has been modeled to have only minor contribution to annual total BVOC emissions. In these regions cold...... temperature has been regulating annual plant biomass production, but ongoing global warming is more pronounced in these regions than what the global average is. This may increase the importance of subarctic and arctic vegetation as a source of BVOC emissions in near future. This thesis aims to increase...

  2. The Late Quaternary history of climate and vegetation in East and southern Africa

    Directory of Open Access Journals (Sweden)

    E. M. van Zinderen Bakker Sr

    1983-11-01

    Full Text Available In the vast region of East and southern Africa the alternating glacial and interglacial periods of the Quaternarv were characterized by considerable changes in temperature and precipitation. During the last glacial maximum the influence of the ITCZ was limited, while the circulation systems were strengthened. The ocean surface waters were cooler and the Benguela Current was activated. In the montane areas of East Africa and also in southern Africa the temperature dropped by about 6°C. During this hypothermal period, rainfall on the east African plateau and mountains diminished. Summer precipitation could still penetrate the eastern half of southern Africa from the Indian Ocean, while the western half was arid to semi-arid. Cyclonic winter rain migrated further north beyond the latitude of the Orange River. The consequences of these climatic changes during the last glacial maximum were that the woodlands of East Africa opened up. On the plateau of South Africa austro-afroalpine vegetation dominated. The south coastal plain was very windy and cold to temperate, while the Namib and Kalahari were respectively hyper-arid and semi-humid. During hyperthermals the vegetation pattern resembled present-day conditions more closely.

  3. Albedo and vegetation demand-side management options for warm climates

    International Nuclear Information System (INIS)

    Hall, Darwin C.

    1997-01-01

    For electric utilities, demand-side management (DSM) can reduce electric load and shift load from peak to off-peak periods. In general, the investor in DSM collects the reward with lower electric bills, excepting a positive externality because of reduced tropospheric and stratospheric air pollution from fossil fuel power plants. In warm climates, DSM options include increasing albedo and vegetation, respectively, by painting surfaces white and planting trees; these DSM options are distinguished from all other DSM options because of ecosystem effects. Ambient temperature falls, mitigating the urban 'heat island', which reduces electric load and ozone formation. The investor in albedo and vegetation DSM options does not collect all of the reward from lower electric bills, since the lower ambient temperature provides savings to all customers who use electricity for air conditioning and refrigeration. Similar to other DSM options, air pollution is also reduced as a result of lower power plant emissions. Complex airshed models and electric utility system dispatch models are applied in this paper to account for some of these ecosystem effects. Unaccounted ecosystem effects remain, stymieing cost effectiveness analysis

  4. Climate and vegetational regime shifts in the late Paleozoic ice age earth.

    Science.gov (United States)

    DiMichele, W A; Montañez, I P; Poulsen, C J; Tabor, N J

    2009-03-01

    The late Paleozoic earth experienced alternation between glacial and non-glacial climates at multiple temporal scales, accompanied by atmospheric CO2 fluctuations and global warming intervals, often attended by significant vegetational changes in equatorial latitudes of Pangaea. We assess the nature of climate-vegetation interaction during two time intervals: middle-late Pennsylvanian transition and Pennsylvanian-Permian transition, each marked by tropical warming and drying. In case study 1, there is a catastrophic intra-biomic reorganization of dominance and diversity in wetland, evergreen vegetation growing under humid climates. This represents a threshold-type change, possibly a regime shift to an alternative stable state. Case study 2 is an inter-biome dominance change in western and central Pangaea from humid wetland and seasonally dry to semi-arid vegetation. Shifts between these vegetation types had been occurring in Euramerican portions of the equatorial region throughout the late middle and late Pennsylvanian, the drier vegetation reaching persistent dominance by Early Permian. The oscillatory transition between humid and seasonally dry vegetation appears to demonstrate a threshold-like behavior but probably not repeated transitions between alternative stable states. Rather, changes in dominance in lowland equatorial regions were driven by long-term, repetitive climatic oscillations, occurring with increasing intensity, within overall shift to seasonal dryness through time. In neither case study are there clear biotic or abiotic warning signs of looming changes in vegetational composition or geographic distribution, nor is it clear that there are specific, absolute values or rates of environmental change in temperature, rainfall distribution and amount, or atmospheric composition, approach to which might indicate proximity to a terrestrial biotic-change threshold.

  5. Transformation of soil and vegetable conditions at oil production territories

    Science.gov (United States)

    Gatina, Evgeniia

    2017-04-01

    On the territory of modern oil production soil, vegetation, ecosystem conditions of the environment are significantly transformed. Researches have been conducted on the oil production territories located in a boreal coniferous forest natural zone from 2005 to 2015. Standard geobotanical and soil methods are used. Mechanical destruction of a plant cover, change of the water conditions, intake of oil products and salty waters in ecosystems, pollution of the atmosphere are considered as the major technology-related factors defining transformation of land ecosystems at operation of the oil field. Under the mechanical destruction of a plant cover the pioneer plant communities are formed. These communities are characterized by most reduced specific wealth with prevalence of types of meadow groups of plants and presence of types of wetland groups of plants. The biodiversity of biocenosis which are affected linear infrastructure facilities of oil production territories and change of the water conditions, decreases. It is observed decrease in species wealth, simplification of structure of communities. Under the salting of soils in ecosystems there is a decrease species diversity of communities to prevalence nitrophilous and meadow plant species. At the increased content of organic substances in the soils that is a consequence of intake of oil products, is characteristic increase in specific richness of communities, introduction of types of wetland and oligotrophic groups of plants in forest communities. Influence depends on distance to an influence source. In process of removal from a source of atmospheric pollution in forest communities there is a decrease in species diversity and complication of structure of community. It is caused by introduction of types of meadow groups of plants in ecotone sites of the forest communities located near a source of influence and restoration of structural features of forest communities in process of removal from an influence source

  6. Response of the mean global vegetation distribution to interannual climate variability

    Energy Technology Data Exchange (ETDEWEB)

    Notaro, Michael [University of Wisconsin-Madison, Center for Climatic Research, Madison, WI (United States)

    2008-06-15

    The impact of interannual variability in temperature and precipitation on global terrestrial ecosystems is investigated using a dynamic global vegetation model driven by gridded climate observations for the twentieth century. Contrasting simulations are driven either by repeated mean climatology or raw climate data with interannual variability included. Interannual climate variability reduces net global vegetation cover, particularly over semi-arid regions, and favors the expansion of grass cover at the expense of tree cover, due to differences in growth rates, fire impacts, and interception. The area burnt by global fires is substantially enhanced by interannual precipitation variability. The current position of the central United States' ecotone, with forests to the east and grasslands to the west, is largely attributed to climate variability. Among woody vegetation, climate variability supports expanded deciduous forest growth and diminished evergreen forest growth, due to difference in bioclimatic limits, leaf longevity, interception rates, and rooting depth. These results offer insight into future ecosystem distributions since climate models generally predict an increase in climate variability and extremes. (orig.)

  7. The impact of future forest dynamics on climate: interactive effects of changing vegetation and disturbance regimes

    Science.gov (United States)

    Thom, Dominik; Rammer, Werner; Seidl, Rupert

    2018-01-01

    Currently, the temperate forest biome cools the earth’s climate and dampens anthropogenic climate change. However, climate change will substantially alter forest dynamics in the future, affecting the climate regulation function of forests. Increasing natural disturbances can reduce carbon uptake and evaporative cooling, but at the same time increase the albedo of a landscape. Simultaneous changes in vegetation composition can mitigate disturbance impacts, but also influence climate regulation directly (e.g., via albedo changes). As a result of a number of interactive drivers (changes in climate, vegetation, and disturbance) and their simultaneous effects on climate-relevant processes (carbon exchange, albedo, latent heat flux) the future climate regulation function of forests remains highly uncertain. Here we address these complex interactions to assess the effect of future forest dynamics on the climate system. Our specific objectives were (1) to investigate the long-term interactions between changing vegetation composition and disturbance regimes under climate change, (2) to quantify the response of climate regulation to changes in forest dynamics, and (3) to identify the main drivers of the future influence of forests on the climate system. We investigated these issues using the individual-based forest landscape and disturbance model (iLand). Simulations were run over 200 yr for Kalkalpen National Park (Austria), assuming different future climate projections, and incorporating dynamically responding wind and bark beetle disturbances. To consistently assess the net effect on climate the simulated responses of carbon exchange, albedo, and latent heat flux were expressed as contributions to radiative forcing. We found that climate change increased disturbances (+27.7% over 200 yr) and specifically bark beetle activity during the 21st century. However, negative feedbacks from a simultaneously changing tree species composition (+28.0% broadleaved species) decreased

  8. The impact of future forest dynamics on climate: interactive effects of changing vegetation and disturbance regimes.

    Science.gov (United States)

    Thom, Dominik; Rammer, Werner; Seidl, Rupert

    2017-11-01

    Currently, the temperate forest biome cools the earth's climate and dampens anthropogenic climate change. However, climate change will substantially alter forest dynamics in the future, affecting the climate regulation function of forests. Increasing natural disturbances can reduce carbon uptake and evaporative cooling, but at the same time increase the albedo of a landscape. Simultaneous changes in vegetation composition can mitigate disturbance impacts, but also influence climate regulation directly (e.g., via albedo changes). As a result of a number of interactive drivers (changes in climate, vegetation, and disturbance) and their simultaneous effects on climate-relevant processes (carbon exchange, albedo, latent heat flux) the future climate regulation function of forests remains highly uncertain. Here we address these complex interactions to assess the effect of future forest dynamics on the climate system. Our specific objectives were (1) to investigate the long-term interactions between changing vegetation composition and disturbance regimes under climate change, (2) to quantify the response of climate regulation to changes in forest dynamics, and (3) to identify the main drivers of the future influence of forests on the climate system. We investigated these issues using the individual-based forest landscape and disturbance model (iLand). Simulations were run over 200 yr for Kalkalpen National Park (Austria), assuming different future climate projections, and incorporating dynamically responding wind and bark beetle disturbances. To consistently assess the net effect on climate the simulated responses of carbon exchange, albedo, and latent heat flux were expressed as contributions to radiative forcing. We found that climate change increased disturbances (+27.7% over 200 yr) and specifically bark beetle activity during the 21st century. However, negative feedbacks from a simultaneously changing tree species composition (+28.0% broadleaved species) decreased

  9. Nile Basin Vegetation Response and Vulnerability to Climate Change: A Multi-Sensor Remote Sensing Approach

    Science.gov (United States)

    Yitayew, M.; Didan, K.; Barreto-munoz, A.

    2013-12-01

    The Nile Basin is one of the world's water resources hotspot that is home to over 437 million people in ten riparian countries with 54% or 238 millions live directly within the basin. The basin like all other basins of the world is facing water resources challenges exacerbated by climate change and increased demand. Nowadays any water resource management action in the basin has to assess the impacts of climate change to be able to predict future water supply and also to help in the negotiation process. Presently, there is a lack of basin wide weather networks to understand sensitivity of the vegetation cover to the impacts of climate change. Vegetation plays major economic and ecological functions in the basin and provides key services ranging from pastoralism, agricultural production, firewood, habitat and food sources for the rich wildlife, as well as a major role in the carbon cycle and climate regulation of the region. Under the threat of climate change and the incessant anthropogenic pressure the distribution and services of the region's ecosystems are projected to change The goal of this work is to assess and characterize how the basin vegetation productivity, distribution, and phenology have changed over the last 30+ years and what are the key climatic drivers of this change. This work makes use of a newly generated multi-sensor long-term land surface data set about vegetation and phenology. Vegetation indices derived from remotely sensed surface reflectance data are commonly used to characterize phenology or vegetation dynamics accurately and with enough spatial and temporal resolution to support change detection. We used more than 30 years of vegetation index and growing season data from AVHRR and MODIS sensors compiled by the Vegetation Index and Phenology laboratory (VIP LAB) at the University of Arizona. Available climate data about precipitation and temperature for the corresponding 30 years period is also used for this analysis. We looked at the

  10. Vegetation-mediated Climate Impacts on Historical and Future Ozone Air Quality

    Science.gov (United States)

    Tai, A. P. K.; Fu, Y.; Mickley, L. J.; Heald, C. L.; Wu, S.

    2014-12-01

    Changes in climate, natural vegetation and human land use are expected to significantly influence air quality in the coming century. These changes and their interactions have important ramifications for the effectiveness of air pollution control strategies. In a series of studies, we use a one-way coupled modeling framework (GEOS-Chem driven by different combinations of historical and future meteorological, land cover and emission data) to investigate the effects of climate-vegetation changes on global and East Asian ozone air quality from 30 years ago to 40 years into the future. We find that future climate and climate-driven vegetation changes combine to increase summertime ozone by 2-6 ppbv in populous regions of the US, Europe, East Asia and South Asia by year 2050, but including the interaction between CO2 and biogenic isoprene emission reduces the climate impacts by more than half. Land use change such as cropland expansion has the potential to either mostly offset the climate-driven ozone increases (e.g., in the US and Europe), or greatly increase ozone (e.g., in Southeast Asia). The projected climate-vegetation effects in East Asia are particularly uncertain, reflecting a less understood ozone production regime. We thus further study how East Asian ozone air quality has evolved since the early 1980s in response to climate, vegetation and emission changes to shed light on its likely future course. We find that warming alone has led to a substantial increase in summertime ozone in populous regions by 1-4 ppbv. Despite significant cropland expansion and urbanization, increased summertime leafiness of vegetation in response to warming and CO2 fertilization has reduced ozone by 1-2 ppbv, driven by enhanced ozone deposition dominating over elevated biogenic emission and partially offsetting the warming effect. The historical role of CO2-isoprene interaction in East Asia, however, remains highly uncertain. Our findings demonstrate the important roles of land cover

  11. Approaching to a model for evaluating of the vulnerability of the vegetable covers of Colombia in a possible climatic change using SIG

    International Nuclear Information System (INIS)

    Gutierrez Rey, Hilda Jeanneth

    2002-01-01

    This technical paper summarizes the gradual thesis Approach to a model for evaluating of the vulnerability of the vegetation covers in Colombia in face of a possible global climate change (Gutierrez, 2001). It present the methodologies and results of the construction of a prospective model using GIS (Geographical Information Systems) for evaluating the vulnerability of the vegetation covers of Colombia, in face of a possible global climate chance. The analysis of the vulnerability of the possible impact on vegetation and for identification of its vulnerability as a consequence of climate change was carried out by application of the method of direct function establishing, recommended by IPCC, Intergovernmental Panel on Climate Change (1999). An analysis of the displacement of Life Zones of Holdridge was made under a scenario with duplication of the CO 2 concentration in the atmosphere and identified vegetation affected by displacement. These results were adjusted to the bioclimatic and biogeographic conditions of the country. The Model of Vulnerability of the Vegetation Covers of Colombia was developed in Spatial Modeler Language, of Arc/lnfo and Erdas Imagine. This model is able to generate the spatial distribution of the climatic variables and Bioclimatic Units, under past, present and future climate scenarios, as well as to evaluate the degree of vulnerability of the vegetation covers of Colombia in face a climatic change. For the improvement of the model of Vulnerability, specially the intermediate products, it was subdivided in three Phases or Subsystems: In the First Phase or Present Subsystem, the sub models generate a Bioclimatic Zonification of the Life Zones of Holdridge, under a currently scenario of Climatic Line Base 1961-1990. In the Second Phase or Subsystem of Climate Change, the sub models develop a Bioclimatic Zonification of the Life Zones of Holdridge, under a future climate Scenario with duplication of the contained of the CO 2 in the atmosphere

  12. Vegetation role in controlling the ecoenvironmental conditions for sustainable urban environments: a comparison of Beijing and Islamabad

    Science.gov (United States)

    Naeem, Shahid; Cao, Chunxiang; Waqar, Mirza Muhammad; Wei, Chen; Acharya, Bipin Kumar

    2018-01-01

    The rapid increase in urbanization due to population growth leads to the degradation of vegetation in major cities. This study investigated the spatial patterns of the ecoenvironmental conditions of inhabitants of two distinct Asian capital cities, Beijing of China and Islamabad of Pakistan, by utilizing Earth observation data products. The significance of urban vegetation for the cooling effect was studied in local climate zones, i.e., urban, suburban, and rural areas within 1-km2 quantiles. Landsat-8 (OLI) and Gaofen-1 satellite imagery were used to assess vegetation cover and land surface temperature, while population datasets were used to evaluate environmental impact. Comparatively, a higher cooling effect of vegetation presence was observed in rural and suburban zones of Beijing as compared to Islamabad, while the urban zone of Islamabad was found comparatively cooler than Beijing's urban zone. The urban thermal field variance index calculated from satellite imagery was ranked into the ecological evaluation index. The worst ecoenvironmental conditions were found in urban zones of both cities where the fraction of vegetation is very low. Meanwhile, this condition is more serious in Beijing, as more than 90% of the total population is living under the worst ecoenvironment conditions, while only 7% of the population is enjoying comfortable conditions. Ecoenvironmental conditions of Islamabad are comparatively better than Beijing where ˜61% of the total population live under the worst ecoenvironmental conditions, and ˜24% are living under good conditions. Thus, Islamabad at this early growth stage can learn from Beijing's ecoenvironmental conditions to improve the quality of living by controlling the associated factors in the future.

  13. Modelling Soil Carbon Content in South Patagonia and Evaluating Changes According to Climate, Vegetation, Desertification and Grazing

    Directory of Open Access Journals (Sweden)

    Pablo Luis Peri

    2018-02-01

    Full Text Available In Southern Patagonia, a long-term monitoring network has been established to assess bio-indicators as an early warning of environmental changes due to climate change and human activities. Soil organic carbon (SOC content in rangelands provides a range of important ecosystem services and supports the capacity of the land to sustain plant and animal productivity. The objectives in this study were to model SOC (30 cm stocks at a regional scale using climatic, topographic and vegetation variables, and to establish a baseline that can be used as an indicator of rangeland condition. For modelling, we used a stepwise multiple regression to identify variables that explain SOC variation at the landscape scale. With the SOC model, we obtained a SOC map for the entire Santa Cruz province, where the variables derived from the multiple linear regression models were integrated into a geographic information system (GIS. SOC stock to 30 cm ranged from 1.38 to 32.63 kg C m−2. The fitted model explained 76.4% of SOC variation using as independent variables isothermality, precipitation seasonality and vegetation cover expressed as a normalized difference vegetation index. The SOC map discriminated in three categories (low, medium, high determined patterns among environmental and land use variables. For example, SOC decreased with desertification due to erosion processes. The understanding and mapping of SOC in Patagonia contributes as a bridge across main issues such as climate change, desertification and biodiversity conservation.

  14. A review on vegetation models and applicability to climate simulations at regional scale

    Science.gov (United States)

    Myoung, Boksoon; Choi, Yong-Sang; Park, Seon Ki

    2011-11-01

    The lack of accurate representations of biospheric components and their biophysical and biogeochemical processes is a great source of uncertainty in current climate models. The interactions between terrestrial ecosystems and the climate include exchanges not only of energy, water and momentum, but also of carbon and nitrogen. Reliable simulations of these interactions are crucial for predicting the potential impacts of future climate change and anthropogenic intervention on terrestrial ecosystems. In this paper, two biogeographical (Neilson's rule-based model and BIOME), two biogeochemical (BIOME-BGC and PnET-BGC), and three dynamic global vegetation models (Hybrid, LPJ, and MC1) were reviewed and compared in terms of their biophysical and physiological processes. The advantages and limitations of the models were also addressed. Lastly, the applications of the dynamic global vegetation models to regional climate simulations have been discussed.

  15. Vegetation dynamics and its driving forces from climate change and human activities in the Three-River Source Region, China from 1982 to 2012

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ying; Zhang, Chaobin; Wang, Zhaoqi; Chen, Yizhao; Gang, Chengcheng [School of Life Science, Nanjing University, Xianlin Road 163, Qixia District, Nanjing, 210046 (China); An, Ru [School of Earth Science and Engineering, Hohai University, Xikang Road 129, Nanjing, 210098 (China); Li, Jianlong, E-mail: lijianlongnju@163.com [School of Life Science, Nanjing University, Xianlin Road 163, Qixia District, Nanjing, 210046 (China)

    2016-09-01

    The Three-River Source Region (TRSR), a region with key importance to the ecological security of China, has undergone climate changes and a shift in human activities driven by a series of ecological restoration projects in recent decades. To reveal the spatiotemporal dynamics of vegetation dynamics and calculate the contributions of driving factors in the TRSR across different periods from 1982 to 2012, net primary productivity (NPP) estimated using the Carnegie–Ames–Stanford approach model was used to assess the status of vegetation. The actual effects of different climatic variation trends on interannual variation in NPP were analyzed. Furthermore, the relationships of NPP with different climate factors and human activities were analyzed quantitatively. Results showed the following: from 1982 to 2012, the average NPP in the study area was 187.37 g cm{sup −2} yr{sup −1}. The average NPP exhibited a fluctuation but presented a generally increasing trend over the 31-year study period, with an increase rate of 1.31 g cm{sup −2} yr{sup −2}. During the entire study period, the average contributions of temperature, precipitation, and solar radiation to NPP interannual variation over the entire region were 0.58, 0.73, and 0.09 g cm{sup −2} yr{sup −2}, respectively. Radiation was the climate factor with the greatest influence on NPP interannual variation. The factor that restricted NPP increase changed from temperature and radiation to precipitation. The average contributions of climate change and human activities to NPP interannual variation were 1.40 g cm{sup −2} yr{sup −2} and − 0.08 g cm{sup −2} yr{sup −2}, respectively. From 1982 to 2000, the general climate conditions were favorable to vegetation recovery, whereas human activities had a weaker negative impact on vegetation growth. From 2001 to 2012, climate conditions began to have a negative impact on vegetation growth, whereas human activities made a favorable impact on vegetation

  16. Vegetation dynamics and its driving forces from climate change and human activities in the Three-River Source Region, China from 1982 to 2012

    International Nuclear Information System (INIS)

    Zhang, Ying; Zhang, Chaobin; Wang, Zhaoqi; Chen, Yizhao; Gang, Chengcheng; An, Ru; Li, Jianlong

    2016-01-01

    The Three-River Source Region (TRSR), a region with key importance to the ecological security of China, has undergone climate changes and a shift in human activities driven by a series of ecological restoration projects in recent decades. To reveal the spatiotemporal dynamics of vegetation dynamics and calculate the contributions of driving factors in the TRSR across different periods from 1982 to 2012, net primary productivity (NPP) estimated using the Carnegie–Ames–Stanford approach model was used to assess the status of vegetation. The actual effects of different climatic variation trends on interannual variation in NPP were analyzed. Furthermore, the relationships of NPP with different climate factors and human activities were analyzed quantitatively. Results showed the following: from 1982 to 2012, the average NPP in the study area was 187.37 g cm"−"2 yr"−"1. The average NPP exhibited a fluctuation but presented a generally increasing trend over the 31-year study period, with an increase rate of 1.31 g cm"−"2 yr"−"2. During the entire study period, the average contributions of temperature, precipitation, and solar radiation to NPP interannual variation over the entire region were 0.58, 0.73, and 0.09 g cm"−"2 yr"−"2, respectively. Radiation was the climate factor with the greatest influence on NPP interannual variation. The factor that restricted NPP increase changed from temperature and radiation to precipitation. The average contributions of climate change and human activities to NPP interannual variation were 1.40 g cm"−"2 yr"−"2 and − 0.08 g cm"−"2 yr"−"2, respectively. From 1982 to 2000, the general climate conditions were favorable to vegetation recovery, whereas human activities had a weaker negative impact on vegetation growth. From 2001 to 2012, climate conditions began to have a negative impact on vegetation growth, whereas human activities made a favorable impact on vegetation recovery. - Highlights: • Partitioned the

  17. Impacts of Vegetation and Urban planning on micro climate in Hashtgerd new Town

    Science.gov (United States)

    Sodoudi, Sahar; langer, Ines; Cubasch, Ulrich

    2013-04-01

    One of the objectives of climatological part of project Young Cities 'Developing Energy-Efficient Urban Fabric in the Tehran-Karaj Region' is to simulate the micro climate (with 1m resolution) in 35ha of new town Hashtgerd, which is located 65 km far from mega city Tehran. The Project aims are developing, implementing and evaluating building and planning schemes and technologies which allow to plan and build sustainable, energy-efficient and climate sensible form mass housing settlements in arid and semi-arid regions ("energy-efficient fabric"). Climate sensitive form also means designing and planning for climate change and its related effects for Hashtgerd New Town. By configuration of buildings and open spaces according to solar radiation, wind and vegetation, climate sensitive urban form can create outdoor thermal comfort. To simulate the climate on small spatial scales, the micro climate model Envi-met has been used to simulate the micro climate in 35 ha. The Eulerian model ENVI-met is a micro-scale climate model which gives information about the influence of architecture and buildings as well as vegetation and green area on the micro climate up to 1 m resolution. Envi-met has been run with information from topography, downscaled climate data with neuro-fuzzy method, meteorological measurements, building height and different vegetation variants (low and high number of trees) Through the optimal Urban Design and Planning for the 35ha area the microclimate results shows, that with vegetation the microclimate in street canopies will be change: • 2 m temperature is decreased by about 2 K • relative humidity increase by about 10 % • soil temperature is decreased by about 3 K • wind speed is decreased by about 60% The style of buildings allows free movement of air, which is of high importance for fresh air supply. The increase of inbuilt areas in 35 ha reduces the heat island effect through cooling caused by vegetation and increase of air humidity which

  18. Quantifying the Impacts of Environmental Factors on Vegetation Dynamics over Climatic and Management Gradients of Central Asia

    Directory of Open Access Journals (Sweden)

    Olena Dubovyk

    2016-07-01

    Full Text Available Currently there is a lack of quantitative information regarding the driving factors of vegetation dynamics in post-Soviet Central Asia. Insufficient knowledge also exists concerning vegetation variability across sub-humid to arid climatic gradients as well as vegetation response to different land uses, from natural rangelands to intensively irrigated croplands. In this study, we analyzed the environmental drivers of vegetation dynamics in five Central Asian countries by coupling key vegetation parameter “overall greenness” derived from Moderate Resolution Imaging Spectroradiometer (MODIS Normalized Difference Vegetation Index (NDVI time series data, with its possible factors across various management and climatic gradients. We developed nine generalized least-squares random effect (GLS-RE models to analyze the relative impact of environmental factors on vegetation dynamics. The obtained results quantitatively indicated the extensive control of climatic factors on managed and unmanaged vegetation cover across Central Asia. The most diverse vegetation dynamics response to climatic variables was observed for “intensively managed irrigated croplands”. Almost no differences in response to these variables were detected for managed non-irrigated vegetation and unmanaged (natural vegetation across all countries. Natural vegetation and rainfed non-irrigated crop dynamics were principally associated with temperature and precipitation parameters. Variables related to temperature had the greatest relative effect on irrigated croplands and on vegetation cover within the mountainous zone. Further research should focus on incorporating the socio-economic factors discussed here in a similar analysis.

  19. Representing climate, disturbance, and vegetation interactions in landscape models

    Science.gov (United States)

    Robert E. Keane; Donald McKenzie; Donald A. Falk; Erica A.H. Smithwick; Carol Miller; Lara-Karena B. Kellogg

    2015-01-01

    The prospect of rapidly changing climates over the next century calls for methods to predict their effects on myriad, interactive ecosystem processes. Spatially explicit models that simulate ecosystem dynamics at fine (plant, stand) to coarse (regional, global) scales are indispensable tools for meeting this challenge under a variety of possible futures. A special...

  20. Predicting Pleistocene climate from vegetation in North America

    Directory of Open Access Journals (Sweden)

    C. Loehle

    2007-01-01

    Full Text Available Climates at the Last Glacial Maximum have been inferred from fossil pollen assemblages, but these inferred climates are colder for eastern North America than those produced by climate simulations. It has been suggested that low CO2 levels could account for this discrepancy. In this study biogeographic evidence is used to test the CO2 effect model. The recolonization of glaciated zones in eastern North America following the last ice age produced distinct biogeographic patterns. It has been assumed that a wide zone south of the ice was tundra or boreal parkland (Boreal-Parkland Zone or BPZ, which would have been recolonized from southern refugia as the ice melted, but the patterns in this zone differ from those in the glaciated zone, which creates a major biogeographic anomaly. In the glacial zone, there are few endemics but in the BPZ there are many across multiple taxa. In the glacial zone, there are the expected gradients of genetic diversity with distance from the ice-free zone, but no evidence of this is found in the BPZ. Many races and related species exist in the BPZ which would have merged or hybridized if confined to the same refugia. Evidence for distinct southern refugia for most temperate species is lacking. Extinctions of temperate flora were rare. The interpretation of spruce as a boreal climate indicator may be mistaken over much of the region if the spruce was actually an extinct temperate species. All of these anomalies call into question the concept that climates in the zone south of the ice were extremely cold or that temperate species had to migrate far to the south. An alternate hypothesis is that low CO2 levels gave an advantage to pine and spruce, which are the dominant trees in the BPZ, and to herbaceous species over trees, which also fits the observed pattern. Thus climate reconstruction from pollen data is probably biased and needs to incorporate CO2 effects. Most temperate species could have survived across their current

  1. Late Holocene vegetation changes in relation with climate fluctuations and human activity in Languedoc (southern France)

    OpenAIRE

    Azuara , J; Combourieu-Nebout , N; Lebreton , V; Mazier , F; Müller , S D; Dezileau , L ,

    2015-01-01

    International audience; Holocene climate fluctuations and human activity since the Neolithic have shaped present-day Mediter-ranean environments. Separating anthropogenic effects from climatic impacts to better understand Mediterranean pale-oenvironmental changes over the last millennia remains a challenging issue. High-resolution pollen analyses were un-dertaken on two cores from the Palavasian lagoon system (Hérault, southern France). These records allow reconstruction of vegetation dynamic...

  2. Climate reconstruction analysis using coexistence likelihood estimation (CRACLE): a method for the estimation of climate using vegetation.

    Science.gov (United States)

    Harbert, Robert S; Nixon, Kevin C

    2015-08-01

    • Plant distributions have long been understood to be correlated with the environmental conditions to which species are adapted. Climate is one of the major components driving species distributions. Therefore, it is expected that the plants coexisting in a community are reflective of the local environment, particularly climate.• Presented here is a method for the estimation of climate from local plant species coexistence data. The method, Climate Reconstruction Analysis using Coexistence Likelihood Estimation (CRACLE), is a likelihood-based method that employs specimen collection data at a global scale for the inference of species climate tolerance. CRACLE calculates the maximum joint likelihood of coexistence given individual species climate tolerance characterization to estimate the expected climate.• Plant distribution data for more than 4000 species were used to show that this method accurately infers expected climate profiles for 165 sites with diverse climatic conditions. Estimates differ from the WorldClim global climate model by less than 1.5°C on average for mean annual temperature and less than ∼250 mm for mean annual precipitation. This is a significant improvement upon other plant-based climate-proxy methods.• CRACLE validates long hypothesized interactions between climate and local associations of plant species. Furthermore, CRACLE successfully estimates climate that is consistent with the widely used WorldClim model and therefore may be applied to the quantitative estimation of paleoclimate in future studies. © 2015 Botanical Society of America, Inc.

  3. Holocene vegetation and climate changes in the central Mediterranean inferred from a high-resolution marine pollen record (Adriatic Sea

    Directory of Open Access Journals (Sweden)

    N. Combourieu-Nebout

    2013-09-01

    resulting in a homogeneous seasonal precipitation regime. After 6000 cal yr BP, summer precipitation decreases towards present-day values while winter precipitation rises regularly showing the setting up of Mediterranean climate conditions. Multiproxy evidence from core MD 90-917 provides a deeper understanding of the role of precipitation and particularly the seasonality of precipitation in mediating vegetation change in the central Mediterranean during the Holocene.

  4. Farmers perceptions on climate change in lowland and highland vegetable production centers of South Sulawesi, Indonesia

    Science.gov (United States)

    Adiyoga, W.

    2018-02-01

    A survey was carried out in South Sulawesi, Indonesia interviewing 220 vegetable farmers. It was aimed at examining the vegetable farmers’ perception of climate change and assessing the consistency of farmers’ perception with available time series meteorological data. Results suggest that meteorological data analysis is in agreement with farmers’ perception regarding faster start, longer ending, and longer duration of rainy season. Further data analysis supports the claim of most farmers who perceive the occurrence of increasing air temperature, changing or shifting of the hottest and coldest month. Most respondents also suggest that climate change has affected vegetable farm yield and profitability. Other respondents even predict that climate change may affect the quality of life of their future descendants. Meanwhile, significant number of farmers is quite optimistic that they can cope with climate change problems through adaptation strategy. However, the attitude of farmers towards climate change is mostly negative as compared to positive or neutral feeling. Informative and educational campaign should be continuously carried out to encourage farmers in developing positive attitude or positive thinking towards climate change. Positive attitude may eventually lead to constructive behavior in selecting and implementing adaptation options.

  5. Tropical climate and vegetation changes during Heinrich Event 1: a model-data comparison

    Directory of Open Access Journals (Sweden)

    D. Handiani

    2012-01-01

    Full Text Available Abrupt climate changes from 18 to 15 thousand years before present (kyr BP associated with Heinrich Event 1 (HE1 had a strong impact on vegetation patterns not only at high latitudes of the Northern Hemisphere, but also in the tropical regions around the Atlantic Ocean. To gain a better understanding of the linkage between high and low latitudes, we used the University of Victoria (UVic Earth System-Climate Model (ESCM with dynamical vegetation and land surface components to simulate four scenarios of climate-vegetation interaction: the pre-industrial era, the Last Glacial Maximum (LGM, and a Heinrich-like event with two different climate backgrounds (interglacial and glacial. We calculated mega-biomes from the plant-functional types (PFTs generated by the model to allow for a direct comparison between model results and palynological vegetation reconstructions.

    Our calculated mega-biomes for the pre-industrial period and the LGM corresponded well with biome reconstructions of the modern and LGM time slices, respectively, except that our pre-industrial simulation predicted the dominance of grassland in southern Europe and our LGM simulation resulted in more forest cover in tropical and sub-tropical South America.

    The HE1-like simulation with a glacial climate background produced sea-surface temperature patterns and enhanced inter-hemispheric thermal gradients in accordance with the "bipolar seesaw" hypothesis. We found that the cooling of the Northern Hemisphere caused a southward shift of those PFTs that are indicative of an increased desertification and a retreat of broadleaf forests in West Africa and northern South America. The mega-biomes from our HE1 simulation agreed well with paleovegetation data from tropical Africa and northern South America. Thus, according to our model-data comparison, the reconstructed vegetation changes for the tropical regions around the Atlantic Ocean were physically consistent with the remote

  6. Simulated Vegetation Response to Climate Change in California: The Importance of Seasonal Production Patterns

    Science.gov (United States)

    Kim, J. B.; Pitts, B.

    2013-12-01

    MC1 dynamic global vegetation model simulates vegetation response to climate change by simulating vegetation production, soil biogeochemistry, plant biogeography and fire. It has been applied at a wide range of spatial scales, yet the spatio-temporal patterns of simulated vegetation production, which drives the model's response to climate change, has not been examined in detail. We ran MC1 for California at a relatively fine scale, 30 arc-seconds, for the historical period (1895-2006) and for the future (2007-2100), using downscaled data from four CMIP3-based climate projections: A2 and B1 GHG emissions scenarios simulated by PCM and GFDL GCMs. The use of these four climate projections aligns our work with a body of climate change research work commissioned by the California Public Interest Energy Research (PIER) Program. The four climate projections vary not only in terms of changes in their annual means, but in the seasonality of projected climate change. We calibrated MC1 using MODIS NPP data for 2000-2011 as a guide, and adapting a published technique for adjusting simulated vegetation production by increasing the simulated plant rooting depths. We evaluated the simulation results by comparing the model output for the historical period with several benchmark datasets, summarizing by EPA Level 3 Ecoregions. Multi-year summary statistics of model predictions compare moderately well with Kuchler's potential natural vegetation map, National Biomass and Carbon Dataset, Leenhouts' compilation of fire return intervals, and, of course, the MODIS NPP data for 2000-2011. When we compared MC1's monthly NPP values with MODIS monthly GPP data (2000-2011), however, the seasonal patterns compared very poorly, with NPP/GPP ratio for spring (Mar-Apr-May) often exceeding 1, and the NPP/GPP ratio for summer (Jun-Jul-Aug) often flattening to zero. This suggests MC1's vegetation production algorithms are overly biased for spring production at the cost of summer production. We

  7. Consequences of changes in vegetation and snow cover for climate feedbacks in Alaska and northwest Canada

    Science.gov (United States)

    Euskirchen, Eugénie S.; Bennett, A. P.; Breen, Amy L.; Genet, Helene; Lindgren, Michael A.; Kurkowski, Tom; McGuire, A. David; Rupp, T. Scott

    2016-01-01

    Changes in vegetation and snow cover may lead to feedbacks to climate through changes in surface albedo and energy fluxes between the land and atmosphere. In addition to these biogeophysical feedbacks, biogeochemical feedbacks associated with changes in carbon (C) storage in the vegetation and soils may also influence climate. Here, using a transient biogeographic model (ALFRESCO) and an ecosystem model (DOS-TEM), we quantified the biogeophysical feedbacks due to changes in vegetation and snow cover across continuous permafrost to non-permafrost ecosystems in Alaska and northwest Canada. We also computed the changes in carbon storage in this region to provide a general assessment of the direction of the biogeochemical feedback. We considered four ecoregions, or Landscape Conservations Cooperatives (LCCs; including the Arctic, North Pacific, Western Alaska, and Northwest Boreal). We examined the 90 year period from 2010 to 2099 using one future emission scenario (A1B), under outputs from two general circulation models (MPI-ECHAM5 and CCCMA-CGCM3.1). We found that changes in snow cover duration, including both the timing of snowmelt in the spring and snow return in the fall, provided the dominant positive biogeophysical feedback to climate across all LCCs, and was greater for the ECHAM (+3.1 W m−2 decade−1regionally) compared to the CCCMA (+1.3 W m−2 decade−1 regionally) scenario due to an increase in loss of snow cover in the ECHAM scenario. The greatest overall negative feedback to climate from changes in vegetation cover was due to fire in spruce forests in the Northwest Boreal LCC and fire in shrub tundra in the Western LCC (−0.2 to −0.3 W m−2 decade−1). With the larger positive feedbacks associated with reductions in snow cover compared to the smaller negative feedbacks associated with shifts in vegetation, the feedback to climate warming was positive (total feedback of +2.7 W m−2decade regionally in the ECHAM scenario compared to +0.76 W

  8. Relationship between climate conditions and nosocomial infection ...

    African Journals Online (AJOL)

    EB

    Conclusion: To decrease NIRs and improve health care quality, it is necessary to strengthen the control of ... level, etc.) and environmental factors (climatic ... those in developing countries the wards are generally ... Therefore, effects of ambient.

  9. 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. © 2011 Blackwell Publishing Ltd/CNRS.

  10. Holocene vegetation, fire and climate interactions on the westernmost fringe of the Mediterranean Basin

    Science.gov (United States)

    Morales-Molino, César; García-Antón, Mercedes; Postigo-Mijarra, José M.; Morla, Carlos

    2013-01-01

    A new palaeoecological sequence from the western Iberian Central Range significantly contributes to the knowledge on the Holocene vegetation dynamics in central Iberia. This sequence supports the existence of time-transgressive changes in the vegetation cover during the beginning of the Holocene over these central Iberian mountains, specifically the replacement of boreal birch-pine forests with Mediterranean communities. Anthracological analyses also indicate the replacement of boreal pines (Pinus sylvestris) with Mediterranean ones (Pinus pinaster) during the early Holocene. The observed vegetation changes were generally synchronous with climatic phases previously reconstructed for the western Mediterranean region, and they suggest that the climatic trends were most similar to those recorded in the northern Mediterranean region and central Europe. Several cycles of secondary succession after fire ending with the recovery of mature forest have been identified, which demonstrates that the vegetation of western Iberia was highly resilient to fire disturbance. However, when the recurrence of fire crossed a certain threshold, the original forests were not able to completely recover and shrublands and grasslands became dominant; this occurred approximately 5800-5400 cal yr BP. Afterwards, heathlands established as the dominant vegetation, which were maintained by frequent and severe wildfires most likely associated with human activities in a climatic framework that was less suitable for temperate trees. Finally, our palaeoecological record provides guidelines on how to manage protected areas in Mediterranean mountains of southwestern Europe, especially regarding the conservation and restoration of temperate communities that are threatened there such as birch stands.

  11. Simulated climate change impact on summer dissolved organic carbon release from peat and surface vegetation: implications for drinking water treatment.

    Science.gov (United States)

    Ritson, Jonathan P; Bell, Michael; Graham, Nigel J D; Templeton, Michael R; Brazier, Richard E; Verhoef, Anne; Freeman, Chris; Clark, Joanna M

    2014-12-15

    Uncertainty regarding changes in dissolved organic carbon (DOC) quantity and quality has created interest in managing peatlands for their ecosystem services such as drinking water provision. The evidence base for such interventions is, however, sometimes contradictory. We performed a laboratory climate manipulation using a factorial design on two dominant peatland vegetation types (Calluna vulgaris and Sphagnum Spp.) and a peat soil collected from a drinking water catchment in Exmoor National Park, UK. Temperature and rainfall were set to represent baseline and future conditions under the UKCP09 2080s high emissions scenario for July and August. DOC leachate then underwent standard water treatment of coagulation/flocculation before chlorination. C. vulgaris leached more DOC than Sphagnum Spp. (7.17 versus 3.00 mg g(-1)) with higher specific ultraviolet (SUVA) values and a greater sensitivity to climate, leaching more DOC under simulated future conditions. The peat soil leached less DOC (0.37 mg g(-1)) than the vegetation and was less sensitive to climate. Differences in coagulation removal efficiency between the DOC sources appears to be driven by relative solubilisation of protein-like DOC, observed through the fluorescence peak C/T. Post-coagulation only differences between vegetation types were detected for the regulated disinfection by-products (DBPs), suggesting climate change influence at this scale can be removed via coagulation. Our results suggest current biodiversity restoration programmes to encourage Sphagnum Spp. will result in lower DOC concentrations and SUVA values, particularly with warmer and drier summers. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Climate Change, Glacier Response, and Vegetation Dynamics in the Himalaya: Contributions Toward Future Earth Initiatives

    Directory of Open Access Journals (Sweden)

    Joseph Shea

    2017-08-01

    Full Text Available Reviewed: Climate Change, Glacier Response, and Vegetation Dynamics in the Himalaya: Contributions Toward Future Earth Initiatives. Edited by R. B. Singh, Udo Schickhoff, and Suraj Mal. Cham, Switzerland: Springer, 2016. xvi + 399 pp. Hardcover: US$ 179.00, ISBN 978-3-319-28975-5. E-book: US$ 139.00, ISBN 978-3-319-28977-9.

  13. Global patterns in the vulnerability of ecosystems to vegetation shifts due to climate change

    Science.gov (United States)

    Patrick Gonzalez; Ronald P. Neilson; James M. Lenihan; Raymond J. Drapek

    2010-01-01

    Climate change threatens to shift vegetation, disrupting ecosystems and damaging human well-being. Field observations in boreal, temperate and tropical ecosystems have detected biome changes in the 20th century, yet a lack of spatial data on vulnerability hinders organizations that manage natural resources from identifying priority areas for adaptation measures. We...

  14. Impacts of climate change on the microbial safety of pre-harvest leafy green vegetables as indicated by Escherichia coli O157 and Salmonella spp.

    NARCIS (Netherlands)

    Liu, C.; Hofstra, N.; Franz, E.

    2013-01-01

    The likelihood of leafy green vegetable (LGV) contamination and the associated pathogen growth and survival are strongly related to climatic conditions. Particularly temperature increase and precipitation pattern changes have a close relationship not only with the fate and transport of enteric

  15. Using management to address vegetation stress related to land-use and climate change

    Science.gov (United States)

    Middleton, Beth A.; Boudell, Jere; Fisichelli, Nicholas

    2017-01-01

    While disturbances such as fire, cutting, and grazing can be an important part of the conservation of natural lands, some adjustments to management designed to mimic natural disturbance may be necessary with ongoing and projected climate change. Stressed vegetation that is incapable of regeneration will be difficult to maintain if adults are experiencing mortality, and/or if their early life-history stages depend on disturbance. A variety of active management strategies employing disturbance are suggested, including resisting, accommodating, or directing vegetation change by manipulating management intensity and frequency. Particularly if land-use change is the main cause of vegetation stress, amelioration of these problems using management may help vegetation resist change (e.g. strategic timing of water release if a water control structure is available). Managers could direct succession by using management to push vegetation toward a new state. Despite the historical effects of management, some vegetation change will not be controllable as climates shift, and managers may have to accept some of these changes. Nevertheless, proactive measures may help managers achieve important conservation goals in the future.

  16. Vegetation dynamic characteristics and its responses to climate change in Jinghe River watershed of Loess Plateau, China

    Science.gov (United States)

    Chang, F.; Liu, W.; Zhou, H.; Ning, T.; Wang, Y.

    2017-12-01

    The Jinghe River is a second-order tributary of the Yellow River, and located in the middle-south part of the Loess Plateau. The watershed area is 45421km², with the mean annual precipitation (P) being about 508mm and aridity index 2.09. For a long time, soil and water loss in this watershed is severe, resulting in very fragile ecological environment. The GIMMS-normalized vegetation index NDVI is used to reflect condition of vegetation cover, and P and Penman potential evapotranspiration (ET) to represent climate water and heat conditions. The annual actual ET is estimated as the difference between P and runoff (ignoring the change of watershed water storage during each hydrological year, May to April of the following year). These concepts were introduced to discuss the dynamic characteristics of vegetation cover and its response to climate change. Results showed that the mean annual NDVI value was 0.51, showing a stable increasing trend from 2000 with an annual increasing rate of 8.7×10¯³. This result is consistent with the implementation of the project that converts farmland to forests and grassland and has achieved remarkable success in the Loess Plateau since 1999. It also indicates that the positive impact of human activity has been strengthened under the background of climate change. From 1982 to 2012, the annual actual ET was 464mm, accounting for 93.6% of annual P over the same period. The NDVI value of main growing season (5-9 months) is significantly correlated with annual P and annual humid index (ratio of annual P to annual potential ET). Vegetation water consumption is the main part of land surface ET, and the relationship between annual actual ET and NDVI value over the same period is also significant. The NDVI value, P and potential ET variation varied substantially within the Jinghe River watershed, and their relationships in different regions at an inter-annual scale are different. Currently, we are investigating the influence of the changes in

  17. Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi; Notaro, Michael; Liu, Zhengyu; Gallimore, Robert; Levis, Samuel; Kutzbach, John E.

    2008-03-31

    Using two climate-vegetation model simulations from the Fast Ocean Atmosphere Model (FOAM) and the Community Climate System Model (CCSM, version 2), we investigate vegetation-precipitation feedbacks across North Africa during the mid-Holocene. From mid-Holocene snapshot runs of FOAM and CCSM2, we detect a negative feedback at the annual timescale with our statistical analysis. Using the Monte- Carlo bootstrap method, the annual negative feedback is further confirmed to be significant in both simulations. Additional analysis shows that this negative interaction is partially caused by the competition between evaporation and transpiration in North African grasslands. Furthermore, we find the feedbacks decrease with increasing timescales, and change signs from positive to negative at increasing timescales in FOAM. The proposed mechanism for this sign switch is associated with the different persistent timescales of upper and lower soil water contents, and their interactions with vegetation and atmospheric precipitation.

  18. The consequences of pleistocene climate change on lowland neotropical vegetation

    Energy Technology Data Exchange (ETDEWEB)

    De Oliveira, P.E.; Colinvaux, P.A. (Smithsonian Tropical Research Institute, Panama City (Panama))

    1994-06-01

    Palynological reconstructions indicate that lowland tropical America was subject to intense cooling during the last ice-age. The descent of presently montane taxa into the lowlands of Amazonia and Minas Gerais indicate temperature depressions ranging from 5[degrees]C to 9[degrees]C cooler-than-present. The strengthened incursion of southerly airmasses caused a reassortment of vegetation throughout Amazonia. Presently allopatric species are found to have been sympatric as novel forest assemblages and formed and dissolved. Modest drying, perhaps a 20% reduction in precipitation, accounts for all the records that show a Pleistocene expansion of savanna. No evidence is found to support the fragmentation of Amazonian forests during glacial times, and the hypothesis of forest refuges as an explanation of tropical speciation is rejected on empirical grounds.

  19. Holocene vegetation and climate change on the Haanja heights, South-East Estonia

    International Nuclear Information System (INIS)

    Saarse, Leili; Rajamaee, Raivo

    1997-01-01

    The development of forests on the Haanja Heights has been controlled by external factors, including climate, soils, hydrology, and human impact. The sediment sequence from Lake Kirikumaee, which covers about 12 000 years, records the vegetation history throughout the Late Glacial and Holocene. In the Alleroed, woodland tundra with sparse birch and willow was established. Grass-shrub tundra in the Younger Dryas was replaced by birch forest in the Pre-Boreal. During the Holocene two major shifts in vegetation dynamics occurred: the first about 8500 BP with a sharp decline in Betula-Pinus forest and development of broad-leaved forest, and the second about 3500 BP, with a decline in broad-leaved forest and regeneration of Pinus-Betula forest with a high share of Picea. The climate modelling, based on pollen record and lake-level changes, suggest cold, severe climate with low precipitation values in the early Pre-Boreal. Between 9500-8500 BP the climate was rather stable. The lake level first rose, then stabilized, and finally dropped. The sharp climate amelioration in the late Boreal together with the humidity increase resulted in a lake-level rise. The decreased precipitation and rather high summer temperatures, increased evapotranspiration, and reduced water balance are characteristic of the Sub-Boreal. Since 3500 BP, the climate deteriorated and mixed coniferous forest started to dominate. Several small climatic fluctuations, including the Little Ice Age cooling, have been traced by modelling. (author)

  20. The role of climate change in regulating Arctic permafrost peatland hydrological and vegetation change over the last millennium

    Science.gov (United States)

    Zhang, Hui; Piilo, Sanna R.; Amesbury, Matthew J.; Charman, Dan J.; Gallego-Sala, Angela V.; Väliranta, Minna M.

    2018-02-01

    Climate warming has inevitable impacts on the vegetation and hydrological dynamics of high-latitude permafrost peatlands. These impacts in turn determine the role of these peatlands in the global biogeochemical cycle. Here, we used six active layer peat cores from four permafrost peatlands in Northeast European Russia and Finnish Lapland to investigate permafrost peatland dynamics over the last millennium. Testate amoeba and plant macrofossils were used as proxies for hydrological and vegetation changes. Our results show that during the Medieval Climate Anomaly (MCA), Russian sites experienced short-term permafrost thawing and this induced alternating dry-wet habitat changes eventually followed by desiccation. During the Little Ice Age (LIA) both sites generally supported dry-hummock habitats, at least partly driven by permafrost aggradation. However, proxy data suggest that occasionally, MCA habitat conditions were drier than during the LIA, implying that evapotranspiration may create important additional eco-hydrological feedback mechanisms under warm conditions. All sites showed a tendency towards dry conditions as inferred from both proxies starting either from ca. 100 years ago or in the past few decades after slight permafrost thawing, suggesting that recent warming has stimulated surface desiccation rather than deeper permafrost thawing. This study shows links between two important controls over hydrology and vegetation changes in high-latitude peatlands: direct temperature-induced surface layer response and deeper permafrost layer-related dynamics. These data provide important backgrounds for predictions of Arctic permafrost peatlands and related feedback mechanisms. Our results highlight the importance of increased evapotranspiration and thus provide an additional perspective to understanding of peatland-climate feedback mechanisms.

  1. Evidence of climatic effects on soil, vegetation and landform in temperate forests of south-eastern Australia

    Science.gov (United States)

    Inbar, Assaf; Nyman, Petter; Lane, Patrick; Sheridan, Gary

    2016-04-01

    Water and radiation are unevenly distributed across the landscape due to variations in topography, which in turn causes water availability differences on the terrain according to elevation and aspect orientation. These differences in water availability can cause differential distribution of vegetation types and indirectly influence the development of soil and even landform, as expressed in hillslope asymmetry. While most of the research on the effects of climate on the vegetation and soil development and landscape evolution has been concentrated in drier semi-arid areas, temperate forested areas has been poorly studied, particularly in South Eastern Australia. This study uses soil profile descriptions and data on soil depth and landform across climatic gradients to explore the degrees to which coevolution of vegetation, soils and landform are controlled by radiative forcing and rainfall. Soil depth measurements were made on polar and equatorial facing hillslopes located at 3 sites along a climatic gradient (mean annual rainfall between 700 - 1800 mm yr-1) in the Victorian Highlands, where forest types range from dry open woodland to closed temperate rainforest. Profile descriptions were taken from soil pits dag on planar hillslopes (50 m from ridge), and samples were taken from each horizon for physical and chemical properties analysis. Hillslope asymmetry in different precipitation regimes of the study region was quantified from Digital Elevation Models (DEMs). Significant vegetation differences between aspects were noted in lower and intermediate rainfall sites, where polar facing aspects expressed higher overall biomass than the drier equatorial slope. Within the study domain, soil depth was strongly correlated with forest type and above ground biomass. Soil depths and chemical properties varied between topographic aspects and along the precipitation gradient, where wetter conditions facilitate deeper and more weathered soils. Furthermore, soil depths showed

  2. Vegetation and Climate Change during the Last Deglaciation in the Great Khingan Mountain, Northeastern China.

    Science.gov (United States)

    Wu, Jing; Liu, Qiang; Wang, Luo; Chu, Guo-qiang; Liu, Jia-qi

    2016-01-01

    The Great Khingan Mountain range, Northeast China, is located on the northern limit of modern East Asian Summer Monsoon (EASM) and thus highly sensitive to the extension of the EASM from glacial to interglacial modes. Here, we present a high-resolution pollen record covering the last glacial maximum and the early Holocene from a closed crater Lake Moon to reconstruct vegetation history during the glacial-interglacial transition and thus register the evolution of the EASM during the last deglaciation. The vegetation history has gone through distinct changes from subalpine meadow in the last glacial maximum to dry steppe dominated by Artemisia from 20.3 to 17.4 ka BP, subalpine meadow dominated by Cyperaceae and Artemisia between 17.4 and 14.4 ka BP, and forest steppe dominated by Betula and Artemisia after 14.4 ka BP. The pollen-based temperature index demonstrates a gradual warming trend started at around 20.3 ka BP with interruptions of several brief events. Two cold conditions occurred around at 17.2-16.6 ka BP and 12.8-11.8 ka BP, temporally correlating to the Henrich 1 and the Younger Dryas events respectively, 1and abrupt warming events occurred around at 14.4 ka BP and 11.8 ka BP, probably relevant to the beginning of the Bølling-Allerød stages and the Holocene. The pollen-based moisture proxy shows distinct drought condition during the last glacial maximum (20.3-18.0 ka BP) and the Younger Dryas. The climate history based on pollen record of Lake Moon suggests that the regional temperature variability was coherent with the classical climate in the North Atlantic, implying the dominance of the high latitude processes on the EASM evolution from the Last Glacial Maximum (LGM) to early Holocene. The local humidity variability was influenced by the EASM limitedly before the Bølling-Allerød warming, which is mainly controlled by the summer rainfall due to the EASM front covering the Northeast China after that.

  3. Vegetation and Climate Change during the Last Deglaciation in the Great Khingan Mountain, Northeastern China.

    Directory of Open Access Journals (Sweden)

    Jing Wu

    Full Text Available The Great Khingan Mountain range, Northeast China, is located on the northern limit of modern East Asian Summer Monsoon (EASM and thus highly sensitive to the extension of the EASM from glacial to interglacial modes. Here, we present a high-resolution pollen record covering the last glacial maximum and the early Holocene from a closed crater Lake Moon to reconstruct vegetation history during the glacial-interglacial transition and thus register the evolution of the EASM during the last deglaciation. The vegetation history has gone through distinct changes from subalpine meadow in the last glacial maximum to dry steppe dominated by Artemisia from 20.3 to 17.4 ka BP, subalpine meadow dominated by Cyperaceae and Artemisia between 17.4 and 14.4 ka BP, and forest steppe dominated by Betula and Artemisia after 14.4 ka BP. The pollen-based temperature index demonstrates a gradual warming trend started at around 20.3 ka BP with interruptions of several brief events. Two cold conditions occurred around at 17.2-16.6 ka BP and 12.8-11.8 ka BP, temporally correlating to the Henrich 1 and the Younger Dryas events respectively, 1and abrupt warming events occurred around at 14.4 ka BP and 11.8 ka BP, probably relevant to the beginning of the Bølling-Allerød stages and the Holocene. The pollen-based moisture proxy shows distinct drought condition during the last glacial maximum (20.3-18.0 ka BP and the Younger Dryas. The climate history based on pollen record of Lake Moon suggests that the regional temperature variability was coherent with the classical climate in the North Atlantic, implying the dominance of the high latitude processes on the EASM evolution from the Last Glacial Maximum (LGM to early Holocene. The local humidity variability was influenced by the EASM limitedly before the Bølling-Allerød warming, which is mainly controlled by the summer rainfall due to the EASM front covering the Northeast China after that.

  4. Changes in vegetation in northern Alaska under scenarios of climate change, 2003-2100: implications for climate feedbacks

    Science.gov (United States)

    Euskirchen, Eugénie S.; McGuire, Anthony David; Chapin, F. Stuart; Yi, S.; Thompson, Catharine Copass

    2009-01-01

    Assessing potential future changes in arctic and boreal plant species productivity, ecosystem composition, and canopy complexity is essential for understanding environmental responses under expected altered climate forcing. We examined potential changes in the dominant plant functional types (PFTs) of the sedge tundra, shrub tundra, and boreal forest ecosystems in ecotonal northern Alaska, USA, for the years 2003–2100. We compared energy feedbacks associated with increases in biomass to energy feedbacks associated with changes in the duration of the snow-free season. We based our simulations on nine input climate scenarios from the Intergovernmental Panel on Climate Change (IPCC) and a new version of the Terrestrial Ecosystem Model (TEM) that incorporates biogeochemistry, vegetation dynamics for multiple PFTs (e.g., trees, shrubs, grasses, sedges, mosses), multiple vegetation pools, and soil thermal regimes. We found mean increases in net primary productivity (NPP) in all PFTs. Most notably, birch (Betula spp.) in the shrub tundra showed increases that were at least three times larger than any other PFT. Increases in NPP were positively related to increases in growing-season length in the sedge tundra, but PFTs in boreal forest and shrub tundra showed a significant response to changes in light availability as well as growing-season length. Significant NPP responses to changes in vegetation uptake of nitrogen by PFT indicated that some PFTs were better competitors for nitrogen than other PFTs. While NPP increased, heterotrophic respiration (RH) also increased, resulting in decreases or no change in net ecosystem carbon uptake. Greater aboveground biomass from increased NPP produced a decrease in summer albedo, greater regional heat absorption (0.34 ± 0.23 W·m−2·10 yr−1 [mean ± SD]), and a positive feedback to climate warming. However, the decrease in albedo due to a shorter snow season (−5.1 ± 1.6 d/10 yr) resulted in much greater regional heat

  5. Emergent properties of climate-vegetation feedbacks in the North American Monsoon Macrosystem

    Science.gov (United States)

    Mathias, A.; Niu, G.; Zeng, X.

    2012-12-01

    The ability of ecosystems to adapt naturally to climate change and associated disturbances (e.g. wildfires, spread of invasive species) is greatly affected by the stability of feedback interactions between climate and vegetation. In order to study climate-vegetation interactions, such as CO2 and H2O exchange in the North American Monsoon System (NAMS), we plan to couple a community land surface model (NoahMP or CLM) used in regional climate models (WRF) with an individual based, spatially explicit vegetation model (ECOTONE). Individual based modeling makes it possible to link individual plant traits with properties of plant communities. Community properties, such as species composition and species distribution arise from dynamic interactions of individual plants with each other, and with their environment. Plants interact with each other through intra- and interspecific competition for resources (H2O, nitrogen), and the outcome of these interactions depends on the properties of the plant community and the environment itself. In turn, the environment is affected by the resulting change in community structure, which may have an impact on the drivers of climate change. First, we performed sensitivity tests of ECOTONE to assess its ability to reproduce vegetation distribution in the NAMS. We compared the land surface model and ECOTONE with regard to their capability to accurately simulate soil moisture, CO2 flux and above ground biomass. For evaluating the models we used the eddy-correlation sensible and latent heat fluxes, CO2 flux and observations of other climate and environmental variables (e.g. soil temperature and moisture) from the Santa Rita experimental range. The model intercomparison helped us understand the advantages and disadvantages of each model, providing us guidance for coupling the community land surface model (NoahMP or CLM) with ECOTONE.

  6. Assessing the vegetation condition impacts of the 2011 drought across the U.S. southern Great Plains using the vegetation drought response index (VegDRI)

    Science.gov (United States)

    Tadesse, Tsegaye; Wardlow, Brian D.; Brown, Jesslyn F.; Svoboda, Mark; Hayes, Michael; Fuchs, Brian; Gutzmer, Denise

    2015-01-01

    The vegetation drought response index (VegDRI), which combines traditional climate- and satellite-based approaches for assessing vegetation conditions, offers new insights into assessing the impacts of drought from local to regional scales. In 2011, the U.S. southern Great Plains, which includes Texas, Oklahoma, and New Mexico, was plagued by moderate to extreme drought that was intensified by an extended period of record-breaking heat. The 2011 drought presented an ideal case study to evaluate the performance of VegDRI in characterizing developing drought conditions. Assessment of the spatiotemporal drought patterns represented in the VegDRI maps showed that the severity and patterns of the drought across the region corresponded well to the record warm temperatures and much-below-normal precipitation reported by the National Climatic Data Center and the sectoral drought impacts documented by the Drought Impact Reporter (DIR). VegDRI values and maps also showed the evolution of the drought signal before the Las Conchas Fire (the largest fire in New Mexico’s history). Reports in the DIR indicated that the 2011 drought had major adverse impacts on most rangeland and pastures in Texas and Oklahoma, resulting in total direct losses of more than $12 billion associated with crop, livestock, and timber production. These severe impacts on vegetation were depicted by the VegDRI at subcounty, state, and regional levels. This study indicates that the VegDRI maps can be used with traditional drought indicators and other in situ measures to help producers and government officials with various management decisions, such as justifying disaster assistance, assessing fire risk, and identifying locations to move livestock for grazing.

  7. Relationship between climate conditions and nosocomial infection ...

    African Journals Online (AJOL)

    Background: Nosocomial infections constitute a global health problem. Objective: To explore the relationship between nosocomial infection rates (NIRs) and climatic factors including temperature and relative humidity in Guangzhou area of China. Methods: 30892 patients in our hospital in 2009 were investigated for ...

  8. Disaggregating Tropical Disease Prevalence by Climatic and Vegetative Zones within Tropical West Africa.

    Science.gov (United States)

    Beckley, Carl S; Shaban, Salisu; Palmer, Guy H; Hudak, Andrew T; Noh, Susan M; Futse, James E

    2016-01-01

    Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly infer that tropical diseases are uniformly prevalent has been partially overcome with solid epidemiologic data. This finer resolution data is important in multiple contexts, including understanding risk, predictive value in disease diagnosis, and population immunity. We hypothesized that within the context of a tropical climate, vector-borne pathogen prevalence would significantly differ according to zonal differences in rainfall, temperature, relative humidity and vegetation condition. We then determined if these environmental data were predictive of pathogen prevalence. First we determined the prevalence of three major pathogens of cattle, Anaplasma marginale, Babesia bigemina and Theileria spp, in the three vegetation zones where cattle are predominantly raised in Ghana: Guinea savannah, semi-deciduous forest, and coastal savannah. The prevalence of A. marginale was 63%, 26% for Theileria spp and 2% for B. bigemina. A. marginale and Theileria spp. were significantly more prevalent in the coastal savannah as compared to either the Guinea savanna or the semi-deciduous forest, supporting acceptance of the first hypothesis. To test the predictive power of environmental variables, the data over a three year period were considered in best subsets multiple linear regression models predicting prevalence of each pathogen. Corrected Akaike Information Criteria (AICc) were assigned to the alternative models to compare their utility. Competitive models for each response were averaged using AICc weights. Rainfall was most predictive of pathogen prevalence, and EVI also contributed to A. marginale and B. bigemina prevalence

  9. Disaggregating Tropical Disease Prevalence by Climatic and Vegetative Zones within Tropical West Africa.

    Directory of Open Access Journals (Sweden)

    Carl S Beckley

    Full Text Available Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly infer that tropical diseases are uniformly prevalent has been partially overcome with solid epidemiologic data. This finer resolution data is important in multiple contexts, including understanding risk, predictive value in disease diagnosis, and population immunity. We hypothesized that within the context of a tropical climate, vector-borne pathogen prevalence would significantly differ according to zonal differences in rainfall, temperature, relative humidity and vegetation condition. We then determined if these environmental data were predictive of pathogen prevalence. First we determined the prevalence of three major pathogens of cattle, Anaplasma marginale, Babesia bigemina and Theileria spp, in the three vegetation zones where cattle are predominantly raised in Ghana: Guinea savannah, semi-deciduous forest, and coastal savannah. The prevalence of A. marginale was 63%, 26% for Theileria spp and 2% for B. bigemina. A. marginale and Theileria spp. were significantly more prevalent in the coastal savannah as compared to either the Guinea savanna or the semi-deciduous forest, supporting acceptance of the first hypothesis. To test the predictive power of environmental variables, the data over a three year period were considered in best subsets multiple linear regression models predicting prevalence of each pathogen. Corrected Akaike Information Criteria (AICc were assigned to the alternative models to compare their utility. Competitive models for each response were averaged using AICc weights. Rainfall was most predictive of pathogen prevalence, and EVI also contributed to A. marginale and B

  10. Climate and vegetation changes during the Lateglacial and early–middle Holocene at Lake Ledro (southern Alps, Italy

    Directory of Open Access Journals (Sweden)

    S. Joannin

    2013-04-01

    Full Text Available Adding to the on-going debate regarding vegetation recolonisation (more particularly the timing in Europe and climate change since the Lateglacial, this study investigates a long sediment core (LL081 from Lake Ledro (652 m a.s.l., southern Alps, Italy. Environmental changes were reconstructed using multiproxy analysis (pollen-based vegetation and climate reconstruction, lake levels, magnetic susceptibility and X-ray fluorescence (XRF measurements recorded climate and land-use changes during the Lateglacial and early–middle Holocene. The well-dated and high-resolution pollen record of Lake Ledro is compared with vegetation records from the southern and northern Alps to trace the history of tree species distribution. An altitude-dependent progressive time delay of the first continuous occurrence of Abies (fir and of the Larix (larch development has been observed since the Lateglacial in the southern Alps. This pattern suggests that the mid-altitude Lake Ledro area was not a refuge and that trees originated from lowlands or hilly areas (e.g. Euganean Hills in northern Italy. Preboreal oscillations (ca. 11 000 cal BP, Boreal oscillations (ca. 10 200, 9300 cal BP and the 8.2 kyr cold event suggest a centennial-scale climate forcing in the studied area. Picea (spruce expansion occurred preferentially around 10 200 and 8200 cal BP in the south-eastern Alps, and therefore reflects the long-lasting cumulative effects of successive boreal and the 8.2 kyr cold event. The extension of Abies is contemporaneous with the 8.2 kyr event, but its development in the southern Alps benefits from the wettest interval 8200–7300 cal BP evidenced in high lake levels, flood activity and pollen-based climate reconstructions. Since ca. 7500 cal BP, a weak signal of pollen-based anthropogenic activities suggest weak human impact. The period between ca. 5700 and ca. 4100 cal BP is considered as a transition period to colder and wetter conditions (particularly during

  11. Isotope techniques in studies of paleontology environmental reconstruction (vegetation and climate) in the delayed quaternario of two Brazilian regions

    International Nuclear Information System (INIS)

    Gouveia, Susy E.M.; Pessenda, Luiz C.R.; Freitas, Hermes A.; Silva, Vanessa F.; Pellegrinotti, Thais C.; Aravena, Ramon; Scheel-Ybert, Rita; Bendassolli, Jose A.

    2000-01-01

    This paper presents an attempt to reconstruct vegetation and climate changes in the central region of the state of Sao Paulo (Jaguariuna) and west of the state of Mato Grosso (Pontes e Lacerda) during the last 12,000 years BP, based on δ 13 C values of soil organic matter (SOM), 14 C dating and botanical identification of buried charcoal in the soil profiles. Sampling site in Sao Paulo was located under natural vegetation ('cerradao'), along the slope of small hills and in the top of slope under the semi-deciduous forest in Mato Grosso. Charcoal was found predominantly between 150 and 50 cm depth, indicating a period of greater frequency of fires in these regions, between 6,000 and 3,000 years BP. More enriched values of δ 13 C of SOM (predominance of C 4 plants) were observed from approximately 12,000 to 7,000 years BP in Jaguariuna, indicating drier climate when compared with nowadays conditions. The charcoal analyses indicated the predominance of cerrado species. In Pontes e Lacerda site, the δ 13 C profile suggests the presence of C 3 vegetation (forest) during the last 10,000 years and the most of identified charcoal fragments indicated the presence of semi-deciduous forest as well as cerrado species. (author)

  12. Vegetation greenness trend (2000 to 2009) and the climate controls in the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Zhang, Li; Guo, Huadong; Ji, Lei; Lei, Liping; Wang, Cuizhen; Yan, Dongmei; Li, Bin; Li, Jing

    2013-01-01

    The Qinghai-Tibetan Plateau has been experiencing a distinct warming trend, and climate warming has a direct and quick impact on the alpine grassland ecosystem. We detected the greenness trend of the grasslands in the plateau using Moderate Resolution Imaging Spectroradiometer data from 2000 to 2009. Weather station data were used to explore the climatic drivers for vegetation greenness variations. The results demonstrated that the region-wide averaged normalized difference vegetation index (NDVI) increased at a rate of 0.036  yr−1. Approximately 20% of the vegetation areas, which were primarily located in the northeastern plateau, exhibited significant NDVI increase trend (p-value plateau. A strong positive relationship between NDVI and precipitation, especially in the northeastern plateau, suggested that precipitation was a favorable factor for the grassland NDVI. Negative correlations between NDVI and temperature, especially in the southern plateau, indicated that higher temperature adversely affected the grassland growth. Although a warming climate was expected to be beneficial to the vegetation growth in cold regions, the grasslands in the central and southwestern plateau showed a decrease in trends influenced by increased temperature coupled with decreased precipitation.

  13. Groundwater recharge - climatic and vegetation induced variations. Simulations in the Emaan and Aespoe areas in southern Sweden

    International Nuclear Information System (INIS)

    Losjoe, K.; Johansson, Barbro; Bringfelt, B.; Oleskog, I.; Bergstroem, S.

    1999-01-01

    Climate change and man-made interference will cause an impact on runoff and groundwater recharge in the future. With the aim to give a conception of seasonal variations and the magnitude of the differences, the HBV model has been used as a tool for simulating five climate alternatives in two areas of south-east Sweden. The climate alternatives include both increased and decreased temperature and precipitation. These are not predictions of a future climate change, and should only be regarded as examples. The purpose has been to exemplify a conceivable magnitude of change during temperate/boreal conditions. It has not been within the scope of this report to evaluate the most probable climate change scenarios. The impacts of different climate scenarios on the total groundwater recharge and the deep groundwater recharge have been calculated as long-term mean values and are presented in comparison with model-simulated values with an actual (recorded) climate sequence. The results show great differences between the climate alternatives. An increase in temperature will decrease snow accumulation and increase the evapotranspiration and can totally extinguish the spring snowmelt peak in runoff and groundwater recharge. A decreased temperature, on the contrary, will imply decreased winter runoff and recharge values and an increase in spring and summer values. Evapotranspiration and soil water content play a key role in the runoff and recharge processes. This report makes a review of some literature about work done within the areas of investigation and calculation of evapotranspiration. Research is in progress, not only on formulating future climate scenarios, but also on distinguishing evapotranspiration from different kinds of vegetation. These are complex questions, but vital ones, as a climate change will also affect the vegetation. Until new research results are presented, well-known methods can be used for simulating the effects of logging on runoff and groundwater

  14. Using MODIS-NDVI for the Modeling of Post-Wildfire Vegetation Response as a Function of Environmental Conditions and Pre-Fire Restoration Treatments

    Directory of Open Access Journals (Sweden)

    Grant M. Casady

    2012-03-01

    Full Text Available Post-fire vegetation response is influenced by the interaction of natural and anthropogenic factors such as topography, climate, vegetation type and restoration practices. Previous research has analyzed the relationship of some of these factors to vegetation response, but few have taken into account the effects of pre-fire restoration practices. We selected three wildfires that occurred in Bandelier National Monument (New Mexico, USA between 1999 and 2007 and three adjacent unburned control areas. We used interannual trends in the Normalized Difference Vegetation Index (NDVI time series data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS to assess vegetation response, which we define as the average potential photosynthetic activity through the summer monsoon. Topography, fire severity and restoration treatment were obtained and used to explain post-fire vegetation response. We applied parametric (Multiple Linear Regressions-MLR and non-parametric tests (Classification and Regression Trees-CART to analyze effects of fire severity, terrain and pre-fire restoration treatments (variable used in CART on post-fire vegetation response. MLR results showed strong relationships between vegetation response and environmental factors (p < 0.1, however the explanatory factors changed among treatments. CART results showed that beside fire severity and topography, pre-fire treatments strongly impact post-fire vegetation response. Results for these three fires show that pre-fire restoration conditions along with local environmental factors constitute key processes that modify post-fire vegetation response.

  15. Establishment and performance of an experimental green roof under extreme climatic conditions.

    Science.gov (United States)

    Klein, Petra M; Coffman, Reid

    2015-04-15

    Green roofs alter the surface energy balance and can help in mitigating urban heat islands. However, the cooling of green roofs due to evapotranspiration strongly depends on the climatic conditions, and vegetation type and density. In the Southern Central Plains of the United States, extreme weather events, such as high winds, heat waves and drought conditions pose challenges for successful implementation of green roofs, and likely alter their standard performance. The National Weather Center Experimental Green Roof, an interdisciplinary research site established in 2010 in Norman, OK, aimed to investigate the ecological performance and surface energy balance of green roof systems. Starting in May 2010, 26 months of vegetation studies were conducted and the radiation balance, air temperature, relative humidity, and buoyancy fluxes were monitored at two meteorological stations during April-October 2011. The establishment of a vegetative community trended towards prairie plant dominance. High mortality of succulents and low germination of grasses and herbaceous plants contributed to low vegetative coverage. In this condition succulent diversity declined. Bouteloua gracilis and Delosperma cooperi showed typological dominance in harsh climatic conditions, while Sedum species experienced high mortality. The plant community diversified through volunteers such as Euphorbia maculate and Portulaca maculate. Net radiation measured at a green-roof meteorological station was higher than at a control station over the original, light-colored roofing material. These findings indicate that the albedo of the green roof was lower than the albedo of the original roofing material. The low vegetative coverage during the heat and drought conditions in 2011, which resulted in the dark substrate used in the green roof containers being exposed, likely contributed to the low albedo values. Nevertheless, air temperatures and buoyancy fluxes were often lower over the green roof indicating

  16. Recent slowdown of atmospheric CO2 amplification due to vegetation-climate feedback over northern lands

    Science.gov (United States)

    Li, Z.; Xia, J.; Ahlström, A.; Rinke, A.; Koven, C.; Hayes, D. J.; Ji, D.; Zhang, G.; Krinner, G.; Chen, G.; Dong, J.; Liang, J.; Moore, J.; Jiang, L.; Yan, L.; Ciais, P.; Peng, S.; Wang, Y.; Xiao, X.; Shi, Z.; McGuire, A. D.; Luo, Y.

    2017-12-01

    The enhanced vegetation growth by climate warming plays a pivotal role in amplifying the seasonal cycle of atmospheric CO2 at northern high latitudes since 1960s1-3. It remains unclear that whether this mechanism is still robust since 1990s, because a paused vegetation growth increase4,5 and weakened temperature control on CO2 uptake6,7 have been detected during this period. Here, based on in-situ atmospheric CO2 concentration records above northern 50o N, we found a slowdown of the atmospheric CO2 amplification from the mid-1990s to mid-2000s. This phenomenon is associated with the pause of vegetation greening trend and slowdown of spring warming. We further showed that both the vegetation greenness and its growing season length are positively correlated to spring but not autumn temperature from 1982 to 2010 over the northern lands. However, the state-of-art terrestrial biosphere models produce positive responses of gross primary productivity to both spring and autumn warming. These findings emphasize the importance of vegetation-climate feedback in shaping the atmospheric CO2 seasonality, and call for an improved carbon-cycle response to non-uniform seasonal warming at high latitudes in current models.

  17. Varying responses of vegetation activity to climate changes on the Tibetan Plateau grassland.

    Science.gov (United States)

    Cong, Nan; Shen, Miaogen; Yang, Wei; Yang, Zhiyong; Zhang, Gengxin; Piao, Shilong

    2017-08-01

    Vegetation activity on the Tibetan Plateau grassland has been substantially enhanced as a result of climate change, as revealed by satellite observations of vegetation greenness (i.e., the normalized difference vegetation index, NDVI). However, little is known about the temporal variations in the relationships between NDVI and temperature and precipitation, and understanding this is essential for predicting how future climate change would affect vegetation activity. Using NDVI data and meteorological records from 1982 to 2011, we found that the inter-annual partial correlation coefficient between growing season (May-September) NDVI and temperature (R NDVI-T ) in a 15-year moving window for alpine meadow showed little change, likely caused by the increasing R NDVI-T in spring (May-June) and autumn (September) and decreasing R NDVI-T in summer (July-August). Growing season R NDVI-T for alpine steppe increased slightly, mainly due to increasing R NDVI-T in spring and autumn. The partial correlation coefficient between growing season NDVI and precipitation (R NDVI-P ) for alpine meadow increased slightly, mainly in spring and summer, and R NDVI-P for alpine steppe increased, mainly in spring. Moreover, R NDVI-T for the growing season was significantly higher in those 15-year windows with more precipitation for alpine steppe. R NDVI-P for the growing season was significantly higher in those 15-year windows with higher temperature, and this tendency was stronger for alpine meadow than for alpine steppe. These results indicate that the impact of warming on vegetation activity of Tibetan Plateau grassland is more positive (or less negative) during periods with more precipitation and that the impact of increasing precipitation is more positive (or less negative) during periods with higher temperature. Such positive effects of the interactions between temperature and precipitation indicate that the projected warmer and wetter future climate will enhance vegetation activity

  18. Effects of projected climate change on vegetation in the Blue Mountains ecoregion, USA

    Directory of Open Access Journals (Sweden)

    Becky K. Kerns

    2018-04-01

    Full Text Available We used autecological, paleoecological, and modeling information to explore the potential effects of climate change on vegetation in the Blue Mountains ecoregion, Oregon (USA. Although uncertainty exists about the exact nature of future vegetation change, we infer that the following are likely to occur by the end of the century: (1 dominance of ponderosa pine and sagebrush will increase in many locations, (2 the forest-steppe ecotone will move upward in latitude and elevation, (3 ponderosa pine will be distributed at higher elevations, (4 subalpine and alpine systems will be replaced by grass species, pine, and Douglas-fir, (5 moist forest types may increase under wetter scenarios, (6 the distribution and abundance of juniper woodlands may decrease if the frequency and extent of wildfire increase, and (7 grasslands and shrublands will increase at lower elevations. Tree growth in energy-limited landscapes (high elevations, north aspects will increase as the climate warms and snowpack decreases, whereas tree growth in water-limited landscapes (low elevations, south aspects will decrease. Ecological disturbances, including wildfire, insect outbreaks, and non-native species, which are expected to increase in a warmer climate, will affect species distribution, tree age, and vegetation structure, facilitating transitions to new combinations of species and vegetation patterns. In dry forests where fire has not occurred for several decades, crown fires may result in high tree mortality, and the interaction of multiple disturbances and stressors will probably exacerbate stress complexes. Increased disturbance will favor species with physiological and phenological traits that allow them to tolerate frequent disturbance. Keywords: Climate change, Disturbance, Vegetation, Wildfire

  19. Assessing 20th century climate-vegetation feedbacks of land-use change and natural vegetation dynamics in a fully coupled vegetation-climate model

    NARCIS (Netherlands)

    Strengers, B.J.; Müller, C.; Schaeffer, M.; Haarsma, R.J.; Severijns, C.; Gerten, D.; Schaphoff, S.; Houdt, Van den R.; Oostenrijk, R.

    2010-01-01

    This study describes the coupling of the dynamic global vegetation model (DGVM), Lund–Potsdam–Jena Model for managed land (LPJmL), with the general circulation model (GCM), Simplified Parameterizations primitivE Equation DYnamics model (SPEEDY), to study the feedbacks between land-use change and

  20. Agroclimatic conditions in Europe under climate change

    Czech Academy of Sciences Publication Activity Database

    Trnka, Miroslav; Olesen, J. E.; Kersebaum, K. C.; Skjelvag, A. O.; Eitzinger, J.; Seguin, B.; Peltonen-Sainio, P.; Rotter, R.; Iglesias, A.; Orlandini, S.; Dubrovský, Martin; Hlavinka, P.; Balek, J.; Eckersten, H.; Cloppet, E.; Calanca, P.; Vucetic, V.; Nejedlík, P.; Kumar, S.; Lalic, B.; Mestre, A.; Rossi, F.; Kozyra, J.; Alexandrov, V.; Semerádová, D.; Žalud, Z.

    2011-01-01

    Roč. 17, č. 7 (2011), s. 2298-2318 ISSN 1354-1013 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional research plan: CEZ:AV0Z60870520; CEZ:AV0Z30420517 Keywords : agroclimatic extremes * agroclimatic index * climate- change impacts * crop production * environmental zones Subject RIV: EH - Ecology, Behaviour Impact factor: 6.862, year: 2011

  1. Vegetation response to climate change : implications for Canada's conservation lands

    Energy Technology Data Exchange (ETDEWEB)

    Scott, D. [Environment Canada, Ottawa, ON (Canada). Adaptation and Impact Research Group; Lemieux, C. [Waterloo Univ., ON (Canada). Dept. of Geography

    2003-05-01

    Studies have shown that Canada's national parks are vulnerable to the impacts of climate change. A wide range of biophysical climate change impacts could affect the integrity of conservation lands in each region of Canada. This report examines the potential impact of climate change on landscape alterations and vegetation distribution in Canada's wide network of conservation lands. It also presents several ways to integrate climate change into existing conservation policy and adaptation strategies. Canada's conservation lands include provincial parks, migratory bird sanctuaries, national wildlife areas and wildlife protected areas. This is the first study to examine biome changes by applying an equilibrium Global Vegetation Model (GVM) to Canada's network of national park systems. Some of the policy and planning challenges posed by changes in landscape level vegetation were also addressed. The report indicates that in terms of potential changes to the biome classification of Canada's national forests, more northern biomes are projected to decrease. These northern biomes include the tundra, taiga and boreal conifer forests. 56 refs., 8 tabs., 6 figs.

  2. A spatio-temporal analysis of climatic drivers for observed changes in Sahelian vegetation productivity 1982-2007

    DEFF Research Database (Denmark)

    Kaspersen, Per; Fensholt, Rasmus; Huber Gharib, Silvia

    2011-01-01

    Linear trend analysis and seasonal trend analysis are performed on gridded data of vegetation, rainfall, solar radiation flux, and air temperature, in order to examine the influence of the past three decades of climate variability and change on the Sahelian vegetation dynamics. Per......-pixel correlation analyses are conducted on annual and monthly data, and analyses of change in the potential climatic constraints to the natural vegetation development from 1982–2007 are performed. The results reveal two distinct periods: (a) 1982–1994 marked by large increases in vegetation productivity...... and rainfall and little change in average air temperatures and solar radiation and (b) 1995–2007 characterized by no distinct trends in vegetation productivity and rainfall and increase in average air temperatures and decrease in solar radiation flux. Correlations between vegetation productivity and climatic...

  3. Recent shifts in Himalayan vegetation activity trends in response to climatic change and environmental drivers

    Science.gov (United States)

    Mishra, N. B.; Mainali, K. P.

    2016-12-01

    Climatic changes along with anthropogenic disturbances are causing dramatic ecological impacts in mid to high latitude mountain vegetation including in the Himalayas which are ecologically sensitive environments. Given the challenges associated with in situ vegetation monitoring in the Himalayas, remote sensing based quantification of vegetation dynamics can provide essential ecological information on changes in vegetation activity that may consist of alternative sequence of greening and/or browning periods. This study utilized a trend break analysis procedure for detection of monotonic as well as abrupt (either interruption or reversal) trend changes in smoothed normalized difference vegetation index satellite time-series data over the Himalayas. Overall, trend breaks in vegetation greenness showed high spatio-temporal variability in distribution considering elevation, ecoregion and land cover/use stratifications. Interrupted greening was spatially most dominant in all Himalayan ecoregions followed by abrupt browning. Areas showing trend reversal and monotonic trends appeared minority. Trend type distribution was strongly dependent on elevation as majority of greening (with or without interruption) occurred at lower elevation areas at higher elevation were dominantly. Ecoregion based stratification of trend types highlighted some exception to this elevational dependence as high altitude ecoregions of western Himalayas showed significantly less browning compared to the ecoregions in eastern Himalaya. Land cover/use based analysis of trend distribution showed that interrupted greening was most dominant in closed needleleafed forest following by rainfed cropland and mosaic croplands while interrupted browning most dominant in closed to open herbaceous vegetation found at higher elevation areas followed by closed needleleafed forest and closed to open broad leafed evergreen forests. Spatial analysis of trend break timing showed that for majority of areas experiencing

  4. A 28,000 year history of vegetation and climate from Lower Red Rock Lake, Centennial Valley, Southwestern Montana, USA

    Science.gov (United States)

    Mumma, Stephanie Ann; Whitlock, Cathy; Pierce, Kenneth

    2012-01-01

    A sediment core extending to 28,000 cal yr BP from Lower Red Rock Lake in the Centennial Valley of southwestern Montana provides new information on the nature of full-glacial vegetation as well as a history of late-glacial and Holocene vegetation and climate in a poorly studied region. Prior to 17,000 cal yr BP, the eastern Centennial Valley was occupied by a large lake (Pleistocene Lake Centennial), and valley glaciers were present in adjacent mountain ranges. The lake lowered upon erosion of a newly formed western outlet in late-glacial time. High pollen percentages of Juniperus, Poaceae, Asteraceae, and other herbs as well as low pollen accumulation rates suggest sparse vegetation cover. Inferred cold dry conditions are consistent with a strengthened glacial anticyclone at this time. Between 17,000 and 10,500 cal yr BP, high Picea and Abies pollen percentages suggest a shift to subalpine parkland and warmer conditions than before. This is attributed to the northward shift of the jet stream and increasing summer insolation. From 10,500 to 7100 cal yr BP, pollen evidence of open dry forests suggests warm conditions, which were likely a response to increased summer insolation and a strengthened Pacific subtropical high-pressure system. From 7100 to 2400 cal yr BP, cooler moister conditions promoted closed forest and wetlands. Increases in Picea and Abies pollen percentages after 2400 cal yr BP suggest increasing effective moisture. The postglacial pattern of Pseudotsuga expansion indicates that it arrived later on the Atlantic side of the Continental Divide than on the Pacific side. The Divide may have been a physical barrier for refugial populations or it delimited different climate regions that influenced the timing of Pseudotsuga expansion.

  5. Modeling current climate conditions for forest pest risk assessment

    Science.gov (United States)

    Frank H. Koch; John W. Coulston

    2010-01-01

    Current information on broad-scale climatic conditions is essential for assessing potential distribution of forest pests. At present, sophisticated spatial interpolation approaches such as the Parameter-elevation Regressions on Independent Slopes Model (PRISM) are used to create high-resolution climatic data sets. Unfortunately, these data sets are based on 30-year...

  6. Arctic Vegetation under Climate Change – Biogenic Volatile Organic Compound Emissions and Leaf Anatomy

    DEFF Research Database (Denmark)

    Schollert, Michelle

    common arctic plant species, illustrating the great importance of vegetation composition for determining ecosystem BVOC emissions. Additionally, this thesis assesses the BVOC emission responses in common arctic plant species to effects of climate change: warming, shading and snow addition. Against...... treatment effects on BVOC emissions. Furthermore, the anatomy of arctic plants seems to respond differently to warming than species at lower latitudes. The results in this thesis demonstrate the complexity of the effects of climate change on BVOC emissions and leaf anatomy of arctic plant species...... emissions from the arctic region are assumed to be low, but data from the region is lacking. BVOC emissions are furthermore expected to change drastically due to the rapidly proceeding climate change in the Arctic, which can provide a feedback to climate warming of unknown direction and magnitude. BVOC...

  7. Power engineering under conditions of climatic changes

    International Nuclear Information System (INIS)

    Wajs, K.

    1993-01-01

    One of the climatic phenomena fairly well connected with power engineering in the so called greenhouse effect. It is caused by increase of emission to the atmosphere of the so called greenhouse gases, especially CO 2 . Mechanism of this phenomenon and the relevant observations are discussed. Basic models of the circulation of greenhouse gases are outlined and the relevant conclusions as to various probable results, especially for a large time scale, are given. Tasks in the area of power engineering activity in the present situation are described. (author). 19 refs

  8. Greenhouse Gas Induced Changes in the Seasonal Cycle of the Amazon Basin in Coupled Climate-Vegetation Regional Model

    Directory of Open Access Journals (Sweden)

    Flavio Justino

    2016-01-01

    Full Text Available Previous work suggests that changes in seasonality could lead to a 70% reduction in the extent of the Amazon rainforest. The primary cause of the dieback of the rainforest is a lengthening of the dry season due to a weakening of the large-scale tropical circulation. Here we examine these changes in the seasonal cycle. Under present day conditions the Amazon climate is characterized by a zonal separation of the dominance of the annual and semi-annual seasonal cycles. This behavior is strongly modified under greenhouse warming conditions, with the annual cycle becoming dominant throughout the Amazon basin, increasing differences between the dry and wet seasons. In particular, there are substantial changes in the annual cycle of temperature due to the increase in the temperature of the warmest month, but the lengthening of the dry season is believed to be particularly important for vegetation-climate feedbacks. Harmonic analysis performed to regional climate model simulations yields results that differ from the global climate model that it is forced from, with the regional model being more sensitive to changes in the seasonal cycle.

  9. Detection of the Coupling between Vegetation Leaf Area and Climate in a Multifunctional Watershed, Northwestern China

    Directory of Open Access Journals (Sweden)

    Lu Hao

    2016-12-01

    Full Text Available Accurate detection and quantification of vegetation dynamics and drivers of observed climatic and anthropogenic change in space and time is fundamental for our understanding of the atmosphere–biosphere interactions at local and global scales. This case study examined the coupled spatial patterns of vegetation dynamics and climatic variabilities during the past three decades in the Upper Heihe River Basin (UHRB, a complex multiple use watershed in arid northwestern China. We apply empirical orthogonal function (EOF and singular value decomposition (SVD analysis to isolate and identify the spatial patterns of satellite-derived leaf area index (LAI and their close relationship with the variability of an aridity index (AI = Precipitation/Potential Evapotranspiration. Results show that UHRB has become increasingly warm and wet during the past three decades. In general, the rise of air temperature and precipitation had a positive impact on mean LAI at the annual scale. At the monthly scale, LAI variations had a lagged response to climate. Two major coupled spatial change patterns explained 29% and 41% of the LAI dynamics during 1983–2000 and 2001–2010, respectively. The strongest connections between climate and LAI were found in the southwest part of the basin prior to 2000, but they shifted towards the north central area afterwards, suggesting that the sensitivity of LAI to climate varied over time, and that human disturbances might play an important role in altering LAI patterns. At the basin level, the positive effects of regional climate warming and precipitation increase as well as local ecological restoration efforts overwhelmed the negative effects of overgrazing. The study results offer insights about the coupled effects of climatic variability and grazing on ecosystem structure and functions at a watershed scale. Findings from this study are useful for land managers and policy makers to make better decisions in response to climate

  10. Late Holocene vegetation changes in relation with climate fluctuations and human activities in Languedoc (Southern France)

    Science.gov (United States)

    Azuara, J.; Combourieu-Nebout, N.; Lebreton, V.; Mazier, F.; Müller, S. D.; Dezileau, L.

    2015-09-01

    Holocene climate fluctuations and human activities since the Neolithic have shaped present-day Mediterranean environments. Separating anthropogenic effects from climatic impacts to reconstruct Mediterranean paleoenvironments over the last millennia remains a challenging issue. High resolution pollen analyses were undertaken on two cores from the Palavasian lagoon system (Hérault, southern France). These records allow reconstruction of vegetation dynamics over the last 4500 years. Results are compared with climatic, historical and archeological archives. A long-term aridification trend is highlighted during the Late Holocene and three superimposed arid events are recorded at 4600-4300, 2800-2400 and 1300-1100 cal BP. These periods of climatic instability coincide in time with the rapid climatic events depicted in the Atlantic Ocean (Bond et al., 2001). From the Bronze Age (4000 cal BP) to the end of the Iron Age (around 2000 cal BP), the spread of evergreen taxa and loss of forest cover result from anthropogenic impact. The Antiquity is characterized by a major reforestation event related to the concentration of rural activities and populations in coastal plains leading to forest recovery in the mountains. A major regional deforestation occurred at the beginning of the High Middle Ages. Around 1000 cal BP, forest cover is minimal while cover of olive, chestnut and walnut expands in relation to increasing human influence. The present day vegetation dominated by Mediterranean shrubland and pines has been in existence since the beginning of the 20th century.

  11. Late Holocene vegetation changes in relation with climate fluctuations and human activity in Languedoc (southern France)

    Science.gov (United States)

    Azuara, J.; Combourieu-Nebout, N.; Lebreton, V.; Mazier, F.; Müller, S. D.; Dezileau, L.

    2015-12-01

    Holocene climate fluctuations and human activity since the Neolithic have shaped present-day Mediterranean environments. Separating anthropogenic effects from climatic impacts to better understand Mediterranean paleoenvironmental changes over the last millennia remains a challenging issue. High-resolution pollen analyses were undertaken on two cores from the Palavasian lagoon system (Hérault, southern France). These records allow reconstruction of vegetation dynamics over the last 4500 years. Results are compared with climatic, historical and archeological archives. A long-term aridification trend is highlighted during the late Holocene, and three superimposed arid events are recorded at 4600-4300, 2800-2400 and 1300-1100 cal BP. These periods of high-frequency climate variability coincide in time with the rapid climatic events observed in the Atlantic Ocean (Bond et al., 2001). From the Bronze Age (4000 cal BP) to the end of the Iron Age (around 2000 cal BP), the spread of sclerophyllous taxa and loss of forest cover result from anthropogenic impact. Classical Antiquity is characterized by a major reforestation event related to the concentration of rural activity and populations in coastal plains leading to forest recovery in the mountains. A major regional deforestation occurred at the beginning of the High Middle Ages. Around 1000 cal BP, forest cover is minimal while the cover of olive, chestnut and walnut expands in relation to increasing human influence. The present-day vegetation dominated by Mediterranean shrubland and pines has been in existence since the beginning of the 20th century.

  12. Climate design of vegetable oil fuels for agricultural equipment; Klimadesign von Pflanzenoelkraftstoffen fuer landwirtschaftliche Maschinen

    Energy Technology Data Exchange (ETDEWEB)

    Stoehr, Michael [B.A.U.M. Consult GmbH, Muenchen (Germany). International and Energy Projects; Pickel, Peter [John Deere European Technology Innovation Center, Kaiserslautern (Germany)

    2012-07-01

    The use of biofuels in agricultural machinery is an option for complying with climate protection requirements that are presently discussed to be placed on manufacturers of mobile off-road machinery by the European Commission. A mathematical model has been developed that allows calculating greenhouse gas emissions (GHGE) of biofuels for complex production paths in a straightforward, transparent manner and in pattern with the EU's Fuel Quality Directive (FQD). Therewith it has been shown that both rape seed and camelina sativa oil fuels can save more than 60 % GHGE. Key parameters have been identified and rules for a climate design of vegetable oil fuels have been formulated. (orig.)

  13. Interactions between Climate, Land Use and Vegetation Fire Occurrences in El Salvador

    Directory of Open Access Journals (Sweden)

    Dolors Armenteras

    2016-02-01

    Full Text Available Vegetation burning is a global environmental threat that results in local ecological, economic and social impacts but also has large-scale implications for global change. The burning is usually a result of interacting factors such as climate, land use and vegetation type. Despite its importance as a factor shaping ecological, economic and social processes, countries highly vulnerable to climate change in Central America, such as El Salvador, lack an assessment of this complex relationship. In this study we rely on remotely sensed measures of the Normalized Vegetation Difference Index (NDVI and thermal anomaly detections by the Moderate Resolution Imaging Spectroradiometer (MODIS sensor to identify vegetation cover changes and fire occurrences. We also use land use data and rainfall observations derived from the Tropical Rainfall Measuring Mission (TRMM data to determine the spatial and temporal variability and interactions of these factors. Our results indicate a highly marked seasonality of fire occurrence linked to the climatic variability with a peak of fire occurrences in 2004 and 2013. Low vegetation indices occurred in March–April, around two months after the driest period of the year (December–February, corresponding to months with high detection of fires. Spatially, 65.6% of the fires were recurrent and clustered in agriculture/cropland areas and within 1 km of roads (70% and only a 4.7% of fires detected were associated with forests. Remaining forests in El Salvador deserve more attention due to underestimated consequences of forest fires. The identification of these clear patterns can be used as a baseline to better shape management of fire regimes and support decision making in this country. Recommendations resulting from this work include focusing on fire risk models and agriculture fires and long-term ecological and economic consequences of those. Furthermore, El Salvador will need to include agricultural fires in the

  14. Vegetation exerts a greater control on litter decomposition than climate warming in peatlands.

    Science.gov (United States)

    Ward, Susan E; Orwin, Kate H; Ostle, Nicholas J; Briones, J I; Thomson, Bruce C; Griffiths, Robert I; Oakley, Simon; Quirk, Helen; Bardget, Richard D

    2015-01-01

    Historically, slow decomposition rates have resulted in the accumulation of large amounts of carbon in northern peatlands. Both climate warming and vegetation change can alter rates of decomposition, and hence affect rates of atmospheric CO2 exchange, with consequences for climate change feedbacks. Although warming and vegetation change are happening concurrently, little is known about their relative and interactive effects on decomposition processes. To test the effects of warming and vegetation change on decomposition rates, we placed litter of three dominant species (Calluna vulgaris, Eriophorum vaginatum, Hypnum jutlandicum) into a peatland field experiment that combined warming.with plant functional group removals, and measured mass loss over two years. To identify potential mechanisms behind effects, we also measured nutrient cycling and soil biota. We found that plant functional group removals exerted a stronger control over short-term litter decomposition than did approximately 1 degrees C warming, and that the plant removal effect depended on litter species identity. Specifically, rates of litter decomposition were faster when shrubs were removed from the plant community, and these effects were strongest for graminoid and bryophyte litter. Plant functional group removals also had strong effects on soil biota and nutrient cycling associated with decomposition, whereby shrub removal had cascading effects on soil fungal community composition, increased enchytraeid abundance, and increased rates of N mineralization. Our findings demonstrate that, in addition to litter quality, changes in vegetation composition play a significant role in regulating short-term litter decomposition and belowground communities in peatland, and that these impacts can be greater than moderate warming effects. Our findings, albeit from a relatively short-term study, highlight the need to consider both vegetation change and its impacts below ground alongside climatic effects when

  15. Assessing vegetation response to climatic variations and human activities: spatiotemporal NDVI variations in the Hexi Corridor and surrounding areas from 2000 to 2010

    Science.gov (United States)

    Guan, Qingyu; Yang, Liqin; Guan, Wenqian; Wang, Feifei; Liu, Zeyu; Xu, Chuanqi

    2018-03-01

    Vegetation cover is a commonly used indicator for evaluating terrestrial environmental conditions, and for revealing environmental evolution and transitions. Spatiotemporal variations in the vegetation cover of the Hexi Corridor and surrounding areas from 2000 to 2010 were investigated using MODIS NDVI data, and the causes of vegetation cover changes were analyzed, considering both climatic variability and human activities. The vegetation cover of the study area increased during 2000-2010. The greenness of the vegetation showed a significant increase from the northwest to the southeast, which was similar to the spatial distribution of the annual precipitation. Variations in vegetation have a close relationship with those in precipitation within the Qilian Mountains region, but the NDVI is negatively correlated with precipitation in oasis areas. Increasing temperatures led to drought, inhibiting vegetation growth in summer; however, increasing temperatures may have also advanced and prolonged the growing periods in spring and autumn. The NDVI showed a slight degradation in March and July, primarily in the Qilian Mountains, and especially the Wushao Mountains. In March, due to low temperatures, the metabolism rate of vegetation was too slow to enable strong plant growth in high elevations of the Qilian Mountains. In July, increasing temperatures enhanced the intensity of transpiration and decreasing precipitation reduced the moisture available to plants, producing a slight degradation of vegetation in the Qilian Mountains. In May and August, the NDVI showed a significant improvement, primarily in the artificial oases and the Qilian Mountains. Abundant precipitation provided the necessary water for plant growth, and suitable temperatures increased the efficiency of photosynthesis, resulting in a significant improvement of vegetation in the Qilian Mountains. The improvement of production technologies, especially in irrigation, has been beneficial to the growth of

  16. Vegetation and climates of the last 45,000 years in the vicinity of the Nevada Test Site, south-central Nevada

    International Nuclear Information System (INIS)

    1985-01-01

    Major changes in the climate of the Nevada Test Site have occurred during the last 45,000 years. Understanding this climate variability is important in assessing the region's suitability for permanent nuclear-waste repositories. Future climatic changes probably will occur within the time the waste materials are hazardous. The nature and magnitude of previous fluctuations indicate the nature of future climatic change that may impact on a nuclear waste repository. Reconstructions of past vegetation are used to infer climatic conditions during the past 45,000 years. Plant macrofossils from ancient packrat (Neotoma spp.) middens provide the data for these analyses. Middens can be older than 50,000 years, and they are common in the region. Each contains abundant mummified plant fossils, representing the plant species growing within about 30 meters of the site. Radiocarbon-dated midden samples provide detailed records of climate-induced vegetation change. Increased atmospheric carbon dioxide within the next 500 years probably will result in a 2 0 to 3 0 C increase in annual temperature and intensified rainfall in the Nevada Test Site region. Analogs with previous glacial-interglacial cycles indicate that this ''superinterglacial'' may be no more than a relatively brief reversal in the protracted trend toward the next ice age. Current models indicate that, within the next 10,000 years, climatic conditions may be similar to those of the last glacial age

  17. Vegetation response to extreme climate events on the Mongolian Plateau from 2000 to 2010

    International Nuclear Information System (INIS)

    John, Ranjeet; Chen Jiquan; Ouyang Zutao; Becker, Richard; Xiao Jingfeng; Samanta, Arindam; Ganguly, Sangram; Yuan Wenping; Batkhishig, Ochirbat

    2013-01-01

    Climate change has led to more frequent extreme winters (aka, dzud) and summer droughts on the Mongolian Plateau during the last decade. Among these events, the 2000–2002 combined summer drought–dzud and 2010 dzud were the most severe on vegetation. We examined the vegetation response to these extremes through the past decade across the Mongolian Plateau as compared to decadal means. We first assessed the severity and extent of drought using the Tropical Rainfall Measuring Mission (TRMM) precipitation data and the Palmer drought severity index (PDSI). We then examined the effects of drought by mapping anomalies in vegetation indices (EVI, EVI2) and land surface temperature derived from MODIS and AVHRR for the period of 2000–2010. We found that the standardized anomalies of vegetation indices exhibited positively skewed frequency distributions in dry years, which were more common for the desert biome than for grasslands. For the desert biome, the dry years (2000–2001, 2005 and 2009) were characterized by negative anomalies with peak values between −1.5 and −0.5 and were statistically different (P 2 = 65 and 60, p 2 = 53, p < 0.05). Our results showed significant differences in the responses to extreme climatic events (summer drought and dzud) between the desert and grassland biomes on the Plateau. (letter)

  18. Rapid characterisation of vegetation structure to predict refugia and climate change impacts across a global biodiversity hotspot.

    Directory of Open Access Journals (Sweden)

    Antonius G T Schut

    Full Text Available Identification of refugia is an increasingly important adaptation strategy in conservation planning under rapid anthropogenic climate change. Granite outcrops (GOs provide extraordinary diversity, including a wide range of taxa, vegetation types and habitats in the Southwest Australian Floristic Region (SWAFR. However, poor characterization of GOs limits the capacity of conservation planning for refugia under climate change. A novel means for the rapid identification of potential refugia is presented, based on the assessment of local-scale environment and vegetation structure in a wider region. This approach was tested on GOs across the SWAFR. Airborne discrete return Light Detection And Ranging (LiDAR data and Red Green and Blue (RGB imagery were acquired. Vertical vegetation profiles were used to derive 54 structural classes. Structural vegetation types were described in three areas for supervised classification of a further 13 GOs across the region. Habitat descriptions based on 494 vegetation plots on and around these GOs were used to quantify relationships between environmental variables, ground cover and canopy height. The vegetation surrounding GOs is strongly related to structural vegetation types (Kappa = 0.8 and to its spatial context. Water gaining sites around GOs are characterized by taller and denser vegetation in all areas. The strong relationship between rainfall, soil-depth, and vegetation structure (R(2 of 0.8-0.9 allowed comparisons of vegetation structure between current and future climate. Significant shifts in vegetation structural types were predicted and mapped for future climates. Water gaining areas below granite outcrops were identified as important putative refugia. A reduction in rainfall may be offset by the occurrence of deeper soil elsewhere on the outcrop. However, climate change interactions with fire and water table declines may render our conclusions conservative. The LiDAR-based mapping approach presented

  19. Assessing the impact of climate variability on catchment water balance and vegetation cover

    Directory of Open Access Journals (Sweden)

    X. Xu

    2012-01-01

    Full Text Available Understanding the interactions among climate, vegetation cover and the water cycle lies at the heart of the study of watershed ecohydrology. Recently, considerable attention is being paid to the effect of climate variability on catchment water balance and also associated vegetation cover. In this paper, we investigate the general pattern of long-term water balance and vegetation cover (as reflected by fPAR among 193 study catchments in Australia through statistical analysis. We then employ the elasticity analysis approach for quantifying the effects of climate variability on hydrologic partitioning (including total, surface and subsurface runoff and on vegetation cover (including total, woody and non-woody vegetation cover. Based on the results of statistical analysis, we conclude that annual runoff (R, evapotranspiration (E and runoff coefficient (R/P increase with vegetation cover for catchments in which woody vegetation is dominant and annual precipitation is relatively high. Control of water available on annual evapotranspiration in non-woody dominated catchments is relatively stronger compared to woody dominated ones. The ratio of subsurface runoff to total runoff (Rg/R also increases with woody vegetation cover. Through the elasticity analysis of catchment runoff, it is shown that precipitation (P in current year is the most important factor affecting the change in annual total runoff (R, surface runoff (Rs and subsurface runoff (Rg. The significance of other controlling factors is in the order of annual precipitation in previous years (P−1 and P−2, which represents the net effect of soil moisture and annual mean temperature (T in current year. Change of P by +1% causes a +3.35% change of R, a +3.47% change of Rs and a +2.89% change of

  20. Nonlinear Variations of Net Primary Productivity and Its Relationship with Climate and Vegetation Phenology, China

    Directory of Open Access Journals (Sweden)

    Jian Yang

    2017-09-01

    Full Text Available Net primary productivity (NPP is an important component of the terrestrial carbon cycle. In this study, NPP was estimated based on two models and Moderate Resolution Imaging Spaectroradiometer (MODIS data. The spatiotemporal patterns of NPP and the correlations with climate factors and vegetation phenology were then analyzed. Our results showed that NPP derived from MODIS performed well in China. Spatially, NPP decreased from the southeast toward the northwest. Temporally, NPP showed a nonlinear increasing trend at a national scale, but the magnitude became slow after 2004. At a regional scale, NPP in Northern China and the Tibetan Plateau showed a nonlinear increasing trend, while the NPP decreased in most areas of Southern China. The decreases in NPP were more than offset by the increases. At the biome level, all vegetation types displayed an increasing trend, except for shrub and evergreen broad forests (EBF. Moreover, a turning point year occurred for all vegetation types, except for EBF. Generally, climatic factors and Length of Season were all positively correlated with the NPP, while the relationships were much more diverse at a regional level. The direct effect of solar radiation on the NPP was larger (0.31 than precipitation (0.25 and temperature (0.07. Our results indicated that China could mitigate climate warming at a regional and/or global scale to some extent during the time period of 2001–2014.

  1. Late glacial vegetation and climate changes in the high mountains of Bulgaria (Southeast Europe)

    International Nuclear Information System (INIS)

    Bozilova, E.D.; Tonkov, S.B.

    2005-01-01

    Full text: The Late glacial vegetation history in the high mountains of Southern Bulgaria (Rila, Pirin, Western Rhodopes) is reconstructed by means of pollen analysis, plant macrofossils and radiocarbon dating of sediments from lakes and peat-bogs located between 1300 and 2200 m a.s.l. The vegetation response to the climate fluctuations after 13000 14 C yrs. BP in the Rila Mountains is bound for the first time to a detailed chronological framework. Two stadial and one interstadial phases are delimited analogous with the Oldest Dryas-Bolling/Allerod-Younger Dryas cycle for Western Europe. During the stadials mountain-steppe vegetation composed of Artemisia, Chenopodiaceae, Poaceae and other cold-resistant herbs dominated at high elevation with sparse stands of Pinus, Betula, and shrubland of Juniperus and Ephedra. The climate improvement in the interstadial resulted in the initial spread of deciduous and coniferous trees (Quercus, Tilia, Corylus, Carpinus, Abies, Picea) from their local refugia below 1000 m. The palaeoecological record from the climate deterioration during the Younger Dryas is documented in thin sections of the cores investigated. (author)

  2. Combined effects of climate change and forest clearing on the Amazon vegetation: Projections for 2080-2100

    Science.gov (United States)

    Cook, K. H.; Vizy, E. K.

    2007-05-01

    A regional climate model with resolution of 60 km coupled with a potential vegetation model is used to simulate future vegetation distributions over South America. The coupled model, which produces an accurate representation of today's climate and vegetation, is forced with increasing atmospheric CO2 concentrations, sea surface temperature from a global model, and scenarios of future land use practices to predict climate and vegetation distributions for the last 2 decades of the 21st century. When only climate change is considered, under a business-as-usual scenario for global emissions, the extent of the Amazon rainforest is reduced by about 70 per cent by the end of this century, and the shrubland (caatinga) vegetation of Brazil's Nordeste region spreads westward and southward. Reductions in annual mean precipitation are widespread and rainfall becomes insufficient to support the rainforest in these regions, but some areas receive more precipitation. The length of the dry season increases in the central and southern Amazon in association with changes in the large-scale tropical circulation. Without this change in seasonality, local refugia of Amazon vegetation would be preserved and the retreat of the rainforest would be somewhat less extensive. Including various projections of future land use practices in addition to climate change may accelerate the unrecoverable demise of the rainforest and feedback to modify climate on regional space scales. The portions of the rainforest that are most vulnerable to climate change are the same as those that are under the most pressure from human activity, presenting a remarkable competition.

  3. Megalake Chad impact on climate and vegetation during the late Pliocene and the mid-Holocene

    Directory of Open Access Journals (Sweden)

    C. Contoux

    2013-07-01

    Full Text Available Given the growing evidence for megalakes in the geological record, assessing their impact on climate and vegetation is important for the validation of palaeoclimate simulations and therefore the accuracy of model–data comparison in lacustrine environments. Megalake Chad (MLC occurrences are documented not only for the mid-Holocene but also for the Mio-Pliocene (Schuster et al., 2009. At this time, the surface covered by water would have reached up to ~350 000 km2 (Ghienne et al., 2002; Schuster et al., 2005; Leblanc et al., 2006, making it an important evaporation source, possibly modifying climate and vegetation in the Chad Basin. We investigated the impact of such a giant continental water area in two different climatic backgrounds within the Paleoclimate Model Intercomparison Project phase 3 (PMIP3: the late Pliocene (3.3 to 3 Ma, i.e. the mid-Piacenzian warm period and the mid-Holocene (6 kyr BP. In all simulations including MLC, precipitation is drastically reduced above the lake surface because deep convection is inhibited by overlying colder air. Meanwhile, convective activity is enhanced around MLC because of the wind increase generated by the flat surface of the megalake, transporting colder and moister air towards the eastern shore of the lake. The effect of MLC on precipitation and temperature is not sufficient to widely impact vegetation patterns. Nevertheless, tropical savanna is present in the Chad Basin in all climatic configurations, even without MLC presence, showing that the climate itself is the driver of favourable environments for sustainable hominid habitats.

  4. Climate-vegetation relationship: adaptations of jarillal community to the semiarid climate. Lihué Calel National Park, province of La Pampa, Argentina

    Directory of Open Access Journals (Sweden)

    Valeria Soledad Duval

    2015-12-01

    Full Text Available The study of vegetation from the Geography perspective focuses on the analysis of the spatial distribution and on the factors affecting it. One of these factors is the climate, which determines the characteristics of the vegetation and, on a larger scale, of the communities. The aim of this paper is to analyze the climate-vegetation relationship by studying adaptations of the jarillal community regarding the semiarid climate in the Lihué Calel National Park, Argentina. Therefore, this contribution is concerned with the knowledge of the characteristics of the environment in order to understand how vegetation responds to certain phenomena, so management of protected areas will be more suitable. Lihué Calel National Park is a national protected area located in the south-center of La Pampa province, Argentina. According to Cabrera (1976 the area belongs to the floristic province of “monte” and the climate is warm and dry. In the interest to achieve the goals of this paper, Thornthwaite and Mather´s water balance was done. The data was collected from a weather station that belongs to the national park, for the period 1995-2010. Emberger›s pluviothermic coefficient, Lang´s rainfall index, De Martonne´s aridity index and Currey´s continentality index were analyzed. In addition, ten stands or plots of vegetation were placed to determine the floristic composition and the vegetation physiognomy. Then, plants species were identified as individuals and their adaptive responses were also analyzed. In conclusion, the survey verified that semi-arid climate conditions determine the morphology and the appearance of jarillal. Climate analysis shows that for the period 1995-2010 the average annual temperature is 16.2° C and reveals that thermal summers and winters are well differentiated. Large water deficit is defined, because water balance indicates that the evapotranspiration exceeds precipitation during every month of the year. According to

  5. Climate and vegetation study using environmental isotope types of stalactite at Seropan Cave, Gunung Kidul Yogyakarta

    International Nuclear Information System (INIS)

    Satrio; Sidauruk, P.; Pratikno, B.

    2012-01-01

    Climate and vegetation study using environmental isotopes (i.e., 13 C, 14 C and 18 O) variations of stalactite has been conducted at Seropan cave, Gunung Kidul Karst area. The stalactite samples were collected from Seropan Cave at Semanu, Gunung Kidul, Yogyakarta. The objective of study is to understand the climate change, and vegetation types, temperature of atmosphere, age and stalactite growth rate through the interpretation of environmental isotopes (i.e., 13 C, 14 C and 18 O) of stalactite samples. The environmental isotope content of stalactite samples were analysed through CaCO 3 compound that was found at the stalactite samples. The 13 C content of samples is important to understand climate undulation and also vegetation variation. On the other hand, the variation of 18 O and 14 C contents is important to predict past temperature of atmosphere, and the age as well as stalactite growth rate, respectively. The result of environmental 13 C isotope analysis showed that Gunung Kidul area in general can be classified as dry climate. It is also indicated that almost 87.5 % of local vegetation can be classified as dry vegetation C4 as can be seen from the variation of δ 13 C content that is -6 ‰ to +2 ‰ vs PDB. This can also mean that only 12.5 % of the time that the vegetation in the area is wet in which the variation of δ 13 C content is in the range -14 ‰ to -6 ‰ vs PDB. The variations of 18 O contents of the samples (carbonate stalactite, or drip water) showed that the average temperature since 1621 to 2011 was around 19.5 °C. On the other hand, the variations of 14 C contents of the samples showed that stalactite growth rate was around 0.1 mm/year or one mm in ten years. The result shows that the stalactite growth is very slow as generally expected in tropical area such as Gunung Kidul. (author)

  6. Childhood intermittent and persistent rhinitis prevalence and climate and vegetation: a global ecologic analysis.

    Science.gov (United States)

    Fuertes, Elaine; Butland, Barbara K; Ross Anderson, H; Carlsten, Chris; Strachan, David P; Brauer, Michael

    2014-10-01

    The effect of climate change and its effects on vegetation growth, and consequently on rhinitis, are uncertain. To examine between- and within-country associations of climate measures and the normalized difference vegetation index with intermittent and persistent rhinitis symptoms in a global context. Questionnaire data from 6- to 7-year-olds and 13- to 14-year-olds were collected in phase 3 of the International Study of Asthma and Allergies in Childhood. Associations of intermittent (>1 symptom report but not for 2 consecutive months) and persistent (symptoms for ≥2 consecutive months) rhinitis symptom prevalences with temperature, precipitation, vapor pressure, and the normalized difference vegetation index were assessed in linear mixed-effects regression models adjusted for gross national income and population density. The mean difference in prevalence per 100 children (with 95% confidence intervals [CIs]) per interquartile range increase of exposure is reported. The country-level intermittent symptom prevalence was associated with several country-level climatic measures, including the country-level mean monthly temperature (6.09 °C; 95% CI, 2.06-10.11°C per 10.4 °C), precipitation (3.10 mm; 95% CI, 0.46-5.73 mm; per 67.0 mm), and vapor pressure (6.21 hPa; 95% CI, 2.17-10.24 hPa; per 10.4 hPa) among 13- to 14-year-olds (222 center in 94 countries). The center-level persistent symptom prevalence was positively associated with several center-level climatic measures. Associations with climate were also found for the 6- to 7-year-olds (132 center in 57 countries). Several between- and within-country spatial associations between climatic factors and intermittent and persistent rhinitis symptom prevalences were observed. These results provide suggestive evidence that climate (and future changes in climate) may influence rhinitis symptom prevalence. Copyright © 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  7. Response and Resiliency of Wildlife and Vegetation to Large-Scale Wildfires and Climate Change in the North Cascades

    Science.gov (United States)

    Bartowitz, K.; Morrison, P.; Romain-Bondi, K.; Smith, C. W.; Warne, L.; McGill, D.

    2016-12-01

    aid in management of the state-threatened species. The combination of severe fire and extreme heat/drought may result in shifts from shrub-steppe to grass/forb communities, as well as range contraction of ponderosa pine forests. The study reveals the importance of subsequent climatic conditions on vegetation recovery after a fire.

  8. The biophysical link between climate, water, and vegetation in bioenergy agro-ecosystems

    International Nuclear Information System (INIS)

    Bagley, Justin E.; Davis, Sarah C.; Georgescu, Matei; Hussain, Mir Zaman; Miller, Jesse; Nesbitt, Stephen W.; VanLoocke, Andy; Bernacchi, Carl J.

    2014-01-01

    Land use change for bioenergy feedstocks is likely to intensify as energy demand rises simultaneously with increased pressure to minimize greenhouse gas emissions. Initial assessments of the impact of adopting bioenergy crops as a significant energy source have largely focused on the potential for bioenergy agroecosystems to provide global-scale climate regulating ecosystem services via biogeochemical processes. Such as those processes associated with carbon uptake, conversion, and storage that have the potential to reduce global greenhouse gas emissions (GHG). However, the expansion of bioenergy crops can also lead to direct biophysical impacts on climate through water regulating services. Perturbations of processes influencing terrestrial energy fluxes can result in impacts on climate and water across a spectrum of spatial and temporal scales. Here, we review the current state of knowledge about biophysical feedbacks between vegetation, water, and climate that would be affected by bioenergy-related land use change. The physical mechanisms involved in biophysical feedbacks are detailed, and interactions at leaf, field, regional, and global spatial scales are described. Locally, impacts on climate of biophysical changes associated with land use change for bioenergy crops can meet or exceed the biogeochemical changes in climate associated with rising GHG's, but these impacts have received far less attention. Realization of the importance of ecosystems in providing services that extend beyond biogeochemical GHG regulation and harvestable yields has led to significant debate regarding the viability of various feedstocks in many locations. The lack of data, and in some cases gaps in knowledge associated with biophysical and biochemical influences on land–atmosphere interactions, can lead to premature policy decisions. - Highlights: • The physical basis for biophysical impacts of expanding bioenergy agroecosystems on climate and water is described. • We

  9. Large-Scale Variation in Forest Carbon Turnover Rate and its Relation to Climate - Remote Sensing vs. Global Vegetation Models

    Science.gov (United States)

    Carvalhais, N.; Thurner, M.; Beer, C.; Forkel, M.; Rademacher, T. T.; Santoro, M.; Tum, M.; Schmullius, C.

    2015-12-01

    While vegetation productivity is known to be strongly correlated to climate, there is a need for an improved understanding of the underlying processes of vegetation carbon turnover and their importance at a global scale. This shortcoming has been due to the lack of spatially extensive information on vegetation carbon stocks, which we recently have been able to overcome by a biomass dataset covering northern boreal and temperate forests originating from radar remote sensing. Based on state-of-the-art products on biomass and NPP, we are for the first time able to study the relation between carbon turnover rate and a set of climate indices in northern boreal and temperate forests. The implementation of climate-related mortality processes, for instance drought, fire, frost or insect effects, is often lacking or insufficient in current global vegetation models. In contrast to our observation-based findings, investigated models from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT, are able to reproduce spatial climate - turnover rate relationships only to a limited extent. While most of the models compare relatively well to observation-based NPP, simulated vegetation carbon stocks are severely biased compared to our biomass dataset. Current limitations lead to considerable uncertainties in the estimated vegetation carbon turnover, contributing substantially to the forest feedback to climate change. Our results are the basis for improving mortality concepts in global vegetation models and estimating their impact on the land carbon balance.

  10. Interannual variability of the normalized difference vegetation index on the Tibetan Plateau and its relationship with climate change

    Science.gov (United States)

    Zhou, Dingwen; Fan, Guangzhou; Huang, Ronghui; Fang, Zhifang; Liu, Yaqin; Li, Hongquan

    2007-05-01

    The Qinghai-Xizang Plateau, or Tibetan Plateau, is a sensitive region for climate change, where the manifestation of global warming is particularly noticeable. The wide climate variability in this region significantly affects the local land ecosystem and could consequently lead to notable vegetation changes. In this paper, the interannual variations of the plateau vegetation are investigated using a 21-year normalized difference vegetation index (NDVI) dataset to quantify the consequences of climate warming for the regional ecosystem and its interactions. The results show that vegetation coverage is best in the eastern and southern plateau regions and deteriorates toward the west and north. On the whole, vegetation activity demonstrates a gradual enhancement in an oscillatory manner during 1982 2002. The temporal variation also exhibits striking regional differences: an increasing trend is most apparent in the west, south, north and southeast, whereas a decreasing trend is present along the southern plateau boundary and in the central-east region. Covariance analysis between the NDVI and surface temperature/precipitation suggests that vegetation change is closely related to climate change. However, the controlling physical processes vary geographically. In the west and east, vegetation variability is found to be driven predominantly by temperature, with the impact of precipitation being of secondary importance. In the central plateau, however, temperature and precipitation factors are equally important in modulating the interannual vegetation variability.

  11. Presence of riparian vegetation increases biotic condition of fish assemblages in two Brazilian reservoirs

    OpenAIRE

    Ferreira, Fabio Cop; Souza, Ursulla Pereira; Petrere Junior2, Miguel

    2015-01-01

    Abstract The riparian vegetation in lakes and reservoirs is source of course wood structures such as trunks and branches and is used as sheltering, spawning and foraging habitats for fishes. The reduction of these submerged structures can thus, affect the composition and structure of fish assemblages in reservoirs. Aim To evaluate the influence of riparian vegetation on the biotic condition of fish assemblage by adapting the Reservoir Fish Assemblage Index (RFAI) to two reservoirs in the Upp...

  12. DEVELOPMENT OF AUTOMATED SYSTEM OF CLIMATE CONDITIONS MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Novikova L.V.

    2017-12-01

    Full Text Available The scientific work is devoted to the analysis and development of the automated control system of the climatic conditions of the minites. The analysis of existing automated control systems is carried out, in particular attention is paid to the systems of climate control of greenhouses. The technical means of the control system are determined. As a platform, Arduino®Uno is selected.

  13. Simulating the Effect of Climate Change on Vegetation Zone Distribution on the Loess Plateau, Northwest China

    Directory of Open Access Journals (Sweden)

    Guoqing Li

    2015-06-01

    Full Text Available A risk assessment of vegetation zone responses to climate change was conducted using the classical Holdridge life zone model on the Loess Plateau of Northwest China. The results show that there are currently ten vegetation zones occurring on the Loess Plateau (1950–2000, including alvar desert, alpine wet tundra, alpine rain tundra, boreal moist forest, boreal wet forest, cool temperate desert, cool temperate desert scrub, cool temperate steppe, cool temperate moist forest, warm temperate desert scrub, warm temperate thorn steppe, and warm temperate dry forest. Seventy years later (2070S, the alvar desert, the alpine wet tundra and the cool temperate desert will disappear, while warm temperate desert scrub and warm temperate thorn steppe will emerge. The area proportion of warm temperate dry forest will expand from 12.2% to 22.8%–37.2%, while that of cool temperate moist forest will decrease from 18.5% to 6.9%–9.5%. The area proportion of cool temperate steppe will decrease from 51.8% to 34.5%–51.6%. Our results suggest that future climate change will be conducive to the growth and expansion of forest zones on the Loess Plateau, which can provide valuable reference information for regional vegetation restoration planning and adaptive strategies in this region.

  14. Hyperspectral Monitoring of Green Roof Vegetation Health State in Sub-Mediterranean Climate: Preliminary Results.

    Science.gov (United States)

    Piro, Patrizia; Porti, Michele; Veltri, Simone; Lupo, Emanuela; Moroni, Monica

    2017-03-23

    In urban and industrial environments, the constant increase of impermeable surfaces has produced drastic changes in the natural hydrological cycle. Decreasing green areas not only produce negative effects from a hydrological-hydraulic perspective, but also from an energy point of view, modifying the urban microclimate and generating, as shown in the literature, heat islands in our cities. In this context, green infrastructures may represent an environmental compensation action that can be used to re-equilibrate the hydrological and energy balance and reduce the impact of pollutant load on receiving water bodies. To ensure that a green infrastructure will work properly, vegetated areas have to be continuously monitored to verify their health state. This paper presents a ground spectroscopy monitoring survey of a green roof installed at the University of Calabria fulfilled via the acquisition and analysis of hyperspectral data. This study is part of a larger research project financed by European Structural funds aimed at understanding the influence of green roofs on rainwater management and energy consumption for air conditioning in the Mediterranean area. Reflectance values were acquired with a field-portable spectroradiometer that operates in the range of wavelengths 350-2500 nm. The survey was carried out during the time period November 2014-June 2015 and data were acquired weekly. Climatic, thermo-physical, hydrological and hydraulic quantities were acquired as well and related to spectral data. Broadband and narrowband spectral indices, related to chlorophyll content and to chlorophyll-carotenoid ratio, were computed. The two narrowband indices NDVI 705 and SIPI turned out to be the most representative indices to detect the plant health status.

  15. Pollen and phytoliths from fired ancient potsherds as potential indicators for deciphering past vegetation and climate in Turpan, Xinjiang, NW China.

    Science.gov (United States)

    Yao, Yi-Feng; Li, Xiao; Jiang, Hong-En; Ferguson, David K; Hueber, Francis; Ghosh, Ruby; Bera, Subir; Li, Cheng-Sen

    2012-01-01

    It is demonstrated that palynomorphs can occur in fired ancient potsherds when the firing temperature was under 350°C. Pollen and phytoliths recovered from incompletely fired and fully fired potsherds (ca. 2700 yrs BP) from the Yanghai Tombs, Turpan, Xinjiang, NW China can be used as potential indicators for reconstructing past vegetation and corresponding climate in the area. The results show a higher rate of recovery of pollen and phytoliths from incompletely fired potsherds than from fully fired ones. Charred phytoliths recovered from both fully fired and incompletely fired potsherds prove that degree and condition of firing result in a permanent change in phytolith color. The palynological data, together with previous data of macrobotanical remains from the Yanghai Tombs, suggest that temperate vegetation and arid climatic conditions dominated in the area ca. 2700 yrs BP.

  16. Effect Of Climatic Conditions On Durability

    Directory of Open Access Journals (Sweden)

    Ibrahem M. Al Kiki

    2013-04-01

    Full Text Available Durability is one of the most important subjects in the soil stabilization. Since there is no specifications concerned the durability of lime stabilized soils, several factors were selected to show their effects on the durability, namely: wetting, drying, freezing, thawing and slaking.The effect of each one of the above factors as well as the combined effect of two or more factors, were studied on the volume change and soil strength and weight loss of soil samples stabilized with optimum lime content except the slaking test at which soil samples stabilized with different lime content.Tests results showed that the higher the lime content the lower the slaking effect, also its found the soil strength decreased when the period of immersion or freezing increased. The strength of the lime stabilized soils decreased when subjected to the cycles of wetting and drying or to the cycles freezing and thawing. However, the  combined effect of wetting, drying, freezing and thawing has a pronounced effect on reduction of the lime stabilized clayey soil. The worst condition recorded when lime stabilized soil undergo to freezing then drying then wetting which should be avoided in the field

  17. Uncertainties in modelling CH4 emissions from northern wetlands in glacial climates: the role of vegetation parameters

    Directory of Open Access Journals (Sweden)

    J. van Huissteden

    2011-10-01

    Full Text Available Marine Isotope Stage 3 (MIS 3 interstadials are marked by a sharp increase in the atmospheric methane (CH4 concentration, as recorded in ice cores. Wetlands are assumed to be the major source of this CH4, although several other hypotheses have been advanced. Modelling of CH4 emissions is crucial to quantify CH4 sources for past climates. Vegetation effects are generally highly generalized in modelling past and present-day CH4 fluxes, but should not be neglected. Plants strongly affect the soil-atmosphere exchange of CH4 and the net primary production of the vegetation supplies organic matter as substrate for methanogens. For modelling past CH4 fluxes from northern wetlands, assumptions on vegetation are highly relevant since paleobotanical data indicate large differences in Last Glacial (LG wetland vegetation composition as compared to modern wetland vegetation. Besides more cold-adapted vegetation, Sphagnum mosses appear to be much less dominant during large parts of the LG than at present, which particularly affects CH4 oxidation and transport. To evaluate the effect of vegetation parameters, we used the PEATLAND-VU wetland CO2/CH4 model to simulate emissions from wetlands in continental Europe during LG and modern climates. We tested the effect of parameters influencing oxidation during plant transport (fox, vegetation net primary production (NPP, parameter symbol Pmax, plant transport rate (Vtransp, maximum rooting depth (Zroot and root exudation rate (fex. Our model results show that modelled CH4 fluxes are sensitive to fox and Zroot in particular. The effects of Pmax, Vtransp and fex are of lesser relevance. Interactions with water table modelling are significant for Vtransp. We conducted experiments with different wetland vegetation types for Marine Isotope Stage 3 (MIS 3 stadial and interstadial climates and the present-day climate, by coupling PEATLAND-VU to high resolution climate model simulations for Europe. Experiments assuming

  18. Uncertainties in modelling CH4 emissions from northern wetlands in glacial climates: the role of vegetation parameters

    Science.gov (United States)

    Berrittella, C.; van Huissteden, J.

    2011-10-01

    Marine Isotope Stage 3 (MIS 3) interstadials are marked by a sharp increase in the atmospheric methane (CH4) concentration, as recorded in ice cores. Wetlands are assumed to be the major source of this CH4, although several other hypotheses have been advanced. Modelling of CH4 emissions is crucial to quantify CH4 sources for past climates. Vegetation effects are generally highly generalized in modelling past and present-day CH4 fluxes, but should not be neglected. Plants strongly affect the soil-atmosphere exchange of CH4 and the net primary production of the vegetation supplies organic matter as substrate for methanogens. For modelling past CH4 fluxes from northern wetlands, assumptions on vegetation are highly relevant since paleobotanical data indicate large differences in Last Glacial (LG) wetland vegetation composition as compared to modern wetland vegetation. Besides more cold-adapted vegetation, Sphagnum mosses appear to be much less dominant during large parts of the LG than at present, which particularly affects CH4 oxidation and transport. To evaluate the effect of vegetation parameters, we used the PEATLAND-VU wetland CO2/CH4 model to simulate emissions from wetlands in continental Europe during LG and modern climates. We tested the effect of parameters influencing oxidation during plant transport (fox), vegetation net primary production (NPP, parameter symbol Pmax), plant transport rate (Vtransp), maximum rooting depth (Zroot) and root exudation rate (fex). Our model results show that modelled CH4 fluxes are sensitive to fox and Zroot in particular. The effects of Pmax, Vtransp and fex are of lesser relevance. Interactions with water table modelling are significant for Vtransp. We conducted experiments with different wetland vegetation types for Marine Isotope Stage 3 (MIS 3) stadial and interstadial climates and the present-day climate, by coupling PEATLAND-VU to high resolution climate model simulations for Europe. Experiments assuming dominance of

  19. Topographically-controlled site conditions drive vegetation pattern on inland dunes in Poland

    Science.gov (United States)

    Sewerniak, Piotr; Jankowski, Michał

    2017-07-01

    The inland dunes of Central Europe are commonly overplanted by Scots pine (Pinus sylvestris) monocultures in which the primary occurrence of the natural vegetation pattern is obliterated. We hypothesize that on naturally revegetated inland dunes the pattern is clear and driven by topographically-controlled site conditions. To test this hypothesis, we addressed the following research questions: (1) Does topography drive vegetation patterns on inland dunes and if so, what are main differences between vegetation in varying relief positions? (2) To what extent does topography involve the variability of microclimates and of soil properties, and how does the topographically-induced differentiation of these site conditions control vegetation patterns? We conducted interdisciplinary studies (applying floristic, pedological and microclimatic research techniques) on a naturally revegetated inland dune area situated on a military artillery training ground near Toruń, northern Poland. We investigated vegetation patterns with reference to three topographical position variants (north-facing slopes, south-facing slopes, and intra-dune depressions). We found distinct differences in vegetation characteristics covering the aforementioned topographical positions. This primarily concerned species composition of ground vegetation: Calluna vulgaris was dominant species on north-facing slopes, Corynephorus canescens on south-facing slopes, while Calamagrostis epigejos in intra-dune depressions. In comparison to dune slopes, the depressions were characterized by much higher biodiversity of vascular plant species. This followed the most favorable soil conditions for the existence of plants (higher moisture and nutrient pools) occurring in low topographical positions. However, tree succession was most advanced not in depressions, where the competitive impact of tall grasses on seedlings was recognized, but on north-facing slopes. Based on our results, we formulated some suggestions, which

  20. The influence of vegetation, mesoclimate and meteorology on urban atmospheric microclimates across a coastal to desert climate gradient.

    Science.gov (United States)

    Crum, Steven M; Shiflett, Sheri A; Jenerette, G Darrel

    2017-09-15

    Many cities are increasing vegetation in part due to the potential for microclimate cooling. However, the magnitude of vegetation cooling and sensitivity to mesoclimate and meteorology are uncertain. To improve understanding of the variation in vegetation's influence on urban microclimates we asked: how do meso- and regional-scale drivers influence the magnitude and timing of vegetation-based moderation on summertime air temperature (T a ), relative humidity (RH) and heat index (HI) across dryland cities? To answer this question we deployed a network of 180 temperature sensors in summer 2015 over 30 high- and 30 low-vegetated plots in three cities across a coastal to inland to desert climate gradient in southern California, USA. In a followup study, we deployed a network of temperature and humidity sensors in the inland city. We found negative T a and HI and positive RH correlations with vegetation intensity. Furthermore, vegetation effects were highest in evening hours, increasing across the climate gradient, with reductions in T a and increases in RH in low-vegetated plots. Vegetation increased temporal variability of T a , which corresponds with increased nighttime cooling. Increasing mean T a was associated with higher spatial variation in T a in coastal cities and lower variation in inland and desert cities, suggesting a climate dependent switch in vegetation sensitivity. These results show that urban vegetation increases spatiotemporal patterns of microclimate with greater cooling in warmer environments and during nighttime hours. Understanding urban microclimate variation will help city planners identify potential risk reductions associated with vegetation and develop effective strategies ameliorating urban microclimate. Published by Elsevier Ltd.

  1. CO2-vegetation feedbacks and other climate changes implicated in reducing base flow

    Science.gov (United States)

    Trancoso, Ralph; Larsen, Joshua R.; McVicar, Tim R.; Phinn, Stuart R.; McAlpine, Clive A.

    2017-03-01

    Changes in the hydrological cycle have a significant impact in water limited environments. Globally, some of these regions are experiencing declining precipitation yet are simultaneously becoming greener, partly due to vegetation feedbacks associated with increasing atmospheric CO2 concentrations. Reduced precipitation together with increasing rates of actual evapotranspiration diminishes streamflow, especially base flow, a critical freshwater dry-season resource. Here we assess recent changes in base flow in Australia from 1981-2013 and 1950-2013 and separate the contribution of precipitation, potential evapotranspiration, and other factors on base flow trends. Our findings reveal that these other factors influencing the base flow trends are best explained by an increase in photosynthetic activity. These results provide the first robust observational evidence that increasing atmospheric CO2 and its associated vegetation feedbacks are reducing base flow in addition to other climatic impacts. These findings have broad implications for water resource management, especially in the world's water limited regions.

  2. Approaches to incorporating climate change effects in state and transition simulation models of vegetation

    Science.gov (United States)

    Becky K. Kerns; Miles A. Hemstrom; David Conklin; Gabriel I. Yospin; Bart Johnson; Dominique Bachelet; Scott Bridgham

    2012-01-01

    Understanding landscape vegetation dynamics often involves the use of scientifically-based modeling tools that are capable of testing alternative management scenarios given complex ecological, management, and social conditions. State-and-transition simulation model (STSM) frameworks and software such as PATH and VDDT are commonly used tools that simulate how landscapes...

  3. Absorption of radioelements from the soil by various vegetables grown under normal condition of cultivation

    International Nuclear Information System (INIS)

    Huguet; Delas; Delmas; Demias; Flanzy; Benard; Puyaubert; Fioramonti; Marty; Barbier; Le Blaye; Michon

    1961-01-01

    Various vegetables were cultivated in 4 different types of soil, having received, or receiving periodically, strontium-90 or caesium-137 in fairly strong doses, in order to facilitate the measurement of the fraction of these radioelements taken up by the vegetables. In sandy soil, whole plants absorbed 2 to 3 per cent of Sr and 3 to 9 parts per thousand of Cs approximately; in clay soils, 1 to 6 parts per thousand of Sr and 0,2 to 2 parts per thousand of Cs; Cs, however, migrates relatively more than Sr in fruits or storage organs. The experiments confirmed that the quotient of the ratios 90 Sr/Ca in the vegetables and in the ploughed layer varies comparatively slightly; these would be a certain safety margin in assuming this ratio to be slightly above unity (to be confirmed after homogenising the ploughed layer). In view of the fact that in an arid climate it is necessary to apply several tens of litres of irrigation water (up to 50) in order to produce 1 kg of vegetables (fresh whole plants) and that furthermore, the radioelements of the residue from the crop harvest return to the soil, it can be expected that the limit of accumulation 1 kg of certain vegetables will contain as much of each radioelement as several tens of litres of irrigation water. (author) [fr

  4. The regional species richness and genetic diversity of Arctic vegetation reflect both past glaciations and current climate

    DEFF Research Database (Denmark)

    Stewart, L.; Alsos, Inger G.; Bay, Christian

    2016-01-01

    Aim The Arctic has experienced marked climatic differences between glacial and interglacial periods and is now subject to a rapidly warming climate. Knowledge of the effects of historical processes on current patterns of diversity may aid predictions of the responses of vegetation to future climate...... species richness of the vascular plant flora of 21 floristic provinces and examined local species richness in 6215 vegetation plots distributed across the Arctic. We assessed levels of genetic diversity inferred from amplified fragment length polymorphism variation across populations of 23 common Arctic...... size compared to the models of bryophyte and lichen richness. Main conclusion Our study suggests that imprints of past glaciations in Arctic vegetation diversity patterns at the regional scale are still detectable today. Since Arctic vegetation is still limited by post-glacial migration lag...

  5. A climate sensitive model of carbon transfer through atmosphere, vegetation and soil in managed forest ecosystems

    Science.gov (United States)

    Loustau, D.; Moreaux, V.; Bosc, A.; Trichet, P.; Kumari, J.; Rabemanantsoa, T.; Balesdent, J.; Jolivet, C.; Medlyn, B. E.; Cavaignac, S.; Nguyen-The, N.

    2012-12-01

    For predicting the future of the forest carbon cycle in forest ecosystems, it is necessary to account for both the climate and management impacts. Climate effects are significant not only at a short time scale but also at the temporal horizon of a forest life cycle e.g. through shift in atmospheric CO2 concentration, temperature and precipitation regimes induced by the enhanced greenhouse effect. Intensification of forest management concerns an increasing fraction of temperate and tropical forests and untouched forests represents only one third of the present forest area. Predicting tools are therefore needed to project climate and management impacts over the forest life cycle and understand the consequence of management on the forest ecosystem carbon cycle. This communication summarizes the structure, main components and properties of a carbon transfer model that describes the processes controlling the carbon cycle of managed forest ecosystems. The model, GO+, links three main components, (i) a module describing the vegetation-atmosphere mass and energy exchanges in 3D, (ii) a plant growth module and a (iii) soil carbon dynamics module in a consistent carbon scheme of transfer from atmosphere back into the atmosphere. It was calibrated and evaluated using observed data collected on coniferous and broadleaved forest stands. The model predicts the soil, water and energy balance of entire rotations of managed stands from the plantation to the final cut and according to a range of management alternatives. It accounts for the main soil and vegetation management operations such as soil preparation, understorey removal, thinnings and clearcutting. Including the available knowledge on the climatic sensitivity of biophysical and biogeochemical processes involved in atmospheric exchanges and carbon cycle of forest ecosystems, GO+ can produce long-term backward or forward simulations of forest carbon and water cycles under a range of climate and management scenarios. This

  6. Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027)

    Science.gov (United States)

    Kotthoff, U.; Greenwood, D. R.; McCarthy, F. M. G.; Müller-Navarra, K.; Prader, S.; Hesselbo, S. P.

    2014-08-01

    We investigated the palynology of sediment cores from Site M0027 of IODP (Integrated Ocean Drilling Program) Expedition 313 on the New Jersey shallow shelf to examine vegetation and climate dynamics on the east coast of North America between 33 and 13 million years ago and to assess the impact of over-regional climate events on the region. Palynological results are complemented with pollen-based quantitative climate reconstructions. Our results indicate that the hinterland vegetation of the New Jersey shelf was characterized by oak-hickory forests in the lowlands and conifer-dominated vegetation in the highlands from the early Oligocene to the middle Miocene. The Oligocene witnessed several expansions of conifer forest, probably related to cooling events. The pollen-based climate data imply an increase in annual temperatures from ∼11.5 °C to more than 16 °C during the Oligocene. The Mi-1 cooling event at the onset of the Miocene is reflected by an expansion of conifers and mean annual temperature decrease of ∼4 °C, from ∼16 °C to ∼12 °C around 23 million years before present. Relatively low annual temperatures are also recorded for several samples during an interval around ∼20 million years before present, which may reflect the Mi-1a and the Mi-1aa cooling events. Generally, the Miocene ecosystem and climate conditions were very similar to those of the Oligocene. Miocene grasslands, as known from other areas in the USA during that time period, are not evident for the hinterland of the New Jersey shelf, possibly reflecting moisture from the proto-Gulf Stream. The palaeovegetation data reveal stable conditions during the mid-Miocene climatic optimum at ∼15 million years before present, with only a minor increase in deciduous-evergreen mixed forest taxa and a decrease in swamp forest taxa. Pollen-based annual temperature reconstructions show average annual temperatures of ∼14 °C during the mid-Miocene climatic optimum, ∼2 °C higher than today

  7. Spatiotemporal Variability and Covariability of Temperature, Precipitation, Soil Moisture, and Vegetation in North America for Regional Climate Model Applications

    Science.gov (United States)

    Castro, C. L.; Beltran-Przekurat, A. B.; Pielke, R. A.

    2007-05-01

    Previous work has established that the dominant modes of Pacific SSTs influence the summer climate of North America through large-scale forcing, and this effect is most pronounced during the early part of the season. It is hypothesized, then, that land surface influences become more dominant in the latter part of the season as remote teleconnection influences diminish. As a first step toward investigation of this hypothesis in a regional climate model (RCM) framework, the statistically signficant spatiotemporal patterns of variability and covariability in North American precipitation (specified by the standardized precipitation index, or SPI), soil moisture, and vegetation are determined for timescales from a month to six months. To specify these respective data we use: CPC gauge- derived precipitation (1950-2000), Variable Infiltration Capacity (VIC) Model and NOAH Model NLDAS soil moisture and temperature, and the Global Inventory Modeling and Mapping Studies Normalized Difference Vegetation Index (GIMMS-NDVI). The principal statistical tool used is multiple taper frequency singular value decomposition (MTM-SVD), and this is supplemented by wavelet analysis for specific areas of interest. The significant interannual variability in all of these data occur at a timescale of about 7 to 9 years and appears to be the integrated effect of remote SST forcing from the Pacific. Considering the entire year, the spatial pattern for precipitation resembles the typical ENSO winter signature. If the summer season is considered seperately, the out of phase relationship between precipitation anomalies in the central U.S. and core monsoon region is apparent. The largest soil moisture anomalies occur in the central U.S., since precipitation in this region has a consistent relationship to Pacific SSTs for the entire year. This helps to explain the approximately 20 year periodicity in drought conditions there. Unlike soil moisture, the largest anomalies in vegetation occur in the

  8. Climate effects on vegetation vitality at the treeline of boreal forests of Mongolia

    Science.gov (United States)

    Klinge, Michael; Dulamsuren, Choimaa; Erasmi, Stefan; Nikolaus Karger, Dirk; Hauck, Markus

    2018-03-01

    In northern Mongolia, at the southern boundary of the Siberian boreal forest belt, the distribution of steppe and forest is generally linked to climate and topography, making this region highly sensitive to climate change and human impact. Detailed investigations on the limiting parameters of forest and steppe in different biomes provide necessary information for paleoenvironmental reconstruction and prognosis of potential landscape change. In this study, remote sensing data and gridded climate data were analyzed in order to identify main distribution patterns of forest and steppe in Mongolia and to detect environmental factors driving forest development. Forest distribution and vegetation vitality derived from the normalized differentiated vegetation index (NDVI) were investigated for the three types of boreal forest present in Mongolia (taiga, subtaiga and forest-steppe), which cover a total area of 73 818 km2. In addition to the forest type areas, the analysis focused on subunits of forest and nonforested areas at the upper and lower treeline, which represent ecological borders between vegetation types. Climate and NDVI data were analyzed for a reference period of 15 years from 1999 to 2013. The presented approach for treeline delineation by identifying representative sites mostly bridges local forest disturbances like fire or tree cutting. Moreover, this procedure provides a valuable tool to distinguish the potential forested area. The upper treeline generally rises from 1800 m above sea level (a.s.l.) in the northeast to 2700 m a.s.l. in the south. The lower treeline locally emerges at 1000 m a.s.l. in the northern taiga and rises southward to 2500 m a.s.l. The latitudinal gradient of both treelines turns into a longitudinal one on the eastern flank of mountain ranges due to higher aridity caused by rain-shadow effects. Less productive trees in terms of NDVI were identified at both the upper and lower treeline in relation to the respective total boreal forest

  9. Climate effects on vegetation vitality at the treeline of boreal forests of Mongolia

    Directory of Open Access Journals (Sweden)

    M. Klinge

    2018-03-01

    Full Text Available In northern Mongolia, at the southern boundary of the Siberian boreal forest belt, the distribution of steppe and forest is generally linked to climate and topography, making this region highly sensitive to climate change and human impact. Detailed investigations on the limiting parameters of forest and steppe in different biomes provide necessary information for paleoenvironmental reconstruction and prognosis of potential landscape change. In this study, remote sensing data and gridded climate data were analyzed in order to identify main distribution patterns of forest and steppe in Mongolia and to detect environmental factors driving forest development. Forest distribution and vegetation vitality derived from the normalized differentiated vegetation index (NDVI were investigated for the three types of boreal forest present in Mongolia (taiga, subtaiga and forest–steppe, which cover a total area of 73 818 km2. In addition to the forest type areas, the analysis focused on subunits of forest and nonforested areas at the upper and lower treeline, which represent ecological borders between vegetation types. Climate and NDVI data were analyzed for a reference period of 15 years from 1999 to 2013. The presented approach for treeline delineation by identifying representative sites mostly bridges local forest disturbances like fire or tree cutting. Moreover, this procedure provides a valuable tool to distinguish the potential forested area. The upper treeline generally rises from 1800 m above sea level (a.s.l. in the northeast to 2700 m a.s.l. in the south. The lower treeline locally emerges at 1000 m a.s.l. in the northern taiga and rises southward to 2500 m a.s.l. The latitudinal gradient of both treelines turns into a longitudinal one on the eastern flank of mountain ranges due to higher aridity caused by rain-shadow effects. Less productive trees in terms of NDVI were identified at both the upper and lower treeline in relation

  10. Middle-Late Holocene environmental history of Kulunda (Southwestern Siberia): vegetation, climate, humans

    Science.gov (United States)

    Rudaya, N.; Nazarova, L.; Papin, D.; Nourgaliev, D.

    2012-04-01

    Environmental reconstruction of Mid-Late Holocene vegetation and climate was inferred from pollen records of Lake Big Yarovoe (Kulunda steppe, Southwestern Siberia). Reconstruction suggests generally prevalence of steppe during last 4.45 ka. Relatively warm and dry climate, open semi-desert and dry steppes with patchy birch forest spread between 4.45 and 3.80 ka BP. The largest development of conifers forest started in Kulunda after 3.80 ka BP. Constant presence of dark-coniferous trees Abies and especially Picea between 3.80 and 2.7 ka BP indicates the most humid period in the region during studied time. Onset of the Late Holocene is characterised by dominance of steppe with birch and pine forests in lowlands and river valleys. After AD 1860, open steppe and semi-desert vegetation with fragmentary birch forest have been dominated parallel to sharp reduction of conifers in Kulunda. These results are in agreement with general scheme of Holocene environmental history of surrounding areas including Baraba forest-steppe, Kazakh Upland and Altai Mountains. Territory of Kulunda consists many archaeological sites of Bronze, Iron and Middle Ages. Second half of Bronze Age (4.45-3.80 ka BP) was represented by local human cultures or migrants from the North Kazakhstan. The main archaeological culture of Kulunda alike in the whole Ob`-Irtysh interfluve in this period was Elunino culture. The economical activities of Elunino community were connected with animal breeding especially with sheep and goats. The most humid period (~1795-710 BC; 3.8-2.7 ka BP) in Kulunda corresponded to the end of early Bronze Age and to the onset of the Iron Age. In 18 century BC Andronovo culture, associated with the Indo-Iranians and migrants from Central Kazakhstan, spread in the region. Cattle breeding economy was distinctive features of Andronovo people, however, increase of sheep, goats and horses with transition to nomadic life style was characteristic of the late Bronze Age. This trend is in

  11. Relationship between climate and vegetation and the stable carbon isotope chemistry of soils in the eastern Mojave Desert, Nevada

    International Nuclear Information System (INIS)

    Amundson, R.G.; Chadwick, O.A.; Sowers, J.M.; Doner, H.E.

    1988-01-01

    The relationship between the stable C-isotope composition of the soil environment and modern climate and vegetation was determined empirically along a present-day climatic transect in the eastern Mojave Desert. The δ 13 C of the soil CO 2 and carbonates decreased with increasing elevation and plant density, even though plant assemblages at all elevations were isotopically similar. Several factors, including differences in the ratios of pedogenic of limestone calcite and differences in past vegetation, were considered as explanations of this trend, However, it appears that in the sparsely vegetated Mojave Desert, the δ 13 C of pedogenic carbonate is controlled by differences in plant density and biological activity. This relationship may provide a tool for assessing past vegetational densities, as long as the vegetation is isotopically homogeneous. (author)

  12. Increasing biological diversity in a dynamic vegetation model and consequences for simulated response to climate change

    Science.gov (United States)

    Keribin, R. M.; Friend, A. D.; Purves, D.; Smith, M. J.

    2013-12-01

    Vegetation, from tropical rainforests to the tundra, is the basis of the world food chain but is also a key component of the Earth system, with biophysical and biogeochemical impacts on the global climate, and Dynamic Global Vegetation Models (DGVMs) are an important integrative tool for understanding its responses to climate change. DGVMs up to now have treated only a small number of plant types representing broad divisions in vegetation worldwide (e.g. trees and grasses, broadleaf and needleleaf, deciduousness), but these categories ignore most of the variation that exists between plant species and between individuals within a species. Research in community ecology makes it clear however that these variations can affect large-scale ecosystem properties such as productivity and resilience to environmental changes. The current challenge is for DGVMs to account for fine-grained variations between plants and a few such models are being developed using newly-available plant trait databases such as the TRY database and insights from community ecology such as habitat filtering. Hybrid is an individual-based DGVM, first published in 1993, that models plant physiology in a mechanistic way. We modified Hybrid 8, the latest version of the model which uses surface physics taken from the GISS ModelE GCM, to include a mechanistic gap-model component with individual-based variation in tree wood density. This key plant trait is known to be strongly correlated with a trade-off between growth and mortality in the majority of forests worldwide, which allows for otherwise-similar individuals to have different life-history strategies. We investigate how the inclusion of continuous variation in wood density into the model affects the ecosystem's transient dynamics under climate change.

  13. Direct and indirect drivers of instream wood in the interior Pacific Northwest, USA: decoupling climate, vegetation, disturbance, and geomorphic setting

    Directory of Open Access Journals (Sweden)

    Hough-Snee Nate

    2014-06-01

    Full Text Available Instream wood is a driver of geomorphic change in low-order streams, frequently altering morphodynamic processes. Instream wood is a frequently measured component of streams, yet it is a complex metric, responding to ecological and geomorphic forcings at a variety of scales. Here we seek to disentangle the relative importance of physical and biological processes that drive wood growth and delivery to streams across broad spatial extents. In so doing, we ask two primary questions: (1 is riparian vegetation a composite variable that captures the indirect effects of climate and disturbance on instream wood dynamics? (2 What are the direct and indirect relationships between geomorphic setting, vegetation, climate, disturbance, and instream wood dynamics? We measured riparian vegetation composition and wood frequency and volume at 720 headwater reaches within the American interior Pacific Northwest. We used ordination to identify relationships between vegetation and environmental attributes, and subsequently built a structural equation model to identify how climate and disturbance directly affect vegetation composition and how vegetation and geomorphic setting directly affect instream wood volume and frequency. We found that large wood volume and frequency are directly driven by vegetation composition and positively correlated to wildfire, elevation, stream gradient, and channel bankfull width. Indicator species at reaches with high volumes of wood were generally long-lived, conifer trees that persist for extended durations once delivered to stream habitats. Wood dynamics were also indirectly mediated by factors that shape vegetation: wildfire, precipitation, elevation, and temperature. We conclude that wood volume and frequency are driven by multiple interrelated climatic, geomorphic, and ecological variables. Vegetation composition and geomorphic setting directly mediate indirect relationships between landscape environmental processes and instream

  14. Unusual climatic conditions and infectious diseases: observations made by Hippocrates.

    Science.gov (United States)

    Falagas, Matthew E; Bliziotis, Ioannis A; Kosmidis, John; Daikos, George K

    2010-12-01

    About 2500 years ago, Hippocrates made noteworthy observations about the influence of climate on public health. He believed that people living in cities with different climate may suffer from different diseases. Hippocrates also observed that abrupt climatic changes or unusual weather conditions affect public health, especially the incidence and severity of various infectious diseases, including gastrointestinal infections, tuberculosis, and central nervous system infections. We believe that Hippocrates' scientific observations are great early historic examples that stress to modern infectious diseases researchers and clinicians the need to study intensively the effect of the occurring global climate changes to infectious diseases in order to help in the prevention of possible epidemics of infections. Copyright © 2009 Elsevier España, S.L. All rights reserved.

  15. Establishment and performance of an experimental green roof under extreme climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Petra M., E-mail: pkklein@ou.edu [School of Meteorology, University of Oklahoma, Norman, OK (United States); Coffman, Reid, E-mail: rcoffma4@kent.edu [College of Architecture and Environmental Design, Kent State University, Kent, OH (United States)

    2015-04-15

    Green roofs alter the surface energy balance and can help in mitigating urban heat islands. However, the cooling of green roofs due to evapotranspiration strongly depends on the climatic conditions, and vegetation type and density. In the Southern Central Plains of the United States, extreme weather events, such as high winds, heat waves and drought conditions pose challenges for successful implementation of green roofs, and likely alter their standard performance. The National Weather Center Experimental Green Roof, an interdisciplinary research site established in 2010 in Norman, OK, aimed to investigate the ecological performance and surface energy balance of green roof systems. Starting in May 2010, 26 months of vegetation studies were conducted and the radiation balance, air temperature, relative humidity, and buoyancy fluxes were monitored at two meteorological stations during April–October 2011. The establishment of a vegetative community trended towards prairie plant dominance. High mortality of succulents and low germination of grasses and herbaceous plants contributed to low vegetative coverage. In this condition succulent diversity declined. Bouteloua gracilis and Delosperma cooperi showed typological dominance in harsh climatic conditions, while Sedum species experienced high mortality. The plant community diversified through volunteers such as Euphorbia maculate and Portulaca maculate. Net radiation measured at a green-roof meteorological station was higher than at a control station over the original, light-colored roofing material. These findings indicate that the albedo of the green roof was lower than the albedo of the original roofing material. The low vegetative coverage during the heat and drought conditions in 2011, which resulted in the dark substrate used in the green roof containers being exposed, likely contributed to the low albedo values. Nevertheless, air temperatures and buoyancy fluxes were often lower over the green roof indicating

  16. Establishment and performance of an experimental green roof under extreme climatic conditions

    International Nuclear Information System (INIS)

    Klein, Petra M.; Coffman, Reid

    2015-01-01

    Green roofs alter the surface energy balance and can help in mitigating urban heat islands. However, the cooling of green roofs due to evapotranspiration strongly depends on the climatic conditions, and vegetation type and density. In the Southern Central Plains of the United States, extreme weather events, such as high winds, heat waves and drought conditions pose challenges for successful implementation of green roofs, and likely alter their standard performance. The National Weather Center Experimental Green Roof, an interdisciplinary research site established in 2010 in Norman, OK, aimed to investigate the ecological performance and surface energy balance of green roof systems. Starting in May 2010, 26 months of vegetation studies were conducted and the radiation balance, air temperature, relative humidity, and buoyancy fluxes were monitored at two meteorological stations during April–October 2011. The establishment of a vegetative community trended towards prairie plant dominance. High mortality of succulents and low germination of grasses and herbaceous plants contributed to low vegetative coverage. In this condition succulent diversity declined. Bouteloua gracilis and Delosperma cooperi showed typological dominance in harsh climatic conditions, while Sedum species experienced high mortality. The plant community diversified through volunteers such as Euphorbia maculate and Portulaca maculate. Net radiation measured at a green-roof meteorological station was higher than at a control station over the original, light-colored roofing material. These findings indicate that the albedo of the green roof was lower than the albedo of the original roofing material. The low vegetative coverage during the heat and drought conditions in 2011, which resulted in the dark substrate used in the green roof containers being exposed, likely contributed to the low albedo values. Nevertheless, air temperatures and buoyancy fluxes were often lower over the green roof indicating

  17. Climate-vegetation-soil interactions and long-term hydrologic partitioning: signatures of catchment co-evolution

    Directory of Open Access Journals (Sweden)

    P. A. Troch

    2013-06-01

    Full Text Available Budyko (1974 postulated that long-term catchment water balance is controlled to first order by the available water and energy. This leads to the interesting question of how do landscape characteristics (soils, geology, vegetation and climate properties (precipitation, potential evaporation, number of wet and dry days interact at the catchment scale to produce such a simple and predictable outcome of hydrological partitioning? Here we use a physically-based hydrologic model separately parameterized in 12 US catchments across a climate gradient to decouple the impact of climate and landscape properties to gain insight into the role of climate-vegetation-soil interactions in long-term hydrologic partitioning. The 12 catchment models (with different paramterizations are subjected to the 12 different climate forcings, resulting in 144 10 yr model simulations. The results are analyzed per catchment (one catchment model subjected to 12 climates and per climate (one climate filtered by 12 different model parameterization, and compared to water balance predictions based on Budyko's hypothesis (E/P = ϕ (Ep/P; E: evaporation, P: precipitation, Ep: potential evaporation. We find significant anti-correlation between average deviations of the evaporation index (E/P computed per catchment vs. per climate, compared to that predicted by Budyko. Catchments that on average produce more E/P have developed in climates that on average produce less E/P, when compared to Budyko's prediction. Water and energy seasonality could not explain these observations, confirming previous results reported by Potter et al. (2005. Next, we analyze which model (i.e., landscape filter characteristics explain the catchment's tendency to produce more or less E/P. We find that the time scale that controls subsurface storage release explains the observed trend. This time scale combines several geomorphologic and hydraulic soil properties. Catchments with relatively longer

  18. Climate change and its impacts on vegetation distribution and net primary productivity of the alpine ecosystem in the Qinghai-Tibetan Plateau.

    Science.gov (United States)

    Gao, Qingzhu; Guo, Yaqi; Xu, Hongmei; Ganjurjav, Hasbagen; Li, Yue; Wan, Yunfan; Qin, Xiaobo; Ma, Xin; Liu, Shuo

    2016-06-01

    Changes in climate have caused impacts on ecosystems on all continents scale, and climate change is also projected to be a stressor on most ecosystems even at the rate of low- to medium-range warming scenarios. Alpine ecosystem in the Qinghai-Tibetan Plateau is vulnerable to climate change. To quantify the climate change impacts on alpine ecosystems, we simulated the vegetation distribution and net primary production in the Qinghai-Tibetan Plateau for three future periods (2020s, 2050s and 2080s) using climate projection for RCPs (Representative Concentration Pathways) RCP4.5 and RCP8.5 scenarios. The modified Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ model) was parameter and test to make it applicable to the Qinghai-Tibetan Plateau. Climate projections that were applied to LPJ model in the Qinghai-Tibetan Plateau showed trends toward warmer and wetter conditions. Results based on climate projections indicated changes from 1.3°C to 4.2°C in annual temperature and changes from 2% to 5% in annual precipitation. The main impacts on vegetation distribution was increase in the area of forests and shrubs, decrease in alpine meadows which mainly replaced by shrubs which dominated the eastern plateau, and expanding in alpine steppes to the northwest dominated the western and northern plateau. The NPP was projected to increase by 79% and 134% under the RCP4.5 and RCP8.5. The projected NPP generally increased about 200gC·m(-2)·yr(-1) in most parts of the plateau with a gradual increase from the eastern to the western region of the Qinghai-Tibetan Plateau at the end of this century. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Forecasting conditional climate-change using a hybrid approach

    Science.gov (United States)

    Esfahani, Akbar Akbari; Friedel, Michael J.

    2014-01-01

    A novel approach is proposed to forecast the likelihood of climate-change across spatial landscape gradients. This hybrid approach involves reconstructing past precipitation and temperature using the self-organizing map technique; determining quantile trends in the climate-change variables by quantile regression modeling; and computing conditional forecasts of climate-change variables based on self-similarity in quantile trends using the fractionally differenced auto-regressive integrated moving average technique. The proposed modeling approach is applied to states (Arizona, California, Colorado, Nevada, New Mexico, and Utah) in the southwestern U.S., where conditional forecasts of climate-change variables are evaluated against recent (2012) observations, evaluated at a future time period (2030), and evaluated as future trends (2009–2059). These results have broad economic, political, and social implications because they quantify uncertainty in climate-change forecasts affecting various sectors of society. Another benefit of the proposed hybrid approach is that it can be extended to any spatiotemporal scale providing self-similarity exists.

  20. Risk and contributing factors of ecosystem shifts over naturally vegetated land under climate change in China.

    Science.gov (United States)

    Yin, Yuanyuan; Tang, Qiuhong; Wang, Lixin; Liu, Xingcai

    2016-02-12

    Identifying the areas at risk of ecosystem transformation and the main contributing factors to the risk is essential to assist ecological adaptation to climate change. We assessed the risk of ecosystem shifts in China using the projections of four global gridded vegetation models (GGVMs) and an aggregate metric. The results show that half of naturally vegetated land surface could be under moderate or severe risk at the end of the 21(st) century under the middle and high emission scenarios. The areas with high risk are the Tibetan Plateau region and an area extended northeastward from the Tibetan Plateau to northeast China. With the three major factors considered, the change in carbon stocks is the main contributing factor to the high risk of ecosystem shifts. The change in carbon fluxes is another important contributing factor under the high emission scenario. The change in water fluxes is a less dominant factor except for the Tibetan Plateau region under the high emission scenario. Although there is considerable uncertainty in the risk assessment, the geographic patterns of the risk are generally consistent across different scenarios. The results could help develop regional strategies for ecosystem conservation to cope with climate change.

  1. Miocene vegetation shift and climate change: Evidence from the Siwalik of Nepal

    Science.gov (United States)

    Srivastava, Gaurav; Paudayal, Khum N.; Utescher, Torsten; Mehrotra, R. C.

    2018-02-01

    We reconstruct climate and vegetation applying the Coexistence Approach (CA) methodology on two palaeofloras recovered from the Lower (middle Miocene; 13-11 Ma) and Middle Siwalik (late Miocene; 9.5-6.8 Ma) sediments of Surai Khola section, Nepal. The reconstructed mean annual temperature (MAT) and cold month mean temperature (CMT) show an increasing trend, while warm month mean temperature (WMT) remains nearly the same during the period. The reconstructed precipitation data indicates that the summer monsoon precipitation was nearly the same during the middle and late Miocene, while the winter season precipitation significantly decreased in the late Miocene. The overall precipitation infers increased rainfall seasonality during the late Miocene. The vegetation during the middle Miocene was dominated by wet evergreen taxa, whereas deciduous ones increased significantly during the late Miocene. The reconstructed climate data indicates that high temperature and significantly low precipitation during the winter season (dry season) in the late Miocene might have enhanced forest fire which favoured the expansion of C4 plants over C3 plants during the period. This idea gets further support not only from a recent forest fire in northern India that was caused by the weakening of winter precipitation, but also from the burnt wood recovered from the late Miocene Siwalik sediments of northern India.

  2. Heterogeneity in global vegetation and terrestrial climate change during the late Eocene to early Oligocene transition.

    Science.gov (United States)

    Pound, Matthew J; Salzmann, Ulrich

    2017-02-24

    Rapid global cooling at the Eocene - Oligocene Transition (EOT), ~33.9-33.5 Ma, is widely considered to mark the onset of the modern icehouse world. A large and rapid drop in atmospheric pCO 2 has been proposed as the driving force behind extinctions in the marine realm and glaciation on Antarctica. However, the global terrestrial response to this cooling is uncertain. Here we present the first global vegetation and terrestrial temperature reconstructions for the EOT. Using an extensive palynological dataset, that has been statistically grouped into palaeo-biomes, we show a more transitional nature of terrestrial climate change by indicating a spatial and temporal heterogeneity of vegetation change at the EOT in both hemispheres. The reconstructed terrestrial temperatures show for many regions a cooling that started well before the EOT and continued into the Early Oligocene. We conclude that the heterogeneous pattern of global vegetation change has been controlled by a combination of multiple forcings, such as tectonics, sea-level fall and long-term decline in greenhouse gas concentrations during the late Eocene to early Oligocene, and does not represent a single response to a rapid decline in atmospheric pCO 2 at the EOT.

  3. Projecting the Dependence of Sage-steppe Vegetation on Redistributed Snow in a Warming Climate.

    Science.gov (United States)

    Soderquist, B.; Kavanagh, K.; Link, T. E.; Seyfried, M. S.; Strand, E. K.

    2015-12-01

    In mountainous regions, the redistribution of snow by wind can increase the effective precipitation available to vegetation. Moisture subsidies caused by drifting snow may be critical to plant productivity in semi-arid ecosystems. However, with increasing temperatures, the distribution of precipitation is becoming more uniform as rain replaces drifting snow. Understanding the ecohydrological interactions between sagebrush steppe vegetation communities and the heterogeneous distribution of soil moisture is essential for predicting and mitigating future losses in ecosystem diversity and productivity in regions characterized by snow dominated precipitation regimes. To address the dependence of vegetation productivity on redistributed snow, we simulated the net primary production (NPP) of aspen, sagebrush, and C3 grass plant functional types spanning a precipitation phase (rain:snow) gradient in the Reynolds Creek Experimental Watershed and Critical Zone Observatory (RCEW-CZO). The biogeochemical process model Biome-BGC was used to simulate NPP at three sites located directly below snowdrifts that provide melt water late into the spring. To assess climate change impacts on future plant productivity, mid-century (2046-2065) NPP was simulated using the average temperature increase from the Multivariate Adaptive Constructed Analogs (MACA) data set under the RCP 8.5 emission scenario. At the driest site, mid-century projections of decreased snow cover and increased growing season evaporative demand resulted in limiting soil moisture up to 30 and 40 days earlier for aspen and sage respectively. While spring green up for aspen occurred an average of 13 days earlier under climate change scenarios, NPP remained negative up to 40 days longer during the growing season. These results indicate that the loss of the soil moisture subsidy stemming from prolonged redistributed snow water resources can directly influence ecosystem productivity in the rain:snow transition zone.

  4. Interactions between vegetation, atmospheric turbulence and clouds under a wide range of background wind conditions

    NARCIS (Netherlands)

    Sikma, M.; Ouwersloot, H.G.; Pedruzo-Bagazgoitia, X.; Heerwaarden, van C.C.; Vilà-Guerau de Arellano, J.

    2018-01-01

    The effects of plant responses to cumulus (Cu) cloud shading are studied from free convective to shear-driven boundary-layer conditions. By using a large-eddy simulation (LES) coupled to a plant physiology embedded land-surface submodel, we study the vegetation-cloud feedbacks for a wide range (44)

  5. Vegetation relevés and soil measurements in the Netherlands: the Ecological Conditions Database (EC)

    NARCIS (Netherlands)

    Wamelink, G.W.W.; Adrichem, van M.H.C.; Dobben, van H.F.; Frissel, J.Y.; Held, den M.E.; Joosten, V.; Malinowska, A.H.; Slim, P.A.; Wegman, R.M.A.

    2012-01-01

    Since its establishment around 1990, the Ecological Conditions Database (EC; GIVD ID EU-00-006) has been accumulating vegetation relevés from the Netherlands, each accompanied by at least one abiotic soil measurement (e.g. pH or nutrient availability). On 1-1-2010, the database contained 8,229

  6. Characterizing phenological vegetation dynamics amidst extreme climate variability in Australia with MODIS VI data

    Science.gov (United States)

    Broich, M.; Huete, A. R.; Xuanlon, M.; Davies, K.; Restrepo-Coupe, N.; Ratana, P.

    2012-12-01

    Australia's climate is extremely variable with inter-annual rainfall at any given site varying by 5- or 6-fold or more, across the continent. In addition to such inter-annual variability, there can be significant intra-annual variability, especially in monsoonal Australia (e.g. the wet tropical savannas) and Mediterranean climates in SW Australia where prolonged dry seasons occur each year. This presents unique challenges to the characterization of seasonal dynamics with satellite datasets. In contrast to annual reoccurring temperature-driven phenology of northern hemisphere mid-latitudes, vegetation dynamics of the vast and dry Australian interior are poorly quantified by existing remote sensing products. For example, in the current global-based MODIS phenology product, central Australia is covered by ~30% fill values for any given year. Two challenges are specific to Australian landscapes: first, the difficulty of characterizing seasonality of rainfall-driven ecosystems in interior Australia where duration and magnitude of green-up and brown down cycles show high inter annual variability; second, modeling two phenologic layers, the trees and the grass in savannas were the trees are evergreen but the herbaceous understory varies with rainfall. Savannas cover >50% of Australia. Australia's vegetation and climate are different from other continents. A MODIS phenology product capable of characterizing vegetation dynamics across the continent is being developed in this research as part of the AusCover national expert network aiming to provide Australian biophysical remote sensing data time-series and continental-scale map products. These products aim to support the Terrestrial Ecosystem Research Network (TERN) serving ecosystem research in Australia. The MODIS land surface product for Australia first searches the entire time series of each Climate Modeling Grid pixel for low-high-low extreme point sequences. A double logistic function is then fit to each of these

  7. Downscaled Climate Change Projections for the Southern Colorado Plateau: Variability and Implications for Vegetation Changes

    Science.gov (United States)

    Garfin, G. M.; Eischeid, J. K.; Cole, K. L.; Ironside, K.; Cobb, N. S.

    2008-12-01

    Recent and rapid forest mortality in western North America and associated changes in fire frequency and area burned are among the chief concerns of ecosystem managers. These examples of climate change surprises demonstrate nonlinear and threshold ecosystem responses to increased temperatures and severe drought. A consistent management request from climate change adaptation workshops held during the last four years in the southwest U.S. is for region-specific estimates of climate and vegetation change, in order to provide guidance for management of federal and state forest, range, and riparian preserves and land holdings. Partly in response to these concerns, and partly in the interest of improving knowledge of potential ecosystem changes and their relationships with observed changes and changes demonstrated in the paleoecological record, we developed a set of integrated climate and ecosystem analyses. We selected five of twenty-two GCMs from the PCMDI archive of IPCC AR4 model runs, based on their approximations of observed critical seasonality for vegetation in the Southern Colorado Plateau (domain: 35°- 38°N, 114°-107°W), centered on the Four Corners states. We used three key seasons in our analysis, winter (November-March), pre-monsoon (May-June), and monsoon (July- September). Projections of monthly and seasonal temperature and precipitation from our five-model ensemble indicate steadily increasing temperatures in our region of interest during the twenty-first century. By 2050, the ensemble projects increases of 3.0°C during May and June, months critical for drought stress and tree mortality, and 4.5-5.0°C by 2090. Projected temperature changes for months during the heart of winter (December and January) are on the order of 2.5°C by 2050 and 3.0°C by 2090; such changes are likely to affect snow hydrology in middle to low elevations in the Southern Colorado Plateau. Summer temperature increases are on the order of 2.5°C (2050) and 4.0°C (2090). The

  8. Changes in Vegetation Growth Dynamics and Relations with Climate over China’s Landmass from 1982 to 2011

    Directory of Open Access Journals (Sweden)

    Guang Xu

    2014-04-01

    Full Text Available Understanding how the dynamics of vegetation growth respond to climate change at different temporal and spatial scales is critical to projecting future ecosystem dynamics and the adaptation of ecosystems to global change. In this study, we investigated vegetated growth dynamics (annual productivity, seasonality and the minimum amount of vegetated cover in China and their relations with climatic factors during 1982–2011, using the updated Global Inventory Modeling and Mapping Studies (GIMMS third generation global satellite Advanced Very High Resolution Radiometer (AVHRR Normalized Difference Vegetation Index (NDVI dataset and climate data acquired from the National Centers for Environmental Prediction (NCEP. Major findings are as follows: (1 annual mean NDVI over China significantly increased by about 0.0006 per year from 1982 to 2011; (2 of the vegetated area in China, over 33% experienced a significant positive trend in vegetation growth, mostly located in central and southern China; about 21% experienced a significant positive trend in growth seasonality, most of which occurred in northern China (>35°N; (3 changes in vegetation growth dynamics were significantly correlated with air temperature and precipitation (p < 0.001 at a region scale; (4 at the country scale, changes in NDVI was significantly and positively correlated with annual air temperature (r = 0.52, p < 0.01 and not associated with annual precipitation (p > 0.1; (5 of the vegetated area, about 24% showed significant correlations between annual mean NDVI and air temperature (93% positive and remainder negative, and 12% showed significant correlations of annual mean NDVI with annual precipitation (65% positive and 35% negative. The spatiotemporal variations in vegetation growth dynamics were controlled primarily by temperature and secondly by precipitation. Vegetation growth was also affected by human activities; and (6 monthly NDVI was significantly correlated with the

  9. Performance of desiccant air conditioning system with geothermal energy under different climatic conditions

    International Nuclear Information System (INIS)

    El-Agouz, S.A.; Kabeel, A.E.

    2014-01-01

    Highlights: • The performance of the hybrid air conditioning system is studied. • The influence of important operating parameters are estimated. • The ventilation, makeup and mix cycles are investigated at different climate. • The highest COP of the hybrid air conditioning system is 1.03. • The hybrid system provides a human thermal comfort at different climates. - Abstract: Energy saving still and continue a major seek in our life, due to the continuous increase in energy consumptions. So, a desiccant air conditioning system with geothermal energy is conducted in the current study. The thermal analysis of air conditioning system with its different components desiccant wheel, solar collector, heat exchanger, ground heat exchanger and water spray evaporative cooler is presented. Three different air conditioning cycles are simulated in the current study for different zones like: hot-dry zone, warm-dry zone, hot-humid zone and the warm-humid zone. The results show that the desiccant air conditioning system successfully provides a better thermal comfort condition in different climates. This hybrid system significantly decreases the supplied air temperature from 12.7 to 21.7 °C at different climate zones. When ω in , air and T Reg increasing, COP decreases and the ventilation cycle provides the better COP. The highest COP value of the desiccant air conditioning system is about 1.03 while the lowest value is about 0.15. The SHR of makeup cycle is higher than that ventilation cycle at warm and hot-humid zone and vice versa at warm and hot-dry zone. The highest SHR value of the desiccant air conditioning system is about 0.99 while the lowest value is about 0.2. The T sup,air , ω sup,air , COP and SHR isolines may easily be used for pre-evaluating of various cooling cycles in different climates. The hybrid system provides a human thermal comfort at different climates

  10. A 13,500 Year Record of Holocene Climate, Fire and Vegetation from Swan Lake, Idaho, USA

    Science.gov (United States)

    Wahl, D.; Anderson, L.; Miller, D. M.; Rosario, J. J.; Starratt, S.; McGeehin, J. P.; Bright, J. E.

    2015-12-01

    Modern climate dynamics in the western US are largely determined by a combination of two factors: 1) the strength and position of midlatitude pressure systems, which, in turn, are responsible for the generation and trajectory of winter storms, and 2) the strength of the North America Monsoon (NAM) which brings summer precipitation northward in response to northern hemisphere warming. Paleoclimate records from the Great Basin of the western US suggest some coherence in the timing of major climatic shifts during the Holocene. However, knowledge of the timing and magnitude of these changes at local scales, which can help explain the relative contribution of midlatitude winter storms vs. NAM, is lacking in many places. Here we present new data that constrain the timing and magnitude of late glacial and Holocene climate variability in the northeastern Great Basin, provide insight into past spatial variability of precipitation patterns in the western US, and improve our understanding of regional scale influences on Great Basin climate. In 2011, a 7.65 m sediment core was raised from Swan Lake, a small wetland located in southeastern Idaho that was formed in the spillway channel created by the catastrophic flooding of Lake Bonneville ~18 ka BP. Pollen, charcoal, clumped isotope, diatom, ostracod, and sedimentological data are used to reconstruct vegetation, fire history, and lake level/groundwater flux over the last 13,500 years. Age control is provided by 19 AMS radiocarbon determinations, which are reported as thousands of calibrated years before present (ka BP). This effort builds on earlier work by Bright (1966) who reported on pollen, macrofossils, and sediment type from Swan Lake. Our data suggest cool and wet conditions prevailed until around 12.3 ka BP, after which a drying trend begins. The early Holocene was marked by a warmer, drier climate, which persisted until around 6.2 ka BP. Moister conditions after 6.2 ka BP likely resulted from a combination of enhanced

  11. Ozone impacts on vegetation in a nitrogen enriched and changing climate

    International Nuclear Information System (INIS)

    Mills, Gina; Harmens, Harry; Wagg, Serena; Sharps, Katrina; Hayes, Felicity; Fowler, David; Sutton, Mark; Davies, Bill

    2016-01-01

    This paper provides a process-oriented perspective on the combined effects of ozone (O_3), climate change and/or nitrogen (N) on vegetation. Whereas increasing CO_2 in controlled environments or open-top chambers often ameliorates effects of O_3 on leaf physiology, growth and C allocation, this is less likely in the field. Combined responses to elevated temperature and O_3 have rarely been studied even though some critical growth stages such as seed initiation are sensitive to both. Under O_3 exposure, many species have smaller roots, thereby enhancing drought sensitivity. Of the 68 species assessed for stomatal responses to ozone, 22.5% were unaffected, 33.5% had sluggish or increased opening and 44% stomatal closure. The beneficial effect of N on root development was lost at higher O_3 treatments whilst the effects of increasing O_3 on root biomass became more pronounced as N increased. Both responses to gradual changes in pollutants and climate and those under extreme weather events require further study. - Highlights: • CO_2 amelioration of O_3 effects on leaf physiology are less likely in the field. • Both extremes of temperature and O_3 impact on critical growth stages. • Many species are more sensitive to drought as a result of exposure to O_3 pollution. • The beneficial effect of N on root development is lost at higher O_3 treatments. • The effects of O_3 on root biomass are higher at high than low N. - A process-oriented perspective on the combined effects of ozone, climate change and/or nitrogen on vegetation.

  12. Impact of climate variability on terrestrial environment in Western Europe between 45 and 9 kyr cal. BP: vegetation dynamics recorded by the Bergsee Lake (Black Forest, Germany).

    Science.gov (United States)

    Duprat-Oualid, Fanny; Begeot, Carole; Rius, Damien; Millet, Laurent; Magny, Michel

    2016-04-01

    changes at millennial/pluri-millennial scale. The well-known afforestation of the Late-Glacial interstadial and the Holocene (with pine and hazel-dominated forests respectively) are recorded. Our results also reveal a three-phase sequence in the Last-Glacial. The persistence of very cold conditions between 24 and 30 kyr cal. BP favored a drastic steppe grassland. In contrast, trees proportion increased during the two other periods (14.7-24 and 30-45 kyr cal. BP) in correlation with a relative favorable climate. Second, the respons of vegetation to centennial scale climatic events is characterized by the successive rapid establishment of two different landscapes. GS are dominated by steppic taxa (Artemisia, Helianthemum), whereas more or less complete ecological successions Juniperus-Betula-Pinus seem to occur for most GIs when edaphic conditions became more favorable. Therefore, we suggest a global forcing defined by the strong impact of the climate variability on vegetation changes. We also propose the contribution of local characteristics (latitude, topography) which favored flora migration and long distance pollen inputs from refuge areas. Heiri O., Koinig K.A., Spötl C., Barrett S, Brauer A., Drescher-Schneider R., Gaar D., Ivy-Ochs S., Kerschner H., Luetscher M., Moran A., Nicolussi K., Preusser F., Schmidt R., Schoeneich P., Schwörer C., Sprafke T., Terhorst B., Tinner W. -2014- "Palaeoclimate records 60-8 ka in the Austrian and Swiss Alps and their forelands", Quaternary Science Review, 106 : 186-205.

  13. Possible climate warming effects on vegetation, forests, biotic (insect, pathogene) disturbances and agriculture in Central Siberia for 1960- 2050

    Science.gov (United States)

    Tchebakova, N. M.; Parfenova, E. I.; Soja, A. J.; Lysanova, G. I.; Baranchikov, Y. N.; Kuzmina, N. A.

    2012-04-01

    Regional Siberian studies have already registered climate warming over the last half a century (1960-2010). Our analysis showed that winters are already 2-3°C warmer in the north and 1-2°C warmer in the south by 2010. Summer temperatures increased by 1°C in the north and by 1-2°C in the south. Change in precipitation is more complicated, increasing on average 10% in middle latitudes and decreasing 10-20% in the south, promoting local drying in already dry landscapes. Our goal was to summarize results of research we have done for the last decade in the context of climate warming and its consequences for biosystems in Central Siberia. We modeled climate change effects on vegetation shifts, on forest composition and agriculture change, on the insect Siberian moth (Dendrolimus suprans sibiricus Tschetv) and pathogene (Lophodermium pinastri Chev) ranges in Central Siberia for a century (1960-2050) based on historical climate data and GCM-predicted data. Principal results are: In the warmer and drier climate projected by these scenarios, Siberian forests are predicted to decrease and shift northwards and forest-steppe and steppe ecosystems are predicted to dominate over 50% of central Siberia due to the dryer climate by 2080. Permafrost is not predicted to thaw deep enough to sustain dark (Pinus sibirica, Abies sibirica, and Picea obovata) taiga. Over eastern Siberia, larch (Larix dahurica) taiga is predicted to continue to be the dominant zonobiome because of its ability to withstand continuous permafrost. The model also predicts new temperate broadleaf forest and forest-steppe habitats; At least half of central Siberia is predicted to be climatically suitable for agriculture at the end of the century although potential croplands would be limited by the availability of suitable soils agriculture in central Siberia would likely benefit from climate warming Crop production may twofold increase as climate warms during the century; traditional crops (grain, potato

  14. Pollen-based reconstruction of Holocene vegetation and climate in southern Italy: the case of Lago Trifoglietti

    Directory of Open Access Journals (Sweden)

    S. Joannin

    2012-12-01

    Full Text Available A high-resolution pollen record from Lago Trifoglietti in Calabria (southern Italy provides new insights into the paleoenvironmental and palaeoclimatic changes which characterise the Holocene period in the southern Italy. The chronology is based on 11 AMS radiocarbon dates from terrestrial organic material. The Holocene history of the vegetation cover shows the persistence of an important and relatively stable Fagus forest present over that entire period, offering a rare example of a beech woodstand able to withstand climate changes for more than 11 000 yr. Probably in relation with early Holocene dry climate conditions which affected southern Italy, the Trifoglietti pollen record supports a southward delay in thermophyllous forest expansion dated to ca. 13 500 cal BP at Monticchio, ca. 11 000 cal BP at Trifoglietti, and finally ca. 9800 cal BP in Sicily. Regarding the human impact history, the Trifoglietti pollen record shows only poor imprints of agricultural activities and anthopogenic indicators, apart from those indicating pastoralism activities beneath forest cover. The selective exploitation of Abies appears to have been the strongest human impact on the Trifoglietti surroundings. On the basis of (1 a specific ratio between hygrophilous and terrestrial taxa, and (2 the Modern Analogue Technique, the pollen data collected at Lago Trifoglietti led to the establishment of two palaeoclimatic records tracing changes in (1 lake depth and (2 annual precipitation. On a millennial scale, these records give evidence of increasing moisture from ca. 11 000 to ca. 9400 cal BP and maximum humidity from ca. 9400 to ca. 6200 cal BP, prior to a general trend towards the drier climate conditions that have prevailed up to the present. In addition, several successive centennial-scale oscillations appear to have punctuated the entire Holocene. The identification of a cold dry event around 11 300 cal BP, responsible for a marked decline in

  15. Performance of three saudi arabian date palm varieties under the agro-climatic conditions of khairpur

    International Nuclear Information System (INIS)

    Soad, A.A.A.

    2013-01-01

    Date palms of 10 year old Ajwa, Safawi and Ruthana varieties from Al-Madina, Saudi Arabia were evaluated under the agro-climatic conditions of Khairpur, Sindh, Pakistan throughout the growing seasons from 2009 to 2011. The results obtained indicated better fruit quality similar to those fruits obtained from the original place of origin. The palms of the three varieties were thriving successfully. The edible stage of vars. Ajwa and Safawi is tamer and rutab for var. Ruthana. The fruit was harvested early from 13 to 20th of July before the onset of monsoons. The fruit size of vars. Ajwa, Safawi and Ruthana at their edible stages were 3.16, 4.25 and 3.52 cm long, and 2.31, 2.05 and 2.38 cm in diameter, respectively. The average fruit and seed weight of vars. Ajwa, Safawi and Ruthana were 11.42, 10.49 and 12.42 g, and 1.23, 0.88 and 1.1 g, respectively. The fruit flesh percentage in vars. Ajwa, Safawi and Ruthana reached 89.14%, 90.84% and 90.92%, respectively. It was found that the climatic conditions of Khairpur are suitable for the cultivation of these three exotic varieties. The vegetative, flowering and fruit characteristics of the three varieties were described, and the impact of climatic conditions on fruit quality was discussed in this study. (author)

  16. Vegetation Response to Changing Climate - A Case Study from Gandaki River Basin in Nepal Himalaya

    Science.gov (United States)

    Panthi, J., Sr.; Kirat, N. H.; Dahal, P.

    2015-12-01

    The climate of the Himalayan region is changing rapidly - temperature is increasingly high and rainfall has become unpredictable. IPCC predicts that average annual mean temperature over the Asian land mass, including the Himalayas, will increase by about 3°C by the 2050s and about 5°C by the 2080s and the average annual precipitation in this region will increase by 10-30% by 2080s. Climate and the human activities can influence the land cover status and the eco-environmental quality. There are enough evidences that there is strong interaction between climate variability and ecosystems. A project was carried out in Gandaki river basin in central Nepal to analyze the relationship of NDVI vegetation index with the temperature, rainfall and snowcover information. The relationships were analyzed for different landuses classes-grassland, forest and agriculture. Results show that the snowcover area is decreasing at the rate of 0.15% per year in the basin. The NDVI shows seasonal fluctuations and lightly correlated with the rainfall and temperature.

  17. Fire, climate and vegetation linkages in the Bolivian Chiquitano seasonally dry tropical forest.

    Science.gov (United States)

    Power, M J; Whitney, B S; Mayle, F E; Neves, D M; de Boer, E J; Maclean, K S

    2016-06-05

    South American seasonally dry tropical forests (SDTFs) are critically endangered, with only a small proportion of their original distribution remaining. This paper presents a 12 000 year reconstruction of climate change, fire and vegetation dynamics in the Bolivian Chiquitano SDTF, based upon pollen and charcoal analysis, to examine the resilience of this ecosystem to drought and fire. Our analysis demonstrates a complex relationship between climate, fire and floristic composition over multi-millennial time scales, and reveals that moisture variability is the dominant control upon community turnover in this ecosystem. Maximum drought during the Early Holocene, consistent with regional drought reconstructions, correlates with a period of significant fire activity between 8000 and 7000 cal yr BP which resulted in a decrease in SDTF diversity. As fire activity declined but severe regional droughts persisted through the Middle Holocene, SDTFs, including Anadenanthera and Astronium, became firmly established in the Bolivian lowlands. The trend of decreasing fire activity during the last two millennia promotes the idea among forest ecologists that SDTFs are threatened by fire. Our analysis shows that the Chiquitano seasonally dry biome has been more resilient to Holocene changes in climate and fire regime than previously assumed, but raises questions over whether this resilience will continue in the future under increased temperatures and drought coupled with a higher frequency anthropogenic fire regime.This article is part of the themed issue 'The interaction of fire and mankind'. © 2016 The Author(s).

  18. Presence of riparian vegetation increases biotic condition of fish assemblages in two Brazilian reservoirs

    Directory of Open Access Journals (Sweden)

    Fabio Cop Ferreira

    2015-09-01

    Full Text Available Abstract The riparian vegetation in lakes and reservoirs is source of course wood structures such as trunks and branches and is used as sheltering, spawning and foraging habitats for fishes. The reduction of these submerged structures can thus, affect the composition and structure of fish assemblages in reservoirs. Aim To evaluate the influence of riparian vegetation on the biotic condition of fish assemblage by adapting the Reservoir Fish Assemblage Index (RFAI to two reservoirs in the Upper Paranapanema river basin, São Paulo State, Brazil. Methods The RFAI was adapted from metrics related to the functional characteristics and composition of fish assemblages through a protocol of metric selection and validation, and to its response to the presence of riparian vegetation. Results The final RFAI was composed by nine metrics, been lower in sites without riparian vegetation as consequence of the predominance of larger individuals and the percent of piscivorous and detritivorous fishes. Conclusions These results suggest that increasing shore habitat complexity in reservoirs by maintaining riparian vegetation increases fish biotic integrity.

  19. Landscape-based hydrological modelling : Understanding the influence of climate, topography, and vegetation on catchment hydrology

    NARCIS (Netherlands)

    Gao, H.

    2015-01-01

    In this thesis, a novel landscape-based hydrological model is presented that was developed and tested in numerous catchments around the world with various landscapes and climate conditions. A landscape is considered to consist of a topography and an ecosystem living on it. Firstly, the influence of

  20. Hydrological Modeling in Northern Tunisia with Regional Climate Model Outputs: Performance Evaluation and Bias-Correction in Present Climate Conditions

    Directory of Open Access Journals (Sweden)

    Asma Foughali

    2015-07-01

    Full Text Available This work aims to evaluate the performance of a hydrological balance model in a watershed located in northern Tunisia (wadi Sejnane, 378 km2 in present climate conditions using input variables provided by four regional climate models. A modified version (MBBH of the lumped and single layer surface model BBH (Bucket with Bottom Hole model, in which pedo-transfer parameters estimated using watershed physiographic characteristics are introduced is adopted to simulate the water balance components. Only two parameters representing respectively the water retention capacity of the soil and the vegetation resistance to evapotranspiration are calibrated using rainfall-runoff data. The evaluation criterions for the MBBH model calibration are: relative bias, mean square error and the ratio of mean actual evapotranspiration to mean potential evapotranspiration. Daily air temperature, rainfall and runoff observations are available from 1960 to 1984. The period 1960–1971 is selected for calibration while the period 1972–1984 is chosen for validation. Air temperature and precipitation series are provided by four regional climate models (DMI, ARP, SMH and ICT from the European program ENSEMBLES, forced by two global climate models (GCM: ECHAM and ARPEGE. The regional climate model outputs (precipitation and air temperature are compared to the observations in terms of statistical distribution. The analysis was performed at the seasonal scale for precipitation. We found out that RCM precipitation must be corrected before being introduced as MBBH inputs. Thus, a non-parametric quantile-quantile bias correction method together with a dry day correction is employed. Finally, simulated runoff generated using corrected precipitation from the regional climate model SMH is found the most acceptable by comparison with runoff simulated using observed precipitation data, to reproduce the temporal variability of mean monthly runoff. The SMH model is the most accurate to

  1. Influence of climate variability, fire and phosphorus limitation on vegetation structure and dynamics of the Amazon-Cerrado border

    Science.gov (United States)

    Ane Dionizio, Emily; Heil Costa, Marcos; de Almeida Castanho, Andrea D.; Ferreira Pires, Gabrielle; Schwantes Marimon, Beatriz; Hur Marimon-Junior, Ben; Lenza, Eddie; Martins Pimenta, Fernando; Yang, Xiaojuan; Jain, Atul K.

    2018-02-01

    Climate, fire and soil nutrient limitation are important elements that affect vegetation dynamics in areas of the forest-savanna transition. In this paper, we use the dynamic vegetation model INLAND to evaluate the influence of interannual climate variability, fire and phosphorus (P) limitation on Amazon-Cerrado transitional vegetation structure and dynamics. We assess how each environmental factor affects net primary production, leaf area index and aboveground biomass (AGB), and compare the AGB simulations to an observed AGB map. We used two climate data sets (monthly average climate for 1961-1990 and interannual climate variability for 1948-2008), two data sets of total soil P content (one based on regional field measurements and one based on global data), and the INLAND fire module. Our results show that the inclusion of interannual climate variability, P limitation and fire occurrence each contribute to simulating vegetation types that more closely match observations. These effects are spatially heterogeneous and synergistic. In terms of magnitude, the effect of fire is strongest and is the main driver of vegetation changes along the transition. Phosphorus limitation, in turn, has a stronger effect on transitional ecosystem dynamics than interannual climate variability does. Overall, INLAND typically simulates more than 80 % of the AGB variability in the transition zone. However, the AGB in many places is clearly not well simulated, indicating that important soil and physiological factors in the Amazon-Cerrado border region, such as lithology, water table depth, carbon allocation strategies and mortality rates, still need to be included in the model.

  2. [Effects of climate and grazing on the vegetation cover change in Xilinguole League of Inner Mongolia, North China].

    Science.gov (United States)

    Wang, Hai-Mei; Li, Zheng-Hai; Wang, Zhen

    2013-01-01

    Based on the monthly temperature and precipitation data of 15 meteorological stations and the statistical data of livestock density in Xilinguole League in 1981-2007, and by using ArcGIS, this paper analyzed the spatial distribution of the climate aridity and livestock density in the League, and in combining with the ten-day data of the normalized difference vegetation index (NDVI) in 1981-2007, the driving factors of the vegetation cover change in the League were discussed. In the study period, there was a satisfactory linear regression relationship between the climate aridity and the vegetation coverage. The NDVI and the livestock density had a favorable binomial regression relationship. With the increase of NDVI, the livestock density increased first and decreased then. The vegetation coverage had a complex linear relationship with livestock density and climate aridity. The NDVI had a positive correlation with climate aridity, but a negative correlation with livestock density. Compared with livestock density, climate aridity had far greater effects on the NDVI.

  3. Ceramic production during changing environmental/climatic conditions

    Science.gov (United States)

    Oestreich, Daniela B.; Glasmacher, Ulrich A.

    2015-04-01

    Ceramics, with regard to their status as largely everlasting everyday object as well as on the basis of their chronological sensitivity, reflect despite their simplicity the technological level of a culture and therefore also, directly or indirectly, the adaptability of a culture with respect to environmental and/or climatic changes. For that reason the question arises, if it is possible to identify changes in production techniques and raw material sources for ceramic production, as a response to environmental change, e.g. climate change. This paper will present results of a research about Paracas Culture (800 - 200 BC), southern Peru. Through several investigations (e.g. Schittek et al., 2014; Eitel and Mächtle, 2009) it is well known that during Paracas period changes in climate and environmental conditions take place. As a consequence, settlement patterns shifted several times through the various stages of Paracas time. Ceramics from three different sites (Jauranga, Cutamalla, Collanco) and temporal phases of the Paracas period are detailed archaeometric, geochemical and mineralogical characterized, e.g. Raman spectroscopy, XRD, and ICP-MS analyses. The aim of this research is to resolve potential differences in the chemical composition of the Paracas ceramics in space and time and to compare the data with the data sets of pre-Columbian environmental conditions. Thus influences of changing environmental conditions on human societies and their cultural conditions will be discussed. References Eitel, B. and Mächtle, B. 2009. Man and Environment in the eastern Atacama Desert (Southern Peru): Holocene climate changes and their impact on pre-Columbian cultures. In: Reindel, M. & Wagner, G. A. (eds.) New Technologies for Archaeology. Berlin Heidelberg: Springer-Verlag. Schittek, K., Mächtle, B., Schäbitz, F., Forbriger, M., Wennrich, V., Reindel, M., and Eitel, B.. Holocene environmental changes in the highlands of the southern Peruvian Andes (14° S) and their

  4. The transferability of hydrological models under nonstationary climatic conditions

    Directory of Open Access Journals (Sweden)

    C. Z. Li

    2012-04-01

    Full Text Available This paper investigates issues involved in calibrating hydrological models against observed data when the aim of the modelling is to predict future runoff under different climatic conditions. To achieve this objective, we tested two hydrological models, DWBM and SIMHYD, using data from 30 unimpaired catchments in Australia which had at least 60 yr of daily precipitation, potential evapotranspiration (PET, and streamflow data. Nash-Sutcliffe efficiency (NSE, modified index of agreement (d1 and water balance error (WBE were used as performance criteria. We used a differential split-sample test to split up the data into 120 sub-periods and 4 different climatic sub-periods in order to assess how well the calibrated model could be transferred different periods. For each catchment, the models were calibrated for one sub-period and validated on the other three. Monte Carlo simulation was used to explore parameter stability compared to historic climatic variability. The chi-square test was used to measure the relationship between the distribution of the parameters and hydroclimatic variability. The results showed that the performance of the two hydrological models differed and depended on the model calibration. We found that if a hydrological model is set up to simulate runoff for a wet climate scenario then it should be calibrated on a wet segment of the historic record, and similarly a dry segment should be used for a dry climate scenario. The Monte Carlo simulation provides an effective and pragmatic approach to explore uncertainty and equifinality in hydrological model parameters. Some parameters of the hydrological models are shown to be significantly more sensitive to the choice of calibration periods. Our findings support the idea that when using conceptual hydrological models to assess future climate change impacts, a differential split-sample test and Monte Carlo simulation should be used to quantify uncertainties due to

  5. Quantitative reconstruction of the last interglacial vegetation and climate based on the pollen record from Lake Baikal, Russia

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, P. [Free University, Institute of Geological Sciences, Palaeontology Department, Berlin (Germany); Granoszewski, W. [Polish Geological Institute, Carpathian Branch, Krakow (Poland); Bezrukova, E.; Abzaeva, A. [Siberian Branch Russian Academy of Sciences, Institute of Geochemistry, Irkutsk (Russian Federation); Brewer, S. [CEREGE CNRS/University P. Cezanne, UMR 6635, BP80, Aix-en-Provence (France); Nita, M. [University of Silesia, Faculty of Earth Sciences, Sosnowiec (Poland); Oberhaensli, H. [GeoForschungsZentrum, Potsdam (Germany)

    2005-11-01

    Changes in mean temperature of the coldest (T{sub c}) and warmest month (T{sub w}), annual precipitation (P{sub ann}) and moisture index ({alpha}) were reconstructed from a continuous pollen record from Lake Baikal, Russia. The pollen sequence CON01-603-2 (53 57'N, 108 54'E) was recovered from a 386 m water depth in the Continent Ridge and dated to ca. 130-114.8 ky BP. This time interval covers the complete last interglacial (LI), corresponding to MIS 5e. Results of pollen analysis and pollen-based quantitative biome reconstruction show pronounced changes in the regional vegetation throughout the record. Shrubby tundra covered the area at the beginning of MIS 5e (ca. 130-128 ky), consistent with the end of the Middle Pleistocene glaciation. The late glacial climate was characterised by low winter and summer temperatures (T{sub c}{proportional_to} -38 to -35 C and T{sub w}{proportional_to}11-13 C) and low annual precipitation (P{sub ann}{proportional_to}300 mm). However, the wide spread of tundra vegetation suggests rather moist environments associated with low temperatures and evaporation (reconstructed {alpha}{proportional_to}1). Tundra was replaced by boreal conifer forest (taiga) by ca. 128 ky BP, suggesting a transition to the interglacial. Taiga-dominant phase lasted until ca. 117.4 ky BP, e.g. about 10 ky. The most favourable climate conditions occurred during the first half of the LI. P{sub ann} reached 500 mm soon after 128 ky BP. However, temperature changed more gradually. Maximum values of T{sub c}{proportional_to} -20 C and T{sub w}{proportional_to}16-17 C are reconstructed from about 126 ky BP. Conditions became gradually colder after ca. 121 ky BP. T{sub c} dropped to {proportional_to} -27 C and T{sub w} to {proportional_to}15 C by 119.5 ky BP. The reconstructed increase in continentality was accompanied by a decrease in P{sub ann} to {proportional_to}400-420 mm. However, the climate was still humid enough ({alpha}{proportional_to}0.9) to

  6. Ecoclimatic indicators to study crop suitability in present and future climatic conditionsTIC CONDITIONS

    Science.gov (United States)

    Caubel, Julie; Garcia de Cortazar Atauri, Inaki; Huard, Frédéric; Launay, Marie; Ripoche, Dominique; Gouache, David; Bancal, Marie-Odile; Graux, Anne-Isabelle; De Noblet, Nathalie

    2013-04-01

    Climate change is expected to affect both regional and global food production through changes in overall agroclimatic conditions. It is therefore necessary to develop simple tools of crop suitability diagnosis in a given area so that stakeholders can envisage land use adaptations under climate change conditions. The most common way to investigate potential impacts of climate on the evolution of agrosystems is to make use of an array of agroclimatic indicators, which provide synthetic information derived from climatic variables and calculated within fixed periods (i.e. January first - 31th July). However, the information obtained during these periods does not enable to take account of the plant response to climate. In this work, we present some results of the research program ORACLE (Opportunities and Risks of Agrosystems & forests in response to CLimate, socio-economic and policy changEs in France (and Europe). We proposed a suite of relevant ecoclimatic indicators, based on temperature and rainfall, in order to evaluate crop suitability for both present and new climatic conditions. Ecoclimatic indicators are agroclimatic indicators (e.g., grain heat stress) calculated during specific phenological phases so as to take account of the plant response to climate (e.g., the grain filling period, flowering- harvest). These indicators are linked with the ecophysiological processes they characterize (for e.g., the grain filling). To represent this methodology, we studied the suitability of winter wheat in future climatic conditions through three distinct French sites, Toulouse, Dijon and Versailles. Indicators have been calculated using climatic data from 1950 to 2100 simulated by the global climate model ARPEGE forced by a greenhouse effect corresponding to the SRES A1B scenario. The Quantile-Quantile downscaling method was applied to obtain data for the three locations. Phenological stages (emergence, ear 1 cm, flowering, beginning of grain filling and harvest) have been

  7. Vegetation Changes along the Qinghai-Tibet Plateau Engineering Corridor Since 2000 Induced by Climate Change and Human Activities

    Directory of Open Access Journals (Sweden)

    Yi Song

    2018-01-01

    Full Text Available The Qinghai-Tibet (QT Plateau Engineering Corridor is located in the hinterland of the QT Plateau, which is highly sensitive to global climate change. Climate change causes permafrost degradation, which subsequently affects vegetation growth. This study focused on the vegetation dynamics and their relationships with climate change and human activities in the region surrounding the QT Plateau Engineering Corridor. The vegetation changes were inferred by applying trend analysis, the Mann-Kendall trend test and abrupt change analysis. Six key regions, each containing 40 nested quadrats that ranged in size from 500 × 500 m to 20 × 20 km, were selected to determine the spatial scales of the impacts from different factors. Cumulative growing season integrated enhanced vegetation index (CGSIEVI values were calculated for each of the nested quadrats of different sizes to indicate the overall vegetation state over the entire year at different spatial scales. The impacts from human activities, a sudden increase in precipitation and permafrost degradation were quantified at different spatial scales using the CGSIEVI values and meteorological data based on the double mass curve method. Three conclusions were derived. First, the vegetation displayed a significant increasing trend over 23.6% of the study area. The areas displaying increases were mainly distributed in the Hoh Xil. Of the area where the vegetation displayed a significant decreasing trend, 72.4% was made up of alpine meadows. Second, more vegetation, especially the alpine meadows, has begun to degenerate or experience more rapid degradation since 2007 due to permafrost degradation and overgrazing. Finally, an active layer depth of 3 m to 3.2 m represents a limiting depth for alpine meadows.

  8. Interannual water-level fluctuations and the vegetation of prairie potholes: Potential impacts of climate change

    Science.gov (United States)

    van der Valk, Arnold; Mushet, David M.

    2016-01-01

    Mean water depth and range of interannual water-level fluctuations over wet-dry cycles in precipitation are major drivers of vegetation zone formation in North American prairie potholes. We used harmonic hydrological models, which require only mean interannual water depth and amplitude of water-level fluctuations over a wet–dry cycle, to examine how the vegetation zones in a pothole would respond to small changes in water depth and/or amplitude of water-level fluctuations. Field data from wetlands in Saskatchewan, North Dakota, and South Dakota were used to parameterize harmonic models for four pothole classes. Six scenarios in which small negative or positive changes in either mean water depth, amplitude of interannual fluctuations, or both, were modeled to predict if they would affect the number of zones in each wetland class. The results indicated that, in some cases, even small changes in mean water depth when coupled with a small change in amplitude of water-level fluctuations can shift a prairie pothole wetland from one class to another. Our results suggest that climate change could alter the relative proportion of different wetland classes in the prairie pothole region.

  9. Effect of limestone dust on vegetation in an area with a Mediterranean climate

    Energy Technology Data Exchange (ETDEWEB)

    Gale, J; Easton, J

    1979-01-01

    Possible effects of limestone dust on photosynthesis and transpiration throughout the summer season were assessed. Calculations were based on measurements of the dust accumulating on the leaves during the summer season, photosynthesis light curves of representative species, effect of dust on the optical characteristics of the leaves and stomatal diffusion resistances in the region of the quarry based on meteorological data. On a seasonal basis the dust was calculated to have only a very small effect in reducing photosynthesis and transpiration. A field experiment in which irrigated Xanthium strumarium plants were grown at different distances downwind from the quarry showed no deleterious effect of the dust even when plants close to the quarry were heavily coated. Comparison of aerial photographs taken just before the quarry was opened and 22 years later revealed no changes in the size, number or distribution pattern of the perennial, tree and shrub vegetation. It is concluded that, in an area with a Mediterranean climate, limestone dust, whilst being aesthetically offensive, does not significantly affect the growth of the natural vegetation. 13 references, 5 figures, 3 tables.

  10. Climate mitigation from vegetation biophysical feedbacks during the past three decades

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Zhenzhong [Peking Univ., Beijing (China); Piao, Shilong [Peking Univ., Beijing (China); Chinese Academy of Sciences (CAS), Beijing (China); Li, Laurent Z. X. [Sorbonne Univ. Paris (France); Zhou, Liming [State Univ. of New York (SUNY), Albany, NY (United States); Ciais, Philippe [Alternative Energies and Atomic Energy Commission (CEA), Gif-sur-Yvette (France); Wang, Tao [Chinese Academy of Sciences (CAS), Beijing (China); Li, Yue [Peking Univ., Beijing (China); Lian, Xu [Peking Univ., Beijing (China); Wood, Eric F. [Princeton Univ., NJ (United States); Friedlingstein, Pierre [Univ. of Exeter (United Kingdom); Mao, Jiafu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Estes, Lyndon D. [Princeton Univ., NJ (United States); Clark Univ., Worcester, MA (United States); Myneni, Ranga B. [Boston Univ., MA (United States); Peng, Shushi [Peking Univ., Beijing (China); Shi, Xiaoying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Seneviratne, Sonia I. [ETH Zurich (Switzerland); Wang, Yingping [Commonwealth Scientific and Industrial Research Organization (CSIRO), Aspendale, VIC (Australia)

    2017-05-22

    The surface air temperature response to vegetation changes has been studied for the extreme case of land-cover change; yet, it has never been quantified for the slow but persistent increase in leaf area index (LAI) observed over the past 30 years (Earth greening). We isolate the fingerprint of increasing LAI on surface air temperature using a coupled land–atmosphere global climate model prescribed with satellite LAI observations. Furthermore, we found that the global greening has slowed down the rise in global land-surface air temperature by 0.09 ± 0.02 °C since 1982. This net cooling effect is the sum of cooling from increased evapotranspiration (70%), changed atmospheric circulation (44%), decreased shortwave transmissivity (21%), and warming from increased longwave air emissivity (-29%) and decreased albedo (-6%). The global cooling originated from the regions where LAI has increased, including boreal Eurasia, Europe, India, northwest Amazonia, and the Sahel. Increasing LAI did not, but, significantly change surface air temperature in eastern North America and East Asia, where the effects of large-scale atmospheric circulation changes mask local vegetation feedbacks. Overall, the sum of biophysical feedbacks related to the greening of the Earth mitigated 12% of global land-surface warming for the past 30 years.

  11. Collaborative Research: Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Melillo, Jerry [Marine Biological Lab., Woods Hole, MA (United States)

    2017-12-12

    Our overall goal in this research was to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal was motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we tested the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming. In collaboration with our Purdue and MIT colleagues, we have attempted to quantify global climate warming effects on land-atmosphere interactions, land-river network interactions, permafrost degradation, vegetation shifts, and land use influence water, carbon, and nitrogen fluxes to and from terrestrial ecosystems in the pan-arctic along with their

  12. Assessment of metals bioavailability to vegetables under field conditions using DGT, single extractions and multivariate statistics

    Science.gov (United States)

    2012-01-01

    Background The metals bioavailability in soils is commonly assessed by chemical extractions; however a generally accepted method is not yet established. In this study, the effectiveness of Diffusive Gradients in Thin-films (DGT) technique and single extractions in the assessment of metals bioaccumulation in vegetables, and the influence of soil parameters on phytoavailability were evaluated using multivariate statistics. Soil and plants grown in vegetable gardens from mining-affected rural areas, NW Romania, were collected and analysed. Results Pseudo-total metal content of Cu, Zn and Cd in soil ranged between 17.3-146 mg kg-1, 141–833 mg kg-1 and 0.15-2.05 mg kg-1, respectively, showing enriched contents of these elements. High degrees of metals extractability in 1M HCl and even in 1M NH4Cl were observed. Despite the relatively high total metal concentrations in soil, those found in vegetables were comparable to values typically reported for agricultural crops, probably due to the low concentrations of metals in soil solution (Csoln) and low effective concentrations (CE), assessed by DGT technique. Among the analysed vegetables, the highest metal concentrations were found in carrots roots. By applying multivariate statistics, it was found that CE, Csoln and extraction in 1M NH4Cl, were better predictors for metals bioavailability than the acid extractions applied in this study. Copper transfer to vegetables was strongly influenced by soil organic carbon (OC) and cation exchange capacity (CEC), while pH had a higher influence on Cd transfer from soil to plants. Conclusions The results showed that DGT can be used for general evaluation of the risks associated to soil contamination with Cu, Zn and Cd in field conditions. Although quantitative information on metals transfer from soil to vegetables was not observed. PMID:23079133

  13. Mid-late Holocene climate and vegetation in northeastern part of the Altai Mountains recorded in Lake Teletskoye

    Science.gov (United States)

    Rudaya, Natalia; Nazarova, Larisa; Novenko, Elena; Babich, Valery; Kalugin, Ivan; Daryin, Andrei

    2015-04-01

    We report the first high-resolution (with intervals ca. 20-50 years) late-Holocene (4200 yr BP) pollen record from Lake Teletskoye, Altai Mountains, obtained from the underwater Ridge of Sofia Lepneva in 2006 (core Tel 2006). The study presents (i) the results of palynological analysis of Tel 2006; (ii) the results of spectral analysis of natural cycles based on the periodical fluctuation of taiga-biome curve; and (iii) quantitative reconstructions of the late-Holocene regional vegetation, woody coverage and climate in northern part of the Altai Mountains in order to define place of Northeast Altai on the map of the late-Holocene Central Asian environmental history. Late Holocene vegetation of the northeastern part of Altai recorded in Tel 2006 core is characterized by spread of dark-coniferous forest with structure similar to modern. Dominant trees, Siberian pine (Pinus sibirica) and Siberian fir (Abies sibirica), are the most ecological sensitive taxa between Siberian conifers (Shumilova, 1962), that as a whole suggests mild and humid climatic conditions during last 4200 years. However, changes of pollen taxa percentages and results of numerical analysis reveal pronounced fluctuation of climate and vegetation. Relatively cool and dry stage occurred prior to ca. 3500 cal yr BP. Open vegetation was widespread in the region with maximum deforestation and minimal July temperatures between 3800-3500 cal yr BP. Steppe-like communities with Artemisia, Chenopodiaceae and Cyperaceae could grow on the open sites around Lake Teletskoye. Reconstructed woody coverage is very low and varies between 29-35%. After ca. 3500 cal yr BP the area of dark-coniferous mountain taiga has significantly enlarged with maximums of woody coverages and taiga biome scores between ca. 2470-1040 cal yr BP. In the period of ~3500-2500 cal yr BP the averages July temperatures increased more than 1 0C. Climate became warmer and wetter. During last millennium (after 1040 cal yr BP) average July

  14. Changes in vegetation and climate as reflected in tooth enamel isotopes of Quaternary mammalian faunas from Indonesia

    Science.gov (United States)

    Janssen, Renee; Joordens, Josephine; Koutamanis, Dafne; Puspaningrum, Mika; de Vos, John; den Ouden, Natasja; van der Lubbe, Jeroen; Reijmer, John; Hampe, Oliver; Davies, Gareth; Vonhof, Hubert

    2017-04-01

    Climate and sea level fluctuations play a dominant role in the Quaternary biodiversity dynamics of Indonesia, with glacial-interglacial cycles affecting hydroclimate, vegetation, and animal migrations. We analyzed the carbon (δ13C), oxygen (δ18O), and strontium (87Sr/86Sr) isotopes of bovid, cervid, and suid teeth from several Pleistocene and Holocene sites on Java and Sumatra, in order to refine reconstructions of the paleohabitats of these faunas, gain more insight into their climatic background, and constrain their chronology. Our carbon isotope data indicate that individual sites are strongly dominated by the presence of either C3-browsers or C4-grazers. Herbivores from the Padang Highlands (Sumatra) and Hoekgrot (Java) cave faunas were mainly C3-browsers, while the studied herbivores from Homo erectus-bearing sites Trinil and Sangiran (Java) utilized an almost exclusive C4 diet. The C4 signal of Trinil herbivores confirms that the Hauptknochenschicht (Trinil HK) was deposited during glacial conditions, allowing us to hypothesize that it can be dated to MIS 16, 14 or 12. We propose that the dominant vegetation signals in Indonesian fossil sites, as revealed by δ13C data, reflect a glacial-interglacial contrast. The scarcity of δ13C values typically indicating mixed C3/C4 feeding may indicate that the transition between glacial and interglacial precipitation regimes was relatively abrupt. The observed positive correlation between δ13C and δ18O values can be attributed to the glacial-interglacial contrast between precipitation δ18O values, caused by differences in monsoon intensity. The 87Sr/86Sr data show that the dominant C4 signal observed in the Sangiran and Trinil herbivore faunas corresponds with roaming in a variety of landscape settings, corroborating our hypothesis that the δ13C values are representative of the overall C3/C4vegetation balance in these areas. These results provide a framework that will allow interpretation of future isotope data

  15. Vegetation change (1988–2010 in Camdeboo National Park (South Africa, using fixed-point photo monitoring: The role of herbivory and climate

    Directory of Open Access Journals (Sweden)

    Mmoto L. Masubelele

    2013-10-01

    Conservation implications: We provided an historical assessment of the pattern of vegetation and climatic trends that can help evaluate many of South African National Parks’ biodiversity monitoring programmes, especially relating to habitat change. It will help arid parks in assessing the trajectories of vegetation in response to herbivory, climate and management interventions.

  16. Sea Slugs, Subliminal Pictures, and Vegetative State Patients: Boundaries of Consciousness in Classical Conditioning

    Science.gov (United States)

    Bekinschtein, Tristan A.; Peeters, Moos; Shalom, Diego; Sigman, Mariano

    2011-01-01

    Classical (trace) conditioning is a specific variant of associative learning in which a neutral stimulus leads to the subsequent prediction of an emotionally charged or noxious stimulus after a temporal gap. When conditioning is concurrent with a distraction task, only participants who can report the relationship (the contingency) between stimuli explicitly show associative learning. This suggests that consciousness is a prerequisite for trace conditioning. We review and question three main controversies concerning this view. Firstly, virtually all animals, even invertebrate sea slugs, show this type of learning; secondly, unconsciously perceived stimuli may elicit trace conditioning; and thirdly, some vegetative state patients show trace learning. We discuss and analyze these seemingly contradictory arguments to find the theoretical boundaries of consciousness in classical conditioning. We conclude that trace conditioning remains one of the best measures to test conscious processing in the absence of explicit reports. PMID:22164148

  17. Sea slugs, subliminal pictures and vegetative state patients: Boundaries of consciousness in classical conditioning.

    Directory of Open Access Journals (Sweden)

    Tristan A Bekinschtein

    2011-12-01

    Full Text Available Classical (trace conditioning is a specific variant of associative learning in which a neutral stimulus leads to the subsequent prediction of an emotionally charged or noxious stimulus after a temporal gap. When conditioning is concurrent with a distraction task, only participants who can report the relationship (the contingency between stimuli explicitly show associative learning. This suggests that consciousness is a prerequisite for trace conditioning. We review and question three main controversies concerning this view. Firstly, virtually all animals, even invertebrate sea slugs, show this type of learning; secondly, unconsciously perceived stimuli may elicit trace conditioning; and thirdly, some vegetative state patients show trace learning. We discuss and analyze these seemingly contradictory arguments to find the theoretical boundaries of consciousness in classical conditioning. We conclude that trace conditioning remains one of the best measures to test conscious processing in the absence of explicit reports.

  18. Reconstructing a lost Eocene Paradise, Part II: On the utility of dynamic global vegetation models in pre-Quaternary climate studies

    Science.gov (United States)

    Shellito, Cindy J.; Sloan, Lisa C.

    2006-02-01

    Models that allow vegetation to respond to and interact with climate provide a unique method for addressing questions regarding feedbacks between the ecosystem and climate in pre-Quaternary time periods. In this paper, we consider how Dynamic Global Vegetation Models (DGVMs), which have been developed for simulations with present day climate, can be used for paleoclimate studies. We begin with a series of tests in the NCAR Land Surface Model (LSM)-DGVM with Eocene geography to examine (1) the effect of removing C 4 grasses from the available plant functional types in the model; (2) model sensitivity to a change in soil texture; and (3), model sensitivity to a change in the value of pCO 2 used in the photosynthetic rate equations. The tests were designed to highlight some of the challenges of using these models and prompt discussion of possible improvements. We discuss how lack of detail in model boundary conditions, uncertainties in the application of modern plant functional types to paleo-flora simulations, and inaccuracies in the model climatology used to drive the DGVM can affect interpretation of model results. However, we also review a number of DGVM features that can facilitate understanding of past climates and offer suggestions for improving paleo-DGVM studies.

  19. The Impact of Climate Change on Recent Vegetation Changes on Dovrefjell, Norway

    Directory of Open Access Journals (Sweden)

    Jarle Inge Holten

    2011-01-01

    Full Text Available The ongoing climate warming has been reported to affect a broad range of organisms, and mountain ecosystems are considered to be particularly sensitive because they are limited by low temperatures. Meteorological data show an increased temperature for the alpine areas at Dovrefjell, Norway, causing a prolonged growing season and increased temperature sum. As part of the worldwide project Global Observation Research Initiative in Alpine Environments (GLORIA, the short-term changes in vascular plant species richness, species composition of lichen and vascular plant communities, and abundance of single species were studied at four summits representing an altitudinal gradient from the low alpine to the high alpine zone. During the period from 2001 to 2008, an increase in species richness at the lowest summit, as well as a change in the composition of vascular plant communities, was found at the two lowest summits. The results also indicate an increase in abundance of some shrubs and graminoids and a decline in the cover of some species of lichens at the lowest summit. These changes are in accordance with climate induced changes reported in other studies, but other causes for the observed vegetation changes, in particular changes in grazing and trampling pressure, cannot be ruled out.

  20. Tundra shrubification and tree-line advance amplify arctic climate warming: results from an individual-based dynamic vegetation model

    Science.gov (United States)

    Zhang, Wenxin; Miller, Paul A.; Smith, Benjamin; Wania, Rita; Koenigk, Torben; Döscher, Ralf

    2013-09-01

    One major challenge to the improvement of regional climate scenarios for the northern high latitudes is to understand land surface feedbacks associated with vegetation shifts and ecosystem biogeochemical cycling. We employed a customized, Arctic version of the individual-based dynamic vegetation model LPJ-GUESS to simulate the dynamics of upland and wetland ecosystems under a regional climate model-downscaled future climate projection for the Arctic and Subarctic. The simulated vegetation distribution (1961-1990) agreed well with a composite map of actual arctic vegetation. In the future (2051-2080), a poleward advance of the forest-tundra boundary, an expansion of tall shrub tundra, and a dominance shift from deciduous to evergreen boreal conifer forest over northern Eurasia were simulated. Ecosystems continued to sink carbon for the next few decades, although the size of these sinks diminished by the late 21st century. Hot spots of increased CH4 emission were identified in the peatlands near Hudson Bay and western Siberia. In terms of their net impact on regional climate forcing, positive feedbacks associated with the negative effects of tree-line, shrub cover and forest phenology changes on snow-season albedo, as well as the larger sources of CH4, may potentially dominate over negative feedbacks due to increased carbon sequestration and increased latent heat flux.

  1. Simulating the Holocene climate evolution at northern high latitudes using a coupled atmosphere-sea ice-ocean-vegetation model

    NARCIS (Netherlands)

    Renssen, H.; Goosse, H.; Fichefet, T.; Brovkin, V.; Driesschaert, E.; Wolk, F.

    2005-01-01

    The response of the climate at high northern latitudes to slowly changing external forcings was studied in a 9,000-year long simulation with the coupled atmosphere-sea ice-ocean-vegetation model ECBilt-CLIO-VECODE. Only long-term changes in insolation and atmospheric CO

  2. Tundra shrubification and tree-line advance amplify arctic climate warming: results from an individual-based dynamic vegetation model

    International Nuclear Information System (INIS)

    Zhang Wenxin; Miller, Paul A; Smith, Benjamin; Wania, Rita; Koenigk, Torben; Döscher, Ralf

    2013-01-01

    One major challenge to the improvement of regional climate scenarios for the northern high latitudes is to understand land surface feedbacks associated with vegetation shifts and ecosystem biogeochemical cycling. We employed a customized, Arctic version of the individual-based dynamic vegetation model LPJ-GUESS to simulate the dynamics of upland and wetland ecosystems under a regional climate model–downscaled future climate projection for the Arctic and Subarctic. The simulated vegetation distribution (1961–1990) agreed well with a composite map of actual arctic vegetation. In the future (2051–2080), a poleward advance of the forest–tundra boundary, an expansion of tall shrub tundra, and a dominance shift from deciduous to evergreen boreal conifer forest over northern Eurasia were simulated. Ecosystems continued to sink carbon for the next few decades, although the size of these sinks diminished by the late 21st century. Hot spots of increased CH 4 emission were identified in the peatlands near Hudson Bay and western Siberia. In terms of their net impact on regional climate forcing, positive feedbacks associated with the negative effects of tree-line, shrub cover and forest phenology changes on snow-season albedo, as well as the larger sources of CH 4 , may potentially dominate over negative feedbacks due to increased carbon sequestration and increased latent heat flux. (letter)

  3. Diverging responses of tropical Andean biomes under future climate conditions.

    Directory of Open Access Journals (Sweden)

    Carolina Tovar

    Full Text Available Observations and projections for mountain regions show a strong tendency towards upslope displacement of their biomes under future climate conditions. Because of their climatic and topographic heterogeneity, a more complex response is expected for biodiversity hotspots such as tropical mountain regions. This study analyzes potential changes in the distribution of biomes in the Tropical Andes and identifies target areas for conservation. Biome distribution models were developed using logistic regressions. These models were then coupled to an ensemble of 8 global climate models to project future distribution of the Andean biomes and their uncertainties. We analysed projected changes in extent and elevational range and identified regions most prone to change. Our results show a heterogeneous response to climate change. Although the wetter biomes exhibit an upslope displacement of both the upper and the lower boundaries as expected, most dry biomes tend to show downslope expansion. Despite important losses being projected for several biomes, projections suggest that between 74.8% and 83.1% of the current total Tropical Andes will remain stable, depending on the emission scenario and time horizon. Between 3.3% and 7.6% of the study area is projected to change, mostly towards an increase in vertical structure. For the remaining area (13.1%-17.4%, there is no agreement between model projections. These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions. Instead, our models project diverging responses, including downslope expansion and large areas projected to remain stable. Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management. This, and the inclusion of a comprehensive uncertainty analysis, will help to inform conservation strategies in the Tropical Andes, and to guide similar

  4. Modelling climate change impacts on stream habitat conditions

    DEFF Research Database (Denmark)

    Boegh, Eva; Conallin, John; Karthikeyan, Matheswaran

    Impact from groundwater abstraction on freshwater resources and ecosystems is an issue of sincere concern in Denmark and many other countries worldwide. In addition, climate change projections add complexity to the existing conflict between water demands to satisfy human needs and water demands...... required to conserve streams as biologically diverse and healthy ecosystems. Solutions to this intensifying conflict require a holistic approach whereby stream biota is related to their physical environment at catchment scale, as also demanded by the EU Water Framework Directive. In the present study......, climate impacts on stream ecological conditions were quantified by combining a heat and mass stream flow with a habitat suitability modelling approach. Habitat suitability indices were developed for stream velocity, water depth, water temperature and substrate. Generally, water depth was found...

  5. Changing climatic conditions in the Upper Thames River Basin

    International Nuclear Information System (INIS)

    Simonovic, S.P.

    2009-01-01

    'Full text:' Many climate change impact studies have been conducted using a top-down approach. First, outputs from Global Circulation Models (GCMs) are considered which are downscaled in a second step to the river basin scale using either a statistical/empirical or a dynamic approach. The local climatic signal that is obtained is then used as input into a hydrological model to assess the direct consequences in the basin. Problems related to this approach include: a high degree of uncertainty associated with GCM outputs; and an increase in uncertainty due to the downscaling approach. An original inverse approach is developed in this work in order to improve the understanding of the processes leading to hydrological hazards, including both flood and drought events. The developed approach starts with the analysis of existing guidelines and management practices in a river basin with respect to critical hydrological exposures that may lead to failure of the water resources system or parts thereof. This implies that vulnerable components of the river basin have to be identified together with the risk exposure. In the next step the critical hydrologic exposures (flood levels for example) are transformed into corresponding critical meteorological conditions (extreme precipitation events for example). These local weather scenarios are then be statistically linked to possible large-scale climate conditions that are available from the GCMs. The developed procedure allows for the assessment of the vulnerability of river basins with respect to climate forcing. It also provides a tool for identifying the spatial distribution of the vulnerability and risk. Vulnerability is here characterized by the incremental losses, expressed either quantitatively or qualitatively, due to a change in the probability and magnitude of hazard events driven by climatic forcing. Vulnerability is seen as the basis for risk mitigation measures for hydrologic extremes at the basin level. The

  6. Future aridity under conditions of global climate change

    Science.gov (United States)

    Asadi Zarch, Mohammad Amin; Sivakumar, Bellie; Malekinezhad, Hossein; Sharma, Ashish

    2017-11-01

    Global climate change is anticipated to cause some major changes in hydroclimatic conditions around the world. As aridity is a reliable indicator of potential available water, assessment of its changes under future climatic conditions is important for proper management of water. This study employs the UNESCO aridity/humidity index, which is a derivative of precipitation (P) and potential evapotranspiration (PET), for assessment of aridity. Historical (1901-2005) simulations and future (2006-2100) projections of 22 global climate models (GCMs) from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) are studied. The Nested Bias Correction (NBC) approach is used to correct possible biases of precipitation (simulated directly by the GCMs) and PET (estimated by applying FAO56-Penman-Monteith model on simulated parameters of the GCMs). To detect future aridity changes, the areal extents of the aridity zones in the past and future periods as well as through four sub-periods (2006-2025, 2026-2050, 2051-2075, and 2076-2100) of the future are compared. The results indicate that changes in climate will alter the areal extents of aridity zones in the future. In general, from the first sub-period towards the last one, the area covered by hyper-arid, arid, semi-arid, and sub-humid zones will increase (by 7.46%, 7.01%, 5.80%, and 2.78%, respectively), while the area of the humid regions will decrease (by 4.76%), suggesting that there will be less water over the global land area in the future. To understand the cause of these changes, precipitation and PET are also separately assumed to be stationary throughout the four future sub-periods and the resulting aridity changes are then analyzed. The results reveal that the aridity changes are mostly caused by the positive PET trends, even though the slight precipitation increase lessens the magnitude of the changes.

  7. Holocene vegetation and climatic variations in Central India: A study based on multiproxy evidences

    Science.gov (United States)

    Chauhan, M. S.; Sharma, Anupam; Phartiyal, Binita; Kumar, Kamlesh

    2013-11-01

    Palynology, texture, mineralogy, geochemistry, and magnetic susceptibility analysis of a 2 m deep sediment core from Padauna Swamp, southeastern Madhya Pradesh infers that between 8600 and 7500 cal yr BP a warm and relatively less-humid climate prevailed with open tree-savannahs dominated by grasses followed by sedges, Artemisia and members of Chenopodiaceae/Amaranthaceae with scanty trees viz., Schrebera, Aegle marmelos and Sterculia urens. This is well supported by lower organic to carbonate carbon ratio, coarser texture having relatively low CIA and magnetic susceptibility values and presence of some primary minerals. Between 7500 and 6250 cal yr BP the tree-savannahs were succeeded by open mixed deciduous forests with the invasion of a few more trees viz., Madhuca indica, Holoptelea, Emblica officinalis, Mitragyna parvifolia and members of Anacardiaceae in response to onset of a warm and humid climate. A considerable rise in organic carbon generated from the degradation of plentiful biomass along with increase in clay content with signs of kaolinite and increase in immobile over mobile elements with slightly higher CIA and magnetic susceptibility values also suggest climatic amelioration. The presence of ruderal plants such as Artemisia, Cannabis sativa and Cheno/Am further infers initiation of human activities in the region. Between 6250 and 2800 cal yr BP, the mixed deciduous forests became more diverse and dense, subduing grasses and other herbaceous elements. Sporadic incursion of Shorea robusta (Sal) in forest floristic was recorded around 5000 cal yr BP. The overall change in the vegetation mosaic reflects that a warm and more-humid climate prevailed in the region, probably on account of invigoration of southwest monsoon. This observation is further corroborated by other proxy data showing a spurt in organic/inorganic carbon ratio, increase in clay content with matured mineralogy, significantly higher CIA and magnetic susceptibility values. Since 2800 cal

  8. Responses of Vegetation Growth to Climatic Factors in Shule River Basin in Northwest China: A Panel Analysis

    Directory of Open Access Journals (Sweden)

    Jinghui Qi

    2017-03-01

    Full Text Available The vegetation response to climatic factors is a hot topic in global change research. However, research on vegetation in Shule River Basin, which is a typical arid region in northwest China, is still limited, especially at micro scale. On the basis of Moderate-resolution Imaging Spectroradiometer (MODIS Normalized Difference Vegetation Index (NDVI data and daily meteorological data, employing panel data models and other mathematical models, the aim of this paper is to reveal the interactive relationship between vegetation variation and climatic factors in Shule River Basin. Results show that there is a widespread greening trend in the whole basin during 2000–2015, and 80.28% of greening areas (areas with vegetation improvement are distributed over upstream region, but the maximum vegetation variation appears in downstream area. The effects of climate change on NDVI lag about half to one month. The parameters estimated using panel data models indicate that precipitation and accumulated temperature have positive contribution to NDVI. With every 1-mm increase in rainfall, NDVI increases by around 0.223‰ in upstream area and 0.6‰ in downstream area. With every 1-°C increase in accumulated temperature, NDVI increases by around 0.241‰ in upstream area and 0.174‰ in downstream area. Responses of NDVI to climatic factors are more sensitive when these factors are limiting than when they are not limiting. NDVI variation has performance in two seasonal and inter-annual directions, and the range of seasonal change is far more than that of inter-annual change. The inverted U-shaped curve of the variable intercepts reflects the seasonal change. Our results might provide some scientific basis for the comprehensive basin management.

  9. Potential impacts of projected climate change on vegetation management in Hawai`i Volcanoes National Park

    Science.gov (United States)

    Camp, Richard J.; Loh, Rhonda; Berkowitz, S. Paul; Brinck, Kevin W.; Jacobi, James D.; Price, Jonathan; McDaniel, Sierra; Fortini, Lucas B.

    2018-01-01

    Climate change will likely alter the seasonal and annual patterns of rainfall and temperature in Hawai`i. This is a major concern for resource managers at Hawai`i Volcanoes National Park where intensely managed Special Ecological Areas (SEAs), focal sites for managing rare and endangered plants, may no longer provide suitable habitat under future climate. Expanding invasive species’ distributions also may pose a threat to areas where native plants currently predominate. We combine recent climate modeling efforts for the state of Hawai`i with plant species distribution models to forecast changes in biodiversity in SEAs under future climate conditions. Based on this bioclimatic envelope model, we generated projected species range maps for four snapshots in time (2000, 2040, 2070, and 2090) to assess whether the range of 39 native and invasive species of management interest are expected to contract, expand, or remain the same under a moderately warmer and more variable precipitation scenario. Approximately two-thirds of the modeled native species were projected to contract in range, while one-third were shown to increase. Most of the park’s SEAs were projected to lose a majority of the native species modeled. Nine of the 10 modeled invasive species were projected to contract within the park; this trend occurred in most SEAs, including those at low, middle, and high elevations. There was good congruence in the current (2000) distribution of species richness and SEA configuration; however, the congruence between species richness hotspots and SEAs diminished by the end of this century. Over time the projected species-rich hotspots increasingly occurred outside of current SEA boundaries. Our research brought together managers and scientists to increase understanding of potential climate change impacts, and provide needed information to address how plants may respond under future conditions relative to current managed areas.

  10. Do downscaled general circulation models reliably simulate historical climatic conditions?

    Science.gov (United States)

    Bock, Andrew R.; Hay, Lauren E.; McCabe, Gregory J.; Markstrom, Steven L.; Atkinson, R. Dwight

    2018-01-01

    The accuracy of statistically downscaled (SD) general circulation model (GCM) simulations of monthly surface climate for historical conditions (1950–2005) was assessed for the conterminous United States (CONUS). The SD monthly precipitation (PPT) and temperature (TAVE) from 95 GCMs from phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5) were used as inputs to a monthly water balance model (MWBM). Distributions of MWBM input (PPT and TAVE) and output [runoff (RUN)] variables derived from gridded station data (GSD) and historical SD climate were compared using the Kolmogorov–Smirnov (KS) test For all three variables considered, the KS test results showed that variables simulated using CMIP5 generally are more reliable than those derived from CMIP3, likely due to improvements in PPT simulations. At most locations across the CONUS, the largest differences between GSD and SD PPT and RUN occurred in the lowest part of the distributions (i.e., low-flow RUN and low-magnitude PPT). Results indicate that for the majority of the CONUS, there are downscaled GCMs that can reliably simulate historical climatic conditions. But, in some geographic locations, none of the SD GCMs replicated historical conditions for two of the three variables (PPT and RUN) based on the KS test, with a significance level of 0.05. In these locations, improved GCM simulations of PPT are needed to more reliably estimate components of the hydrologic cycle. Simple metrics and statistical tests, such as those described here, can provide an initial set of criteria to help simplify GCM selection.

  11. Application-Ready Expedited MODIS Data for Operational Land Surface Monitoring of Vegetation Condition

    Directory of Open Access Journals (Sweden)

    Jesslyn F. Brown

    2015-12-01

    Full Text Available Monitoring systems benefit from high temporal frequency image data collected from the Moderate Resolution Imaging Spectroradiometer (MODIS system. Because of near-daily global coverage, MODIS data are beneficial to applications that require timely information about vegetation condition related to drought, flooding, or fire danger. Rapid satellite data streams in operational applications have clear benefits for monitoring vegetation, especially when information can be delivered as fast as changing surface conditions. An “expedited” processing system called “eMODIS” operated by the U.S. Geological Survey provides rapid MODIS surface reflectance data to operational applications in less than 24 h offering tailored, consistently-processed information products that complement standard MODIS products. We assessed eMODIS quality and consistency by comparing to standard MODIS data. Only land data with known high quality were analyzed in a central U.S. study area. When compared to standard MODIS (MOD/MYD09Q1, the eMODIS Normalized Difference Vegetation Index (NDVI maintained a strong, significant relationship to standard MODIS NDVI, whether from morning (Terra or afternoon (Aqua orbits. The Aqua eMODIS data were more prone to noise than the Terra data, likely due to differences in the internal cloud mask used in MOD/MYD09Q1 or compositing rules. Post-processing temporal smoothing decreased noise in eMODIS data.

  12. Challenges of using air conditioning in an increasingly hot climate

    Science.gov (United States)

    Lundgren-Kownacki, Karin; Hornyanszky, Elisabeth Dalholm; Chu, Tuan Anh; Olsson, Johanna Alkan; Becker, Per

    2018-03-01

    At present, air conditioning (AC) is the most effective means for the cooling of indoor space. However, its increased global use is problematic for various reasons. This paper explores the challenges linked to increased AC use and discusses more sustainable alternatives. A literature review was conducted applying a transdisciplinary approach. It was further complemented by examples from cities in hot climates. To analyse the findings, an analytical framework was developed which considers four societal levels—individual, community, city, and national. The main challenges identified from the literature review are as follows: environmental, organisational, socio-economical, biophysical and behavioural. The paper also identifies several measures that could be taken to reduce the fast growth of AC use. However, due to the complex nature of the problem, there is no single solution to provide sustainable cooling. Alternative solutions were categorised in three broad categories: climate-sensitive urban planning and building design, alternative cooling technologies, and climate-sensitive attitudes and behaviour. The main findings concern the problems arising from leaving the responsibility to come up with cooling solutions entirely to the individual, and how different societal levels can work towards more sustainable cooling options. It is concluded that there is a need for a more holistic view both when it comes to combining various solutions as well as involving various levels in society.

  13. Using remotely sensed vegetation indices to model ecological pasture conditions in Kara-Unkur watershed, Kyrgyzstan

    Science.gov (United States)

    Masselink, Loes; Baartman, Jantiene; Verbesselt, Jan; Borchardt, Peter

    2017-04-01

    Kyrgyzstan has a long history of nomadic lifestyle in which pastures play an important role. However, currently the pastures are subject to severe grazing-induced degradation. Deteriorating levels of biomass, palatability and biodiversity reduce the pastures' productivity. To counter this and introduce sustainable pasture management, up-to-date information regarding the ecological conditions of the pastures is essential. This research aimed to investigate the potential of a remote sensing-based methodology to detect changing ecological pasture conditions in the Kara-Unkur watershed, Kyrgyzstan. The relations between Vegetation Indices (VIs) from Landsat ETM+ images and biomass, palatability and species richness field data were investigated. Both simple and multiple linear regression (MLR) analyses, including terrain attributes, were applied. Subsequently, trends of these three pasture conditions were mapped using time series analysis. The results show that biomass is most accurately estimated by a model including the Modified Soil Adjusted Vegetation Index (MSAVI) and a slope factor (R2 = 0.65, F = 0.0006). Regarding palatability, a model including the Enhanced Vegetation Index (EVI), Northness Index, Near Infrared (NIR) and Red band was most accurate (R2 = 0.61, F = 0.0160). Species richness was most accurately estimated by a model including Topographic Wetness Index (TWI), Eastness Index and estimated biomass (R2 = 0.81, F = 0.0028). Subsequent trend analyses of all three estimated ecological pasture conditions presented very similar trend patterns. Despite the need for a more robust validation, this study confirms the high potential of a remote sensing based methodology to detect changing ecological pasture conditions.

  14. Centennial-scale vegetation dynamics and climate variability in SE Europe during Marine Isotope Stage 11 based on a pollen record from Lake Ohrid

    Science.gov (United States)

    Kousis, Ilias; Koutsodendris, Andreas; Peyron, Odile; Leicher, Niklas; Francke, Alexander; Wagner, Bernd; Giaccio, Biagio; Knipping, Maria; Pross, Jörg

    2018-06-01

    To better understand climate variability during Marine Isotope Stage (MIS) 11, we here present a new, centennial-scale-resolution pollen record from Lake Ohrid (Balkan Peninsula) derived from sediment cores retrieved during an International Continental Scientific Drilling Program (ICDP) campaign. Our palynological data, augmented by quantitative pollen-based climate reconstructions, provide insight into the vegetation dynamics and thus also climate variability in SE Europe during one of the best orbital analogues for the Holocene. Comparison of our palynological results with other proxy data from Lake Ohrid as well as with regional and global climate records shows that the vegetation in SE Europe responded sensitively both to long- and short-term climate change during MIS 11. The chronology of our palynological record is based on orbital tuning, and is further supported by the detection of a new tephra from the Vico volcano, central Italy, dated to 410 ± 2 ka. Our study indicates that MIS 11c (∼424-398 ka) was the warmest interval of MIS 11. The younger part of the interglacial (i.e., MIS 11b-11a; ∼398-367 ka) exhibits a gradual cooling trend passing over into MIS 10. It is characterized by considerable millennial-scale variability as inferred by six abrupt forest-contraction events. Interestingly, the first forest contraction occurred during full interglacial conditions of MIS 11c; this event lasted for ∼1.7 kyrs (406.2-404.5 ka) and was characterized by substantial reductions in winter temperature and annual precipitation. Most notably, it occurred ∼7 ka before the end of MIS 11c and ∼15 ka before the first strong ice-rafted debris event in the North Atlantic. Our findings suggest that millennial-scale climate variability during MIS 11 was established in Southern Europe already during MIS 11c, which is earlier than in the North Atlantic where it is registered only from MIS 11b onwards.

  15. Impact of boiling conditions on the molecular and sensory profile of a vegetable broth.

    Science.gov (United States)

    Mougin, Alice; Mauroux, Olivier; Matthey-Doret, Walter; Barcos, Eugenia Maria; Beaud, Fernand; Bousbaine, Ahmed; Viton, Florian; Smarrito-Menozzi, Candice

    2015-02-11

    Low-pressure cooking has recently been identified as an alternative to ambient and high-pressure cooking to provide food with enhanced organoleptic properties. This work investigates the impact of the cooking process at different pressures on the molecular and sensory profile of a vegetable broth. Experimental results showed similar sensory and chemical profiles of vegetable broths when boiling at 0.93 and 1.5 bar, while an enhancement of sulfur volatile compounds correlated with a greater leek content and savory aroma was observed when boiling at low pressure (80 °C/0.48 bar). Thus, low-pressure cooking would allow preserving the most labile volatiles likely due to the lower water boiling temperature and the reduced level of oxygen. This study evidenced chemical and sensory impact of pressure during cooking and demonstrated that the flavor profile of culinary preparations can be enhanced by applying low-pressure conditions.

  16. The effects of climatic conditions on attitudinal changes towards ...

    African Journals Online (AJOL)

    changes associated with climate change and climatic events. The .... influence of rainfall on differences in perceptions towards building materials in poor ...... in the form of flash floods, cloud bursts, or sudden climatic events. Unusually high or ...

  17. The Energy Impact in Buildings of Vegetative Solutions for Extensive Green Roofs in Temperate Climates

    Directory of Open Access Journals (Sweden)

    Benedetta Barozzi

    2016-08-01

    Full Text Available Many bibliographical studies have highlighted the positive effects of green roofs as technological solutions both for new and renovated buildings. The one-year experimental monitoring campaign conducted has investigated, in detail, some aspects related to the surface temperature variation induced by the presence of different types of vegetation compared to traditional finishing systems for flat roofs and their impact from an energy and environmental point of view. The results obtained underlined how an appropriate vegetative solution selection can contribute to a significant reduction of the external surface temperatures (10 °C–20 °C for I > 500 W/m2 and 0 °C–5 °C for I < 500 W/m2, regardless of the season compared to traditional flat roofs. During the winter season, the thermal gradients of the planted surface temperatures are close to zero compared to the floor, except under special improving conditions. This entails a significant reduction of the energy loads from summer air conditioning, and an almost conservative behavior with respect to that from winter heating consumption. The analysis of the inside growing medium temperatures returned a further interesting datum, too: the temperature gradient with respect to surface temperature (annual average 4 °C–9 °C is a function of solar radiation and involves the insulating contribution of the soil.

  18. Projection of climatic suitability for Aedes albopictus Skuse (Culicidae) in Europe under climate change conditions

    Science.gov (United States)

    Fischer, Dominik; Thomas, Stephanie Margarete; Niemitz, Franziska; Reineking, Björn; Beierkuhnlein, Carl

    2011-07-01

    During the last decades the disease vector Aedes albopictus ( Ae. albopictus) has rapidly spread around the globe. The spread of this species raises serious public health concerns. Here, we model the present distribution and the future climatic suitability of Europe for this vector in the face of climate change. In order to achieve the most realistic current prediction and future projection, we compare the performance of four different modelling approaches, differentiated by the selection of climate variables (based on expert knowledge vs. statistical criteria) and by the geographical range of presence records (native range vs. global range). First, models of the native and global range were built with MaxEnt and were either based on (1) statistically selected climatic input variables or (2) input variables selected with expert knowledge from the literature. Native models show high model performance (AUC: 0.91-0.94) for the native range, but do not predict the European distribution well (AUC: 0.70-0.72). Models based on the global distribution of the species, however, were able to identify all regions where Ae. albopictus is currently established, including Europe (AUC: 0.89-0.91). In a second step, the modelled bioclimatic envelope of the global range was projected to future climatic conditions in Europe using two emission scenarios implemented in the regional climate model COSMO-CLM for three time periods 2011-2040, 2041-2070, and 2071-2100. For both global-driven models, the results indicate that climatically suitable areas for the establishment of Ae. albopictus will increase in western and central Europe already in 2011-2040 and with a temporal delay in eastern Europe. On the other hand, a decline in climatically suitable areas in southern Europe is pronounced in the Expert knowledge based model. Our projections appear unaffected by non-analogue climate, as this is not detected by Multivariate Environmental Similarity Surface analysis. The generated risk maps

  19. Analysis of agricultural drought using vegetation temperature condition index (VTCI) from Terra/MODIS satellite data.

    Science.gov (United States)

    Patel, N R; Parida, B R; Venus, V; Saha, S K; Dadhwal, V K

    2012-12-01

    The most commonly used normalized difference vegetation index (NDVI) from remote sensing often fall short in real-time drought monitoring due to a lagged vegetation response to drought. Therefore, research recently emphasized on the use of combination of surface temperature and NDVI which provides vegetation and moisture conditions simultaneously. Since drought stress effects on agriculture are closely linked to actual evapotranspiration, we used a vegetation temperature condition index (VTCI) which is more closely related to crop water status and holds a key place in real-time drought monitoring and assessment. In this study, NDVI and land surface temperature (T (s)) from MODIS 8-day composite data during cloud-free period (September-October) were adopted to construct an NDVI-T (s) space, from which the VTCI was computed. The crop moisture index (based on estimates of potential evapotranspiration and soil moisture depletion) was calculated to represent soil moisture stress on weekly basis for 20 weather monitoring stations. Correlation and regression analysis were attempted to relate VTCI with crop moisture status and crop performance. VTCI was found to accurately access the degree and spatial extent of drought stress in all years (2000, 2002, and 2004). The temporal variation of VTCI also provides drought pattern changes over space and time. Results showed significant and positive relations between CMI (crop moisture index) and VTCI observed particularly during prominent drought periods which proved VTCI as an ideal index to monitor terminal drought at regional scale. VTCI had significant positive relationship with yield but weakly related to crop anomalies. Duration of terminal drought stress derived from VTCI has a significant negative relationship with yields of major grain and oilseeds crops, particularly, groundnut.

  20. Vegetation, climate and fire-dynamics in East Africa inferred from the Maundi crater pollen record from Mt Kilimanjaro during the last glacial-interglacial cycle

    Science.gov (United States)

    Schüler, Lisa; Hemp, Andreas; Zech, Wolfgang; Behling, Hermann

    2012-04-01

    The pollen, charcoal and sedimentological record from the Maundi crater, located at 2780 m elevation on the south-eastern slope of Mt Kilimanjaro, is one of the longest terrestrial records in equatorial East Africa, giving an interesting insight into the vegetation and climate dynamics back to the early last Glacial period. Our sediment record has a reliable chronology until 42 ka BP. An extrapolation of the age-depth model, as well as matching with other palaeo-records from tropical East Africa, suggest a total age of about 90 ka BP at the bottom of the record. During the last Glacial the distribution as well as the composition of the vegetation belts classified as colline savanna, submontane woodland, montane forest, ericaceous belt, and alpine vegetation changed. The early last Glacial is characterized by high amounts of Poaceae and Asteraceae pollen suggesting a climatically dry but stable phase. Based on the absence of pollen grains in samples deposited around 70 ka BP, we assume the occurrence of distinct drought periods. During the pre-LGM (Last Glacial Maximum) a higher taxa diversity of the ericaceous and montane zone is recorded and suggests a spread of forest and shrub vegetation, thus indicating a more humid period. The taxa diversity increases steadily during the recorded time span. The decent of vegetation zones indicate dry and cold conditions during the LGM and seem to have been detrimental for many taxa, especially those of the forest vegetation; however, the early last Glacial seems to have been markedly drier than the LGM. The reappearance of most of the taxa (most importantly Alchemilla, Araliaceae, Dodonea, Hagenia, Ilex, Myrsine, Moraceae, Piperaceae) during the deglacial and Holocene period suggest a shift into humid conditions. An increase in ferns and the decrease in grasses during the Holocene also indicate increasing humidity. Fire played an important role in controlling the development and elevation of the ericaceous zone and the tree

  1. Response of vegetation NDVI to climatic extremes in the arid region of Central Asia: a case study in Xinjiang, China

    Science.gov (United States)

    Yao, Junqiang; Chen, Yaning; Zhao, Yong; Mao, Weiyi; Xu, Xinbing; Liu, Yang; Yang, Qing

    2018-02-01

    Observed data showed the climatic transition from warm-dry to warm-wet in Xinjiang during the past 30 years and will probably affect vegetation dynamics. Here, we analyze the interannual change of vegetation index based on the satellite-derived normalized difference vegetation index (NDVI) with temperature and precipitation extreme over the Xinjiang, using the 8-km NDVI third-generation (NDVI3g) from the Global Inventory Modelling and Mapping Studies (GIMMS) from 1982 to 2010. Few previous studies analyzed the link between climate extremes and vegetation response. From the satellite-based results, annual NDVI significantly increased in the first two decades (1981-1998) and then decreased after 1998. We show that the NDVI decrease over the past decade may conjointly be triggered by the increases of temperature and precipitation extremes. The correlation analyses demonstrated that the trends of NDVI was close to the trend of extreme precipitation; that is, consecutive dry days (CDD) and torrential rainfall days (R24) positively correlated with NDVI during 1998-2010. For the temperature extreme, while the decreases of NDVI correlate positively with warmer mean minimum temperature ( Tnav), it correlates negatively with the number of warmest night days ( Rwn). The results suggest that the climatic extremes have possible negative effects on the ecosystem.

  2. Developing digital vegetation for central hardwood forest types: A case study from Leslie County, KY

    Science.gov (United States)

    Bo Song; Wei-lun Tsai; Chiao-ying Chou; Thomas M. Williams; William Conner; Brian J. Williams

    2011-01-01

    Digital vegetation is the computerized representation, with either virtual images or animations, of vegetation types and conditions based on current measurements or ecological models. Digital vegetation can be useful in evaluating past, present, or future land use; changes in vegetation linked to climate change; or restoration efforts. Digital vegetation can be...

  3. Satellite assessment of early-season forecasts for vegetation conditions of grazing allotments in Nevada, United States

    Science.gov (United States)

    Fifteen years of enhanced vegetation index data from the MODIS sensor are examined in conjunction with precipitation and the Palmer drought severity index to assess how well growing season conditions for vegetation within grazing allotments of Nevada can be predicted at different times of the year. ...

  4. Response of dry grassland vegetation to fluctuations in weather conditions: a 9-year case study in Prague (Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Dostálek, J.; Frantík, Tomáš

    2011-01-01

    Roč. 66, č. 5 (2011), s. 837-847 ISSN 0006-3088 R&D Projects: GA MŠk 1M0571 Institutional research plan: CEZ:AV0Z60050516 Keywords : climate change * dry grassland * vegetation coverage Subject RIV: EF - Botanics Impact factor: 0.557, year: 2011

  5. Evaluating the coupling effects of climate aridity and vegetation restoration on soil erosion over the Loess Plateau in China.

    Science.gov (United States)

    Zhang, Baoqing; He, Chansheng; Burnham, Morey; Zhang, Lanhui

    2016-01-01

    In this study, the coupling effects of climate aridity and vegetation restoration on runoff and sediment yield over the Loess Plateau were examined and characterized. To take into consideration the complexity of drought, as well as the varied strengths and weaknesses of different drought measures, two drought indices are selected to identify and evaluate drought variability. The Normalized Difference Vegetation Index (NDVI) data were obtained to monitor and express spatiotemporal variations in vegetation cover. The results show that most regions of the Loess Plateau experienced increasingly severe droughts over the past 40years, and these regions comprise the major source of the Yellow River sediment. Climatic drying initially occurred in the 1990s, and became statistically significant in 2000s. The increasingly severe droughts could negatively impact surface and groundwater supplies as well as soil water storage, but may also minimize surface runoff yield, which is one of the major causes of soil erosion on the Loess Plateau. Vegetation cover on the Loess Plateau was significantly improved after the implementation of "Grain for Green" project, which were helpful for controlling severe soil erosion. With the impacts of the construction of check dams, terraces and large reservoirs, runoff and sediment yield over the Loess Plateau initially exhibited downward trends between 1970 and 1990. After 1990, with the effects of the climate warming and drying, a second sharp reduction in runoff and sediment yield occurred. The coupling effects of climate aridity and vegetation restoration have led to a third significant decrease in runoff and sediment yield over the Loess Plateau after 2000. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Potential use of vegetal Biomass as insulation in extreme climates of Ecuador

    Directory of Open Access Journals (Sweden)

    Luis Velasco Roldan

    2015-12-01

    Full Text Available In Ecuador, a factor of great ecological wealth is linked to its tradition in the use of fibers and other organic waste composite character as filler element, reinforcement or insulation in the field of housing construction, which carries great potential under the most viable architecture. The climate variability in Ecuador and the low purchasing power of their inhabitants forced to use local available building materials inexpensive or at no cost, in order to achieve economic and comfortable housing. That is why we have analyzed the presence of natural resources and waste biomass confronting regional building tradition, later superimpose geographically with major climatic variables affecting energy efficiency. This makes it possible to determine what, where and how to use the different biomass resources to allow a response to build that has a strong social, economic, environmental and energy argument in order to facilitate the conditions for access to economic habitat efficient, safe and dignified.

  7. Properties of volcanic soils in cold climate conditions

    Science.gov (United States)

    Kuznetsova, Elena

    2017-04-01

    Layers of volcanic ash and the Andosol soils derived from them may play an important role in preserving snow and ice as well as developing permafrost conditions in the immediate vicinity of volcanoes of high elevation or those situated at high latitudes, and land areas, often distant from volcanic activity that are either prone to permafrost or covered by snow and ice, but are affected by the deposition of subaerial ash. The special properties of volcanic ash that are responsible are critically reviewed particularly in relation to recent research in Kamchatka in the Far East of Russia. Of particular importance are the thermal properties and the unfrozen water contents of ash layers and the rate at which the weathering of volcanic glass takes place. Volcanic glass is the most easily weathered component of volcanic ejecta (Shoji et al., 1993; Kimble et al., 2000). There are many specific environmental conditions, including paleoclimate and present-day climate, the composition of volcanic tephra and glaciation history, which cause the differences in weathering and development of volcanic ash soils (Zehetner et al., 2003). The preservation of in situ, unweathered, and unaltered surficial ash-fall deposits in the cold regions has important implications for paleoclimate and glacial history. Ash-fall deposits, which trap and preserve the soils, sediments, and landforms on which they fall, can be used to resolve local climate conditions (temperature and moisture) at the ash site during ash-fall deposition. The preservation of detailed sedimentary features (e.g. bedding in the ash, sharpness of stratigraphic contacts) can tell us about their post-depositional history, whether they have been redeposited by wind or water, or overridden by glaciers (Marchant et al., 1996). Weathering of volcanic glass results in the development of amorphous clay minerals (e.g. allophane, opal, palagonite) but this takes place much slower in cold than under warmer climate conditions. Only few

  8. Short-term fluctuations in vegetation and phytoplankton during the Middle Eocene greenhouse climate: a 640-kyr record from the Messel oil shale (Germany)

    Science.gov (United States)

    Lenz, Olaf K.; Wilde, Volker; Riegel, Walter

    2011-11-01

    The Palaeogene was the most recent greenhouse period on Earth. Especially for the Late Palaeocene and Early Eocene, several superimposed short-term hyperthermal events have been described, including extremes such as the Palaeocene-Eocene Thermal Maximum. Major faunal and floral turnovers in the marine and terrestrial realms were recorded in association with these events. High-resolution palynological analysis of the early Middle Eocene maar lake sediments at Messel, near Darmstadt, Germany, provides an insight into the dynamics of a climax vegetation during the Middle Eocene greenhouse climate in a time span without significant climatic excursions. Numerical techniques like detrended correspondence analysis and wavelet analysis have been applied to recognize cyclic fluctuations and long-term trends in the vegetation through a time interval of approximately 640 kyr. Based on the numerical zoning of the pollen diagram, three phases in the development of the vegetation may be distinguished. Throughout these phases, the climax vegetation did not change substantially in qualitative composition, but a trend towards noticeably less humid conditions probably in combination with a drop of the water level in the lake may be recognized. A shift in algal population from the freshwater dinoflagellate cyst Messelodinium thielepfeifferae to a dominance of Botryococcus in the uppermost part of the core is interpreted as a response to changes in acidity and nutrient availability within the lake. Time series analyses of pollen assemblages show that variations in the Milankovitch range of eccentricity, obliquity and precession can be distinguished. In addition, fluctuations in the sub-Milankovitch range are indicated. This demonstrates that floral changes during steady depositional conditions in the Middle Eocene of Messel were controlled by orbital forcing.

  9. Spatio-temporal variation of vegetation coverage and its response to climate change in North China plain in the last 33 years

    Science.gov (United States)

    A, Duo; Zhao, Wenji; Qu, Xinyuan; Jing, Ran; Xiong, Kai

    2016-12-01

    Global climate change has led to significant vegetation changes in the past half century. North China Plain, the most important grain production base of china, is undergoing a process of prominent warming and drying. The vegetation coverage, which is used to monitor vegetation change, can respond to climate change (temperature and precipitation). In this study, GIMMS (Global Inventory Modelling and Mapping Studies)-NDVI (Normalized Difference Vegetation Index) data, MODIS (Moderate-resolution Imaging Spectroradiometer) - NDVI data and climate data, during 1981-2013, were used to investigate the spatial distribution and changes of vegetation. The relationship between climate and vegetation on different spatial (agriculture, forest and grassland) and temporal (yearly, decadal and monthly) scales were also analyzed in North China Plain. (1) It was found that temperature exhibiting a slight increase trend (0.20 °C/10a, P 0.05). The climate mutation period was during 1991-1994. (2) Vegetation coverage slight increase was observed in the 55% of total study area, with a change rate of 0.00039/10a. Human activities may not only accelerate the changes of the vegetation coverage, but also c effect to the rate of these changes. (3) Overall, the correlation between the vegetation coverage and climatic factor is higher in monthly scale than yearly scale. The correlation analysis between vegetation coverage and climate changes showed that annual vegetation coverage was better correlatend with precipitation in grassland biome; but it showed a better correlated with temperature i the agriculture biome and forest biome. In addition, the vegetation coverage had sensitive time-effect respond to precipitation. (4) The vegetation coverage showed the same increasing trend before and after the climatic variations, but the rate of increase slowed down. From the vegetation coverage point of view, the grassland ecological zone had an obvious response to the climatic variations, but the

  10. Analysis and mapping of present and future drought conditions over Greek areas with different climate conditions

    Science.gov (United States)

    Paparrizos, Spyridon; Maris, Fotios; Weiler, Markus; Matzarakis, Andreas

    2018-01-01

    Estimation of drought in a certain temporal and spatial scale is crucial in climate change studies. The current study targets on three agricultural areas widespread in Greece, Ardas River Basin in Northeastern Greece, Sperchios River Basin in Central Greece, and Geropotamos River Basin in Crete Island in South Greece that are characterized by diverse climates as they are located in various regions. The objective is to assess the spatiotemporal variation of drought conditions prevailing in these areas. The Standardized Precipitation Index (SPI) was used to identify and assess the present and future drought conditions. Future simulated data were derived from a number of Regional Climatic Models (RCMs) from the ENSEMBLES European Project. The analysis was performed for the future periods of 2021-2050 and 2071-2100, implementing A1B and B1 scenarios. The spatial analysis of the drought conditions was performed using a combined downscaling technique and the Ordinary Kriging. The Mann-Kendall test was implemented for trend investigation. During both periods and scenarios, drought conditions will tend to be more severe in the upcoming years. The decrease of the SPI values in the Sperchios River Basin is expected to be the strongest, as it is the only study area that will show a negative balance (in SPI values), regarding the drought conditions. For the Ardas and the Geropotamos River Basins, a great increase of the drought conditions will occur during the 2021-2050 period, while for 2071-2100 period, the decrease will continue but it will be tempered. Nevertheless, the situation in all study areas according to the SPI classification is characterized as "Near-normal", in terms of drought conditions.

  11. Sales down due to particularly mild climatic conditions

    International Nuclear Information System (INIS)

    2007-01-01

    Paris, 27 July 2007 - For the six months to 30 June 2007, Gaz de France's consolidated sales amounted to euro 13,778 million, down 11 per cent compared to the same period in 2006. This performance continues the trend seen over the first quarter of 2007 and in particular reflects the continuation into the second quarter of the climatic factors that affected the start of the year: an exceptionally warm 2006/2007 winter, followed by a spring season with particularly high temperatures. The average temperature of the first half of 2007 corresponds to a heat risk of less than one per cent, meaning that the probability of such a temperature taking place is less than one per cent. Over the first half of the year, volumes distributed in France were down by 25 TWh compared to a comparable period with average weather conditions, whereas in 2006 they were 15 TWh above average. The impact of the weather had similar effects outside of France. Under average weather conditions, the downturn in Group sales was limited to only 0.8 per cent mainly due to market conditions made difficult by the climate, leading to a lower level of gas production and arbitrage activities. Over the first six months of 2007, the Group sought to: - Continue to strengthen its international presence, currently with euro 5,602 million in sales outside of France. The percentage of sales generated outside of France represented 41 per cent of the Group total at the end of June 2007 and increased by 4 percentage points between the first half of 2006 and the first half of 2007. - Prepare for the deregulation of the markets on 1 July 2007 and a new commercial policy for retail customers that has been built around multi-energy and multi-service market offerings. - Create a new subsidiary for the distribution, a process which will be effective at the end of the year as announced. In spite of this unfavourable context, the Group maintains the financial objective for 2007 presented with the 2006 accounts: '2007 will

  12. Sales down due to particularly mild climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    Paris, 27 July 2007 - For the six months to 30 June 2007, Gaz de France's consolidated sales amounted to euro 13,778 million, down 11 per cent compared to the same period in 2006. This performance continues the trend seen over the first quarter of 2007 and in particular reflects the continuation into the second quarter of the climatic factors that affected the start of the year: an exceptionally warm 2006/2007 winter, followed by a spring season with particularly high temperatures. The average temperature of the first half of 2007 corresponds to a heat risk of less than one per cent, meaning that the probability of such a temperature taking place is less than one per cent. Over the first half of the year, volumes distributed in France were down by 25 TWh compared to a comparable period with average weather conditions, whereas in 2006 they were 15 TWh above average. The impact of the weather had similar effects outside of France. Under average weather conditions, the downturn in Group sales was limited to only 0.8 per cent mainly due to market conditions made difficult by the climate, leading to a lower level of gas production and arbitrage activities. Over the first six months of 2007, the Group sought to: - Continue to strengthen its international presence, currently with euro 5,602 million in sales outside of France. The percentage of sales generated outside of France represented 41 per cent of the Group total at the end of June 2007 and increased by 4 percentage points between the first half of 2006 and the first half of 2007. - Prepare for the deregulation of the markets on 1 July 2007 and a new commercial policy for retail customers that has been built around multi-energy and multi-service market offerings. - Create a new subsidiary for the distribution, a process which will be effective at the end of the year as announced. In spite of this unfavourable context, the Group maintains the financial objective for 2007 presented with the 2006 accounts: &apos

  13. Smart city planning under the climate change condition

    Science.gov (United States)

    Deng, Dexiang; Zhao, Yue; Zhou, Xi

    2017-08-01

    With the aggravation of climate change, extreme weather events occur continuously, cities are not resilient to climate change, and we need to change the concept of urban planning, centering on climate research and its research achievements, combining with the modern intelligent technology and formulating a smart city that resilience to the climate change, realizing the sustainable development of human, city, environment and society.

  14. Feasibility of coupled empirical and dynamic modeling to assess climate change and air pollution impacts on temperate forest vegetation of the eastern United States.

    Science.gov (United States)

    McDonnell, T C; Reinds, G J; Sullivan, T J; Clark, C M; Bonten, L T C; Mol-Dijkstra, J P; Wamelink, G W W; Dovciak, M

    2018-03-01

    Changes in climate and atmospheric nitrogen (N) deposition caused pronounced changes in soil conditions and habitat suitability for many plant species over the latter half of the previous century. Such changes are expected to continue in the future with anticipated further changing air temperature and precipitation that will likely influence the effects of N deposition. To investigate the potential long-term impacts of atmospheric N deposition on hardwood forest ecosystems in the eastern United States in the context of climate change, application of the coupled biogeochemical and vegetation community model VSD+PROPS was explored at three sites in New Hampshire, Virginia, and Tennessee. This represents the first application of VSD+PROPS to forest ecosystems in the United States. Climate change and elevated (above mid-19th century) N deposition were simulated to be important factors for determining habitat suitability. Although simulation results suggested that the suitability of these forests to support the continued presence of their characteristic understory plant species might decline by the year 2100, low data availability for building vegetation response models with PROPS resulted in uncertain results at the extremes of simulated N deposition. Future PROPS model development in the United States should focus on inclusion of additional foundational data or alternate candidate predictor variables to reduce these uncertainties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Human-animal agency in reindeer management: Sami herders' perspectives on Fennoscandian tundra vegetation dynamics under climate change

    Science.gov (United States)

    Forbes, B. C.; Horstkotte, T.; Utsi, T. A.; Larsson-Blind, Å.; Burgess, P.; Käyhkö, J.; Oksanen, L.; Johansen, B.

    2016-12-01

    Many primary livelihoods in Arctic and sub-Arctic regions are increasingly faced with accelerating effects of climate change and resource exploitation. The often close connection between indigenous populations and the dynamics of their respective territories allows them to make detailed observations of how these changes transform the landscapes where they practice their daily activities. Here, we report Sami reindeer herders' observations based on their long-term occupancy and use of contrasting pastoral landscapes in northern Fennoscandia. In particular, we focus on the capacity for various herd management regimes to prevent a potential transformation of open tundra vegetation to shrubland or woodland. Fennoscandian Sami herders did not confirm a substantial, rapid or large-scale transformation of treeless arctic-alpine areas into shrub- and/or woodlands as a consequence of climate change. However, where encroachment of open tundra landscapes has been observed, a range of drivers were deemed responsible. These included abiotic conditions, anthropogenic influences and the direct and indirect effects of reindeer. Mountain birch tree line advances were in some cases associated with reduced or discontinued grazing, depending on the seasonal significance of these particular areas. In the many places where tree line has risen, herding practices have by necessity adapted to these changes. Exploiting the capacity of reindeer grazing/browsing as a conservation tool offers new adaptive strategies of ecosystem management to counteract a potential encroachment of the tundra by woody plants. However, such novel solutions in environmental governance are confronted with difficult trade-offs involved in ecosystem management for ecologically reasonable, economically viable and socially desirable management strategies.

  16. Global isoprene and monoterpene emissions under changing climate, vegetation, CO2 and land use

    DEFF Research Database (Denmark)

    Hantson, Stijn; Knorr, Wolfgang; Schurgers, Guy

    2017-01-01

    Plants emit large quantities of isoprene and monoterpenes, the main components of global biogenic volatile organic compound (BVOC) emissions. BVOCs have an important impact on the atmospheric composition of methane, and of short-lived radiative forcing agents (e.g. ozone, aerosols etc.). It is th......Plants emit large quantities of isoprene and monoterpenes, the main components of global biogenic volatile organic compound (BVOC) emissions. BVOCs have an important impact on the atmospheric composition of methane, and of short-lived radiative forcing agents (e.g. ozone, aerosols etc.......). It is therefore necessary to know how isoprene and monoterpene emissions have changed over the past and how future changes in climate, land-use and other factors will impact them. Here we present emission estimates of isoprene and monoterpenes over the period 1901–2 100 based on the dynamic global vegetation...... model LPJ-GUESS, including the effects of all known important drivers. We find that both isoprene and monoterpene emissions at the beginning of the 20th century were higher than at present. While anthropogenic land-use change largely drives the global decreasing trend for isoprene over the 20th century...

  17. Normalized difference vegetation index for the South American continent used as a climatic variability indicator

    International Nuclear Information System (INIS)

    Liu, W.T.; Massambani, O.; Festa, M.

    1992-01-01

    The NOAA AVHRR GAC data set was used to produce Normalized Difference Vegetation Index (NDVI) maps for the South American Continent covering the period from August 1, 1981 to June 30, 1987. A 15-day maximum value composite procedure was used to partially eliminate the cloud contamination and atmospheric attenuation. Monthly evolution of NDVI for a dry and a wet year within the period studied was used to estimate the area covered by NDVI value less than 0.223, This value was used as an indicator of the drought area and the delineation of the Low rainfall areas in the continent. It was observed a well defined regional dependence of the drought area variability for the Northeast, Southwest and Northwest continent and also for the Amazon region. It is shown a relative estimation of the area coverage with NDVI less than 0.223 for the years 1982/83 and 1984/85. The dynamics of the drought area evolution in the continent is discussed. It is also presented a diagnosis of regional variability of the continental distribution of drought area from 1981 to 1987 for the months of May and September. This information is also used to discuss its relationship with the EL-Nino-Southern Oscillation (ENSO) and the South American Precipitation patterns during this period. It is suggested that the use of NDVI image to identify the dynamics of the drought induced by low rainfall may provide us valuable information to study the large scale climatic variation

  18. Effect of greenhouse micro-climate on the selected summer vegetables

    International Nuclear Information System (INIS)

    Sethi, V.P.; Lal, T.; Gupta, Y.P.; Hans, V.S.

    2003-01-01

    The study deals with creating suitable environment for the germination and subsequent growth of plants in the greenhouse of size 7 m x 3 m x 2 m for raising early summer vegetable nursery. It was observed that the average air temperature inside the greenhouse was 10–12°C higher than the ambient air temperature. Inside average soil temperature was also 5–7°C higher than the corresponding temperature outside the greenhouse. Greenhouse night micro-climate was modified by covering its roof with a polyester sheet to cut down the effect of night sky radiation thereby raising the inside minimum temperature. The effect of elevated temperature was monitored on the germination and subsequent growth of “muskmelon” seedlings up to two true leaf stage. It was observed that the germination of seeds, sown inside the greenhouse occurred one week earlier as compared to the seeds sown in the open field. The rate of growth of the seedlings inside the greenhouse took only three weeks to attain two-leaf stage, whereas seedlings sown in the open field took five weeks to reach up to two-leaf stage. Thus, there was a clear saving of 15 days in raising the nursery under the greenhouse. (author)

  19. Long-Term Arctic Peatland Dynamics, Vegetation and Climate History of the Pur-Taz Region, Western Siberia

    Science.gov (United States)

    Peteet, Dorothy; Andreev, Andrei; Bardeen, William; Mistretta, Francesca

    1998-01-01

    Stratigraphic analyses of peat composition, LOI, pollen, spores, macrofossils, charcoal, and AMS ages are used to reconstruct the peatland, vegetation and climatic dynamics in the Pur-Taz region of western Siberia over 5000 years (9300 - 4500 BP). Section stratigraphy shows many changes from shallow lake sediment to different combinations of forested or open sedge, moss, and Equisetum fen and peatland environments. Macrofossil and pollen data indicate that Larix sibirica and Betula pubescens trees were first to arrive, followed by Picea obovata. The dominance of Picea macrofossils 6000-5000 BP in the Pur-Taz peatland along with regional Picea pollen maxima indicate warmer conditions and movement of the spruce treeline northward at this time. The decline of pollen and macrofossils from all of these tree species in uppermost peats suggests a change in the environment less favorable for their growth, perhaps cooler temperatures and/or less moisture. Of major significance is the evidence for old ages of the uppermost peats in this area of Siberia, suggesting a real lack of peat accumulation in recent millennia or recent oxidation of uppermost peat.

  20. Late Pliocene diversity and distribution of Drynaria (Polypodiaceae in western Yunnan explained by forest vegetation and humid climates

    Directory of Open Access Journals (Sweden)

    Yong-Jiang Huang

    2016-08-01

    Full Text Available The palaeodiversity of flowering plants in Yunnan has been extensively interpreted from both a molecular and fossil perspective. However, for cryptogamic plants such as ferns, the palaeodiversity remains poorly known. In this study, we describe a new ferny fossil taxon, Drynaria lanpingensis sp. nov. Huang, Su et Zhou (Polypodiaceae, from the late Pliocene of northwestern Yunnan based on fragmentary frond and pinna with in situ spores. The frond is pinnatifid and the pinnae are entirely margined. The sori are arranged in one row on each side of the primary vein. The spores have a semicircular to bean-shaped equatorial view and a tuberculate surface. Taken together with previously described fossils, there are now representatives of three known fossil taxa of Drynaria from the late Pliocene of western Yunnan. These finds suggest that Drynaria diversity was considerable in the region at that time. As Drynaria is a shade-tolerant plant, growing preferably in wet conditions in the understory of forests, its extensive existence may indicate forest vegetation and humid climates in western Yunnan during the late Pliocene. This is in line with results from floristic investigations and palaeoclimatic reconstructions based on fossil floras.

  1. Fire regimes and vegetation responses in two Mediterranean-climate regions

    Science.gov (United States)

    Montenegro, G.; Ginocchio, R.; Segura, A.; Keely, J.E.; Gomez, M.

    2004-01-01

    Wildfires resulting from thunderstorms are common in some Mediterranean-climate regions, such as southern California, and have played an important role in the ecology and evolution of the flora. Mediterranean-climate regions are major centers for human population and thus anthropogenic impacts on fire regimes may have important consequences on these plant formations. However, changes in fire regimes may have different impacts on Mediterranean type-ecosystems depending on the capability of plants to respond to such perturbations. Therefore, we compare here fire regimes and vegetation responses of two Mediterranean-climate regions which differ in wildfire regimes and history of human occupation, the central zone of Chile (matorral) and the southern area of California in United States (chaparral). In Chile almost all fires result from anthropogenic activities, whereas lightning fires resulting from thunderstorms are frequent in California. In both regions fires are more frequent in summer, due to high accumulation of dry plant biomass for ignition. Humans have markedly increased fires frequency both in the matorral and chaparral, but extent of burned areas has remained unaltered, probably due to better fire suppression actions and a decline in the built-up of dry plant fuel associated to increased landscape fragmentation with less flammable agricultural and urban developments. As expected, post-fire plant regeneration responses differs between the matorral and chaparral due to differences in the importance of wildfires as a natural evolutionary force in the system. Plants from the chaparral show a broader range of post-fire regeneration responses than the matorral, from basal resprouting, to lignotuber resprouting, and to fire-stimulated germination and flowering with fire-specific clues such as heat shock, chemicals from smoke or charred wood. Plants from the matorral have some resprouting capabilities after fire, but these probably evolved from other environmental

  2. Bioclim Deliverable D4/5: global climatic characteristics, including vegetation and seasonal cycles over Europe, for snapshots over the next 200,000 years

    International Nuclear Information System (INIS)

    2003-01-01

    either significantly warmer or cooler than the present. The next stage in the hierarchical strategy was to use a GCM and biosphere model, to simulate in more detail these extreme time periods. This deliverable starts with a description of the GCM and biosphere models used, and continues with an assessment of the models' performance in simulating the present day climate. It then gives a summary of the boundary conditions that constrain the model for the future climate simulations, as indicated by the LLN-2D model, and describes how these boundary conditions are implemented in the models. The majority of the deliverable is a description of the GCM results for the future climate simulations, and the resulting vegetation distributions. This is followed by a section focusing on the areas of specific interest. Finally, there is a critical discussion, which includes a comparison of some of the results with previous work, and an assessment of the uncertainty in the model results. There are many figures in this deliverable, all of which are included at the back. However, not all of the potentially interesting data from the models is discussed or presented. Therefore, data from all the simulations are available on the business collaborator at http://cobweb.businesscollaborator.com/bc/bc.cgi

  3. Soil Water Balance and Vegetation Dynamics in two Water-limited Mediterranean Ecosystem on Sardinia under past and future climate change

    Science.gov (United States)

    Corona, R.; Montaldo, N.; Albertson, J. D.

    2016-12-01

    Water limited conditions strongly impacts soil and vegetation dynamics in Mediterranean regions, which are commonly heterogeneous ecosystems, characterized by inter-annual rainfall variability, topography variability and contrasting plant functional types (PFTs) competing for water use. Historical human influences (e.g., deforestation, urbanization) further altered these ecosystems. Sardinia island is a representative region of Mediterranean ecosystems. It is low urbanized except some plan areas close to the main cities where main agricultural activities are concentrated. Two contrasting case study sites are within the Flumendosa river basin (1700 km2). The first site is a typical grassland on an alluvial plan valley (soil depth > 2m) while the second is a patchy mixture of Mediterranean vegetation species (mainly wild olive trees and C3 herbaceous) that grow in a soil bounded from below by a rocky layer of basalt, partially fractured (soil depth 15 - 40 cm). In both sites land-surface fluxes and CO2 fluxes are estimated by the eddy correlation technique while soil moisture was continuously estimated with water content reflectometers, and periodically leaf area index (LAI) was estimated. The following objectives are addressed:1) pointing out the dynamics of land surface fluxes, soil moisture, CO2 and vegetation cover for two contrasting water-limited ecosystems; 2) assess the impact of the soil depth and type on the CO2 and water balance dynamics; 3) evaluate the impact of past and future climate change scenarios on the two contrasting ecosystems. For reaching the objectives an ecohydrologic model that couples a vegetation dynamic model (VDM), and a 3-component (bare soil, grass and woody vegetation) land surface model (LSM) has been used. Historical meteorological data are available from 1922 and hydro-meteorological scenarios are then generated using a weather generator. The VDM-LSM model predict soil water balance and vegetation dynamics for the generated

  4. Climate and vegetation in a semi-arid savanna: Development of a climate–vegetation response model linking plant metabolic performance to climate and the effects on forage availability for large herbivores

    Directory of Open Access Journals (Sweden)

    Armin H. Seydack

    2012-02-01

    Developing the climate–vegetation response model involved three main components, namely (1 defining indicators of forage availability to herbivores (nitrogen productivity, nitrogen quality, carbon-nutrient quality, (2 identifying herbivore species guilds of similar nutritional requirements with respect to these indicators [bulk feeders with tolerance to fibrous herbage (buffalo, waterbuck, bulk feeders with preference for high nitrogen quality forage (short grass preference grazers: blue wildebeest and zebra and selective feeders where dietary items of relatively high carbon-nutrient quality represented key forage resources (selective grazers: sable antelope, roan antelope, tsessebe, eland] and (3 developing a process model where the expected effects of plant metabolic responses to climate on key forage resources were made explicit. According to the climate–vegetation response model both shorter-term transient temperature acclimation pulses and longer-term shifts in plant metabolic functionality settings were predicted to have occurred in response to temperature trends over the past century. These temperature acclimation responses were expected to have resulted in transient pulses of increased forage availability (increased nitrogen- and carbon-nutrient quality, as well as the progressive long-term decline of the carbon-nutrient quality of forage. Conservation implications: The climate–vegetation response model represents a research framework for further studies contributing towards the enhanced understanding of landscape-scale functioning of savanna systems with reference to the interplay between climate, vegetation and herbivore population dynamics. Gains in such understanding can support sound conservation management.

  5. Monitoring of vegetation dynamics and assessing vegetation response to drought in the Iberian Peninsula

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Haro, F. J.; Moreno, A.; Perez-Hoyos, A.; Gilabert, M. A.; Melia, J.; Belda, F.; Poquet, D.; Martinez, B.; Verger, A.

    2009-07-01

    Monitoring the vegetation activity over long time-scales is necessary to discern ecosystem response to climate variability. Spatial and temporally consistent estimates of the biophysical variables such as fractional vegetation cover (FVC) and leaf area index (LAI) have been obtained in the context of DULCINEA Project. We used long-term monthly climate statistics to build simple climatic indices (SPI, moisture index) at different time scales. From these indices, we estimated that the climatic disturbances affected both the growing season and the total amount of vegetation. This implies that the anomaly of vegetation cover is a good indicator of moisture condition and can be an important data source when used for detecting an monitoring drought in the Iberian Peninsula. The impact of climate variability on the vegetation dynamics has shown not to be the same for every region. We concluded that the relationships between vegetation anomaly and moisture availability are significant for the arid and semiarid areas. (Author) 6 refs.

  6. Monitoring of vegetation dynamics and assessing vegetation response to drought in the Iberian Peninsula

    International Nuclear Information System (INIS)

    Garcia-Haro, F. J.; Moreno, A.; Perez-Hoyos, A.; Gilabert, M. A.; Melia, J.; Belda, F.; Poquet, D.; Martinez, B.; Verger, A.

    2009-01-01

    Monitoring the vegetation activity over long time-scales is necessary to discern ecosystem response to climate variability. Spatial and temporally consistent estimates of the biophysical variables such as fractional vegetation cover (FVC) and leaf area index (LAI) have been obtained in the context of DULCINEA Project. We used long-term monthly climate statistics to build simple climatic indices (SPI, moisture index) at different time scales. From these indices, we estimated that the climatic disturbances affected both the growing season and the total amount of vegetation. This implies that the anomaly of vegetation cover is a good indicator of moisture condition and can be an important data source when used for detecting an monitoring drought in the Iberian Peninsula. The impact of climate variability on the vegetation dynamics has shown not to be the same for every region. We concluded that the relationships between vegetation anomaly and moisture availability are significant for the arid and semiarid areas. (Author) 6 refs.

  7. Detecting hotspots of atmosphere–vegetation interaction via slowing down – Part 2: Application to a global climate model

    Directory of Open Access Journals (Sweden)

    S. Bathiany

    2013-02-01

    Full Text Available Early warning signals (EWS have become a popular statistical tool to infer stability properties of the climate system. In Part 1 of this two-part paper we have presented a diagnostic method to find the hotspot of a sudden transition as opposed to regions that experience an externally induced tipping as a mere response. Here, we apply our method to the atmosphere–vegetation model PlanetSimulator (PlaSim – VECODE using a regression model. For each of two vegetation collapses in PlaSim-VECODE, we identify a hotspot of one particular grid cell. We demonstrate with additional experiments that the detected hotspots are indeed a particularly sensitive region in the model and give a physical explanation for these results. The method can thus provide information on the causality of sudden transitions and may help to improve the knowledge on the vulnerability of certain subsystems in climate models.

  8. Variability and climate change trend in vegetation phenology of recent decades in the Greater Khingan Mountain area, Northeastern China

    Directory of Open Access Journals (Sweden)

    Huan Tang

    2015-09-01

    Full Text Available Vegetation phenology has been used in studies as an indicator of an ecosystem’s responses to climate change. Satellite remote sensing techniques can capture changes in vegetation greenness, which can be used to estimate vegetation phenology. In this study, a long-term vegetation phenology study of the Greater Khingan Mountain area in Northeastern China was performed by using the Global Inventory Modeling and Mapping Studies (GIMMS normalized difference vegetation index version 3 (NDVI3g dataset from the years 1982–2012. After reconstructing the NDVI time series, the start date of the growing season (SOS, the end date of the growing season (EOS and the length of the growing season (LOS were extracted using a dynamic threshold method. The response of the variation in phenology with climatic factors was also analyzed. The results showed that the phenology in the study area changed significantly in the three decades between 1982 and 2012, including a 12.1-day increase in the entire region’s average LOS, a 3.3-day advance in the SOS and an 8.8-day delay in the EOS. However, differences existed between the steppe, forest and agricultural regions, with the LOSs of the steppe region, forest region and agricultural region increasing by 4.40 days, 10.42 days and 1.71 days, respectively, and a later EOS seemed to more strongly affect the extension of the growing season. Additionally, temperature and precipitation were closely correlated with the phenology variations. This study provides a useful understanding of the recent change in phenology and its variability in this high-latitude study area, and this study also details the responses of several ecosystems to climate change.

  9. Climate and Health Vulnerability to Vector-Borne Diseases: Increasing Resilience under Climate Change Conditions in Africa

    Science.gov (United States)

    Ceccato, P.

    2015-12-01

    The International Research Institute for Climate and Society (IRI), the City University of New York (CUNY) and NASA Jet Propulsion Laboratory (JPL) in collaboration with NASA SERVIR are developing tools to monitor climate variables (precipitation, temperature, vegetation, water bodies, inundation) that help projects in Africa to increase resilience to climate change for vector-borne diseases ( malaria, trypanosomiasis, leishmaniasis, and schistosomiasis). Through the development of new products to monitor precipitation, water bodies and inundation, IRI, CUNY and JPL provide tools and capacity building to research communities; ministries of health; the WMO Global Framework for Climate and Services; and World Health Organization in Africa to: 1) Develop research teams' ability to appropriately use climate data as part of their research 2) Enable research teams and ministries to integrate climate information into social and economic drivers of vulnerability and opportunities for adaptation to climate change 3) Inform better policies and programs for climate change adaptation. This oral presentation will demonstrate how IRI, CUNY, and JPL developed new products, tools and capacity building to achieve the three objectives mentioned above with examples in South Africa, Zimbabwe, Tanzania and Malawi.

  10. Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

    Science.gov (United States)

    Ager, T.A.

    2003-01-01

    Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ???30,000 14C yr B.P. During the late middle Wisconsin interstadial (???30,000-26,000 14C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows (Salix) and minor dwarf birch (Betula nana) and Ericales. During the late Wisconsin glacial interval (26,000-15,000 14C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ???30,000 to 15,000 14C yr B.P. Between 15,000 and 13,000 14C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca. 11,000-9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs (Alnus crispa) colonized the St. Michael Island area ca. 8000 14C yr B.P. Boreal forests dominated by spruce (Picea) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  11. The role of tectonic uplift, climate, and vegetation in the long-term terrestrial phosphorous cycle

    Directory of Open Access Journals (Sweden)

    C. Buendía

    2010-06-01

    Full Text Available Phosphorus (P is a crucial element for life and therefore for maintaining ecosystem productivity. Its local availability to the terrestrial biosphere results from the interaction between climate, tectonic uplift, atmospheric transport, and biotic cycling. Here we present a mathematical model that describes the terrestrial P-cycle in a simple but comprehensive way. The resulting dynamical system can be solved analytically for steady-state conditions, allowing us to test the sensitivity of the P-availability to the key parameters and processes. Given constant inputs, we find that humid ecosystems exhibit lower P availability due to higher runoff and losses, and that tectonic uplift is a fundamental constraint. In particular, we find that in humid ecosystems the biotic cycling seem essential to maintain long-term P-availability. The time-dependent P dynamics for the Franz Josef and Hawaii chronosequences show how tectonic uplift is an important constraint on ecosystem productivity, while hydroclimatic conditions control the P-losses and speed towards steady-state. The model also helps describe how, with limited uplift and atmospheric input, as in the case of the Amazon Basin, ecosystems must rely on mechanisms that enhance P-availability and retention. Our novel model has a limited number of parameters and can be easily integrated into global climate models to provide a representation of the response of the terrestrial biosphere to global change.

  12. Preliminary assessment of late quaternary vegetation and climate of southeastern Utah based on analyses of packrat middens

    International Nuclear Information System (INIS)

    Betancourt, J.L.; Biggar, N.

    1985-06-01

    Packrat midden sequences from two caves (elevations 1585 and 2195 m; 5200 and 7200 ft) southwest of the Abajo Mountains in southeast Utah record vegetation changes that are attributed to climatic changes occurring during the last 13,000 years. These data are useful in assessing potential future climates at proposed nuclear waste sites in the area. Paleoclimates are reconstructed by defining modern elevational analogs for the vegetation assemblages identified in the middens. Based on the midden record, a climate most extreme from the present occurred prior to approximately 10,000 years before present (BP), when mean annual temperature was probably 3 to 4C (5.5 to 7F) cooler than present. However, cooling could not have exceeded 5C (9F) at 1585 m (5200 ft). Accompanying mean annual precipitation is estimated to have been from 35 to 140% greater than at present, with rainfall concentrated in the winter months. Vegetational changes beginning approximately 10,000 years BP are attributed to increased summer and mean annual temperatures, a decreasing frequency of spring freezes, and a shift from winter- to summer-dominant rainfall. Greater effective moisture than present is inferred at both cave sites from approximately 8000 to 4000 years BP. Modern flora was present at both sites by about 2000 years BP

  13. Projecting climate change, drought conditions and crop productivity in Turkey

    NARCIS (Netherlands)

    Sen, B.; Topcu, S.; Türkes, M.; Warner, J.F.

    2012-01-01

    This paper focuses on the evaluation of regional climate model simulation for Turkey for the 21st century. A regional climate model, ICTP-RegCM3, with 20 km horizontal resolution, is used to downscale the reference and future climate scenario (IPCC-A2) simulations. Characteristics of droughts as

  14. [Effects of climate and land use change on the changes of vegetation coverage in farming-pastoral ecotone of Northern China].

    Science.gov (United States)

    Liu, Jun-Hui; Gao, Ji-Xi

    2008-09-01

    Based on the remote sensing images and the meteorological data in 1986 and 2000, and by using the model of extracting vegetation coverage, the spatiotemporal changes of vegetation coverage in the farming-pastoral ecotone of Northern China in 1986-2000 were studied, with the effects of climate and land use change on the changes analyzed. The results showed that in this ecotone, the area with lower vegetation coverage was increasing, while that with higher vegetation coverage was in adverse. The regions with increasing vegetation coverage were mainly in the east of northeast section, the west of north section, and the west of northwest section of the ecotone, while the vegetation coverage in the other sections was obviously degraded. The vegetation coverage were positively correlated with precipitation and aridity index, but negatively correlated with temperature. The change direction and extent of the vegetation coverage varied with land use types.

  15. Productive and qualitative evaluation of onion cultivars under agro-climatic conditions of faisalabad

    International Nuclear Information System (INIS)

    Mushtaq, S.; Amjad, M.; Ziaf, K.; Cheema, K.L.

    2013-01-01

    Onion varieties are very specific in their photoperiod and vernalization requirements and therefore vary for yield, yield related traits and bolting in a specific agro-climate. Therefore, performance of nineteen onion varieties for these traits was evaluated at Vegetable Research Institute, Faisalabad. The maximum bolting percentage was recorded in Desi Red (46.67%) that indicates less vernalization requirement of this variety while it was the minimum in Faisal Red and VRIO-6 (13.33%). The cultivar Phulkara produced larger size bulbs (73.22 mm diameter) as well as highest yield (21.90 t ha/sup -1/) and bulb to neck diameter ratio (6.75). Similarly, minimum weight loss during curing was observed in Desi Red (4.64%), Pusa Red (4.76%) and Phulkara (4.83%), indicating higher dry matter contents while maximum weight loss (6%) was recorded in VRIO-6. Overall results revealed that both Phulkara and Desi Red are excellent for processing while Dark Red for cooking purpose under agro-climatic conditions of Faisalabad. (author)

  16. Late Holocene vegetation, climate, and land-use impacts on carbon dynamics in the Florida Everglades

    Science.gov (United States)

    Jones, Miriam C.; Bernhardt, Christopher E.; Willard, Debra A.

    2014-01-01

    Tropical and subtropical peatlands are considered a significant carbon sink. The Florida Everglades includes 6000-km2 of peat-accumulating wetland; however, detailed carbon dynamics from different environments within the Everglades have not been extensively studied or compared. Here we present carbon accumulation rates from 13 cores and 4 different environments, including sawgrass ridges and sloughs, tree islands, and marl prairies, whose hydroperiods and vegetation communities differ. We find that the lowest rates of C accumulation occur in sloughs in the southern Everglades. The highest rates are found where hydroperiods are generally shorter, including near-tails of tree islands and drier ridges. Long-term average rates of 100 to >200 g C m−2 yr−1 are as high, and in some cases, higher than rates recorded from the tropics and 10–20 times higher than boreal averages. C accumulation rates were impacted by both the Medieval Climate Anomaly and the Little Ice Age, but the largest impacts to C accumulation rates over the Holocene record have been the anthropogenic changes associated with expansion of agriculture and construction of canals and levees to control movement of surface water. Water management practices in the 20th century have altered the natural hydroperiods and fire regimes of the Everglades. The Florida Everglades as a whole has acted as a significant carbon sink over the mid- to late-Holocene, but reduction of the spatial extent of the original wetland area, as well as the alteration of natural hydrology in the late 19th and 20th centuries, have significantly reduced the carbon sink capacity of this subtropical wetland.

  17. Multi-scale enhancement of climate prediction over land by improving the model sensitivity to vegetation variability

    Science.gov (United States)

    Alessandri, A.; Catalano, F.; De Felice, M.; Hurk, B. V. D.; Doblas-Reyes, F. J.; Boussetta, S.; Balsamo, G.; Miller, P. A.

    2017-12-01

    Here we demonstrate, for the first time, that the implementation of a realistic representation of vegetation in Earth System Models (ESMs) can significantly improve climate simulation and prediction across multiple time-scales. The effective sub-grid vegetation fractional coverage vary seasonally and at interannual time-scales in response to leaf-canopy growth, phenology and senescence. Therefore it affects biophysical parameters such as the surface resistance to evapotranspiration, albedo, roughness lenght, and soil field capacity. To adequately represent this effect in the EC-Earth ESM, we included an exponential dependence of the vegetation cover on the Leaf Area Index.By comparing two sets of simulations performed with and without the new variable fractional-coverage parameterization, spanning from centennial (20th Century) simulations and retrospective predictions to the decadal (5-years), seasonal (2-4 months) and weather (4 days) time-scales, we show for the first time a significant multi-scale enhancement of vegetation impacts in climate simulation and prediction over land. Particularly large effects at multiple time scales are shown over boreal winter middle-to-high latitudes over Canada, West US, Eastern Europe, Russia and eastern Siberia due to the implemented time-varying shadowing effect by tree-vegetation on snow surfaces. Over Northern Hemisphere boreal forest regions the improved representation of vegetation-cover consistently correct the winter warm biases, improves the climate change sensitivity, the decadal potential predictability as well as the skill of forecasts at seasonal and weather time-scales. Significant improvements of the prediction of 2m temperature and rainfall are also shown over transitional land surface hot spots. Both the potential predictability at decadal time-scale and seasonal-forecasts skill are enhanced over Sahel, North American Great Plains, Nordeste Brazil and South East Asia, mainly related to improved performance in

  18. Impact of the Little Ice Age cooling and 20th century climate change on peatland vegetation dynamics in central and northern Alberta using a multi-proxy approach and high-resolution peat chronologies

    Science.gov (United States)

    Magnan, Gabriel; van Bellen, Simon; Davies, Lauren; Froese, Duane; Garneau, Michelle; Mullan-Boudreau, Gillian; Zaccone, Claudio; Shotyk, William

    2018-04-01

    Northern boreal peatlands are major terrestrial sinks of organic carbon and these ecosystems, which are highly sensitive to human activities and climate change, act as sensitive archives of past environmental change at various timescales. This study aims at understanding how the climate changes of the last 1000 years have affected peatland vegetation dynamics in the boreal region of Alberta in western Canada. Peat cores were collected from five bogs in the Fort McMurray region (56-57° N), at the southern limit of sporadic permafrost, and two in central Alberta (53° N and 55° N) outside the present-day limit of permafrost peatlands. The past changes in vegetation communities were reconstructed using detailed plant macrofossil analyses combined with high-resolution peat chronologies (14C, atmospheric bomb-pulse 14C, 210Pb and cryptotephras). Peat humification proxies (C/N, H/C, bulk density) and records of pH and ash content were also used to improve the interpretation of climate-related vegetation changes. Our study shows important changes in peatland vegetation and physical and chemical peat properties during the Little Ice Age (LIA) cooling period mainly from around 1700 CE and the subsequent climate warming of the 20th century. In some bogs, the plant macrofossils have recorded periods of permafrost aggradation during the LIA with drier surface conditions, increased peat humification and high abundance of ericaceous shrubs and black spruce (Picea mariana). The subsequent permafrost thaw was characterized by a short-term shift towards wetter conditions (Sphagnum sect. Cuspidata) and a decline in Picea mariana. Finally, a shift to a dominance of Sphagnum sect. Acutifolia (mainly Sphagnum fuscum) occurred in all the bogs during the second half of the 20th century, indicating the establishment of dry ombrotrophic conditions under the recent warmer and drier climate conditions.

  19. Vegetation Responses to Climate Variability in the Northern Arid to Sub-Humid Zones of Sub-Saharan Africa

    Directory of Open Access Journals (Sweden)

    Khaldoun Rishmawi

    2016-11-01

    Full Text Available In water limited environments precipitation is often considered the key factor influencing vegetation growth and rates of development. However; other climate variables including temperature; humidity; the frequency and intensity of precipitation events are also known to affect productivity; either directly by changing photosynthesis and transpiration rates or indirectly by influencing water availability and plant physiology. The aim here is to quantify the spatiotemporal patterns of vegetation responses to precipitation and to additional; relevant; meteorological variables. First; an empirical; statistical analysis of the relationship between precipitation and the additional meteorological variables and a proxy of vegetation productivity (the Normalized Difference Vegetation Index; NDVI is reported and; second; a process-oriented modeling approach to explore the hydrologic and biophysical mechanisms to which the significant empirical relationships might be attributed. The analysis was conducted in Sub-Saharan Africa; between 5 and 18°N; for a 25-year period 1982–2006; and used a new quasi-daily Advanced Very High Resolution Radiometer (AVHRR dataset. The results suggest that vegetation; particularly in the wetter areas; does not always respond directly and proportionately to precipitation variation; either because of the non-linearity of soil moisture recharge in response to increases in precipitation; or because variations in temperature and humidity attenuate the vegetation responses to changes in water availability. We also find that productivity; independent of changes in total precipitation; is responsive to intra-annual precipitation variation. A significant consequence is that the degree of correlation of all the meteorological variables with productivity varies geographically; so no one formulation is adequate for the entire region. Put together; these results demonstrate that vegetation responses to meteorological variation are more

  20. Climate and Population Health Vulnerabilities to Vector-Borne Diseases: Increasing Resilience Under Climate Change Conditions in Africa

    Science.gov (United States)

    Ceccato, P.; McDonald, K. C.; Podest, E.; De La Torre Juarez, M.; Kruczkiewicz, A.; Lessel, J.; Jensen, K.; Thomson, M. C.

    2014-12-01

    The International Research Institute for Climate and Society (IRI), the City University of New York (CUNY) and NASA Jet Propulsion Laboratory (JPL) in collaboration with NASA SERVIR are developing tools to monitor climate variables (precipitation, temperature, vegetation, water bodies, inundation) that help projects in Africa to increase resilience to climate change for vector-borne diseases (i.e. malaria, trypanosomiasis, leishmaniasis, and schistosomiasis). Through the development of new products to monitor precipitation, water bodies and inundation, IRI, CUNY and JPL provide tools and capacity building to research communities, ministries of health and World Health Organization in Africa to: 1) Develop research teams' ability to appropriately use climate data as part of their research 2) Enable research teams and ministries to integrate climate information into social and economic drivers of vulnerability and opportunities for adaptation to climate change 3) Inform better policies and programs for climate change adaptation. This oral presentation will demonstrate how IRI, CUNY, and JPL developed new products, tools and capacity building to achieve the three objectives mentioned above.

  1. Climate induced changes in biome distribution, NPP and hydrology for potential vegetation of the Upper Midwest U.S

    Science.gov (United States)

    Motew, M.; Kucharik, C. J.

    2011-12-01

    While much attention is focused on future impacts of climate change on ecosystems, much can be learned about the previous interactions of ecosystems with recent climate change. In this study, we investigated the impacts of climate change on potential vegetation distributions (i.e. grasses, trees, and shrubs) and carbon and water cycling across the Upper Midwest USA from 1948-2007 using the Agro-IBIS dynamic vegetation model. We drove the model using a historical, gridded daily climate data set (temperature, precipitation, humidity, solar radiation, and wind speed) at a spatial resolution of 5 min x 5 min. While trends in climate variables exhibited heterogeneous spatial patterns over the study period, the overall impact of climate change on vegetation productivity was positive. We observed total increases in net primary productivity (NPP) ranging from 20-150 g C m-2, based on linear regression analysis. We determined that increased summer relative humidity, increased annual precipitation and decreased mean maximum summer temperatures were key variables contributing to these positive trends, likely through a reduction in soil moisture stress (e.g., increased available water) and heat stress. Model simulations also illustrated an increase in annual drainage throughout the region of 20-140 mm yr-1, driven by substantial increases in annual precipitation. Evapotranspiration had a highly variable spatial trend over the 60-year period, with total change over the study period ranging between -100 and +100 mm yr-1. We also analyzed potential changes in plant functional type (PFT) distributions at the biome level, but hypothesize that the model may be unable to adequately capture competitive interactions among PFTs as well as the dynamics between upper and lower canopies consisting of trees, grasses and shrubs. An analysis of the bioclimatic envelopes for PFTs common to the region revealed no significant change to the boreal conifer tree climatic domain over the study

  2. Interactions between climate and vegetation during the Lateglacial period as recorded by lake and mire sediment archives in Northern Italy and Southern Switzerland

    NARCIS (Netherlands)

    Vescovi, E.; Ravazzi, C.; Arpenti, E.; Finsinger, W.; Pini, R.; Valsecchi, V.; Wick, L.; Ammann, B.; Tinner, W.

    2007-01-01

    We reconstruct the vegetational history of the southern side of the Alps at 18,000–10,000 cal yr BP using previous and new AMS-dated stratigraphic records of pollen, stomata, and macrofossils. To address potential effects of climatic change on vegetation, we compare our results with independent

  3. Climate change-induced vegetation change as a driver of increased subarctic biogenic volatile organic compound emissions.

    Science.gov (United States)

    Valolahti, Hanna; Kivimäenpää, Minna; Faubert, Patrick; Michelsen, Anders; Rinnan, Riikka

    2015-09-01

    Emissions of biogenic volatile organic compounds (BVOCs) have been earlier shown to be highly temperature sensitive in subarctic ecosystems. As these ecosystems experience rapidly advancing pronounced climate warming, we aimed to investigate how warming affects the BVOC emissions in the long term (up to 13 treatment years). We also aimed to assess whether the increased litterfall resulting from the vegetation changes in the warming subarctic would affect the emissions. The study was conducted in a field experiment with factorial open-top chamber warming and annual litter addition treatments on subarctic heath in Abisko, northern Sweden. After 11 and 13 treatment years, BVOCs were sampled from plant communities in the experimental plots using a push-pull enclosure technique and collection into adsorbent cartridges during the growing season and analyzed with gas chromatography-mass spectrometry. Plant species coverage in the plots was analyzed by the point intercept method. Warming by 2 °C caused a 2-fold increase in monoterpene and 5-fold increase in sesquiterpene emissions, averaged over all measurements. When the momentary effect of temperature was diminished by standardization of emissions to a fixed temperature, warming still had a significant effect suggesting that emissions were also indirectly increased. This indirect increase appeared to result from increased plant coverage and changes in vegetation composition. The litter addition treatment also caused significant increases in the emission rates of some BVOC groups, especially when combined with warming. The combined treatment had both the largest vegetation changes and the highest BVOC emissions. The increased emissions under litter addition were probably a result of a changed vegetation composition due to alleviated nutrient limitation and stimulated microbial production of BVOCs. We suggest that the changes in the subarctic vegetation composition induced by climate warming will be the major factor

  4. Icing Conditions Over Northern Eurasia in Changing Climate

    Science.gov (United States)

    Bulygina, O.; Arzhanova, N.; Groisman, P. Y.

    2013-12-01

    Climate of the Russian Federation for the national territory. This Reference Book addresses the current state of these weather phenomena. However, the ongoing and projected humidity changes in the high latitudes will strongly affect the circum-polar area (land and ocean) and impact the frequency and intensity of these potentially dangerous weather phenomena across the entire extratropical land area. Therefore the goal of the present study is to quantify icing conditions over the northern Eurasia. Our analysis includes data of 958 Russian stations from 1977 to 2012. Regional analysis of gololed characteristics was carried out using quasi-homogeneous climatic regions. Maps (climatology, trends) are presented mostly for visualization purposes. The area-averaging technique using station values converted to anomalies with respect to a common reference period (in this study, from 1977 to 2012). Anomalies were arithmetically averaged first within 1N x 2E grid cells and thereafter by a weighted average value derived over the quasi-homogeneous climatic regions. This approach provides a more uniform spatial field for averaging.

  5. Changes in autumn vegetation dormancy onset date and the climate controls across temperate ecosystems in China from 1982 to 2010.

    Science.gov (United States)

    Yang, Yuting; Guan, Huade; Shen, Miaogen; Liang, Wei; Jiang, Lei

    2015-02-01

    Vegetation phenology is a sensitive indicator of the dynamic response of terrestrial ecosystems to climate change. In this study, the spatiotemporal pattern of vegetation dormancy onset date (DOD) and its climate controls over temperate China were examined by analysing the satellite-derived normalized difference vegetation index and concurrent climate data from 1982 to 2010. Results show that preseason (May through October) air temperature is the primary climatic control of the DOD spatial pattern across temperate China, whereas preseason cumulative precipitation is dominantly associated with the DOD spatial pattern in relatively cold regions. Temporally, the average DOD over China's temperate ecosystems has delayed by 0.13 days per year during the past three decades. However, the delay trends are not continuous throughout the 29-year period. The DOD experienced the largest delay during the 1980s, but the delay trend slowed down or even reversed during the 1990s and 2000s. Our results also show that interannual variations in DOD are most significantly related with preseason mean temperature in most ecosystems, except for the desert ecosystem for which the variations in DOD are mainly regulated by preseason cumulative precipitation. Moreover, temperature also determines the spatial pattern of temperature sensitivity of DOD, which became significantly lower as temperature increased. On the other hand, the temperature sensitivity of DOD increases with increasing precipitation, especially in relatively dry areas (e.g. temperate grassland). This finding stresses the importance of hydrological control on the response of autumn phenology to changes in temperature, which must be accounted in current temperature-driven phenological models. © 2014 John Wiley & Sons Ltd.

  6. Late-Holocene vegetation dynamics in response to a changing climate and anthropogenic influences - Insights from stratigraphic records and subfossil trees from southeast Lithuania

    Science.gov (United States)

    Edvardsson, Johannes; Stančikaitė, Miglė; Miras, Yannick; Corona, Christophe; Gryguc, Gražyna; Gedminienė, Laura; Mažeika, Jonas; Stoffel, Markus

    2018-04-01

    To increase our understanding of long-term climate dynamics and its effects on different ecosystems, palaeoclimatic and long-term botanical reconstructions need to be improved, in particular in underutilized geographical regions. In this study, vegetation, (hydro)climate, and land-use changes were documented at two southeast Lithuanian peatland complexes - Čepkeliai and Rieznyčia - for the Late-Holocene period. The documentation was based on a combination of pollen, plant macrofossils, peat stratigraphic records, and subfossil trees. Our results cover the last two millennia and reveal the existence of moist conditions in Southern Lithuania between 300 and 500 CE and from 950 to 1850 CE. Conversely, changes towards warmer and/or dryer conditions have been recorded in 100, 600, and 750 CE, and since the 1850s. Significant differences with other Baltic proxies prevent deriving a complete and precise long-term reconstruction of past hydroclimatic variability at the regional scale. Yet, our results provide an important cornerstone for an improved understanding of regional climate change, i.e. in a region for which only (i) few detailed palaeobotanical studies exist and which has, in addition, been considered as (ii) an ecologically sensitive region at the interface between the temperate and boreal bioclimatic zones.

  7. Climate change and wildfire effects in aridland riparian ecosystems: An examination of current and future conditions

    Science.gov (United States)

    D. Max Smith; Deborah M. Finch

    2017-01-01

    Aridland riparian ecosystems are limited, the climate is changing, and further hydrological change is likely in the American Southwest. To protect riparian ecosystems and organisms, we need to understand how they are affected by disturbance processes and stressors such as fire, drought, and non-native plant invasions. Riparian vegetation is critically important as...

  8. Exergy characteristics of a ceiling-type residential air conditioning system operating under different climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ozbek, Arif [Dept. of Mechanical Engineering, Ceyhan Engineering Faculty, Cukurova University, Adana (Turkmenistan)

    2016-11-15

    In this study an energy and exergy analysis of a Ceiling-type residential air conditioning (CTRAC) system operating under different climatic conditions have been investigated for provinces within the different geographic regions of Turkey. Primarily, the hourly cooling load capacities of a sample building (Q{sub evap}) during the months of April, May, June, July, August and September were determined. The hourly total heat gain of the sample building was determined using the Hourly analysis program (HAP). The Coefficient of performance (COP), exergy efficiency (η) and exergy destruction (Ex{sub dest}) values for the whole system and for each component were obtained. The results showed that lower atmospheric temperature (T{sub atm}) influenced the performance of the system and each of its components.

  9. Icing conditions over Northern Eurasia in changing climate

    International Nuclear Information System (INIS)

    Bulygina, Olga N; Arzhanova, Natalia M; Groisman, Pavel Ya

    2015-01-01

    Icing conditions, particularly in combination with wind, affect greatly the operation of overhead communication and transmission lines causing serious failures, which result in tremendous economic damage. Icing formation is dangerous to agriculture, forestry, high seas fishery, for land and off coast man-made infrastructure. Quantitative icing characteristics such as weight, thickness, and duration are very important for the economy and human wellbeing when their maximum values exceed certain thresholds. Russian meteorological stations perform both visual and instrumental monitoring of icing deposits. Visual monitoring is ocular estimation of the type and intensity of icing and the date of ice appearance and disappearance. Instrumental monitoring is performed by ice accretion indicator that in addition to the type, intensity and duration of ice deposits reports also their weight and size. We used observations at 958 Russian stations for the period 1977–2013 to analyze changes in the ice formation frequency at individual meteorological stations and on the territory of quasi-homogeneous climatic regions in Russia. It was found that hoar frosts are observed in most parts of Russia, but icing only occurs in European Russia and the Far East. On the Arctic coast of Russia, this phenomenon can even be observed in summer months. Statistically significant decreasing trends in occurrence of icing and hoar frost events are found over most of Russia. An increasing trend in icing weights (IWs) was found in the Atlantic Arctic region in autumn. Statistically significant large negative trends in IWs were found in the Pacific Arctic in winter and spring. (letter)

  10. Spirometry Changes in Cold Climatic Conditions of Antarctica.

    Science.gov (United States)

    Udaya, Iyamanda B; Laxmi, Chettangada C; Abhishekh, Hulegar A; Raju, Trichur R; Sathyaprabha, Talakad N

    2015-01-01

    Pulmonary function is one of the important physiological measures that is known to be affected during the changes in the altitude. There is dearth of literature on changes in the pulmonary function variables in the cold climate conditions of Antarctica. We carried out spirometry before, during and after one year stay at Antarctica in members of the Indian expedition. Spirometry was carried out on 23 members of the XXVI Indian Scientific Expedition to Antarctica at baseline, after six months of expedition and at the end of one year, using standard guidelines. The tests were carried out indoor in temperature controlled laboratory. The pulmonary function test parameters did not vary across the period. Although, both forced vital capacity (FVC) and forced expiratory volume in first second (FEV1) showed a decreasing trend but did not attain any statistical significance. However, peak expiratory flow (PEFR) rate was reduced significantly. Our study did not show consistently significant change in the pulmonary function parameters in the members of the Indian Antarctic expedition.

  11. Vegetation, soil property and climatic controls over greenhouse gas fluxes in a blanket peatland hosting a wind farm

    Science.gov (United States)

    Armstrong, Alona; Waldron, Susan; Ostle, Nick; Whitaker, Jeanette

    2013-04-01

    Peatlands are important carbon (C) stores, with boreal and subarctic peatlands containing 15-30 % of the world soil carbon stock (Limpens et al., 2008). Research has demonstrated that greenhouse gas (GHG) fluxes in peatlands are influenced by vegetation, soil property and climatic variables, including plant functional type (PFT), water table height and temperature. In this paper we present data from Black Law Wind Farm, Scotland, where we examined the effect of a predicted wind turbine-induced microclimatic gradient and PFT on carbon dioxide (CO2) and methane (CH4) fluxes. Moreover, we determined the role of vegetation, soil property and climatic variables as predictors of the variation in CO2 and CH4 emissions. We measured CO2 and CH4 at 48 plots within Black Law Wind Farm at monthly intervals from May 2011 to April 2012. Four sampling sites were located along a predicted wind turbine-induced microclimatic gradient. At each site four blocks were established, each with plots in areas dominated by mosses, sedges and shrubs. Plant biomass and PFT (vegetation factors); soil moisture, water table height, peat depth, C content, nitrogen (N) content and C:N (soil properties); and soil temperature and photosynthetically active radiation (PAR) (climatic variables) were measured. Analysis of variance (ANOVA) models based on the microclimatic gradient site, PFT and season when measurements were made explained 58 %, 44 % and 49 % of the variation in ecosystem respiration, photosynthesis and CH4, respectively. Site, PFT, season and their interactions were all significant for respiration and photosynthesis (with the exception of the PFT*site interaction) but for CH4 only the main effects were significant. Parsimonious ANOVA models using the biotic, soil property and climatic explanatory data explained 62 %, 55 % and 49 % of the variation in respiration, photosynthesis and CH4, respectively. Published studies (Baidya Roy and Traiteur 2010; Zhou et al., 2012) and preliminary

  12. Carbon Storage of Forest Vegetation in China and its Relationship with Climatic Factors

    International Nuclear Information System (INIS)

    Zhao, M.; Zhou, Guang-Sheng

    2006-01-01

    Estimates of forest vegetation carbon storage in China varied due to different methods used in the assessments. In this paper, we estimated the forest vegetation carbon storage from the Fourth Forest Inventory Data (FFID) in China using a modified volume-derived method. Results showed that total carbon storage and mean carbon density of forest vegetation in China were 3.8 Pg C (about 1.1% of the global vegetation carbon stock) and 41.32 Mg/ha, respectively. In addition, based on linear multiple regression equation and factor analysis method, we analyzed contributions of biotic and abiotic factors (including mean forest age, mean annual temperature, annual precipitation, and altitude) to forest carbon storage. Our results indicated that forest vegetation carbon storage was more sensitive to changes of mean annual temperature than other factors, suggesting that global warming would seriously affect the forest carbon storage

  13. Groundwater flow modelling of periods with temperate climate conditions - Laxemar

    International Nuclear Information System (INIS)

    Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Roberts, David; Swan, David; Gylling, Bjoern; Marsic, Niko; Rhen, Ingvar

    2010-12-01

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Laxemar-Simpevarp site during temperate climate conditions as a comparison to corresponding modelling carried out for Forsmark /Joyce et al. 2010/. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a Hydrogeological base case (reference case conceptualisation) and then an examination of various areas of uncertainty within the current understanding by a series of model variants. The Hydrogeological base case models at three different scales, 'repository', 'site' and 'regional' make use of a discrete fracture network (DFN) and equivalent continuous porous medium (ECPM) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 15,000 AD. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  14. Groundwater flow modelling of periods with temperate climate conditions - Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Swan, David (Serco Technical Consulting Services (United Kingdom)); Marsic, Niko (Kemakta Konsult AB (Sweden)); Follin, Sven (SF GeoLogic AB (Sweden))

    2010-11-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Forsmark site during temperate conditions; i.e. from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 12,000 AD. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a hydrogeological base case (reference case conceptualisation) and then in an examination of various areas of uncertainty within the current understanding by a series of model variants. The hydrogeological base case models at three different scales, 'repository', 'site' and 'regional', make use of continuous porous medium (CPM), equivalent continuous porous medium (ECPM) and discrete fracture network (DFN) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  15. Groundwater flow modelling of periods with temperate climate conditions - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Roberts, David; Swan, David (Serco Technical Consulting Services (United Kingdom)); Gylling, Bjoern; Marsic, Niko (Kemakta Konsult AB, Stockholm (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Laxemar-Simpevarp site during temperate climate conditions as a comparison to corresponding modelling carried out for Forsmark /Joyce et al. 2010/. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a Hydrogeological base case (reference case conceptualisation) and then an examination of various areas of uncertainty within the current understanding by a series of model variants. The Hydrogeological base case models at three different scales, 'repository', 'site' and 'regional' make use of a discrete fracture network (DFN) and equivalent continuous porous medium (ECPM) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 15,000 AD. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  16. Climate-vegetation-fire interactions and their impact on long-term carbon dynamics in a boreal peatland landscape in northern Manitoba, Canada

    Science.gov (United States)

    Camill, Philip; Barry, Ann; Williams, Evie; Andreassi, Christian; Limmer, Jacob; Solick, Donald

    2009-12-01

    Climate warming may increase the size and frequency of fires in the boreal biome, possibly causing greater carbon release that amplifies warming. However, in peatlands, vegetation change may also control long-term fire and carbon accumulation, confounding simple relationships between climate, fire, and carbon accumulation. Using 17 peat cores dating to 8000 cal years B.P. from northern Manitoba, Canada, we addressed the following questions: (1) Do past climate changes correlate with shifts in peatland vegetation? (2) What is the relationship between peatland vegetation and fire severity? (3) What is the mean return interval for boreal peat fires, and how does it change across fires of different severities? (4) How does fire severity affect carbon accumulation rates? (5) Do fire and long-term carbon accumulation change directly in response to climate or indirectly though climate-driven changes in vegetation? We measured carbon accumulation rates, fire severity, and return intervals using macroscopic charcoal and changes in vegetation using macrofossils. Climate and vegetation changes covaried, with shifts from wetter fen to drier, forested bog communities during the Holocene Thermal Maximum (HTM). Fires became more severe following the shift to forested bogs, with fire severity peaking after 4000 cal years B.P. rather than during the HTM. Rising fire severity, in turn, was correlated with a significant decrease in carbon accumulation from ˜6000 to 2000 cal years B.P. The Medieval Warm Period and Little Ice Age affected vegetation composition and permafrost, further impacting fire and carbon accumulation. Our results indicate that long-term changes in fire and carbon dynamics are mediated by climate-driven changes in vegetation.

  17. Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes.

    NARCIS (Netherlands)

    Cornelissen, J.H.C.; van Bodegom, P.M.; Aerts, R.; Gallaghan, T.V.; van Logtestijn, R.S.P; Alatalo, J.; Chapin, F.S. III; Gerdol, R.; Gudmundsson, J.; Gwynn-Jones, D.; Hartley, A.E.; Hik, D.S.; Hofgaard, A.; Jonsdottir, I.S.; Karlsson, S.; Klein, J.A.; Laundre, J.; Magnusson, B.; Michelsel, A.; Molau, U.; Onipchenko, V.G.; Quested, H.M.; Sandvik, S.M.; Schmidt, I.K.; Shaver, G.R.; Solhleim, B.; Soudzilovskaia, N.A.; Stenstrom, A.; Tolvanen, A.; Totland, O.; Wada, N.; Welker, J.M.; Zhao, X.; Team, M.O.L.

    2007-01-01

    Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition.

  18. GWAS of Barley Phenotypes Established Under Future Climate Conditions of Elevated Temperature, CO2, O3 and Elevated Temperature and CO2 Combined

    DEFF Research Database (Denmark)

    Ingvordsen, Cathrine Heinz; Backes, G.; Lyngkjær, M. F.

    2015-01-01

    Climate change is likely to decrease crop yields worldwide. Developing climate resilient cultivars is one way to combat this production scarcity, however, little is known of crop response to future climate conditions and in particular the variability within crops.In Scandinavia, barley is widely...... cultivated, but yields have stagnated since the start of this century. In this study we cultivated 138 spring barley accessions in a climate phytotron under four treatments mimicking forecasted levels of temperature, carbon dioxide concentration ([CO2]) and ozone ([O3]) at the end of the 21st century1...... yield, grain protein concentration, grain protein harvested, number of grains, number of ears, aboveground vegetative biomass and harvest index. In addition, stability of the production was calculated over the applied treatments for the assessed parameters.In the climate scenario of elevated temperature...

  19. Climate Change and Crop Exposure to Adverse Weather: Changes to Frost Risk and Grapevine Flowering Conditions.

    Science.gov (United States)

    Mosedale, Jonathan R; Wilson, Robert J; Maclean, Ilya M D

    2015-01-01

    The cultivation of grapevines in the UK and many other cool climate regions is expected to benefit from the higher growing season temperatures predicted under future climate scenarios. Yet the effects of climate change on the risk of adverse weather conditions or events at key stages of crop development are not always captured by aggregated measures of seasonal or yearly climates, or by downscaling techniques that assume climate variability will remain unchanged under future scenarios. Using fine resolution projections of future climate scenarios for south-west England and grapevine phenology models we explore how risks to cool-climate vineyard harvests vary under future climate conditions. Results indicate that the risk of adverse conditions during flowering declines under all future climate scenarios. In contrast, the risk of late spring frosts increases under many future climate projections due to advancement in the timing of budbreak. Estimates of frost risk, however, were highly sensitive to the choice of phenology model, and future frost exposure declined when budbreak was calculated using models that included a winter chill requirement for dormancy break. The lack of robust phenological models is a major source of uncertainty concerning the impacts of future climate change on the development of cool-climate viticulture in historically marginal climatic regions.

  20. Assessing Lebanon's wildfire potential in association with current and future climatic conditions

    Science.gov (United States)

    George H. Mitri; Mireille G. Jazi; David McWethy

    2015-01-01

    The increasing occurrence and extent of large-scale wildfires in the Mediterranean have been linked to extended periods of warm and dry weather. We set out to assess Lebanon's wildfire potential in association with current and future climatic conditions. The Keetch-Byram Drought Index (KBDI) was the primary climate variable used in our evaluation of climate/fire...

  1. Vegetation Activity Trend and Its Relationship with Climate Change in the Three Gorges Area, China

    Directory of Open Access Journals (Sweden)

    Guifeng Han

    2013-01-01

    Full Text Available Based on SPOT/VGT NDVI time series images from 1999 to 2009 in the Three Gorges Area (TGA, we detected vegetation activity and trends using two methods, the Mann-Kendall and Slope tests. The relationships between vegetation activity trends and annual average temperature and annual total precipitation were analyzed using observational data in seven typical meteorological stations. Vegetation activity presents a distinctive uptrend during the study period, especially in Fengjie, Yunyang, Wushan, Wuxi, and Badong counties located in the midstream of the Three Gorges Reservoir. However, in the Chongqing major area (CMA and its surrounding areas and Fuling, Yichang, and part of Wanzhou, vegetation activity shows a decreasing trend as a result of urban expansion. The NDVI has two fluctuation troughs in 2004 and 2006. The annual mean temperature presents a slight overall upward trend, but the annual total precipitation does not present a significant trend. And they almost have no significant correlations with the NDVI. Therefore, temperature and precipitation are not major influences on vegetation activity change. Instead, increasing vegetation cover benefits from a number of environment protection policies and management, and ecological construction is a major factor resulting in the upward trend. In addition, resettlement schemes mitigate the impact of human activity on vegetation activity.

  2. Climate change and its potential impact on mechanical, hydraulic and chemical conditions

    International Nuclear Information System (INIS)

    Naslund, J.O.

    2009-01-01

    The strategy for managing climate related conditions in SKB ' s safety assessments are based on the notion that it is not possible to predict climate in a 100 000-year time perspective. Instead, the approach in the SR-Can safety assessment was to identify and analyse both moderate climate evolutions as well as extremes within which the climate in Scandinavia may vary. To this end, knowledge on general climate variations in Scandinavia was used to identify characteristic climate domains which in turn were used to build a number of selected climate scenarios. The relevant climate domains for the Forsmark and Laxemar sites in the 100 000-year time perspective are; 1) a temperate climate domain, 2) a peri-glacial climate domain, and 3) a glacial climate domain. Also submerged/non-submerged conditions at the sites are of importance. In the SR-Can safety assessment several climate scenarios were investigated, including a reference evolution based on a repetition of reconstructed conditions for last glacial cycle (the Weichselian glaciation and the Holocene interglacial). For this reconstruction, extensive numerical simulations of ice sheets, isostatic changes, and permafrost were conducted. The resulting scenario showed site-specific timing and duration of the three climate domains and submerged periods for the full glacial cycle. This scenario is not a prediction of a future climate evolution. Instead it is one example of a future evolution that in a realistic and consistent way covers all relevant climate related changes that can be expected in a 100 000-year time perspective. Subsequently, this scenario formed the basis for the construction of additional climate scenarios that were used to analyse the effects of more extreme climate evolutions than during the last glacial cycle. Examples of complementary scenarios are a warmer and wetter climate scenario caused by an increased greenhouse effect, and colder scenarios with deeper permafrost or thicker ice sheets than in

  3. A 15,000 year record of vegetation and climate change from a treeline lake in the Rocky Mountains, Wyoming, USA

    Science.gov (United States)

    Scott A. Mensing; John L. Korfmacher; Thomas Minckley; Robert C. Musselman

    2012-01-01

    Future climate projections predict warming at high elevations that will impact treeline species, but complex topographic relief in mountains complicates ecologic response, and we have a limited number of long-term studies examining vegetation change related to climate. In this study, pollen and conifer stomata were analyzed from a 2.3 m sediment core extending to 15,...

  4. The effects of past climate variability on fire and vegetation in the cerrãdo savanna ecosystem of the Huanchaca Mesetta, Noel Kempff Mercado National Park, NE Bolivia

    Science.gov (United States)

    Maezumi, S. Y.; Power, M. J.; Mayle, F. E.; McLauchlan, K.; Iriarte, J.

    2015-01-01

    Cerrãdo savannas have the greatest fire activity of all major global land-cover types and play a significant role in the global carbon cycle. During the 21st century, temperatures are predicted to increase by ~ 3 °C coupled with a precipitation decrease of ~ 20%. Although these conditions could potentially intensify drought stress, it is unknown how that might alter vegetation composition and fire regimes. To assess how Neotropical savannas responded to past climate changes, a 14 500 year, high-resolution, sedimentary record from Huanchaca Mesetta, a palm swamp located in the cerrãdo savanna in northeastern Bolivia, was analyzed for phytoliths, stable isotopes and charcoal. A non-analogue, cold-adapted vegetation community dominated the Late Glacial-Early Holocene period (14 500-9000 ka), that included trees and C3 Pooideae and C4 Panicoideae grasses. The Late Glacial vegetation was fire sensitive and fire activity during this period was low, likely responding to fuel availability and limitation. Although similar vegetation characterized the Early Holocene, the warming conditions associated with the onset of the Holocene led to an initial increase in fire activity. Huanchaca Mesetta became increasingly fire-dependent during the Middle Holocene with the expansion of C4 fire adapted grasses. However, as warm, dry conditions, characterized by increased length and severity of the dry season, continued, fuel availability decreased. The establishment of the modern palm swamp vegetation occurred at 5000 cal yr BP. Edaphic factors are the first order control on vegetation on the rocky quartzite mesetta. Where soils are sufficiently thick, climate is the second order control of vegetation on the mesetta. The presence of the modern palm swamp is attributed to two factors: (1) increased precipitation that increased water table levels, and (2) decreased frequency and duration of surazos leading to increased temperature minima. Natural (soil, climate, fire) drivers rather

  5. Using historical simulations of vegetation to assess departure of current vegetation conditions across large landscapes[Chapter 11

    Science.gov (United States)

    Lisa Holsinger; Robert E. Keane; Brian Steele; Matthew C. Reeves; Sarah Pratt

    2006-01-01

    The Landscape Fire and Resource Management Planning Tools Prototype Project, or LANDFIRE Prototype Project, was conceived, in part, to identify areas across the nation where existing landscape conditions are markedly different from historical conditions (Keane and Rollins, Ch. 3). This objective arose from the recognition that over 100 years of land use and wildland...

  6. Is the co-occurrence of smoking and poor consumption of fruits and vegetables confounded by socioeconomic conditions?

    Science.gov (United States)

    Muff, Christine; Dragano, N; Jöckel, K-H; Moebus, S; Möhlenkamp, S; Erbel, R; Mann, K; Siegrist, J

    2010-08-01

    As smoking and unhealthy diet are more prevalent in lower socioeconomic groups, this study aims at exploring whether associations between smoking and fruit and vegetable consumption are confounded by socioeconomic conditions or if smoking is independently associated with consumption. Cross-sectional analyses of 4,814 middle-aged participants from the Heinz Nixdorf recall study, a population-based cohort study in Germany. Fruit and vegetable consumption was assessed by a food frequency questionnaire. Education and income were used as indicators for socioeconomic groups. Logistic regression models were run to estimate odds ratios for consumption by smoking status. Smoking is associated with poor consumption of fruits and raw vegetables/salad in both genders, and with poor consumption of boiled vegetables and fruit/vegetable juice in men. Importantly, poor consumption is related to smoking independently of people's socioeconomic conditions. The findings imply that smokers in all socioeconomic groups are at higher risk for unhealthy intake of fruits and vegetables. Public health interventions targeted to smokers should include dietary instructions.

  7. The relative importance of climate and vegetation properties on patterns of North American breeding bird species richness

    International Nuclear Information System (INIS)

    Goetz, Scott J; Sun, Mindy; Zolkos, Scott; Hansen, Andy; Dubayah, Ralph

    2014-01-01

    Recent advances in remote sensing and ecological modeling warrant a timely and robust investigation of the ecological variables that underlie large-scale patterns of breeding bird species richness, particularly in the context of intensifying land use and climate change. Our objective was to address this need using an array of bioclimatic and remotely sensed data sets representing vegetation properties and structure, and other aspects of the physical environment. We first build models of bird species richness across breeding bird survey (BBS) routes, and then spatially predict richness across the coterminous US at moderately high spatial resolution (1 km). Predictor variables were derived from various sources and maps of species richness were generated for four groups (guilds) of birds with different breeding habitat affiliation (forest, grassland, open woodland, scrub/shrub), as well as all guilds combined. Predictions of forest bird distributions were strong (R 2 = 0.85), followed by grassland (0.76), scrub/shrub (0.63) and open woodland (0.60) species. Vegetation properties were generally the strongest determinants of species richness, whereas bioclimatic and lidar-derived vertical structure metrics were of variable importance and dependent upon the guild type. Environmental variables (climate and the physical environment) were also frequently selected predictors, but canopy structure variables were not as important as expected based on more local to regional scale studies. Relatively sparse sampling of canopy structure metrics from the satellite lidar sensor may have reduced their importance relative to other predictor variables across the study domain. We discuss these results in the context of the ecological drivers of species richness patterns, the spatial scale of bird diversity analyses, and the potential of next generation space-borne lidar systems relevant to vegetation and ecosystem studies. This study strengthens current understanding of bird species–climate–vegetation

  8. Effect of climate-related change in vegetation on leaf litter consumption and energy storage by Gammarus pulex from Continental or Mediterranean populations.

    Directory of Open Access Journals (Sweden)

    Natacha Foucreau

    Full Text Available As a consequence of global warming, it is important to characterise the potential changes occurring for some functional processes through the intra-specific study of key species. Changes in species distribution, particularly when key or engineer species are affected, should contribute to global changes in ecosystem functioning. In this study, we examined the potential consequences induced by global warming on ecosystem functioning in term of organic matter recycling. We compared consumption of leaf litter by some shredder populations (Gammarus pulex between five tree species inhabiting continental (i.e., the northern region of the Rhône River Valley and/or Mediterranean (i.e., the southern region of the Rhône River Valley conditions. To consider any potential adaptation of the gammarid population to vegetation in the same climate conditions, three populations of the key shredder Gammarus pulex from the northern region and three from the southern region of the Rhône River Valley were used. We experimentally compared the effects of the geographical origin of both the gammarid populations and the leaf litter species on the shredding activity and the physiological state of animals (through body triglyceride content. This study demonstrated that leaf toughness is more important than geographical origin for determining shredder leaf litter consumption. The overall consumption rate of the gammarid populations from the southern region of Rhône Valley was much higher than that of the populations from the northern region, but no clear differences between the origins of the leaf litter (i.e., continental vs. Mediterranean were observed. The northwards shift of G. pulex populations adapted to warmer conditions might significantly modify organic matter recycling in continental streams. As gammarid populations can demonstrate local adaptations to certain leaf species as a trophic resource, changes in riparian vegetation associated with climate change

  9. Equilibrium of vegetation and climate at the European rear edge. A reference for climate change planning in mountainous Mediterranean regions.

    Science.gov (United States)

    Ruiz-Labourdette, Diego; Martínez, Felipe; Martín-López, Berta; Montes, Carlos; Pineda, Francisco D

    2011-05-01

    Mediterranean mountains harbour some of Europe's highest floristic richness. This is accounted for largely by the mesoclimatic variety in these areas, along with the co-occurrence of a small area of Eurosiberian, Boreal and Mediterranean species, and those of Tertiary Subtropical origin. Throughout the twenty-first century, we are likely to witness a climate change-related modification of the biogeographic scenario in these mountains, and there is therefore a need for accurate climate regionalisations to serve as a reference of the abundance and distribution of species and communities, particularly those of a relictic nature. This paper presents an objective mapping method focussing on climate regions in a mountain range. The procedure was tested in the Cordillera Central Mountains of the Iberian Peninsula, in the western Mediterranean, one of the ranges occupying the largest area of the Mediterranean Basin. This regionalisation is based upon multivariate analyses and upon detailed cartography employing 27 climatic variables. We used spatial interpolation of data based on geographic information. We detected high climatic diversity in the mountain range studied. We identified 13 climatic regions, all of which form a varying mosaic throughout the annual temperature and rainfall cycle. This heterogeneity results from two geographically opposed gradients. The first one is the Mediterranean-Euro-Siberian variation of the mountain range. The second gradient involves the degree of oceanicity, which is negatively related to distance from the Atlantic Ocean. The existing correlation between the climatic regions detected and the flora existing therein enables the results to be situated within the projected trends of global warming, and their biogeographic and ecological consequences to be analysed.

  10. Climate policy in developing countries and conditional transfers

    International Nuclear Information System (INIS)

    Ruebbelke, Dirk T.G.

    2006-01-01

    This paper analyzes the role international transfers may play in international climate policy in consideration of the policy's ancillary benefits, such as air quality improvements. Ancillary benefits are especially important in many developing countries, while climate protection benefits or primary benefits play a minor role on the political agenda of these countries. In contrast, industrialized countries have a strong interest in combating climate change. These often neglected asymmetries between the developing and industrialized world affect the impacts of transfers. Interestingly, as we will show, the cost differentials between different environmental technologies among countries are the crucial prerequisite for the functioning of a transfer scheme and not the cost differentials in the execution of climate policy. This result has been overlooked by standard pure public good approaches

  11. Uncertainties in extreme precipitation under climate change conditions

    DEFF Research Database (Denmark)

    Sunyer Pinya, Maria Antonia

    of adaptation strategies, but these changes are subject to uncertainties. The focus of this PhD thesis is the quantification of uncertainties in changes in extreme precipitation. It addresses two of the main sources of uncertainty in climate change impact studies: regional climate models (RCMs) and statistical...... downscaling methods (SDMs). RCMs provide information on climate change at the regional scale. SDMs are used to bias-correct and downscale the outputs of the RCMs to the local scale of interest in adaptation strategies. In the first part of the study, a multi-model ensemble of RCMs from the European ENSEMBLES...... project was used to quantify the uncertainty in RCM projections over Denmark. Three aspects of the RCMs relevant for the uncertainty quantification were first identified and investigated. These are: the interdependency of the RCMs; the performance in current climate; and the change in the performance...

  12. Blue Water Trade-Offs With Vegetation in a CO2-Enriched Climate

    Science.gov (United States)

    Mankin, Justin S.; Seager, Richard; Smerdon, Jason E.; Cook, Benjamin I.; Williams, A. Park; Horton, Radley M.

    2018-04-01

    Present and future freshwater availability and drought risks are physically tied to the responses of surface vegetation to increasing CO2. A single-model large ensemble identifies the occurrence of colocated warming- and CO2-induced leaf area index increases with summer soil moisture declines. This pattern of "greening" and "drying," which occurs over 42% of global vegetated land area, is largely attributable to changes in the partitioning of precipitation at the land surface away from runoff and toward terrestrial vegetation ecosystems. Changes in runoff and ecosystem partitioning are inversely related, with changes in runoff partitioning being governed by changes in precipitation (mean and extremes) and ecosystem partitioning being governed by ecosystem water use and surface resistance to evapotranspiration (ET). Projections show that warming-influenced and CO2-enriched terrestrial vegetation ecosystems use water that historically would have been partitioned to runoff over 48% of global vegetated land areas, largely in Western North America, the Amazon, and Europe, many of the same regions with colocated greening and drying. These results have implications for how water available for people will change in response to anthropogenic warming and raise important questions about model representations of vegetation water responses to high CO2.

  13. Calibration of transfer functions between phytolith, vegetation and climate for integration of grassland dynamics in vegetation models. Application to a 50,000 yr crater lake core in Tanzania.

    Science.gov (United States)

    Bremond, L.; Alexandre, A.; Hely, C.; Vincens, A.; Williamson, D.; Guiot, J.

    2004-12-01

    Global vegetation models provide a way to translate the outputs from climate models into maps of potential vegetation distribution for present, past and future. Validation of these models goes through the comparison between model outputs and vegetation proxies for well constrained past climatic periods. Grass-dominated biomes are widespread and numerous. This diversity is hardly mirrored by common proxies such as pollen, charcoal or carbon isotopes. Phytoliths are amorphous silica that precipitate in and/or between living plant cells. They are commonly used to trace grasslands dynamics. However, calibration between phytolith assemblages, vegetation, and climate parameters are scarce. This work introduces transfer functions between phytolith indices, inter-tropical grassland physiognomy, and bio-climatic data that will be available for model/data comparisons. The Iph phytolith index discriminates tall from short grass savannas in West Africa. A transfer function allows to estimate evapo-transpiration AET/PET. The Ic phytolith index accurately estimates the proportion of Pooideae and Panicoideae grass sub-families, and potentially the C4/C3 grass dominance on East African mountains. The D/P index appears as a good proxy of Leaf Area Index (LAI) in tropical areas. These environmental parameters are commonly used as vegetation model outputs, but have been, up to now, hardly estimated by vegetation proxies. These transfer functions are applied to a 50,000 yr phytolith sequence from a crater lake (9°S; 33°E Tanzania). The record is compared to the pollen vegetation reconstruction and confronted to simulations of the LPJ-GUESS vegetation model (Stitch et. al, 2003).

  14. Vegetation Response to Climate Change in the Southern Part of Qinghai-Tibet Plateau at Basinal Scale

    Science.gov (United States)

    Liu, X.; Liu, C.; Kang, Q.; Yin, B.

    2018-04-01

    Global climate change has significantly affected vegetation variation in the third-polar region of the world - the Qinghai-Tibet Plateau. As one of the most important indicators of vegetation variation (growth, coverage and tempo-spatial change), the Normalized Difference Vegetation Index (NDVI) is widely employed to study the response of vegetation to climate change. However, a long-term series analysis cannot be achieved because a single data source is constrained by time sequence. Therefore, a new framework was presented in this paper to extend the product series of monthly NDVI, taking as an example the Yarlung Zangbo River Basin, one of the most important river basins in the Qinghai-Tibet Plateau. NDVI products were acquired from two public sources: Global Inventory Modeling and Mapping Studies (GIMMS) Advanced Very High Resolution Radiometer (AVHRR) and Moderate-Resolution Imaging spectroradiometer (MODIS). After having been extended using the new framework, the new time series of NDVI covers a 384 months period (1982-2013), 84 months longer than previous time series of NDVI product, greatly facilitating NDVI related scientific research. In the new framework, the Gauss Filtering Method was employed to filter out noise in the NDVI product. Next, the standard method was introduced to enhance the comparability of the two data sources, and a pixel-based regression method was used to construct NDVI-extending models with one pixel after another. The extended series of NDVI fit well with original AVHRR-NDVI. With the extended time-series, temporal trends and spatial heterogeneity of NDVI in the study area were studied. Principal influencing factors on NDVI were further determined. The monthly NDVI is highly correlated with air temperature and precipitation in terms of climatic change wherein the spatially averaged NDVI slightly increases in the summer and has increased in temperature and decreased in precipitation in the 32 years period. The spatial heterogeneity of

  15. VEGETATION RESPONSE TO CLIMATE CHANGE IN THE SOUTHERN PART OF QINGHAI-TIBET PLATEAU AT BASINAL SCALE

    Directory of Open Access Journals (Sweden)

    X. Liu

    2018-04-01

    Full Text Available Global climate change has significantly affected vegetation variation in the third-polar region of the world – the Qinghai-Tibet Plateau. As one of the most important indicators of vegetation variation (growth, coverage and tempo-spatial change, the Normalized Difference Vegetation Index (NDVI is widely employed to study the response of vegetation to climate change. However, a long-term series analysis cannot be achieved because a single data source is constrained by time sequence. Therefore, a new framework was presented in this paper to extend the product series of monthly NDVI, taking as an example the Yarlung Zangbo River Basin, one of the most important river basins in the Qinghai-Tibet Plateau. NDVI products were acquired from two public sources: Global Inventory Modeling and Mapping Studies (GIMMS Advanced Very High Resolution Radiometer (AVHRR and Moderate-Resolution Imaging spectroradiometer (MODIS. After having been extended using the new framework, the new time series of NDVI covers a 384 months period (1982–2013, 84 months longer than previous time series of NDVI product, greatly facilitating NDVI related scientific research. In the new framework, the Gauss Filtering Method was employed to filter out noise in the NDVI product. Next, the standard method was introduced to enhance the comparability of the two data sources, and a pixel-based regression method was used to construct NDVI-extending models with one pixel after another. The extended series of NDVI fit well with original AVHRR-NDVI. With the extended time-series, temporal trends and spatial heterogeneity of NDVI in the study area were studied. Principal influencing factors on NDVI were further determined. The monthly NDVI is highly correlated with air temperature and precipitation in terms of climatic change wherein the spatially averaged NDVI slightly increases in the summer and has increased in temperature and decreased in precipitation in the 32 years period. The

  16. Lake-level increasing under the climate cryoaridization conditions during the Last Glacial Maximum

    Science.gov (United States)

    Amosov, Mikhail; Strelkov, Ivan

    2017-04-01

    A lake genesis and lake-level increasing during the Last Glacial Maximum (LGM) are the paramount issues in paleoclimatology. Investigating these problems reveals the regularities of lake development and figures out an arid territory conditions at the LGM stage. Pluvial theory is the most prevalent conception of lake formation during the LGM. This theory is based on a fact that the water bodies emerged and their level increased due to torrential rainfalls. In this study, it is paid attention to an alternative assumption of lake genesis at the LGM stage, which is called climate cryoaridization. In accordance with this hypothesis, the endorheic water basins had their level enlarged because of a simultaneous climate aridity and temperature decrease. In this research, a lake-level increasing in endorheic regions of Central Asia and South American Altiplano of the Andes is described. The lake investigation is related to its conditions during the LGM. The study also includes a lake catalogue clearly presenting the basin conditions at the LGM stage and nowadays. The data compilation partly consists of information from an earlier work of Mikhail Amosov, Lake-levels, Vegetation And Climate In Central Asia During The Last Glacial Maximum (EGU2014-3015). According to the investigation, a lake catalogue on 27 lakes showed that most of the water bodies had higher level. This feature could be mentioned for the biggest lakes of the Aral Sea, Lake Balkhash, Issyk-Kul etc. and for the small ones located in the mountains, such as Pamir, Tian-Shan and Tibet. Yet some lakes that are situated in Central Asian periphery (Lake Qinghai and lakes in Inner Mongolia) used to be lower than nowadays. Also, the lake-level increasing of Altiplano turned to be a significant feature during the LGM in accordance with the data of 5 lakes, such as Titicaca, Coipasa-Uyuni, Lejia, Miscanti and Santa-Maria. Most of the current endorheic basins at the LGM stage were filled with water due to abundant

  17. Drought, climate change and vegetation response in the succulent karoo, South Africa

    Directory of Open Access Journals (Sweden)

    M. T. Hoffman

    2009-12-01

    Full Text Available For the winter-rainfall region of South Africa, the frequency of drought is predicted to increase over the next 100 years, with dire consequences for the vegetation of this biodiversity hotspot. We analysed historical 20th century rainfall records for six rainfall stations within the succulent karoo biome to determine if the signal of increasing drought frequency is already apparent, and whether mean annual rainfall is decreasing. We found no evidence for a decrease either in mean annual rainfall or in the incidence of drought, as measured by the Standardised Precipitation Index (SPI over the 20th century. Evidence points to a drying trend from 1900–1950 while no significant trend in rainfall and drought was found at most stations from 1951–2000. In a second analysis we synthesised the information concerning the response of adult succulent karoo biome plants and seedlings to extended drought conditions. General findings are that responses to drought differ between species, and that longevity is an important life history trait related to drought survival. Growth form is a poor predictor of drought response across the biome. There was a range of responses to drought among adult plants of various growth forms, and among non-succulent seedlings. Leaf-succulent seedlings, however, exhibited phenomenal drought resistance, the majority surviving drought long after all the experimentally comparative non-succulent seedlings had died. Our synthesis showed that previous studies on the impact of drought on succulent karoo biome plants differ greatly in terms of their location, sampling design, measured values and plant responses. A suite of coordinated long-term field observations, experiments and models are therefore needed to assess the response of succulent karoo biome species to key drought events as they occur over time and to integrate this information into conservation planning.

  18. Food Security Under Shifting Economic, Demographic, and Climatic Conditions (Invited)

    Science.gov (United States)

    Naylor, R. L.

    2013-12-01

    Global demand for food, feed, and fuel will continue to rise in a more populous and affluent world. Meeting this demand in the future will become increasingly challenging with global climate change; when production shocks stemming from climate variability are added to the new mean climate state, food markets could become more volatile. This talk will focus on the interacting market effects of demand and supply for major food commodities, with an eye on climate-related supply trends and shocks. Lessons from historical patterns of climate variability (e.g., ENSO and its global teleconnections) will be used to infer potential food security outcomes in the event of abrupt changes in the mean climate state. Domestic food and trade policy responses to crop output and price volatility in key producing and consuming nations, such as export bans and import tariffs, will be discussed as a potentially major destabilizing force, underscoring the important influence of uncertainty in achieving--or failing to achieve--food security.

  19. Late-glacial and Holocene Vegetation and Climate Variability, Including Major Droughts, in the Sky Lakes Region of Southeastern New York State

    Science.gov (United States)

    Menking, Kirsten M.; Peteet, Dorothy M.; Anderson, Roger Y.

    2012-01-01

    Sediment cores from Lakes Minnewaska and Mohonk in the Shawangunk Mountains of southeastern New York were analyzed for pollen, plantmacrofossils, macroscopic charcoal, organic carbon content, carbon isotopic composition, carbon/nitrogen ratio, and lithologic changes to determine the vegetation and landscape history of the greater Catskill Mountain region since deglaciation. Pollen stratigraphy generally matches the New England pollen zones identified by Deevey (1939) and Davis (1969), with boreal genera (Picea, Abies) present during the late Pleistocene yielding to a mixed Pinus, Quercus and Tsuga forest in the early Holocene. Lake Minnewaska sediments record the Younger Dryas and