WorldWideScience

Sample records for temperate heath vegetation

  1. Variations in mountain vegetation use by reindeer (Rangifer tarandus) affects dry heath but not grass heath

    NARCIS (Netherlands)

    Moen, J.; Boogerd, C.; Skarin, A.

    2009-01-01

    Question: Are differences in landscape use of semi-domesticated reindeer reflected in the vegetation of summer grazing grounds? Location: Alpine heaths, central east Sweden. Methods: Dry heath and grass heath vegetation plots with inferred grazing intensities (high, intermediate and low) were

  2. Off-season biogenic volatile organic compound emissions from heath mesocosms: responses to vegetation cutting.

    Science.gov (United States)

    Rinnan, Riikka; Gierth, Diana; Bilde, Merete; Rosenørn, Thomas; Michelsen, Anders

    2013-01-01

    Biogenic volatile organic compounds (BVOCs) affect both atmospheric processes and ecological interactions. Our primary aim was to differentiate between BVOC emissions from above- and belowground plant parts and heath soil outside the growing season. The second aim was to assess emissions from herbivory, mimicked by cutting the plants. Mesocosms from a temperate Deschampsia flexuosa-dominated heath ecosystem and a subarctic mixed heath ecosystem were either left intact, the aboveground vegetation was cut, or all plant parts (including roots) were removed. For 3-5 weeks, BVOC emissions were measured in growth chambers by an enclosure method using gas chromatography-mass spectrometry. CO2 exchange, soil microbial biomass, and soil carbon and nitrogen concentrations were also analyzed. Vegetation cutting increased BVOC emissions by more than 20-fold, and the induced compounds were mainly eight-carbon compounds and sesquiterpenes. In the Deschampsia heath, the overall low BVOC emissions originated mainly from soil. In the mixed heath, root, and soil emissions were negligible. Net BVOC emissions from roots and soil of these well-drained heaths do not significantly contribute to ecosystem emissions, at least outside the growing season. If insect outbreaks become more frequent with climate change, ecosystem BVOC emissions will periodically increase due to herbivory.

  3. Ecosystem respiration depends strongly on photosynthesis in a temperate heath

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Ibrom, Andreas; Beier, Claus

    2007-01-01

    We measured net ecosystem CO2 flux (F-n) and ecosystem respiration (R-E), and estimated gross ecosystem photosynthesis (P-g) by difference, for two years in a temperate heath ecosystem using a chamber method. The exchange rates of carbon were high and of similar magnitude as for productive forest...... ecosystems with a net ecosystem carbon gain during the second year of 293 +/- 11 g C m(-2) year(-1) showing that the carbon sink strength of heather-dominated ecosystems may be considerable when C. vulgaris is in the building phase of its life cycle. The estimated gross ecosystem photosynthesis and ecosystem.......65) was improved when the P-g rate was incorporated into the model (second year; R-2 = 0.79), suggesting that daytime R-E increased with increasing photosynthesis. Furthermore, the temperature sensitivity of R-E decreased from apparent Q(10) values of 3.3 to 3.9 by the classic equation to a more realistic Q(10...

  4. Temperate heath plant response to dry conditions depends on growth strategy and less on physiology

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Kongstad, J.; Schmidt, I. K.

    2012-01-01

    of these differences in response in dry versus rewetting conditions can be used to highlight the limitations coherent in different strategies adopted by, for example, evergreen shrubs and grasses. We investigated the leaf-level photosynthetic performance, leaf C, N and d13C along with vegetation cover and biomass...... in the evergreen dwarf shrub Calluna vulgaris and the grass species Deschampsia flexuosa in a temperate heath during seasonal changes in soil moisture. Higher photosynthetic capacity compensated for lower stomatal conductance and sustained higher rates of photosynthesis in the grass compared to the dwarf shrub....... In combination with dieback of aboveground biomass and reduction of stomatal conductance reduction during dry conditions, the grass continued to have high carbon uptake in the remaining leaves. The dwarf shrub endured the dry conditions by preserving shoot biomass and reducing stomatal conductance. Soil...

  5. Fuel dynamics and fire behaviour in Australian mallee and heath vegetation

    Science.gov (United States)

    Juanita Myers; Jim Gould; Miguel Cruz; Meredith Henderson

    2007-01-01

    In southern Australia, shrubby heath vegetation together with woodlands dominated by multistemmed eucalypts (mallee) comprise areas of native vegetation with important biodiversity values. These vegetation types occur in semiarid and mediterranean climates and can experience large frequent fires. This study is investigating changes in the fuel complex with time, fuel...

  6. Monoterpene emissions in response to long-term night-time warming, elevated CO2 and extended summer drought in a temperate heath ecosystem

    DEFF Research Database (Denmark)

    Tiiva, Päivi; Tang, Jing; Michelsen, Anders

    2017-01-01

    Monoterpenes emitted from plants have an important role in atmospheric chemistry through changing atmospheric oxidative capacity, forming new particles and secondary organic aerosols. The emission rates and patterns can be affected by changing climate. In this study, emission responses to six years...... of climatic manipulations (elevated CO2, extended summer drought and night-time warming) were investigated in a temperate semi-natural heath ecosystem. Samples for monoterpene analysis were collected in seven campaigns during an entire growing season (April-November, 2011). The results showed...... that the temperate heath ecosystem was a considerable source of monoterpenes to the atmosphere, with the emission averaged over the 8month measurement period of 21.7±6.8μgm(-2)groundareah(-1) for the untreated heath. Altogether, 16 monoterpenes were detected, of which the most abundant were α-pinene, δ-3-carene...

  7. A monitoring protocol for vegetation change on Irish peatland and heath

    Science.gov (United States)

    O'Connell, J.; Connolly, J.; Holden, N. M.

    2014-09-01

    Amendments to Articles 3.3 and 3.4 of the Kyoto Protocol have meant that detection of vegetation change may now form an interracial part of national soil carbon stocks. In this study multispectral multi-platform satellite data was processed to detect change to the surface vegetation of four peatland sites and one heath in Ireland. Spectral and spatial thresholds were used on difference images between master and slave data in the extraction of temporally invariant targets for multi-platform cross calibration. The Kolmogorov-Smirnov test was used to evaluate any difference in the cumulative probability distributions of the master, slave and calibrated slave data as expressed by the D statistic, with values reduced by an average of 89.7% due to the cross calibration procedure. A change detection model was created which incorporated a spatial threshold of 9 pixels and a standard deviation (SD) spectral threshold. Kappa accuracy values for the five sites ranged from 80 to 97%, showing that 1.5 SD was the optimum spectral threshold for detecting vegetation change. Change detection results showed mean percentage change ranging from 2.11 to 3.28% of total area and cumulative change over the observed time period of between 15.24 and 49.27% of total area.

  8. Organic matter flow in the food web at a temperate heath under multifactorial climate change

    DEFF Research Database (Denmark)

    Andresen, Louise C.; Konestabo, Heidi S.; Maraldo, Kristine

    2011-01-01

    climate change factors (elevated CO2, increased temperature and drought) were investigated in a full factorial field experiment at a temperate heathland location. The combined effect of biotic and abiotic factors on nitrogen and carbon flows was traced in plant root → litter → microbe → detritivore....../omnivore → predator food‐web for one year after amendment with 15N13C2‐glycine. Isotope ratio mass spectrometry (IRMS) measurement of 15N/14N and 13C/12C in soil extracts and functional ecosystem compartments revealed that the recovery of 15N sometimes decreased through the chain of consumption, with the largest...

  9. Effects of elevated CO2, warming and drought episodes on plant carbon uptake in a temperate heath ecosystem are controlled by soil water status

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Ro-Poulsen, H.; Mikkelsen, Teis Nørgaard

    2011-01-01

    The impact of elevated CO2, periodic drought and warming on photosynthesis and leaf characteristics of the evergreen dwarf shrub Calluna vulgaris in a temperate heath ecosystem was investigated. Photosynthesis was reduced by drought in midsummer and increased by elevated CO2 throughout the growing...... season, whereas warming only stimulated photosynthesis early in the year. At the beginning and end of the growing season, a T × CO2 interaction synergistically stimulated plant carbon uptake in the combination of warming and elevated CO2. At peak drought, the D × CO2 interaction antagonistically down......-regulated photosynthesis, suggesting a limited ability of elevated CO2 to counteract the negative effect of drought. The response of photosynthesis in the full factorial combination (TDCO2) could be explained by the main effect of experimental treatments (T, D, CO2) and the two-factor interactions (D × CO2, T × CO2...

  10. 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...

  11. Responses of vegetation and soil microbial communities to warming and simulated herbivory in a subarctic heath

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Stark, Sari; Tolvanen, Anne

    2009-01-01

    Climate warming increases the cover of deciduous shrubs in arctic ecosystems and herbivory is also known to have a strong influence on the biomass and composition of vegetation. However, research combining herbivory with warming is largely lacking. Our study describes how warming and simulated...... setup of the International Tundra Experiment (ITEX). Wounding of the dominant deciduous dwarf shrub Vaccinium myrtillus L. to simulate herbivory was carried out annually. We measured vegetation cover in 2003 and 2007, soil nutrient concentrations in 2003 and 2006, soil microbial respiration in 2003...... and herbivory. 6 Synthesis. Our results show that warming increases the cover of V. myrtillus, which seems to enhance the nutrient sink strength of vegetation in the studied ecosystem. However, herbivory partially negates the effect of warming on plant N uptake and interacts with the effect of warming...

  12. Off-season biogenic volatile organic compound emissions from heath mesocosms

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Gierth, Diana; Bilde, Merete

    2013-01-01

    herbivory, mimicked by cutting the plants. Mesocosms from a temperate Deschampsia flexuosa-dominated heath ecosystem and a subarctic mixed heath ecosystem were either left intact, the aboveground vegetation was cut, or all plant parts (including roots) were removed. For 3-5 weeks, BVOC emissions were...... measured in growth chambers by an enclosure method using gas chromatography-mass spectrometry. CO2 exchange, soil microbial biomass and soil carbon and nitrogen concentrations were also analyzed. Vegetation cutting increased BVOC emissions by more than 20-fold, and the induced compounds were mainly eight...

  13. [Factors affecting the vegetation restoration after fires in cold temperate wetlands: A review].

    Science.gov (United States)

    Zhao, Feng-Jun; Wang, Li-Zhong; Shu, Li-Fu; Chen, Peng-Yu; Chen, Li-guang

    2013-03-01

    Cold temperate wetland plays an important role in maintaining regional ecological balance. Fire is an important disturbance factor in wetland ecosystem. Severe burning can induce the marked degradation of the ecological functions of wetland ecosystem. The vegetation restoration, especially the early vegetation restoration, after fires, is the premise and basis for the recovery of the ecological functions of the ecosystem. This paper reviewed the research progress on the factors affecting the vegetation restoration after fires in wetlands. The vegetation restoration after fires in cold temperate wetlands was controlled by the fire intensity, fire size, vegetation types before fires, regeneration characteristics of plant species, and site conditions. It was considered that the long-term monitoring on the post-fire vegetation restoration in cold temperate wetland, the key factors affecting the vegetation restoration, the roles of frozen soil layer on the post-fire vegetation restoration, and the theories and technologies on the vegetation restoration would be the main research directions in the future.

  14. 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

  15. Do multiple fires interact to affect vegetation structure in temperate eucalypt forests?

    Science.gov (United States)

    Haslem, Angie; Leonard, Steve W J; Bruce, Matthew J; Christie, Fiona; Holland, Greg J; Kelly, Luke T; MacHunter, Josephine; Bennett, Andrew F; Clarke, Michael F; York, Alan

    2016-12-01

    Fire plays an important role in structuring vegetation in fire-prone regions worldwide. Progress has been made towards documenting the effects of individual fire events and fire regimes on vegetation structure; less is known of how different fire history attributes (e.g., time since fire, fire frequency) interact to affect vegetation. Using the temperate eucalypt foothill forests of southeastern Australia as a case study system, we examine two hypotheses about such interactions: (1) post-fire vegetation succession (e.g., time-since-fire effects) is influenced by other fire regime attributes and (2) the severity of the most recent fire overrides the effect of preceding fires on vegetation structure. Empirical data on vegetation structure were collected from 540 sites distributed across central and eastern Victoria, Australia. Linear mixed models were used to examine these hypotheses and determine the relative influence of fire and environmental attributes on vegetation structure. Fire history measures, particularly time since fire, affected several vegetation attributes including ground and canopy strata; others such as low and sub-canopy vegetation were more strongly influenced by environmental characteristics like rainfall. There was little support for the hypothesis that post-fire succession is influenced by fire history attributes other than time since fire; only canopy regeneration was influenced by another variable (fire type, representing severity). Our capacity to detect an overriding effect of the severity of the most recent fire was limited by a consistently weak effect of preceding fires on vegetation structure. Overall, results suggest the primary way that fire affects vegetation structure in foothill forests is via attributes of the most recent fire, both its severity and time since its occurrence; other attributes of fire regimes (e.g., fire interval, frequency) have less influence. The strong effect of environmental drivers, such as rainfall and

  16. Effects of wind farm construction and operation on mire and wet heath vegetation in the Monte Maior SCI, north-west Spain

    Directory of Open Access Journals (Sweden)

    J. Fagúndez

    2008-07-01

    Full Text Available As part of the environmental impact assessment for the construction of a wind farm within the Monte Maior Natura 2000 Site of Community Importance (SCI in Galicia, north-west Spain, a complete analysis of the development site’s important mire and wet heath plant communities was performed. The study included phytosociological characterisation, species-area metrics, calculation of α and β diversity, and analysis of physiognomical characteristics such as life forms, distribution ranges and phenology. Permanent quadrats were monitored for three years after construction of the wind farm in order to identify and describe any changes in floristic composition. Two phytosociological associations were recognised in mire habitat, namely Eleocharitetum multicaulis (Litorelletea uniflorae and Carici durieui-Sphagnetum papillosi subas. ericetosum mackaianae (Oxycocco-Sphagnetea, whilst the wet heath was assigned to Gentiano pneumonanthe-Ericetum mackaianae (Calluno-Ulicetea. The two plant communities shared most physiognomical characteristics and 13–33% of species. Low values were obtained for α and β diversity, with about nine species per square metre for heathland and ten species per square metre for mire habitat. Hemicryptophytes dominated and no therophytes were recorded. The dominant plant families were Poaceae in heathlands and Cyperaceae in mires, and most of the species flowered in early or late summer. Both communities were stable and no change in any of the attributes investigated was observed during the study period. The results indicate that, so long as the traditional land use of low-intensity grazing can be maintained, there are no major hazards for these plant communities. However, some of the data suggest that the improvement of access to the area provided by the wind farm may result in an increase in human activity which could affect environmental conditions and thus the longer-term stability of the plant communities.

  17. Vegetation Indices for Mapping Canopy Foliar Nitrogen in a Mixed Temperate Forest

    Directory of Open Access Journals (Sweden)

    Zhihui Wang

    2016-06-01

    findings demonstrated the feasibility of using hyperspectral vegetation indices to estimate %N in a mixed temperate forest which may relate to the effect of the physical basis of nitrogen absorption features on canopy reflectance, or the biological links between nitrogen, chlorophyll, and canopy structure.

  18. Estimating carbon dioxide fluxes from temperate mountain grasslands using broad-band vegetation indices

    Directory of Open Access Journals (Sweden)

    G. Wohlfahrt

    2010-02-01

    Full Text Available The broad-band normalised difference vegetation index (NDVI and the simple ratio (SR were calculated from measurements of reflectance of photosynthetically active and short-wave radiation at two temperate mountain grasslands in Austria and related to the net ecosystem CO2 exchange (NEE measured concurrently by means of the eddy covariance method. There was no significant statistical difference between the relationships of midday mean NEE with narrow- and broad-band NDVI and SR, measured during and calculated for that same time window, respectively. The skill of broad-band NDVI and SR in predicting CO2 fluxes was higher for metrics dominated by gross photosynthesis and lowest for ecosystem respiration, with NEE in between. A method based on a simple light response model whose parameters were parameterised based on broad-band NDVI allowed to improve predictions of daily NEE and is suggested to hold promise for filling gaps in the NEE time series. Relationships of CO2 flux metrics with broad-band NDVI and SR however generally differed between the two studied grassland sites indicting an influence of additional factors not yet accounted for.

  19. 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.

  20. Carbon stock and carbon turnover in boreal and temperate forests - Integration of remote sensing data and global vegetation models

    Science.gov (United States)

    Thurner, Martin; Beer, Christian; Carvalhais, Nuno; Forkel, Matthias; Tito Rademacher, Tim; Santoro, Maurizio; Tum, Markus; Schmullius, Christiane

    2016-04-01

    Long-term vegetation dynamics are one of the key uncertainties of the carbon cycle. There are large differences in simulated vegetation carbon stocks and fluxes including productivity, respiration and carbon turnover between global vegetation models. Especially the implementation of climate-related mortality processes, for instance drought, fire, frost or insect effects, is often lacking or insufficient in current models and their importance at global scale is highly uncertain. These shortcomings have been due to the lack of spatially extensive information on vegetation carbon stocks, which cannot be provided by inventory data alone. Instead, we recently have been able to estimate northern boreal and temperate forest carbon stocks based on radar remote sensing data. Our spatially explicit product (0.01° resolution) shows strong agreement to inventory-based estimates at a regional scale and allows for a spatial evaluation of carbon stocks and dynamics simulated by global vegetation models. By combining this state-of-the-art biomass product and NPP datasets originating from remote sensing, we are able to study the relation between carbon turnover rate and a set of climate indices in northern boreal and temperate forests along spatial gradients. We observe an increasing turnover rate with colder winter temperatures and longer winters in boreal forests, suggesting frost damage and the trade-off between frost adaptation and growth being important mortality processes in this ecosystem. In contrast, turnover rate increases with climatic conditions favouring drought and insect outbreaks in temperate forests. Investigated global vegetation models from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT, are able to reproduce observation-based spatial climate - turnover rate relationships only to a limited extent. While most of the models compare relatively well in terms of NPP, simulated

  1. Heath Bunting / Heath Bunting ; interv. Tilman Baumgärtel

    Index Scriptorium Estoniae

    Bunting, Heath

    2006-01-01

    Inglise kunstnikust Heath Bunting'ust (sünd. 1966) ja tema loomingust, intervjuu kunstnikuga 19. VI 1997 Kasselis. H. Bunting tegelemisest grafitiga, oma Interneti-projektist "A visitor's guide to London", võrguprojektidest ja muust

  2. Water level, vegetation composition, and plant productivity explain greenhouse gas fluxes in temperate cutover fens after inundation

    Science.gov (United States)

    Minke, Merten; Augustin, Jürgen; Burlo, Andrei; Yarmashuk, Tatsiana; Chuvashova, Hanna; Thiele, Annett; Freibauer, Annette; Tikhonov, Vitalij; Hoffmann, Mathias

    2016-07-01

    Peat extraction leaves a land surface with a strong relief of deep cutover areas and higher ridges. Rewetting inundates the deep parts, while less deeply extracted zones remain at or above the water level. In temperate fens the flooded areas are colonized by helophytes such as Eriophorum angustifolium, Carex spp., Typha latifolia or Phragmites australis dependent on water depth. Reeds of Typha and Phragmites are reported as large sources of methane, but data on net CO2 uptake are contradictory for Typha and rare for Phragmites. Here, we analyze the effect of vegetation, water level and nutrient conditions on greenhouse gas (GHG) emissions for representative vegetation types along water level gradients at two rewetted cutover fens (mesotrophic and eutrophic) in Belarus. Greenhouse gas emissions were measured campaign-wise with manual chambers every 2 to 4 weeks for 2 years and interpolated by modelling. All sites had negligible nitrous oxide exchange rates. Most sites were carbon sinks and small GHG sources. Methane emissions generally increased with net ecosystem CO2 uptake. Mesotrophic small sedge reeds with water table around the land surface were small GHG sources in the range of 2.3 to 4.2 t CO2 eq. ha-1 yr-1. Eutrophic tall sedge - Typha latifolia reeds on newly formed floating mats were substantial net GHG emitters in the range of 25.1 to 39.1 t CO2 eq. ha-1 yr. They represent transient vegetation stages. Phragmites reeds ranged between -1.7 to 4.2 t CO2 eq. ha-1 yr-1 with an overall mean GHG emission of 1.3 t CO2 eq. ha-1 yr-1. The annual CO2 balance was best explained by vegetation biomass, which includes the role of vegetation composition and species. Methane emissions were obviously driven by biological activity of vegetation and soil organisms. Shallow flooding of cutover temperate fens is a suitable measure to arrive at low GHG emissions. Phragmites australis establishment should be promoted in deeper flooded areas and will lead to moderate, but

  3. 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

  4. Phytogeographical relations in the North West European heath

    NARCIS (Netherlands)

    Smidt, de J.T.

    1967-01-01

    The water economy, the mineral content of the soil, and human influence are the principal ecological factors governing the variation of the heath vegetation of a limited region. Sloping of the surface is also an important factor. In hilly country it is of a twofold nature: on the one hand the

  5. 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

  6. 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

  7. Feeding ecology of Rhabdosargus holubi (family Sparidae) in multiple vegetated refugia of selected warm temperate estuaries in South Africa

    Science.gov (United States)

    Nel, L.; Strydom, N. A.; Perissinotto, R.; Adams, J. B.; Lemley, D. A.

    2017-10-01

    Estuarine marine-dependent species, such as Rhabdosargus holubi, depend greatly on structured sheltered environments and important feeding areas provided by estuaries. In this study, we investigate the ecological feeding niches of the estuarine marine-dependent sparid, R. holubi, by using conventional stomach contents and stable isotope methods (δ13C and δ15N signatures). The study has been carried out in five temperate estuaries in order to understand how fish feed in multiple intertidal vegetated habitats. These habitats included the submerged seagrass, Zostera capensis, and both previously unexplored small intertidal cord grass, Spartina maritima, and the common reed, Phragmites australis. The diet varied amongst habitats, estuaries and fish sizes and data consistently confirmed their omnivorous diet relating to ontogenetic niche shifts. Stomach contents revealed the importance of benthic prey within both the S. maritima and P. australis habitats in the absence of large intertidal vegetation, available during low tides. Similarly, isotopic mixing models showed that R. holubi from these habitats have a greater isotopic niche compared to the Z. capensis habitat, due to their limited availability during the falling tide, suggesting migration between available habitats. Stable isotopes confirmed that R. holubi actively feeds on the epiphytic algae (especially diatoms) covering the leaves and stalks of plant matter, as supported by Bayesian mixing models. These findings add to the current knowledge regarding habitat partitioning in multiple aquatic vegetation types critical to fish ecology and the effective management and conservation of estuaries.

  8. Evaluation of climate-related carbon turnover processes in global vegetation models for boreal and temperate forests.

    Science.gov (United States)

    Thurner, Martin; Beer, Christian; Ciais, Philippe; Friend, Andrew D; Ito, Akihiko; Kleidon, Axel; Lomas, Mark R; Quegan, Shaun; Rademacher, Tim T; Schaphoff, Sibyll; Tum, Markus; Wiltshire, Andy; Carvalhais, Nuno

    2017-08-01

    Turnover concepts in state-of-the-art global vegetation models (GVMs) account for various processes, but are often highly simplified and may not include an adequate representation of the dominant processes that shape vegetation carbon turnover rates in real forest ecosystems at a large spatial scale. Here, we evaluate vegetation carbon turnover processes in GVMs participating in the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP, including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT) using estimates of vegetation carbon turnover rate (k) derived from a combination of remote sensing based products of biomass and net primary production (NPP). We find that current model limitations lead to considerable biases in the simulated biomass and in k (severe underestimations by all models except JeDi and VISIT compared to observation-based average k), likely contributing to underestimation of positive feedbacks of the northern forest carbon balance to climate change caused by changes in forest mortality. A need for improved turnover concepts related to frost damage, drought, and insect outbreaks to better reproduce observation-based spatial patterns in k is identified. As direct frost damage effects on mortality are usually not accounted for in these GVMs, simulated relationships between k and winter length in boreal forests are not consistent between different regions and strongly biased compared to the observation-based relationships. Some models show a response of k to drought in temperate forests as a result of impacts of water availability on NPP, growth efficiency or carbon balance dependent mortality as well as soil or litter moisture effects on leaf turnover or fire. However, further direct drought effects such as carbon starvation (only in HYBRID4) or hydraulic failure are usually not taken into account by the investigated GVMs. While they are considered dominant large-scale mortality agents, mortality mechanisms related to insects and

  9. Differentiating drought legacy effects on vegetation growth over the temperate Northern Hemisphere

    Czech Academy of Sciences Publication Activity Database

    Wu, X.; Liu, H.; Li, X.; Ciais, P.; Babst, F.; Guo, W.; Zhang, C.; Magliulo, V.; Pavelka, Marian; Liu, S.; Huang, Y.; Wang, P.; Shi, C. D.; Ma, Y.

    2018-01-01

    Roč. 24, č. 1 (2018), s. 504-516 ISSN 1354-1013 EU Projects: European Commission(XE) 640176 Institutional support: RVO:86652079 Keywords : drought legacy effect * drought resilience * ecohydrological responses * extreme drought * plant functional groups * rooting system * stomatal conductance * vegetation growth Subject RIV: EH - Ecology, Behaviour Impact factor: 8.502, year: 2016

  10. Variation in vegetation and microbial linkages with slope aspect in a montane temperate hardwood forest

    Czech Academy of Sciences Publication Activity Database

    Gilliam, F. S.; Hédl, Radim; Chudomelová, Markéta; McCulley, R. L.; Nelson, J. A.

    2014-01-01

    Roč. 5, č. 5 (2014), s. 1-17, A66 ISSN 2150-8925 R&D Projects: GA MŠk(CZ) EE2.3.20.0267 Institutional support: RVO:67985939 Keywords : vegetation * soil microorganisms * slope aspect Subject RIV: EH - Ecology, Behaviour Impact factor: 2.255, year: 2014

  11. Reproduction and vegetative growth in the dioecious shrub Acer barbinerve in temperate forests of Northeast China.

    Science.gov (United States)

    Wang, Juan; Zhang, Chunyu; Gadow, Klaus V; Cheng, Yanxia; Zhao, Xiuhai

    2015-06-01

    Trade-off in dioecious plant. The trade-off between reproduction, vegetative growth and maintenance is a major issue in the life history of an organism and a record of the process which is producing the largest possible number of living offspring by natural selection. Dioecious species afford an excellent opportunity for detecting such possible trade-offs in resource allocation. In this study, we selected the dioecious shrub Acer barbinerve to examine possible trade-offs between reproduction and vegetative growth in both genders at different modular levels during three successive years. Reproductive and vegetative biomass values were assessed during successive years to evaluate their intra-annual and inter-annual trade-offs. These trade-offs were examined at shoot, branch and shrub modular levels in Acer barbinerve shrubs. An intra-annual trade-off was detected at the shoot level for both genders in 2011 and 2012. Both males and females showed a negative correlation between reproduction and vegetative growth, but this was more prominent in males. For the females of the species, inter-annual trade-offs were only found at branch and shrub levels. Slightly negative correlations in females were detected between the reproduction in 2012 and the reproduction in the two previous years. The gender ratio was significantly male biased during the three successive years of our investigation. Females had higher mortality rates in the larger diameter classes, both in 2011 and 2012. This study revealed a clear trade-off between reproduction and vegetative growth in Acer barbinerve, but results varied between males and females. The degree of autonomy of the different modular levels may affect the ability to detect such trade-offs.

  12. Intensive measurements of gas, water, and energy exchange between vegetation and troposphere during the MONTES Campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean basin

    Science.gov (United States)

    MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Wester...

  13. Intensive measurements of gas, water, and energy exchange between vegetation and troposhere during the MONTES campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean Basin

    NARCIS (Netherlands)

    Penuelas, J.; Guenther, A.; Rapparini, F.; Llusia, J.; Vilà-Guerau De Arellano, J.

    2013-01-01

    MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Western Mediterranean

  14. 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.

  15. Influences of Different Halophyte Vegetation on Soil Microbial Community at Temperate Salt Marsh.

    Science.gov (United States)

    Chaudhary, Doongar R; Kim, Jinhyun; Kang, Hojeong

    2018-04-01

    Salt marshes are transitional zone between terrestrial and aquatic ecosystems, occupied mainly by halophytic vegetation which provides numerous ecological services to coastal ecosystem. Halophyte-associated microbial community plays an important role in the adaptation of plants to adverse condition and also affected habitat characteristics. To explore the relationship between halophytes and soil microbial community, we studied the soil enzyme activities, soil microbial community structure, and functional gene abundance in halophytes- (Carex scabrifolia, Phragmites australis, and Suaeda japonica) covered and un-vegetated (mud flat) soils at Suncheon Bay, South Korea. Higher concentrations of total, Gram-positive, Gram-negative, total bacterial, and actinomycetes PLFAs (phospholipid fatty acids) were observed in the soil underneath the halophytes compared with mud flat soil and were highest in Carex soil. Halophyte-covered soils had different microbial community composition due to higher abundance of Gram-negative bacteria than mud flat soil. Similar to PLFA concentrations, the increased activities of β-glucosidase, cellulase, phosphatase, and sulfatase enzymes were observed under halophyte soil compared to mud flat soil and Carex exhibited highest activities. The abundance of archaeal 16S rRNA, fungal ITS, and denitrifying genes (nirK, nirS, and nosZ) were not influenced by the halophytes. Abundance bacterial 16S rRNA and dissimilatory (bi)sulfite (dsrA) genes were highest in Carex-covered soil. The abundance of functional genes involved in methane cycle (mcrA and pmoA) was not affected by the halophytes. However, the ratios of mcrA/pmoA and mcrA/dsrA increased in halophyte-covered soils which indicate higher methanogenesis activities. The finding of the study also suggests that halophytes had increased the microbial and enzyme activities, and played a pivotal role in shaping microbial community structure.

  16. Vulnerability and Resilience of Temperate Forest Landscapes to Broad-Scale Deforestation in Response to Changing Fire Regimes and Altered Post-Fire Vegetation Dynamics

    Science.gov (United States)

    Tepley, A. J.; Veblen, T. T.; Perry, G.; Anderson-Teixeira, K. J.

    2015-12-01

    In the face of on-going climatic warming and land-use change, there is growing concern that temperate forest landscapes could be near a tipping point where relatively small changes to the fire regime or altered post-fire vegetation dynamics could lead to extensive conversion to shrublands or savannas. To evaluate vulnerability and resilience to such conversion, we develop a simple model based on three factors we hypothesize to be key in predicting temperate forest responses to changing fire regimes: (1) the hazard rate (i.e., the probability of burning in the next year given the time since the last fire) in closed-canopy forests, (2) the hazard rate for recently-burned, open-canopy vegetation, and (3) the time to redevelop canopy closure following fire. We generate a response surface representing the proportions of the landscape potentially supporting closed-canopy forest and non-forest vegetation under nearly all combinations of these three factors. We then place real landscapes on this response surface to assess the type and magnitude of changes to the fire regime that would drive extensive forest loss. We show that the deforestation of much of New Zealand that followed initial human colonization and the introduction of a new ignition source ca. 750 years ago was essentially inevitable due to the slow rate of forest recovery after fire and the high flammability of post-fire vegetation. In North America's Pacific Northwest, by contrast, a predominantly forested landscape persisted despite two periods of widespread burning in the recent past due in large part to faster post-fire forest recovery and less pronounced differences in flammability between forests and the post-fire vegetation. We also assess the factors that could drive extensive deforestation in other regions to identify where management could reduce this potential and to guide field and modeling work to better understand the responses and ecological feedbacks to changing fire regimes.

  17. Estimation of carbon flow in a Calluna heath system

    International Nuclear Information System (INIS)

    Roesberg, I.; Oevstedal, D.O.; Seljelid, R.; Schreiner, Oe.; Goksoeyr, J.

    1981-01-01

    In a Culluna heath, plots of 1 m 2 were pulse labelled with 14 CO 2 , and the radioactivity in vegetation above ground, roots, litter and soil organic matter followed for almost two years. In a separate experiment, radioactivity in above ground and root respiration and in soil microbial biomass was determined. A kinetic model for the carbon transfer reaction is presented, and shown to give a satisfactory agreement with the experimental data. The results demonstrate that a major part of the assimilated carbon passes through the roots and into the soil, where it is rapidly mineralized. (author)

  18. Nitrogen limitation in the coastal heath at Anholt, Denmark

    DEFF Research Database (Denmark)

    Johnsen, Ib; Christensen, Steen; Riis-Nielsen, Torben

    2014-01-01

    ) and phosphorus as KH2PO4 (P-addition) was carried out in the coastal grey dune vegetation of Anholt. The Naddition corresponded to 40 kg N ha−1 year−1 and the Paddition to 7 kg P ha−1 year−1 The experiment included N-, P-, N + P-addition and control. Lichens (genera: mainly Cladonia, Stereocaulon, Cetraria......The purpose of the study was to investigate, whether the coastal grey dune vegetation at Anholt, Denmark, is limited by nitrogen or phosphorus. The island Anholt (22,37 km2) is situated in the centre of Kattegat A two factor fertilization experiment with nitrogen as NH4NO3 (Naddition...... significantly following N and N + P addition. No effect was observed by P addition alone. N limitation of this coastal heath vegetation remote from agricultural and industrial activities was evident. The effect on the plant species of the single application was short-lived. After two-three years of enhanced...

  19. Arctic, Antarctic, and temperate green algae Zygnema spp. under UV-B stress: vegetative cells perform better than pre-akinetes.

    Science.gov (United States)

    Holzinger, Andreas; Albert, Andreas; Aigner, Siegfried; Uhl, Jenny; Schmitt-Kopplin, Philippe; Trumhová, Kateřina; Pichrtová, Martina

    2018-02-22

    Species of Zygnema form macroscopically visible mats in polar and temperate terrestrial habitats, where they are exposed to environmental stresses. Three previously characterized isolates (Arctic Zygnema sp. B, Antarctic Zygnema sp. C, and temperate Zygnema sp. S) were tested for their tolerance to experimental UV radiation. Samples of young vegetative cells (1 month old) and pre-akinetes (6 months old) were exposed to photosynthetically active radiation (PAR, 400-700 nm, 400 μmol photons m -2  s -1 ) in combination with experimental UV-A (315-400 nm, 5.7 W m -2 , no UV-B), designated as PA, or UV-A (10.1 W m -2 ) + UV-B (280-315 nm, 1.0 W m -2 ), designated as PAB. The experimental period lasted for 74 h; the radiation period was 16 h PAR/UV-A per day, or with additional UV-B for 14 h per day. The effective quantum yield, generally lower in pre-akinetes, was mostly reduced during the UV treatment, and recovery was significantly higher in young vegetative cells vs. pre-akinetes during the experiment. Analysis of the deepoxidation state of the xanthophyll-cycle pigments revealed a statistically significant (p UV-absorbing phenolic compounds was significantly higher (p UV-B stress than pre-akinetes.

  20. Upscaling from leaf to canopy chlorophyll/carotenoid pigment based vegetation indices reveal phenology of photosynthesis in temperate evergreen and deciduous trees

    Science.gov (United States)

    Wong, C. Y.; Bhathena, Y.; Arain, M. A.; Ensminger, I.

    2017-12-01

    Optically derived vegetation indices have been developed to provide information about plant status including photosynthetic activity. They reflect changes in leaf pigments, which vary seasonally in pigment composition, enabling them to be used as a proxy of photosynthetic phenology. Important pigments in photosynthetic activity are carotenoids and chlorophylls, which are associated with light harvesting and energy dissipation. In temperate forests, which consist of deciduous and evergreen trees, there are difficulties resolving evergreen phenology using the most widely used index, the normalized difference vegetation index (NDVI). NDVI works well in deciduous trees, which exhibit a "visible" phenological process of leaf growth in the spring, and leaf senescence and abscission in the autumn. Evergreen conifers stay green year-round and utilize "invisible" changes of overwintering pigment composition that NDVI cannot resolve, so carotenoid pigment sensitive vegetation indices have been suggested for evergreens. The aim of this study was to evaluate carotenoid based vegetation indices over the chlorophyll sensitive NDVI. For this purpose, we evaluated the greenness index, NDVI, and carotenoid pigment sensitive indices: photochemical reflectance index (PRI) and chlorophyll/carotenoid index (CCI) in red maple, white oak and eastern white pine for two years. We also measured leaf gas exchange and pigment concentrations. We observed that NDVI correlated with photosynthetic activity in deciduous trees, whereas PRI and CCI correlated with photosynthesis across both evergreen and deciduous trees. This pattern was consistent, upscaling from leaf- to canopy-scales indicating that the mechanisms involved in winter acclimation can be resolved at larger spatial scales. PRI and CCI detected seasonal changes in carotenoids and chlorophylls linked to photoprotection and are suitable as a proxy of photosynthetic activity. These findings have implications to improve our use and

  1. Diversity patterns of ground beetles and understory vegetation in mature, secondary, and plantation forest regions of temperate northern China.

    Science.gov (United States)

    Zou, Yi; Sang, Weiguo; Wang, Shunzhong; Warren-Thomas, Eleanor; Liu, Yunhui; Yu, Zhenrong; Wang, Changliu; Axmacher, Jan Christoph

    2015-02-01

    Plantation and secondary forests form increasingly important components of the global forest cover, but our current knowledge about their potential contribution to biodiversity conservation is limited. We surveyed understory plant and carabid species assemblages at three distinct regions in temperate northeastern China, dominated by mature forest (Changbaishan Nature Reserve, sampled in 2011 and 2012), secondary forest (Dongling Mountain, sampled in 2011 and 2012), and forest plantation habitats (Bashang Plateau, sampled in 2006 and 2007), respectively. The α-diversity of both taxonomic groups was highest in plantation forests of the Bashang Plateau. Beetle α-diversity was lowest, but plant and beetle species turnover peaked in the secondary forests of Dongling Mountain, while habitats in the Changbaishan Nature Reserve showed the lowest turnover rates for both taxa. Changbaishan Nature Reserve harbored the highest proportion of forest specialists. Our results suggest that in temperate regions of northern China, the protected larch plantation forest established over extensive areas might play a considerable role in maintaining a high biodiversity in relation to understory herbaceous plant species and carabid assemblages, which can be seen as indicators of forest disturbance. The high proportion of phytophagous carabids and the rarity of forest specialists reflect the relatively homogenous, immature status of the forest ecosystems on the Bashang Plateau. China's last remaining large old-growth forests like the ones on Changbaishan represent stable, mature ecosystems which require particular conservation attention.

  2. Emergent and floating-leaved macrophytes as refuge for zooplankton in a eutrophic temperate lake without submerged vegetation

    DEFF Research Database (Denmark)

    Cazzanelli, Matteo; Perlt, Trine Warming; Christoffersen, Kirsten Seestern

    2008-01-01

    Several studies have shown that submerged macrophytes provide a refuge for zooplankton against fish predation, whereas the role of emergent and floating-leaved species, which are often dominant in eutrophic turbid lakes, is far less investigated. Zooplankton density in open water and amongst....... As a consequence, especially in turbid lakes, the ecological role of these functional types of vegetation, and not merely that of submerged macrophyte species, should be taken into consideration....

  3. Phenology Shifts at Start vs. End of Growing Season in Temperate Vegetation Over the Northern Hemisphere for the Period 1982-2008

    Science.gov (United States)

    Jeong, Su-Jong; Ho, Chang-Hoi; Gim, Hyeon-Ju; Brown, Molley E.

    2011-01-01

    Changes in vegetative growing seasons are dominant indicators of the dynamic response of ecosystems to climate change. Therefore, knowledge of growing seasons over the past decades is essential to predict ecosystem changes. In this study, the long-term changes in the growing seasons of temperate vegetation over the Northern Hemisphere were examined by analyzing satellite-measured normalized difference vegetation index and reanalysis temperature during 1982 2008. Results showed that the length of the growing season (LOS) increased over the analysis period; however, the role of changes at the start of the growing season (SOS) and at the end of the growing season (EOS) differed depending on the time period. On a hemispheric scale, SOS advanced by 5.2 days in the early period (1982-1999) but advanced by only 0.2 days in the later period (2000-2008). EOS was delayed by 4.3 days in the early period, and it was further delayed by another 2.3 days in the later period. The difference between SOS and EOS in the later period was due to less warming during the preseason (January-April) before SOS compared with the magnitude of warming in the preseason (June September) before EOS. At a regional scale, delayed EOS in later periods was shown. In North America, EOS was delayed by 8.1 days in the early period and delayed by another 1.3 days in the later period. In Europe, the delayed EOS by 8.2 days was more significant than the advanced SOS by 3.2 days in the later period. However, in East Asia, the overall increase in LOS during the early period was weakened in the later period. Admitting regional heterogeneity, changes in hemispheric features suggest that the longer-lasting vegetation growth in recent decades can be attributed to extended leaf senescence in autumn rather than earlier spring leaf-out. Keywords: climate change, growing season, NDVI (normalized difference vegetation index), Northern Hemisphere, phenology,

  4. Intensive measurements of gas, water, and energy exchange between vegetation and troposphere during the MONTES campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean Basin

    Science.gov (United States)

    Peñuelas, J.; Guenther, A.; Rapparini, F.; Llusia, J.; Filella, I.; Seco, R.; Estiarte, M.; Mejia-Chang, M.; Ogaya, R.; Ibañez, J.; Sardans, J.; Castaño, L. M.; Turnipseed, A.; Duhl, T.; Harley, P.; Vila, J.; Estavillo, J. M.; Menéndez, S.; Facini, O.; Baraldi, R.; Geron, C.; Mak, J.; Patton, E. G.; Jiang, X.; Greenberg, J.

    2013-08-01

    MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Western Mediterranean Basin (WMB). The measurements were performed at a semidesertic area (Monegros), at a coastal Mediterranean shrubland area (Garraf), at a typical Mediterranean holm oak forest area (Prades) and at a wet temperate beech forest (Montseny) during spring (April 2010) under optimal plant physiological conditions in driest-warmest sites and during summer (July 2010) with drought and heat stresses in the driest-warmest sites and optimal conditions in the wettest-coolest site. The objective of this campaign was to study the differences in gas, water and energy exchange occurring at different vegetation coverages and biomasses. Particular attention was devoted to quantitatively understand the exchange of biogenic volatile organic compounds (BVOCs) because of their biological and environmental effects in the WMB. A wide range of instruments (GC-MS, PTR-MS, meteorological sensors, O3 monitors,…) and vertical platforms such as masts, tethered balloons and aircraft were used to characterize the gas, water and energy exchange at increasing footprint areas by measuring vertical profiles. In this paper we provide an overview of the MONTES campaign: the objectives, the characterization of the biomass and gas, water and energy exchange in the 4 sites-areas using satellite data, the estimation of isoprene and monoterpene emissions using MEGAN model, the measurements performed and the first results. The isoprene and monoterpene emission rates estimated with MEGAN and emission factors measured at the foliar level for the dominant species ranged from about 0 to 0.2 mg m-2 h-1 in April. The warmer temperature in July resulted in higher model estimates from about 0 to ca. 1.6 mg m-2 h-1 for

  5. Vegetation-zonation patterns across a temperate mountain cloud forest ecotone are not explained by variation in hydraulic functioning or water relations.

    Science.gov (United States)

    Berry, Z Carter; Johnson, Daniel M; Reinhardt, Keith

    2015-09-01

    Many studies have demonstrated linkages between the occurrence of fog and ecophysiological functioning in cloud forests, but few have investigated hydraulic functioning as a determining factor that explains sharp changes in vegetation. The objective of this study was to compare the plant water status during cloud-immersed and non-immersed conditions and hydraulic vulnerability in branches and roots of species across a temperate, mountain fog ecotone. Because cloud forests are often dark, cool and very moist, we expected cloud forest species to have less drought-tolerant characteristics (i.e., lower Pe and P50-the pressures required to induce a 12 and 50% loss in hydraulic conductivity, respectively) relative to non-cloud forest species in adjacent (lower elevation) forests. Additionally, due to the ability of cloud forest species to absorb cloud-fog water, we predicted greater improvements in hydraulic functioning during fog in cloud forest species relative to non-cloud forest species. Across the cloud forest ecotone, most species measured were very resistant to losses in conductivity with branch P50 values from -4.5 to -6.0 MPa, hydraulic safety margins (Ψmin - P50) >1.5 MPa and low calculated hydraulic conductivity losses. Roots had greater vulnerabilities, with P50 values ranging from -1.4 to -2.5 MPa, leading to greater predicted losses in conductivity (∼20%). Calculated values suggested strong losses of midday leaf hydraulic conductance in three of the four species, supporting the hydraulic segmentation hypothesis. In both cloud forest and hardwood species, Ψs were greater on foggy days than sunny days, demonstrating the importance of fog periods to plant water balance across fog regimes. Thus, frequent fog did not result in systemic changes in hydraulic functioning or vulnerability to embolism across our temperate cloud forest ecotone. Finally, roots functioned with lower hydraulic conductivity than branches, suggesting that they may serve as more

  6. Temper Tantrums

    Science.gov (United States)

    ... Nine Steps to More Effective Parenting How Can Parents Discipline Without Spanking? Delayed Speech or Language Development Talking to Your Child's Preschool Teacher Your Child's Habits Separation Anxiety Breath-Holding Spells Train Your Temper View ...

  7. RiverHeath: Neighborhood Loop Geothermal Exchange System

    Energy Technology Data Exchange (ETDEWEB)

    Geall, Mark [RiverHeath LLC, Appleton, WI (United States)

    2016-07-11

    The goal of the RiverHeath project is to develop a geothermal exchange system at lower capital infrastructure cost than current geothermal exchange systems. The RiverHeath system features an innovative design that incorporates use of the adjacent river through river-based heat exchange plates. The flowing water provides a tremendous amount of heat transfer. As a result, the installation cost of this geothermal exchange system is lower than more traditional vertical bore systems. Many urban areas are located along rivers and other waterways. RiverHeath will serve as a template for other projects adjacent to the water.

  8. Glycine uptake in heath plants and soil microbes responds to elevated temperature, CO2 and drought

    DEFF Research Database (Denmark)

    Andresen, Luise C.; Michelsen, Anders; Jonasson, Sven

    2009-01-01

    the responses to single factors treatments. The soil microbes were superior to plants in the short-term competition for the added glycine, as indicated by an 18 times larger 15N recovery in the microbial biomass compared to the plant biomass. The soil microbes acquired glycine largely as an intact compound (87...... here present results from a field experiment in which the effects of these three climate change factors are investigated solely and in all combinations at a temperate heath dominated by heather (Calluna vulgaris) and wavy hair-grass (Deschampsia flexuosa). Climate induced increases in plant production...... may increase plant root exudation of dissolved organic compounds such as amino acids, and the release of amino acids during decomposition of organic matter. Such free amino acids in soil serve as substrates for soil microorganisms and are also acquired as nutrients directly by plants. We investigated...

  9. 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....

  10. The impact of climate change on ecosystem carbon dynamics at the Scandinavian mountain birch forest-tundra heath ecotone.

    Science.gov (United States)

    Sjögersten, Sofie; Wookey, Philip A

    2009-02-01

    Changes in temperature and moisture resulting from climate change are likely to strongly modify the ecosystem carbon sequestration capacity in high-latitude areas, both through vegetation shifts and via direct warming effects on photosynthesis and decomposition. This paper offers a synthesis of research addressing the potential impacts of climate warming on soil processes and carbon fluxes at the forest-tundra ecotone in Scandinavia. Our results demonstrated higher rates of organic matter decomposition in mountain birch forest than in tundra heath soils, with markedly shallower organic matter horizons in the forest. Field and laboratory experiments suggest that increased temperatures are likely to increase CO2 efflux from both tundra and forest soil providing moisture availability does not become limiting for the decomposition process. Furthermore, colonization of tundra heath by mountain birch forest would increase rates of decomposition, and thus CO2 emissions, from the tundra heath soils, which currently store substantial amounts of potentially labile carbon. Mesic soils underlying both forest and tundra heath are currently weak sinks of atmospheric methane, but the strength of this sink could be increased with climate warming and/or drying.

  11. Determining the age of CO2 Released From Mountain Birch Forest and Heath in Arctic Sweden

    Science.gov (United States)

    Hartley, I. P.; Garnett, M. H.; Hopkins, D. W.; Sommerkorn, M.; Wookey, P. A.

    2008-12-01

    Nuclear weapons testing released a large amount of 14C into the atmosphere during the mid 20th Century. This radiocarbon pulse provides a tracer that can be used to determine the age of C released from plants and soils. Such information is critical for predicting how terrestrial C storage will respond to global change. If respired CO2 is mainly modern, then respiration and photosynthesis are tightly coupled. In contrast, if older C is being mineralized then there is more potential for climate change to induce C loss. We carried out one of the first studies to measure seasonal variations in the 14C content of CO2 released from arctic ecosystems. Using molecular sieves, we trapped CO2 respired from a mountain birch forest and heath near Abisko, northern Sweden and measured 14C contents by accelerator mass spectrometry. CO2 was collected from both vegetated plots (control) and clipped and trenched plots (CT) on three occasions during the 2007 growing season. In addition, we used a new passive sampling technique to collect CO2 from the CT plots during winter 2007-2008. Assuming that the respired C was derived from post bomb sources (justifiable as the majority of each soil profile was enriched with bomb C), we estimated the age of the CO2 and how it changed during the year in response to changes in plant activity and key environmental drivers. On the heath, the mean age of the CO2 respired from the control plots increased from 4 to 6 years old during the growing season. The CO2 respired from the CT plots increased from 5 years old in early June to 11 years old by July, but then declined to 8 years old in September. The C released during winter was also 8 years old. In the Birch forest, the mean age of CO2 respired from the CT plots increased from 4 years old in late May to 8-9 years old during July and September. However, during winter, the CO2 released was >10 years old. In the control plots, the age of respired CO2 increased from being 1 year old in late May to 6

  12. Monitoring phenology of photosynthesis in temperate evergreen and mixed deciduous forests using the normalized difference vegetation index (NDVI) and the photochemical reflectance index (PRI) at leaf and canopy scales

    Science.gov (United States)

    Wong, C. Y.; Arain, M. A.; Ensminger, I.

    2016-12-01

    Evergreen conifers in boreal and temperate regions undergo strong seasonal changes in photoperiod and temperatures, which determines their phenology of high photosynthetic activity in the growing season and downregulation during the winter. Monitoring the timing of the transition between summer activity and winter downregulation in evergreens is difficult since this is a largely invisible process, unlike in deciduous trees that have a visible budding and a sequence of leaf unfolding in the spring and leaf abscission in the fall. The light-use efficiency (LUE) model estimates gross primary productivity (GPP) and may be parameterized using remotely sensed vegetation indices. Using spectral reflectance data, we derived the normalized difference vegetation index (NDVI), a measure of leaf "greenness", and the photochemical reflectance index (PRI), a proxy for chlorophyll:carotenoid ratios which is related to photosynthetic activity. To better understand the relationship between these vegetation indices and photosynthetic activity and to contrast this relationship between plant functional types, the phenology of NDVI, PRI and photosynthesis was monitored in an evergreen forest and a mixed deciduous forest at the leaf and canopy scale. Our data indicates that the LUE model can be parameterized by NDVI and PRI to track forest phenology. Differences in the sensitivity of PRI and NDVI will be discussed. These findings have implications to address the phenology of evergreen conifers by using PRI to complement NDVI in the LUE model, potentially improving model productivity estimates in northern hemisphere forests, that are dominated by conifers.

  13. Tempered fractional calculus

    Energy Technology Data Exchange (ETDEWEB)

    Sabzikar, Farzad, E-mail: sabzika2@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Meerschaert, Mark M., E-mail: mcubed@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Chen, Jinghua, E-mail: cjhdzdz@163.com [School of Sciences, Jimei University, Xiamen, Fujian, 361021 (China)

    2015-07-15

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  14. Tempered fractional calculus

    Science.gov (United States)

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-07-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  15. Tempered fractional calculus

    International Nuclear Information System (INIS)

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-01-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series

  16. 2015-2016 Expense report for Alanna Heath | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2015-07-13

    2015-2016 Expense report for Alanna Heath. Total travel expenses: CA$912.20. Board meetings. July 13, 2015 to July 14, 2015. CA$912.20. What we do · Funding · Resources · About IDRC. Knowledge. Innovation. Solutions. Careers · Contact Us · Site map. Sign up now for IDRC news and views sent directly to your inbox ...

  17. Heath Ledgeri viimane film tehakse lõpuni

    Index Scriptorium Estoniae

    2008-01-01

    Terry Gilliam teatas, et jätkab võtteid mängufilmi "The Imaginarium of Doctor Parnassus" lõpetamiseks (film jäi näitleja Heath Ledgeri surma tõttu pooleli), lastes tema rolli esitada kolmel väljapaistval näitlejal (Johnny Depp, Colin Farrell, Jude Law)

  18. Assessing the recovery potential of alpine moss-sedge heath: Reciprocal transplants along a nitrogen deposition gradient

    Energy Technology Data Exchange (ETDEWEB)

    Armitage, Heather F., E-mail: h.armitage@abdn.ac.u [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom); Britton, Andrea J. [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Woodin, Sarah J. [Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom); Wal, Rene van der [Aberdeen Centre for Environmental Sustainability (ACES), School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom)

    2011-01-15

    The potential of alpine moss-sedge heath to recover from elevated nitrogen (N) deposition was assessed by transplanting Racomitrium lanuginosum shoots and vegetation turfs between 10 elevated N deposition sites (8.2-32.9 kg ha{sup -1} yr{sup -1}) and a low N deposition site, Ben Wyvis (7.2 kg ha{sup -1} yr{sup -1}). After two years, tissue N of Racomitrium shoots transplanted from higher N sites to Ben Wyvis only partially equilibrated to reduced N deposition whereas reciprocal transplants almost matched the tissue N of indigenous moss. Unexpectedly, moss shoot growth was stimulated at higher N deposition sites. However, moss depth and biomass increased in turfs transplanted to Ben Wyvis, apparently due to slower shoot turnover (suggested to result partly from decreased tissue C:N slowing decomposition), whilst abundance of vascular species declined. Racomitrium heath has the potential to recover from the impacts of N deposition; however, this is constrained by the persistence of enhanced moss tissue N contents. - Alpine moss-sedge heath, dominated by Racomitrium lanuginosum, from across the UK has the potential to recover from the impacts of N pollution; however, this is constrained by persistence of enhanced moss tissue N contents.

  19. Assessing the recovery potential of alpine moss-sedge heath: Reciprocal transplants along a nitrogen deposition gradient

    International Nuclear Information System (INIS)

    Armitage, Heather F.; Britton, Andrea J.; Woodin, Sarah J.; Wal, Rene van der

    2011-01-01

    The potential of alpine moss-sedge heath to recover from elevated nitrogen (N) deposition was assessed by transplanting Racomitrium lanuginosum shoots and vegetation turfs between 10 elevated N deposition sites (8.2-32.9 kg ha -1 yr -1 ) and a low N deposition site, Ben Wyvis (7.2 kg ha -1 yr -1 ). After two years, tissue N of Racomitrium shoots transplanted from higher N sites to Ben Wyvis only partially equilibrated to reduced N deposition whereas reciprocal transplants almost matched the tissue N of indigenous moss. Unexpectedly, moss shoot growth was stimulated at higher N deposition sites. However, moss depth and biomass increased in turfs transplanted to Ben Wyvis, apparently due to slower shoot turnover (suggested to result partly from decreased tissue C:N slowing decomposition), whilst abundance of vascular species declined. Racomitrium heath has the potential to recover from the impacts of N deposition; however, this is constrained by the persistence of enhanced moss tissue N contents. - Alpine moss-sedge heath, dominated by Racomitrium lanuginosum, from across the UK has the potential to recover from the impacts of N pollution; however, this is constrained by persistence of enhanced moss tissue N contents.

  20. 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.

  1. Surficial geology map of the Great Heath, Washington County, Maine

    Science.gov (United States)

    Cameron, Cornelia Clermont; Mullen, Michael K.

    1983-01-01

    The major portion of the Great Heath, comprising 2,645 acres in the Cherryfield quadrangle, Washington County, Maine, generally averaging 13 feet in thickness, but with as great an average as 15 feet, contain an estimated 6,953 ,000 short tons air-dried peat. The peat #s chiefly sphagnum moss with some reed-sedge of high quality according to ASTM standards for agricultural and horticultural use. This same volume of peat may be considered for use as fuel because BTO per pound ranges from 8,600 to 10,500 with low sulfur and high hydrogen contents.

  2. The Need for Temperance

    Directory of Open Access Journals (Sweden)

    Karl Inge Tangen

    2015-11-01

    Full Text Available This article explores how temperance as a virtue relates to organizational leadership. The study begins with a short survey of classical Greek and Christian notions of temperance before proceeding to ex-plore temperance in relation to self-leadership, visionary and strategic leadership, and relational lead-ership. The final part of the article offers reflections on how temperance might be cultivated from a theological perspective. Temperance is understood not only as sound thinking but also as embodied self-control and active patience. On the level of self-leadership, it is argued that temperance enables the leader to establish forms of integrity that protect the leader’s self from chaos and destruction. Moreover, temperance may also nurture focused visionary leadership that accepts ethical limits and has an eye to the common good. The study also suggests that organizations should cultivate a culture of strategic discipline that is capable of realizing such visions. On the interpersonal level, temperance is viewed as critical in terms of enabling leaders to treat co-workers with respect and wisdom and han-dle conflict with consideration. Finally, is argued that that the cultivation of temperance is not a one-way street from the inside to the outside or a subordination of feelings to reason but rather a very complex process that includes interpersonal humility, finds vision in an encounter with the good, and yet remains a personal responsibility.

  3. Structure and Processes in Temperate Grassland Vegetation

    DEFF Research Database (Denmark)

    Ejrnæs, R.

    , modern (geognostic, topographical, and climatic), and in part historical. The limits of distribution of a species may depend upon prevailing conditions, upon barriers now existing in the form of a mountain, sea, soil, and cli-mate, which oppose its spread ; but they may also depend upon geohistoric...... or geological and climatic conditions of ages long past, and upon the whole evolutionary history of the species, the site of this, and the facilities for and means of migration. In addition, problems must be dealt with concerning centres of development, the rise and age of species and genera ; and behind...

  4. Robert Heath Lock and his textbook of genetics, 1906.

    Science.gov (United States)

    Edwards, A W F

    2013-07-01

    Robert Heath Lock (1879-1915), a Cambridge botanist associated with William Bateson and R. C. Punnett, published his book Recent Progress in the Study of Variation, Heredity, and Evolution in 1906. This was a remarkable textbook of genetics for one appearing so early in the Mendelian era. It covered not only Mendelism but evolution, natural selection, biometry, mutation, and cytology. It ran to five editions but was, despite its success, largely forgotten following Lock's early death in 1915. Nevertheless it was the book that inspired H. J. Muller to do genetics and was remembered by A. H. Sturtevant as the source of the earliest suggestion that linkage might be related to the exchange of parts between homologous chromosomes. Here we also put forward evidence that it had a major influence on the statistician and geneticist R. A. Fisher at the time he was a mathematics student at Cambridge.

  5. Effect of climate change on temperate forest ecosystems

    NARCIS (Netherlands)

    Brolsma, R.J.

    2010-01-01

    In temperate climates groundwater can have a strong effect on vegetation, because it can influence the spatio-temporal distribution of soil moisture and therefore water and oxygen stress of vegetation. Current IPCC climate projections based on CO2 emission scenarios show a global temperature rise

  6. Characteristics of summer-time energy exchange in a high Arctic tundra heath 2000–2010

    Directory of Open Access Journals (Sweden)

    Magnus Lund

    2014-07-01

    Full Text Available Global warming will bring about changes in surface energy balance of Arctic ecosystems, which will have implications for ecosystem structure and functioning, as well as for climate system feedback mechanisms. In this study, we present a unique, long-term (2000–2010 record of summer-time energy balance components (net radiation, R n; sensible heat flux, H; latent heat flux, LE; and soil heat flux, G from a high Arctic tundra heath in Zackenberg, Northeast Greenland. This area has been subjected to strong summer-time warming with increasing active layer depths (ALD during the last decades. We observe high energy partitioning into H, low partitioning into LE and high Bowen ratio (β=H/LE compared with other Arctic sites, associated with local climatic conditions dominated by onshore winds, slender vegetation with low transpiration activity and relatively dry soils. Surface saturation vapour pressure deficit (D s was found to be an important variable controlling within-year surface energy partitioning. Throughout the study period, we observe increasing H/R n and LE/R n and decreasing G/R n and β, related to increasing ALD and decreasing soil wetness. Thus, changes in summer-time surface energy balance partitioning in Arctic ecosystems may be of importance for the climate system.

  7. Growth responses of low-alpine dwarf-shrub heath species to nitrogen deposition and management

    International Nuclear Information System (INIS)

    Britton, Andrea J.; Fisher, Julia M.

    2008-01-01

    Nitrogen deposition is a continuing problem in European alpine regions. We hypothesised that, despite climatic limitations, low-alpine Calluna heathland would respond to nitrogen addition with increased shoot growth and flowering and that fire and grazing would modify responses. In a five-year study, 0-50 kg N ha -1 y -1 were added, combined with burning (+/-) and clipping (+/-). Calluna vulgaris responded with increased shoot extension, but effects on flowering were variable. Burning enhanced the positive effect of nitrogen addition and negative effects of clipping. Sub-dominant shrubs generally did not respond to nitrogen. C. vulgaris shoot extension was stimulated by nitrogen addition of 10 kg N ha -1 y -1 (above background) supporting suggestions that alpine heathlands are sensitive to low levels of nitrogen deposition. Increased C. vulgaris growth could negatively impact on important lichen components of this vegetation through increased shading and competition. Climatic factors constrain productivity in this community, but do not prevent rapid responses to nitrogen deposition by some species. - Low levels of N deposition increase productivity in alpine dwarf-shrub heath despite strong climatic constraints

  8. Fisonomía vegetal y abundancia de aves en un bosque templado con dos niveles de perturbación en el Eje Neovolcánico Transversal Vegetation physiognomy and abundance of birds in a temperate forest with two disturbance levels in the Eje Neovolcanico Transversal

    Directory of Open Access Journals (Sweden)

    Saúl Ugalde-Lezama

    2012-03-01

    Full Text Available Durante noviembre 2003 y junio 2004 se estudió la abundancia de especies de aves y su relación con la fisonomía vegetal en un bosque templado bajo 2 condiciones: bosque de pino no perturbado (ZOQ1 y bosque de pino perturbado (ZOQ2 de la Estación Forestal Experimental Zoquiapan (EFEZ, Estado de México. Para el conteo de aves se empleó el método de puntos de conteo con radio fijo (25 m. Los principales gradientes de las variables descriptoras de la vegetación se determinaron con análisis de componentes principales (ACP y la relación fisonomía-abundancia por especie y grupos de aves mediante análisis de regresión Poisson (ARP. Los ejes principales del ACP explicaron el 84.3, 83.4 y 81.7% de la variabilidad presente en la vegetación de ZOQ1, ZOQ2 y ZOQ1-ZOQ2. La cobertura, diámetro y altura de árboles fueron las variables que explicaron el 41.5, 43.7 y 41.8% de la varianza para el componente 1. La cobertura, diámetro y altura de arbustivas explicaron el 28.4, 25.0 y 25.3% para el 2; por último, la cobertura de herbáceas y arbustivas el 14.4, 14.6 y 14.5% para el componente 3. Los ARP indicaron una relación estadísticamente significativa (pFrom November 2003 to June 2004, we studied the abundance of bird species and their relationship with vegetation physiognomy (structure in a temperate forest under 2 conditions: undisturbed forest (ZOQ1 and disturbed forest (ZOQ2 of the Zoquiapan Forest Experimental Station (EFEZ, acronym in Spanish in central Mexico. Birds were recorded using the method of fixed radius point counts (25 m. We identified the major gradients of variation of descriptive variables of vegetation using Principal Component Analysis (PCA, and the relationship between vegetation physiognomy and bird abundance through Poisson regression analyses (ARP. The three main axes of PCA explained the 84.3, 83.4 and 81.7% of the variability present in the vegetation of ZOQ1, ZOQ2 and ZOQ1-ZOQ2, respectively. Tree cover, diameter

  9. Stem water transport and freeze-thaw xylem embolism in conifers and angiosperms in a Tasmanian treeline heath.

    Science.gov (United States)

    Feild, Taylor S; Brodribb, Tim

    2001-05-01

    The effect of freezing on stem xylem hydraulic conductivity and leaf chlorophyll a fluorescence was measured in 12 tree and shrub species from a treeline heath in Tasmania, Australia. Reduction in stem hydraulic conductivity after a single freeze-thaw cycle was minimal in conifers and the vessel-less angiosperm species Tasmannia lanceolata (Winteraceae), whereas mean loss of conductivity in vessel-forming angiosperms fell in the range 17-83%. A positive linear relationship was observed between percentage loss of hydraulic conductivity by freeze-thaw and the average conduit diameter across all 12 species. This supports the hypothesis that large-diameter vascular conduits have a greater likelihood of freeze-thaw cavitation because larger bubbles are produced, which are more likely to expand under tension. Leaf frost tolerances, as measured by a 50% loss of maximum PSII quantum yield, varied from -6 to -13°C, indicating that these species were more frost-sensitive than plants from northern hemisphere temperate forest and treeline communities. There was no evidence of a relationship between frost tolerance of leaves and the resilience of stem water transport to freezing, suggesting that low temperature survival and the resistance of stem water transport to freezing are independently evolving traits. The results of this study bear on the ecological importance of stem freezing in the southern hemisphere treeline zones.

  10. Interactive effects of drought, elevated CO2 and warming on photosynthetic capacity and photosystem performance in temperate heath plants

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Michelsen, Anders

    2011-01-01

    performance was negatively influenced by high air temperature, low soil water content and high irradiance dose. The experimental treatments of elevated CO2 and prolonged drought generally down-regulated Jmax, Vcmax and PItotal. Recovery from these depressions was found in the evergreen shrub after rewetting......, leaf nitrogen content and chlorophyll-a fluorescence OJIP induction curves. The PSII performance was evaluated via the total performance index PItotal, which integrates the function of antenna, reaction centers, electron transport and end-acceptor reduction according to the OJIP-test. The PSII...

  11. Interactive effects of elevated CO2, warming, and drought on photosynthesis of Deschampsia flexuosa in a temperate heath ecosystem

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Ro-Poulsen, H.; Mikkelsen, Teis Nørgaard

    2011-01-01

    Global change factors affect plant carbon uptake in concert. In order to investigate the response directions and potential interactive effects, and to understand the underlying mechanisms, multifactor experiments are needed. The focus of this study was on the photosynthetic response to elevated CO2...... not decrease gs, but stimulated Pn via increased Ci. The T×CO2 synergistically increased plant carbon uptake via photosynthetic capacity up-regulation in early season and by better access to water after rewetting. The effects of the combination of drought and elevated CO2 depended on soil water availability......, with additive effects when the soil water content was low and D×CO2 synergistic stimulation of Pn after rewetting. The photosynthetic responses appeared to be highly influenced by growth pattern. The grass has opportunistic water consumption, and a biphasic growth pattern allowing for leaf dieback at low soil...

  12. High-Resolution Remote Sensing and Stable Isotope Patterns Across Heath-Shrub-Forest Ecotone at Abisko and Vassijaure, Northern Sweden

    Science.gov (United States)

    Schwan, M. R.; Herrick, C.; Hobbie, E. A.; Chen, J.; Varner, R. K.; Palace, M. W.; Marek, E.; Kashi, N. N.; Smith, S. L.

    2015-12-01

    Rapid warming in arctic and sub-arctic environments shifts plant community structure which in turn can alter carbon cycling by releasing large stocks of carbon sequestered in arctic soils. Much work has been done in sub-arctic peatlands to understand how shifts in dominant vegetation cover can ultimately affect global carbon balances, but less focus has been given to upland environments where similar changes are occurring. Recent circumpolar expansion of deciduous shrubs and trees in sub-arctic upland environments may alter carbon cycling due to shrubs and trees sequestering less C in soils than the heath plants they typically replace. In this study we explored the relationship between nutrient and carbon cycling and above-ground vegetation on six transects which traverse an ecotone gradient from heath tundra (dominated by ericoid mycorrhizal plants) through deciduous shrubs to deciduous trees (dominated by ectomycorrhizal plants) in upland environments of sub-arctic Sweden near Vassijaure (~850 mm precipitation) and Abisko (~300 mm precipitation). We collected soil and foliage for analysis of natural abundances of stable carbon and nitrogen isotopes (δ13C and δ15N), which can be a sensitive indicator of C and N dynamics. We also took high-resolution remote aerial imagery over the transects to calculate percent cover of vegetation types using GIS software. We concurrently estimated percent cover in smaller plots on the ground of three dominant species, Empetrum nigrum, Betula nana, and Betula pubescens, to serve as ground-truthing for the aerial imagery. Analysis of vegetation cover data shows significant differences in vegetation types along the transects. Preliminary multiple regression analysis of isotopes shows that δ13C in organic soil at the Vassijaure site is mostly controlled by distance along the transect, an interaction term between transect distance and soil depth, and δ15N (adjusted r2 = 0.85, p regression analyses, δ15N was primarily controlled by

  13. Effects of contrasting omnivorous fish on submerged macrophyte biomass in temperate lakes: a mesocosm experiment

    NARCIS (Netherlands)

    Dorenbosch, M.; Bakker, E.S.

    2012-01-01

    1.Freshwater fish can affect aquatic vegetation directly by consuming macrophytes or indirectly by changing water quality. However, most fish in the temperate climate zone have an omnivorous diet. The impact of fish as aquatic herbivores in temperate climates therefore remains unclear and depends on

  14. Characterisation of organic carbon in mire and heath soils at the Elgea-Urkilla Wind Farm, northern Spain

    Directory of Open Access Journals (Sweden)

    Z. Azkorra

    2008-07-01

    Full Text Available This paper describes a detailed comparative study of carbon storage in mire and heath soils within the Elgea-Urkilla Wind Farm (Basque Country, northern Spain. Different methods for estimating organic C stocks in the uppermost 15 cm of the soil profile were evaluated in an attempt to determine whether there was any spatial variability. The dominant vegetation of the study area was acidophilic and Atlantic heathland, with scattered areas of mire vegetation associated with spring lines. Soils were classified as Haplic Leptic Umbrisols (Oxyaquic, Molliglosic. Two sampling plots (900 m2 and 600 m2 were established adjacent to wind turbines. Mire vegetation was present in the larger plot (PLOT-A and absent from the smaller one (PLOT-B. Fourier-transformed infra-red (FTIR spectra indicated no noteworthy structural dissimilarities in the organic matter characteristics of the soils beneath the two types of vegetation. Soil samples were taken every week at systematically chosen points lying on fixed transects. Estimates of organic C stocks based on single sampling dates were 94–141 t C ha-1 for PLOT-A and 70–105 t C ha-1 for PLOT-B, and tended to increase as the weather became drier. When the estimates were derived from samples taken on several dates but from single transects, the range of the estimate for each plot was reduced to 111–116 t ha-1 for PLOT-A and 81–89 t ha-1 for PLOT-B. The results suggest that organic C stocks vary seasonally, and highlight difficulties that may be encountered in attempting to detect long-term changes in C storage.

  15. Study of the transfer of tritium in cultivated vegetation in Mediterranean temperate regions. Part of a coordinated programme on the cycling of tritium and other radionuclides of global character in different types of ecosystems

    International Nuclear Information System (INIS)

    Grauby, A.

    1979-06-01

    The utilization for agricultural purposes of water from rivers in which tritium has been dumped, and possible food chain hazards has stimulated investigations by the Cadarache, Mol and Wageningen centres on the contamination rate of products harvested in the Mediterranean region and in temperate climates; transfer via water, forage, cattle, and milk products and any food chain contamination attributable to technology. In agriculture, experiments have been concerned with potatoes, sugar beet, carrots and peas, and with vine, olive and orange trees. Tritium retention time has been determined in various parts of the plant; also tritium incorporation in tissue water and organic matter; and the distribution of tritium in progressive layers of soil

  16. The impact of ancestral heath management on soils and landscapes. A reconstruction based on paleoecological analyses of soil records in the middle and southeast Netherlands.

    Science.gov (United States)

    van Mourik, Jan; Doorenbosch, Marieke

    2016-04-01

    The evolution of heath lands during the Holocene has been registered in various soil records . Paleoecological analyses of these records enable to reconstruct the changing economic and cultural management of heaths and the consequences for landscape and soils. Heaths are characteristic components of cultural landscape mosaics on sandy soils in the Netherlands. The natural habitat of heather species was moorland. At first, natural events like forest fires and storms caused small-scale forest degradation, in addition on the forest degradation accelerated due to cultural activities like forest grazing, wood cutting and shifting cultivation. Heather plants invaded on degraded forest soils and heaths developed. People learned to use the heaths for economic and cultural purposes. The impact of the heath management on landscape and soils was registered in soil records of barrows, drift sand sequences and plaggic Anthrosols. Based on pollen diagrams of such records we could reconstruct that heaths were developed and used for cattle grazing before the Bronze Age. During the Late Neolithic, the Bronze Age and Iron Age, people created the barrow landscape on the ancestral heaths. After the Iron Age people probably continued with cattle grazing on the heaths and plaggic agriculture until the Early Middle Ages. After 1000 AD two events affected the heaths. At first deforestation for the sale of wood resulted in the first regional extension of sand drifting and heath degradation. After that the introduction of the deep stable economy and heath sods digging resulted in acceleration of the rise of plaggic horizons, severe heath degradation and the second extension of sand drifting. At the end of the 19th century the heath lost its economic value due to the introduction of chemical fertilizers. The heaths were transformed into 'new' arable fields and forests and due to deep ploughing most soil archives were destroyed. Since 1980 AD, the remaining relicts of the ancestral heaths are

  17. 2015-2016 Travel and Hospitality Expense Reports for Alanna Heath

    International Development Research Centre (IDRC) Digital Library (Canada)

    Ruxandra Staicu

    Purpose: Board meetings. Date(s):. 2015-07-13 to 2015-07-14. Destination(s):. Ottawa. Airfare: $448.24. Other. Transportation: $115.45. Accommodation: $344.56. Meals and. Incidentals: $3.95. Other: Total: $912.20 ... and Hospitality Expense. Reports for Alanna Heath - Governor,. Chairperson of the Finance and Audit.

  18. System design and equipment reliability for wide web working at Hem Heath Colliery

    Energy Technology Data Exchange (ETDEWEB)

    Hall, L

    1982-02-01

    This paper outlines the challenge to mining engineers on system design and reliability of equipment and how Hem Heath Colliery in the UK, is meeting this challenge, by describing current systems of work and equipment on the faces, summarising experience gained with succeeding faces, the results achieved, and posing considerations for the future.

  19. Heaths and forests of the western hills of Chia, Bogota savanna, Colombia

    International Nuclear Information System (INIS)

    Cortes S, Sandra P.; Van der Hammen, Thomas; Rangel Ch, J Orlando

    2000-01-01

    The authors make a study of the heaths and forests of the western hills of the population of Chia, located in the savanna of Bogota and the presence or absences of these in the same Bogota savanna; the authors treat topics like their physiognomy and composition, distribution and ecology among other topics

  20. New species of Drymopsalta Heath Cicadas (Cicadidae: Cicadettinae: Cicadettini) from Queensland and Northern Territory, Australia, with overview of genus.

    Science.gov (United States)

    Ewart, A; Popple, L W

    2013-01-01

    Three new species are described in the genus Drymopsalta Ewart, previously known only from D. crepitum Ewart and D. daemeli Distant. The three new species occur in Southern Queensland and Northern Territory. D. wallumi sp. nov. occurs along coastal S.E. Queensland, whereas D. hobsoni sp. nov. is restricted to the Bringalily State Forest, near Inglewood, southern inland Queensland. D. acrotela sp. nov. is found in the Litchfield National Park and other locations near Jabaluka, Cahills Crossing, E. Alligator River and Nourlangie, all across the northern Northern Territory. D. crepitum occurs on the Cape York Peninsular extending into the southern Gulf, while D. daemeli occurs in two localised regions in central coastal N.S.W. Each of the species inhabits heath vegetation, often spilling-over into adjacent tree foliage. The species of Drymopsalta are small and inconspicuous cicadas (cicadas. Two additional song variants are described, a more unstructured chirping song without intervening single ticks observed in each of the species except D. crepitum, and periodic extended buzzing echemes emitted within the calling songs (excepting the D. wallumi song).

  1. 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.

  2. Rapport de frais de 2015-2016 pour Alanna Heath | CRDI - Centre ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Accueil · À propos du CRDI · Obligation de rendre compte · Transparence · Déplacements et accueil. Rapport de frais de 2015-2016 pour Alanna Heath. Total des frais de déplacement : CAD$912.20. Réunion du Conseil des gouverneurs. 13 juillet 2015 au 14 juillet 2015. CAD$912.20. Ce que nous faisons · Financement ...

  3. Dr. Robert G. Heath: a controversial figure in the history of deep brain stimulation.

    Science.gov (United States)

    O'Neal, Christen M; Baker, Cordell M; Glenn, Chad A; Conner, Andrew K; Sughrue, Michael E

    2017-09-01

    The history of psychosurgery is filled with tales of researchers pushing the boundaries of science and ethics. These stories often create a dark historical framework for some of the most important medical and surgical advancements. Dr. Robert G. Heath, a board-certified neurologist, psychiatrist, and psychoanalyst, holds a debated position within this framework and is most notably remembered for his research on schizophrenia. Dr. Heath was one of the first physicians to implant electrodes in deep cortical structures as a psychosurgical intervention. He used electrical stimulation in an attempt to cure patients with schizophrenia and as a method of conversion therapy in a homosexual man. This research was highly controversial, even prior to the implementation of current ethics standards for clinical research and often goes unmentioned within the historical narrative of deep brain stimulation (DBS). While distinction between the modern practice of DBS and its controversial origins is necessary, it is important to examine Dr. Heath's work as it allows for reflection on current neurosurgical practices and questioning the ethical implication of these advancements.

  4. The geology of selected peat-forming environments in temperate and tropical latitudes

    Science.gov (United States)

    Cameron, C.C.; Palmer, C.A.; Esterle, J.S.

    1990-01-01

    and aerobic microbial activity. Stratigraphic distribution of various textures and amounts of inorganic components within a peat deposit is largely determined by the vertical positions occupied by peat-forming environments, such as pond, marsh, swamp and heath where vegetation accumulated, and the depth to zones of unoxygenated water. Peat also differs in the rate of accumulation. On the basis of carbon-14 dating, an estimated 8 m of peat in the tropical Batang Hari River deposit in Sumatra has been accumulating at the rate of about 1.5 m/1,000 yr, whereas peat in the cold-temperate deposit in Maine has been accumulating at the rate of 0.66 m/1,000 yr. Accumulation rates in domed deposits such as these are affected not only by factors controlling volume of biomass and aerobic decay but also by stream erosion and fires that remove peat. Such disconformities (see Fig. 2) within the deposit may be recognized by sudden vertical changes in degree of decomposition and/or the presence of charcoal. The trace-element content of peat deposits is affected by the environments of their settings. Samples of peat that have an ash content of less than 25% dry weight and that are from small, almost level swamp deposits along the Atlantic Coastal Plain of North Carolina were compared with similar samples from small domed bogs in Maine, a glaciated area. Samples from Nort Carolina, which are from deposits in thick fluvial and nearshore marine sediments far from the bedrock source, are generally higher in Ti, Cr and Pb. The Maine samples from deposits in glacial drift close to the bedrock source contain more Zn, Mn, P, Ca, Na and Fe. The kind and amount of trace elements within the deposits appear to relate largely to depositional setting, to kinds of bedrock source, and to the modes of transportation from source to peat swamp. Trace-element concentrations in the extensive Sumatra peat deposit, which represents a potentially commercial coal bed, are similar to those found in Appalachian

  5. Challenges in modelling isoprene and monoterpene emission dynamics of Arctic plants: a case study from a subarctic tundra heath

    Science.gov (United States)

    Tang, Jing; Schurgers, Guy; Valolahti, Hanna; Faubert, Patrick; Tiiva, Päivi; Michelsen, Anders; Rinnan, Riikka

    2016-12-01

    The Arctic is warming at twice the global average speed, and the warming-induced increases in biogenic volatile organic compounds (BVOCs) emissions from Arctic plants are expected to be drastic. The current global models' estimations of minimal BVOC emissions from the Arctic are based on very few observations and have been challenged increasingly by field data. This study applied a dynamic ecosystem model, LPJ-GUESS, as a platform to investigate short-term and long-term BVOC emission responses to Arctic climate warming. Field observations in a subarctic tundra heath with long-term (13-year) warming treatments were extensively used for parameterizing and evaluating BVOC-related processes (photosynthesis, emission responses to temperature and vegetation composition). We propose an adjusted temperature (T) response curve for Arctic plants with much stronger T sensitivity than the commonly used algorithms for large-scale modelling. The simulated emission responses to 2 °C warming between the adjusted and original T response curves were evaluated against the observed warming responses (WRs) at short-term scales. Moreover, the model responses to warming by 4 and 8 °C were also investigated as a sensitivity test. The model showed reasonable agreement to the observed vegetation CO2 fluxes in the main growing season as well as day-to-day variability of isoprene and monoterpene emissions. The observed relatively high WRs were better captured by the adjusted T response curve than by the common one. During 1999-2012, the modelled annual mean isoprene and monoterpene emissions were 20 and 8 mg C m-2 yr-1, with an increase by 55 and 57 % for 2 °C summertime warming, respectively. Warming by 4 and 8 °C for the same period further elevated isoprene emission for all years, but the impacts on monoterpene emissions levelled off during the last few years. At hour-day scale, the WRs seem to be strongly impacted by canopy air T, while at the day-year scale, the WRs are a combined

  6. The geology, botany and chemistry of selected peat-forming environments from temperate and tropical latitudes

    Science.gov (United States)

    Cameron, C.C.; Esterle, J.S.; Palmer, C.A.

    1989-01-01

    Peat has been studied in several geologic settings: (1) glaciated terrain in cold temperate Maine and Minnesota, U.S.A.; (2) an island in the Atlantic Ocean off the coast of Maine, where sea level is rising; (3) the warm temperate U.S. Atlantic and Gulf Coastal Plains, where sea level has changed often; and (4) the tropical coast of Sarawak, Malaysia, and the tropical delta of the Batang Hari River, Sumatra, Indonesia. Most of these deposits are domed (ombrotrophic or partly ombrotrophic) bogs in which peat accumulation continued above the surface of the surrounding soil. However, the bogs of the U.S. Atlantic and Gulf Coastal Plains are comparatively not as domed, and many have almost level surfaces. In some bogs, aquatic or semi-aquatic plant materials accumulated, replaced water in the depressions, and formed a surface on which marsh or swamp vegetation could subsequently live, die, and accumulate. In others, the plant materials accumulated initially on level silt or sand surfaces supporting marshes or swamps. As the peat dome formed, plants growing on it changed from luxuriant ones near the base of the dome, where nutrients were brought into the bog by surface and ground water, to stunted ones at the top of the dome, where the raised bogs are fed by nutrient-poor precipitation. The physical and chemical changes that take place in the sequence of environments from the pond stage of deposit development, through the grassy marsh stage, through the forested swamp stage, and finally through the heath dome stage can be measured in terms of acidity and ash, volatile matter, carbon, hydrogen, nitrogen, sulfur and oxygen contents, as well as in the kind and distribution of trace elements. The organic and inorganic contents of the deposits relate to geomorphology, and geomorphology relates to their settings. As models of coal formation, some domed peat deposits may help in solving problems of distribution and character of ancient coal beds. But clearly not all peat

  7. The impact of ancestral heath management on soils and landscapes: a reconstruction based on paleoecological analyses of soil records in the central and southeastern Netherlands

    Science.gov (United States)

    Doorenbosch, Marieke; van Mourik, Jan M.

    2016-07-01

    The evolution of heathlands during the Holocene has been registered in various soil records. Paleoecological analyses of these records enable reconstruction of the changing economic and cultural management of heaths and the consequences for landscape and soils. Heaths are characteristic components of cultural landscape mosaics on sandy soils in the Netherlands. The natural habitat of heather species was moorland. At first, natural events like forest fires and storms caused small-scale forest degradation; in addition on that, the forest degradation accelerated due to cultural activities like forest grazing, wood cutting, and shifting cultivation. Heather plants invaded degraded forest soils, and heaths developed. People learned to use the heaths for economic and cultural purposes. The impact of the heath management on landscape and soils was registered in soil records of barrows, drift sand sequences, and plaggic Anthrosols. Based on pollen diagrams of such records we could reconstruct that heaths were developed and used for cattle grazing before the Bronze Age. During the late Neolithic, the Bronze Age, and Iron Age, people created the barrow landscape on the ancestral heaths. After the Iron Age, people probably continued with cattle grazing on the heaths and plaggic agriculture until the early Middle Ages. Severe forest degradation by the production of charcoal for melting iron during the Iron Age till the 6th-7th century and during the 11th-13th century for the trade of wood resulted in extensive sand drifting, a threat to the valuable heaths. The introduction of the deep, stable economy and heath sods digging in the course of the 18th century resulted in acceleration of the rise of plaggic horizons, severe heath degradation, and again extension of sand drifting. At the end of the 19th century heath lost its economic value due to the introduction of chemical fertilizers. The heaths were transformed into "new" arable fields and forests, and due to deep ploughing

  8. Impact of decade-long warming, nutrient addition and shading on emission and carbon isotopic composition of CO2 from two subarctic dwarf shrub heaths

    DEFF Research Database (Denmark)

    Ravn, Nynne R.; Ambus, Per Lennart; Michelsen, Anders

    2017-01-01

    This study investigated ecosystem respiration, soil respiration and carbon isotopic composition in CO2 emitted from two subarctic shrub heaths with contrasting moisture regimes. The reported measurements were conducted 22 years (mesic heath) and 12 years (wet heath) upon initiation of in situ...... the growing season. However, there was a tendency across growing season towards an increased δ13C source value after 22 years of warming in the mesic shrub heath, and the effect was statistically significant in June, indicating increased decomposition of 13C enriched material. Hence, although more of the old...

  9. The Social Structure of Participants of the Battle of Blore Heath (September 23, 1459)

    OpenAIRE

    Andrey G. Prazdnikov

    2017-01-01

    The battle of Blore Heath which took place on September 23, 1459, marked the new stage of the Wars of Roses, which led to the change of dynasties at the English throne in less than two years. As it was not the clash of the main forces of House of Lancaster and House of York, the sources contain poor information about the battle’s participants. However, the analysis different sources let identify the names of 22 participants. Prosopographic study of this group contributes to the study of socia...

  10. Time-temperature equivalence in Martensite tempering

    Energy Technology Data Exchange (ETDEWEB)

    Hackenberg, Robert E. [Los Alamos National Laboratory; Thomas, Grant A. [CSM; Speer, John G. [CSM; Matlock, David K. [CSM; Krauss, George [CSM

    2008-06-16

    The relationship between time and temperature is of great consequence in many materials-related processes including the tempering of martensite. In 1945, Hollomon and Jaffe quantified the 'degree of tempering' as a function of both tempering time, t, and tempering temperature, T, using the expression, T(log t + c). Here, c is thought to be a material constant and appears to decrease linearly with increasing carbon content. The Hollomon-Jaffe tempering parameter is frequently cited in the literature. This work reviews the original derivation of the tempering parameter concept, and presents the use of the characteristics diffusion distance as an alternative time-temperature relationship during martensite tempering. During the tempering of martensite, interstitial carbon atoms diffuse to form carbides. In addition, austenite decomposes, dislocations and grain boundaries rearrange, associated with iron self diffusion. Since these are all diffusional processes, it is reasonable to expect the degree of tempering to relate to the extent of diffusion.

  11. Tempered stable laws as random walk limits

    OpenAIRE

    Chakrabarty, Arijit; Meerschaert, Mark M.

    2010-01-01

    Stable laws can be tempered by modifying the L\\'evy measure to cool the probability of large jumps. Tempered stable laws retain their signature power law behavior at infinity, and infinite divisibility. This paper develops random walk models that converge to a tempered stable law under a triangular array scheme. Since tempered stable laws and processes are useful in statistical physics, these random walk models can provide a basic physical model for the underlying physical phenomena.

  12. 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...

  13. 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

  14. Camera derived vegetation greenness index as proxy for gross primary production in a low Arctic wetland area

    DEFF Research Database (Denmark)

    Westergaard-Nielsen, Andreas; Lund, Magnus; Hansen, Birger Ulf

    2013-01-01

    vegetation index (NDVI) product derived from the WorldView-2 satellite. An object-based classification based on a bi-temporal image composite was used to classify the study area into heath, copse, fen, and bedrock. Temporal evolution of vegetation greenness was evaluated and modeled with double sigmoid...... and GPP (R-2 = 0.85, p remote Arctic regions....... (C) 2013 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS) Published by Elsevier B.V. All rights reserved....

  15. Nonvascular contribution to ecosystem NPP in a subarctic heath during early and late growing season

    DEFF Research Database (Denmark)

    Campioli, Matteo; Samson, Roeland; Michelsen, Anders

    2009-01-01

    significant when vascular plants are less active and ecosystems act as a source of carbon (C). To clarify these dynamics, nonvascular and vascular aboveground NPP was compared for a subarctic heath during two contrasting periods of the growing season, viz. early-mid summer and late summer-early autumn...... measurements of shoot length increase. Vascular NPP was determined by harvesting shrub and herb apical growth and considering production due to stem secondary growth of shrubs. Hylocomium splendens and Pleurozium schreberi showed highest biomass growth in late summer, whereas for D. elongatum this occurred...... weight m-2 d-1, in early and late summer, respectively, whereas in the same periods vascular NPP was 3.6 and 1.1 g dry weight m-2 d-1. The contribution of nonvascular NPP to total aboveground NPP was therefore minor in early summer but substantial in late summer, when 25% of the C accumulated...

  16. Significance of cold-season respiration and photosynthesis in a subarctic heath ecosystem in Northern Sweden

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Ibrom, Andreas; Jonasson, S.

    2007-01-01

    While substantial cold-season respiration has been documented in most arctic and alpine ecosystems in recent years, the significance of cold-season photosynthesis in these biomes is still believed to be small. In a mesic, subartic heath during both the cold and warm season, we measured in situ...... ecosystem respiration and photosynthesis with a chamber technique at ambient conditions and at artificially, increased frequency of freeze-thaw (FT) cycles during fall and spring. We fitted the measured ecosystem exchange rates to respiration and photosynthesis models with R-2-values ranging from 0.81 to 0.......85. As expected, estimated cold-season (October, November, April and May) respiration was significant and accounted for at least 22% of the annual respiratory CO2 flux. More surprisingly, estimated photosynthesis during this period accounted for up to 19% of the annual gross CO2 uptake, suggesting that cold...

  17. Short-term utilization of carbon by the soil microbial community under future climatic conditions in a temperate heathland

    DEFF Research Database (Denmark)

    Reinsch, Sabine; Michelsen, Anders; Sárossy, Zsuzsa

    2014-01-01

    An in-situ13C pulse-labeling experiment was carried out in a temperate heath/grassland to study the impacts of elevated CO2 concentration (510ppm), prolonged summer droughts (annual exclusion of 7.6±0.8%) and increased temperature (~1°C) on belowground carbon (C) utilization. Recently assimilated C...... (13C from the pulse-label) was traced into roots, soil and microbial biomass 1, 2 and 8 days after pulse-labeling. The importance of the microbial community in C utilization was investigated using 13C enrichment patterns in different microbial functional groups on the basis of phospholipid fatty acid...... (PLFA) biomarker profiles. Climate treatments did not affect microbial abundance in soil or rhizosphere fractions in terms of total PLFA-C concentration. Elevated CO2 significantly reduced the abundance of gram-negative bacteria (17:0cy), but did not affect the abundance of decomposers (fungi...

  18. On choice of tempered steels

    International Nuclear Information System (INIS)

    Govorov, A.A.; Pan'shin, I.F.; Rakhmanov, V.I.

    1978-01-01

    For the purpose of developing a graphical method for choosing structural steels, a change in the propagation work of a crack and in the critical temperature of brittleness of 40, 40Kh, 40KhN, and 40KhNM steels, was examined depending on the hardness after hardening and tempering. A diagram enabling to choose the grade of steel for making an article of known dimensions according to the preset values of its mechanical properties has been plotted. The developed selection scheme takes into account the hardenability of steels and the influence of the hardness after thermal treatment on the cold-shortness of steel

  19. The Performance Of Alternative Interest Rate Risk Measures And Immunization Strategies Under A Heath-Jarrow-Morton Framework

    OpenAIRE

    Agca, Senay

    2002-01-01

    The Heath-Jarrow-Morton (HJM) model represents the latest in powerful arbitrage-free technology for modeling the term structure and managing interest rate risk. Yet risk management strategies in the form of immunization portfolios using duration, convexity, and M-square are still widely used in bond portfolio management today. This study addresses the question of how traditional risk measures and immunization strategies perform when the term structure evolves in the HJM manner. Using Monte Ca...

  20. CLIMOOR. Climate driven changes in the functioning of heath and moorland ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Beier, C. [ed.; Tietema, A.; Riis Nielsen, T.; Emmett, B.; Estiarte, M.; Penuelas, J.; Llorens Guash, L.; Williams, D.; Gordon, C.; Pugh, B.; Roda, F.; Gundersen, P.; Gorissen, A.

    2000-01-01

    Emission of green house gases, partly generated from human activities, reduces the loss of heat from the earth thereby potentially causing climate change. This change in climate has been predicted to result in a 1-3 deg. C increase in temperature with more vigorous rainstorms and prolonged drought periods in the coming 100 years. The consequence of such climatic changes for the terrestrial ecosystems are largely unknown. In order to improve our understanding of the ecosystem response to climate change and thereby to improve the basis for the international negotiations and political decisions to avoid or minimise climate change and its effects, a European research project CLIMOOR has been initiated. The project is a cross European research project involving 6 research groups from Denmark, the Netherlands, UK and Spain and is funded by EU and the participating institutions. The project investigates the potential effects of warming and drought on heath and moorland ecosystems at four European sites. The ecosystems are manipulated at field scale by reducing the heat loss at night by IR-reflective curtains and by removing the precipitation during a 2 month period in the summer. The effects of these manipulations on the plants and the soil are studied. This report describes the technique used to apply the climate change at field scale and presents some preliminary results after the first growing season. EU and the participating institutions fund CLIMOOR. (au)

  1. The Heath government and British defence policy in Southeast Asia at the end of empire (1970-71).

    Science.gov (United States)

    Andrea, Benvenuti

    2009-01-01

    This article examines the rationale behind the Heath government's 1970 decision to negotiate a Five Power Defence agreement with Australia, New Zealand, Singapore and Malaysia and to maintain a small British military contingent in Southeast Asia as a part of this new politico-military framework. It argues that while its overriding foreign policy concern was to end Britain's problematic relationship with the European Economic Community and to make membership of this grouping the cornerstone of its foreign policy, the Heath government was careful not to cast Britain's post-imperial future in purely European terms. The successful negotiation of the Five Power Defence Arrangements in 1970-71 was instrumental in achieving this by ensuring that London would maintain close links with key Commonwealth partners in the Asian region. In what was not only an attempt to neutralize potential domestic opposition to Britain's entry into the EEC, but also a lingering reluctance to do away with the rhetoric of Britain as a leading power with extra-European interests, Heath was eager to show that by making a contribution to the stability of Southeast Asia, Britain still had a role to play outside Europe.

  2. 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)

  3. The Social Structure of Participants of the Battle of Blore Heath (September 23, 1459

    Directory of Open Access Journals (Sweden)

    Andrey G. Prazdnikov

    2017-03-01

    Full Text Available The battle of Blore Heath which took place on September 23, 1459, marked the new stage of the Wars of Roses, which led to the change of dynasties at the English throne in less than two years. As it was not the clash of the main forces of House of Lancaster and House of York, the sources contain poor information about the battle’s participants. However, the analysis different sources let identify the names of 22 participants. Prosopographic study of this group contributes to the study of social behavior models, the degree of influence of the Wars of Roses on English society, the activity of representatives of different social strata. The social structure of the group, most of which are the representatives of the English gentry, is the object of the article. There is information in the sources about the origin of the knights. The House of York under the command of Earl of Salisbury were mostly from Northern and North-Western counties (Yorkshire, Westmorland, whereas House of Lancaster formed their troops in Cheshire, Staffordshire and Lancashire. As a rule, officers in the army of the Earl of Salisbury, were in close personal or family ties with him. The study of further lives of the participants of the battle and biographies of their children showed that the adherence of the chosen dynasty was preserved by generations and change of the parties was rather a deviation from the norm. English nobility of the second half of the 15th century had a high opinion of the value of loyalty and honor.

  4. New temperable solar coatings: Tempsol

    Science.gov (United States)

    Demiryont, Hulya

    2001-11-01

    This paper deals with the large area deposition and coating properties of the thermo-stable (temperable/bendable) solar coating material, CuO, and some new optical coating systems comprising CuO films for architectural and automotive/transportation applications. The CuO solar coating is combined with other coating layers, for example, an anti-reflection film, a reflection film, a coloration coating layer, etc., which are also thermo-stable. The film systems are developed at the research laboratory by D.C. Magnetron reactive sputtering process. The new developed technologies then transferred to the production line. Product performances are compared before and after heat treatment of the coating systems. Performance tables and other physical properties, including optical parameters, mechanical and environmental stability, storage properties, etc., are also presented for this new product series.

  5. Development of silvicultural systems for maintaining old-growth conditions in the temperate rainforest of southeast Alaska.

    Science.gov (United States)

    Michael H. McClellan

    2004-01-01

    In the old-growth temperate rainforests of southeast Alaska, concerns over clearcutting effects on habitat, visual quality, slope stability, and biodiversity have created a demand for the use of other silvicultural systems. The forest vegetation and animal taxa of southeast Alaska appear to be well adapted to frequent, widespread, small-scale disturbance, suggesting...

  6. Fungal associations of roots of dominant and sub-dominant plants in high-alpine vegetation systems with special reference to mycorrhiza.

    Science.gov (United States)

    Haselwandter, K; Read, D J

    1980-04-01

    Types of root infection were analysed in healthy dominant and sub-dominant plants of zonal and azonal vegetation above the timberline in the Central and Northern Calcareous Alps of Austria. In the open nival zone vegetation, infection by fungi of the Rhizoctonia type was predominant, vesicular-arbuscular mycorrhizal infection, which was mostly of the fine endophyte (Glomus tenuis) type, being light and mainly restricted to grasses in closed vegetation patches. More extensive Glomus tenuis infection was found in the alpine grass heath, but in Carex, Rhizoctonia was again the most important fungus. The ericaceous plants of the dwarf shrub heath have typical ericoid infection, but quantitative analysis reveals a decrease of infection intensity with increase of altitude. The possible function of the various types of root infection are discussed, and the status of Rhizoctonia as a possible mycorrhizal fungus is considered.

  7. Plant Traits Demonstrate That Temperate and Tropical Giant Eucalypt Forests Are Ecologically Convergent with Rainforest Not Savanna

    Science.gov (United States)

    Tng, David Y. P.; Jordan, Greg J.; Bowman, David M. J. S.

    2013-01-01

    Ecological theory differentiates rainforest and open vegetation in many regions as functionally divergent alternative stable states with transitional (ecotonal) vegetation between the two forming transient unstable states. This transitional vegetation is of considerable significance, not only as a test case for theories of vegetation dynamics, but also because this type of vegetation is of major economic importance, and is home to a suite of species of conservation significance, including the world’s tallest flowering plants. We therefore created predictions of patterns in plant functional traits that would test the alternative stable states model of these systems. We measured functional traits of 128 trees and shrubs across tropical and temperate rainforest – open vegetation transitions in Australia, with giant eucalypt forests situated between these vegetation types. We analysed a set of functional traits: leaf carbon isotopes, leaf area, leaf mass per area, leaf slenderness, wood density, maximum height and bark thickness, using univariate and multivariate methods. For most traits, giant eucalypt forest was similar to rainforest, while rainforest, particularly tropical rainforest, was significantly different from the open vegetation. In multivariate analyses, tropical and temperate rainforest diverged functionally, and both segregated from open vegetation. Furthermore, the giant eucalypt forests overlapped in function with their respective rainforests. The two types of giant eucalypt forests also exhibited greater overall functional similarity to each other than to any of the open vegetation types. We conclude that tropical and temperate giant eucalypt forests are ecologically and functionally convergent. The lack of clear functional differentiation from rainforest suggests that giant eucalypt forests are unstable states within the basin of attraction of rainforest. Our results have important implications for giant eucalypt forest management. PMID:24358359

  8. Rapid carbon turnover beneath shrub and tree vegetation is associated with low soil carbon stocks at a subarctic treeline.

    Science.gov (United States)

    Parker, Thomas C; Subke, Jens-Arne; Wookey, Philip A

    2015-05-01

    Climate warming at high northern latitudes has caused substantial increases in plant productivity of tundra vegetation and an expansion of the range of deciduous shrub species. However significant the increase in carbon (C) contained within above-ground shrub biomass, it is modest in comparison with the amount of C stored in the soil in tundra ecosystems. Here, we use a 'space-for-time' approach to test the hypothesis that a shift from lower-productivity tundra heath to higher-productivity deciduous shrub vegetation in the sub-Arctic may lead to a loss of soil C that out-weighs the increase in above-ground shrub biomass. We further hypothesize that a shift from ericoid to ectomycorrhizal systems coincident with this vegetation change provides a mechanism for the loss of soil C. We sampled soil C stocks, soil surface CO2 flux rates and fungal growth rates along replicated natural transitions from birch forest (Betula pubescens), through deciduous shrub tundra (Betula nana) to tundra heaths (Empetrum nigrum) near Abisko, Swedish Lapland. We demonstrate that organic horizon soil organic C (SOCorg ) is significantly lower at shrub (2.98 ± 0.48 kg m(-2) ) and forest (2.04 ± 0.25 kg m(-2) ) plots than at heath plots (7.03 ± 0.79 kg m(-2) ). Shrub vegetation had the highest respiration rates, suggesting that despite higher rates of C assimilation, C turnover was also very high and less C is sequestered in the ecosystem. Growth rates of fungal hyphae increased across the transition from heath to shrub, suggesting that the action of ectomycorrhizal symbionts in the scavenging of organically bound nutrients is an important pathway by which soil C is made available to microbial degradation. The expansion of deciduous shrubs onto potentially vulnerable arctic soils with large stores of C could therefore represent a significant positive feedback to the climate system. © 2014 John Wiley & Sons Ltd.

  9. Ecological legacies of Indigenous fire management in high-latitude coastal temperate rainforests, Canada

    Science.gov (United States)

    Hoffman, K.; Lertzman, K. P.; Starzomski, B. M.

    2016-12-01

    Anthropogenic burning is considered to have little impact on coastal temperate rainforest fire regimes in the Pacific Northwest (PNW) of North America, yet few long-term fire histories have been reconstructed in these forests. We use a multidisciplinary approach to reconstruct the ecological impact, scale, and legacies of historic fire regime variability in high-latitude coastal temperate rainforests located in British Columbia, Canada. We map seven centuries of fire activity with fire scars and records of stand establishment, and examine patterns in the distribution and composition of vegetation to assess whether fire was historically used as a tool for resource management. We conduct a paired study of 20 former Indigenous habitation and control sites across a 100 km2 island group to relate historic fire activity with long-term patterns of human land use and contemporary lightning strike densities. Fires were significantly associated with the locations of former Indigenous habitation sites, low and mixed in severity, and likely intentionally used to influence the composition and structure of vegetation, thus increasing the productivity of culturally important plants such as western redcedar, berry-producing shrubs, and bracken fern. Centuries of repeated anthropogenic burning have resulted in a mosaic of vegetation types in different stages of succession. These data are directly relevant to the management of contemporary forests as they do not support the widespread contention that old growth coastal temperate rainforests in this region are pristine landscapes where fire is rare, but more likely the result of long-term human land use practices.

  10. The Effect of Tempering on Strength Properties and Seed Coat ...

    African Journals Online (AJOL)

    The effect of tempering on seed coat adhesion strength and mechanical strength of sorghum and millet grain kernels was investigated at different tempering durations. Tempering reduced the kernel breaking strength and had significant effect on seed coat adhesion strength. Tempering the grain for 60 minutes at ambient ...

  11. Intensity of Urban Heat Islands in Tropical and Temperate Climates

    Directory of Open Access Journals (Sweden)

    Margarete Cristiane de Costa Trindade Amorim

    2017-12-01

    Full Text Available Nowadays, most of the Earth’s population lives in urban areas. The replacement of vegetation by buildings and the general soil sealing, associated with human activity, lead to a rise in cities temperature, resulting in the formation of urban heat islands. This article aims to evaluate the intensity and the hourly maintenance of the atmospheric heat islands in two climates: one tropical (Presidente Prudente, Brazil and one temperate (Rennes, France throughout 2016. For this, air temperature and hourly averages were measured and calculated using both a HOBO datalogger (U23-002—protected under the same RS3 brand and weather stations Davis Vantage PRO 2. The daily evolution of the heat islands presented characteristics that varied according to the hours and seasons of the year. For both Rennes and Presidente Prudente, the largest magnitudes occurred overnight, being more greatly expressed in the tropical environment and during the driest months (winter in the tropical city and summer in the temperate one. The variability of synoptic conditions from one month to another also leads to a great heterogeneity of UHI intensity throughout the year.

  12. Surface energy exchanges over contrasting vegetation types on a subtropical sand island

    Science.gov (United States)

    Gray, Michael; McGowan, Hamish; Lowry, Andrew; Guyot, Adrien

    2017-04-01

    The surface energy balance of subtropical coastal vegetation communities has thus far received little attention. Here we present a multi-year observational data set using the eddy covariance method to quantify for the first time the surface energy balance over three contrasting vegetation types on a subtropical sand island in eastern Australia: a periodically inundated sedge swamp, an exotic pine plantation and a coastal heath. Maximum daily sensible heat flux varied between sites but was typically > 280 Wm-2 in the coastal heath and pine plantation but no more than 250 Wm-2 in the swamp when dry and 1. The partitioning of energy, as represented by β, is similar to a variety of Australian ecosystems, and a range of coastal vegetation types in other latitudes, but differs from other tropical or subtropical locations which have strongly seasonal rainfall patterns and therefore a switch from β > 1 before rainfall to β changes in background meteorology with the most important influences being net radiation, absolute humidity, and rainfall. The main factor differentiating the sites was soil water content, with the remnant coastal heath and swamp having ready access to water but the exotic pine plantation having much drier soils. Should the current balance between remnant vegetation and the pine plantation undergo changes there would be a corresponding shift in the surface energy balance of the island as a whole, and altered plant water use may lead to reduced water table depth, important because the groundwater of the local islands is used as part of a regional water grid. A better understanding of the response of coastal vegetation to atmospheric forcing will enable more informed decision making on land use changes, as coastal regions the world over face development pressure.

  13. Comparisons of invasive plants in southern Africa originating from southern temperate, northern temperate and tropical regions

    Directory of Open Access Journals (Sweden)

    L. Henderson

    2006-08-01

    Full Text Available A subset of invasive alien plant species in southern Africa was analysed in terms of their history of introduction, rate of spread, countries/region of origin, taxonomy, growth forms, cultivated uses, weed status and current distribution in southern Africa, and comparisons made of those originating from south of the tropic of Capricorn, north of the tropic of Cancer and from the tropics. The subset of 233 species, belonging to 58 families, includes all important declared species and some potentially important species. Almost as many species originate from temperate regions (112 as from the tropics (121. Most southern temperate species came from Australia (28/36, most tropical species from tropical America (92/121 and most northern temperate species from Europe (including the Mediterranean and Asia (58/76. Transformers account for 33% of  all species. More transformers are of tropical origin (36 than of northern temperate (24 and southern temperate origin (18. However. 50% of southern temperate species are transformers, compared to 32% of northern temperate and 29% of tropical species. Southern temperate transformer species are mainly woody trees and shrubs that were established on a grand scale as silvicultural crops, barriers (hedges, windbreaks and screens and cover/binders. Most aquatics, herbs, climbers and succulent shrubs an. trom the tropics. Ornamentals are the single largest category of plants from all three regions, the tropics having contributed twice as many species as temperate regions.

  14. Kuchler Vegetation

    Data.gov (United States)

    California Natural Resource Agency — Digital version of potential natural plant communites as compiled and published on 'Map of the Natural Vegetation of California' by A. W. Kuchler, 1976. Source map...

  15. Wieslander Vegetation

    Data.gov (United States)

    California Natural Resource Agency — Digital version of the 1945 California Vegetation Type Maps by A. E. Wieslander of the U.S. Forest Service. Source scale of maps are 1:100,000. These compiled maps...

  16. Impacts of short-term heatwaves on sun-induced chlorophyll fluorescence(SiF) in temperate tree species

    Science.gov (United States)

    Wang, F.; Gu, L.; Guha, A.; Han, J.; Warren, J.

    2017-12-01

    The current projections for global climate change forecast an increase in the intensity and frequency of extreme climatic events, such as droughts and short-term heat waves. Understanding the effects of short-term heat wave on photosynthesis process is of critical importance to predict global impacts of extreme weather event on vegetation. The diurnal and seasonal characteristics of SIF emitted from natural vegetation, e.g., forest and crop, have been studied at the ecosystem-scale, regional-scale and global-scale. However, the detailed response of SIF from different plant species under extremely weather event, especially short-term heat wave, have not been reported. The purpose of this study was to study the response of solar-induced chlorophyll fluorescence, gas exchange and continuous fluorescence at leaf scale for different temperate tree species. The short-term heatwave experiment was conducted using plant growth chamber (CMP6050, Conviron Inc., Canada). We developed an advanced spectral fitting method to obtain the plant SIF in the plant growth chamber. We compared SIF variation among different wavelength and chlorophyll difference among four temperate tree species. The diurnal variation of SIF signals at leaf-scales for temperate tree species are different under heat stress. The SIF response at leaf-scales and their difference for four temperate tree species are different during a cycle of short-term heatwave stress. We infer that SIF be used as a measure of heat tolerance for temperate tree species.

  17. 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

  18. Uptake of pulse injected nitrogen by soil microbes and mycorrhizal and non-mycorrhizal plants in a species-diverse subarctic heath ecosystem

    DEFF Research Database (Denmark)

    Andresen, Louise Christoffersen; Jonasson, Sven; Strom, Lena

    2008-01-01

    15N labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of 15N label in mycorrhizal and non-mycorrhiza......15N labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of 15N label in mycorrhizal and non...

  19. VEGETATION MAPPING IN WETLANDS

    Directory of Open Access Journals (Sweden)

    F. PEDROTTI

    2004-01-01

    Full Text Available The current work examines the main aspects of wetland vegetation mapping, which can be summarized as analysis of the ecological-vegetational (ecotone gradients; vegetation complexes; relationships between vegetation distribution and geomorphology; vegetation of the hydrographic basin lo which the wetland in question belongs; vegetation monitoring with help of four vegetation maps: phytosociological map of the real and potential vegetation, map of vegetation dynamical tendencies, map of vegetation series.

  20. Assessment of Soil Organic Carbon Stock of Temperate Coniferous Forests in Northern Kashmir

    Directory of Open Access Journals (Sweden)

    Davood A. Dar

    2015-02-01

    Full Text Available  Soil organic carbon (SOC estimation in temperate forests of the Himalaya is important to estimate their contribution to regional, national and global carbon stocks. Physico chemical properties of soil were quantified to assess soil organic carbon density (SOC and SOC CO2 mitigation density at two soil depths (0-10 and 10-20 cms under temperate forest in the Northern region of Kashmir Himalayas India. The results indicate that conductance, moisture content, organic carbon and organic matter were significantly higher while as pH and bulk density were lower at Gulmarg forest site. SOC % was ranging from 2.31± 0.96 at Gulmarg meadow site to 2.31 ± 0.26 in Gulmarg forest site. SOC stocks in these temperate forests were from 36.39 ±15.40 to 50.09 ± 15.51 Mg C ha-1. The present study reveals that natural vegetation is the main contributor of soil quality as it maintained the soil organic carbon stock. In addition, organic matter is an important indicator of soil quality and environmental parameters such as soil moisture and soil biological activity change soil carbon sequestration potential in temperate forest ecosystems.DOI: http://dx.doi.org/10.3126/ije.v4i1.12186International Journal of Environment Volume-4, Issue-1, Dec-Feb 2014/15; page: 161-178

  1. First Temperate Exoplanet Sized Up

    Science.gov (United States)

    2010-03-01

    Combining observations from the CoRoT satellite and the ESO HARPS instrument, astronomers have discovered the first "normal" exoplanet that can be studied in great detail. Designated Corot-9b, the planet regularly passes in front of a star similar to the Sun located 1500 light-years away from Earth towards the constellation of Serpens (the Snake). "This is a normal, temperate exoplanet just like dozens we already know, but this is the first whose properties we can study in depth," says Claire Moutou, who is part of the international team of 60 astronomers that made the discovery. "It is bound to become a Rosetta stone in exoplanet research." "Corot-9b is the first exoplanet that really does resemble planets in our solar system," adds lead author Hans Deeg. "It has the size of Jupiter and an orbit similar to that of Mercury." "Like our own giant planets, Jupiter and Saturn, the planet is mostly made of hydrogen and helium," says team member Tristan Guillot, "and it may contain up to 20 Earth masses of other elements, including water and rock at high temperatures and pressures." Corot-9b passes in front of its host star every 95 days, as seen from Earth [1]. This "transit" lasts for about 8 hours, and provides astronomers with much additional information on the planet. This is fortunate as the gas giant shares many features with the majority of exoplanets discovered so far [2]. "Our analysis has provided more information on Corot-9b than for other exoplanets of the same type," says co-author Didier Queloz. "It may open up a new field of research to understand the atmospheres of moderate- and low-temperature planets, and in particular a completely new window in our understanding of low-temperature chemistry." More than 400 exoplanets have been discovered so far, 70 of them through the transit method. Corot-9b is special in that its distance from its host star is about ten times larger than that of any planet previously discovered by this method. And unlike all such

  2. Vegetative regeneration

    Science.gov (United States)

    George A. Schier; John R. Jones; Robert P. Winokur

    1985-01-01

    Aspen is noted for its ability to regenerate vegetatively by adventitious shoots or suckers that arise on its long lateral roots. It also produces sprouts from stumps and root collars; but they are not common. In a survey of regeneration after clearcutting mature aspen in Utah. Baker (1918b) found that 92% of the shoots originated from roots, 7% from root collars, and...

  3. Understory vegetation

    Science.gov (United States)

    Steve Sutherland; Todd F. Hutchinson; Jennifer L. Windus

    2003-01-01

    This chapter documents patterns of species composition and diversity within the understory vegetation layer and provides a species list for the four study areas in southern Ohio. Within each of 108 plots, we recorded the frequency of all vascular plant species in sixteen 2-m² quadrats. We recorded 297 species, including 187 forbs (176 perennials, 9 annuals, 2...

  4. Fog reduces transpiration in tree species of the Canarian relict heath-laurel cloud forest (Garajonay National Park, Spain).

    Science.gov (United States)

    Ritter, Axel; Regalado, Carlos M; Aschan, Guido

    2009-04-01

    The ecophysiologic role of fog in the evergreen heath-laurel 'laurisilva' cloud forests of the Canary Islands has not been unequivocally demonstrated, although it is generally assumed that fog water is important for the survival and the distribution of this relict paleoecosystem of the North Atlantic Macaronesian archipelagos. To determine the role of fog in this ecosystem, we combined direct transpiration measurements of heath-laurel tree species, obtained with Granier's heat dissipation probes, with micrometeorological and artificial fog collection measurements carried out in a 43.7-ha watershed located in the Garajonay National Park (La Gomera, Canary Islands, Spain) over a 10-month period. Median ambient temperature spanned from 7 to 15 degrees C under foggy conditions whereas higher values, ranging from 9 to 21 degrees C, were registered during fog-free periods. Additionally, during the periods when fog water was collected, global solar radiation values were linearly related (r2=0.831) to those under fog-free conditions, such that there was a 75+/-1% reduction in median radiation in response to fog. Fog events greatly reduced median diurnal tree transpiration, with rates about 30 times lower than that during fog-free conditions and approximating the nighttime rates in both species studied (the needle-like leaf Erica arborea L. and the broadleaf Myrica faya Ait.). This large decrease in transpiration in response to fog was independent of the time of the day, tree size and species and micrometeorological status, both when expressed on a median basis and in cumulative terms for the entire 10-month measuring period. We conclude that, in contrast to the turbulent deposition of fog water droplets on the heath-laurel species, which may be regarded as a localized hydrological phenomenon that is important for high-altitude wind-exposed E. arborea trees, the cooler, wetter and shaded microenvironment provided by the cloud immersion belt represents a large-scale effect

  5. Tempering of Low-Temperature Bainite

    Science.gov (United States)

    Peet, Mathew J.; Babu, Sudarsanam Suresh; Miller, Mike K.; Bhadeshia, H. K. D. H.

    2017-07-01

    Electron microscopy, X-ray diffraction, and atom probe tomography have been used to identify the changes which occur during the tempering of a carbide-free bainitic steel transformed at 473 K (200 °C). Partitioning of solute between ferrite and thin-films of retained austenite was observed on tempering at 673 K (400 °C) for 30 minutes. After tempering at 673 K (400 °C) and 773 K (500 °C) for 30 minutes, cementite was observed in the form of nanometre scale precipitates. Proximity histograms showed that the partitioning of solutes other than silicon from the cementite was slight at 673 K (400 °C) and more obvious at 773 K (500 °C). In both cases, the nanometre scale carbides are greatly depleted in silicon.

  6. Well-Tempered Metadynamics Converges Asymptotically

    Science.gov (United States)

    Dama, James F.; Parrinello, Michele; Voth, Gregory A.

    2014-06-01

    Metadynamics is a versatile and capable enhanced sampling method for the computational study of soft matter materials and biomolecular systems. However, over a decade of application and several attempts to give this adaptive umbrella sampling method a firm theoretical grounding prove that a rigorous convergence analysis is elusive. This Letter describes such an analysis, demonstrating that well-tempered metadynamics converges to the final state it was designed to reach and, therefore, that the simple formulas currently used to interpret the final converged state of tempered metadynamics are correct and exact. The results do not rely on any assumption that the collective variable dynamics are effectively Brownian or any idealizations of the hill deposition function; instead, they suggest new, more permissive criteria for the method to be well behaved. The results apply to tempered metadynamics with or without adaptive Gaussians or boundary corrections and whether the bias is stored approximately on a grid or exactly.

  7. Does water stress, nutrient limitation, or H-toxicity explain the differential stature among Heath Forest types in Central Kalimantan, Indonesia?

    NARCIS (Netherlands)

    Vernimmen, R.R.E.; Bruijnzeel, L.A.; Proctor, J.; Verhoef, H.A.; Klomp, N.

    2013-01-01

    To investigate the causes of the reduced stature of heath forest compared to lowland evergreen rain forest (LERF), the quantity and quality of small litterfall (LF), the standing crop of litter on the forest floor (LSC), and the annual rates of litter decay were determined over a period of 12 months

  8. Nitrogen Uptake During Fall, Winter and Spring Differs Among Plant Functional Groups in a Subarctic Heath Ecosystem

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Michelsen, Anders; Jonasson, Sven

    2012-01-01

    Nitrogen (N) is a critical resource for plant growth in tundra ecosystems, and species differences in the timing of N uptake may be an important feature regulating community composition and ecosystem productivity. We added 15N-labelled glycine to a subarctic heath tundra dominated by dwarf shrubs...... to 37 ± 7% by April indicating significant microbial N turnover prior to spring thaw. Only the evergreen dwarf shrubs showed active 15N acquisition before early May indicating that they had the highest potential of all functional groups for acquiring nutrients that became available in early spring....... The faster-growing deciduous shrubs did not resume 15N acquisition until after early May indicating that they relied more on nitrogen made available later during the spring/early summer. The graminoids and mosses had no significant increases in 15N tracer recovery or tissue 15N tracer concentrations after...

  9. Seasonal variations in methane fluxes in response to summer warming and leaf litter addition in a subarctic heath ecosystem

    Science.gov (United States)

    Pedersen, Emily Pickering; Elberling, Bo; Michelsen, Anders

    2017-08-01

    Methane (CH4) is a powerful greenhouse gas controlled by both biotic and abiotic processes. Few studies have investigated CH4 fluxes in subarctic heath ecosystems, and climate change-induced shifts in CH4 flux and the overall carbon budget are therefore largely unknown. Hence, there is an urgent need for long-term in situ experiments allowing for the study of ecosystem processes over time scales relevant to environmental change. Here we present in situ CH4 and CO2 flux measurements from a wet heath ecosystem in northern Sweden subjected to 16 years of manipulations, including summer warming with open-top chambers, birch leaf litter addition, and the combination thereof. Throughout the snow-free season, the ecosystem was a net sink of CH4 and CO2 (CH4 -0.27 mg C m-2 d-1; net ecosystem exchange -1827 mg C m-2 d-1), with highest CH4 uptake rates (-0.70 mg C m-2 d-1) during fall. Warming enhanced net CO2 flux, while net CH4 flux was governed by soil moisture. Litter addition and the combination with warming significantly increased CH4 uptake rates, explained by a pronounced soil drying effect of up to 32% relative to ambient conditions. Both warming and litter addition also increased the seasonal average concentration of dissolved organic carbon in the soil. The site was a carbon sink with a net uptake of 60 g C m-2 over the snow-free season. However, warming reduced net carbon uptake by 77%, suggesting that this ecosystem type might shift from snow-free season sink to source with increasing summer temperatures.

  10. componente vegetal

    Directory of Open Access Journals (Sweden)

    Fabio Moscovich

    2005-01-01

    Full Text Available In order to determine environmental impact, indicators based on vegetation characteristics that would generate the forestry monoculture with the adjacent native forest, 32 sample unit were installed in an area of LIPSIA private enterprise, Esperanza Department, Misiones with those characteristics. The plots of 100 m2 were distributed systematically every 25 meters. The vegetation was divided in stratum: superior (DBH ≥ 10 cm, middle (1,6 cm ≤ DBH > 10 cm and inferior (DBH< cm. There were installed 10 plots in a logged native forest, 10 plots in a 18 years old Pinus elliottii Engelm. with approximately 400 trees/ha., 6 plots in a 10 – 25 years old Araucaria angustifolia (Bertd. Kuntze limiting area with approximately 900 trees/ha., and 6 plots located in this plantation. In the studied area were identified 150 vegetation species. In the inferior stratum there were found differences as function of various floristic diversity indexes. In all the cases the native forest showed larger diversity than plantations, followed by Pinus elliottii, Araucaria plantation and Araucaria limiting area. All the studied forest fitted to a logarithmical series of species distributions, that would indicate the incidence of a environmental factor in this distribution.

  11. Role of temperate zone forests in the world carbon cycle: problem definition and research needs

    Energy Technology Data Exchange (ETDEWEB)

    Armentano, T.V.; Hett, J. (eds.)

    1979-01-01

    The proceedings of a workshop on carbon uptake and losses from temperate zone forests are presented. The goals of the workshop were to analyze existing data on growth and utilization of the temperate zone forest carbon pool and to identify further research needs in relation to the role of temperate forests in the global carbon cycle. Total standing stock and growth recovery transients were examined for most of the temperate region over a period from pre-settlement times to the present, with emphasis on the last three decades. Because of data availability, certain regions and topics were covered more in detail than others. Forest inventory data from most of the commercial timberlands of the north temperate zone suggest these forests have functioned over the past several decades as an annual sink for about 10/sup 9/ metric tons of carbon. Thus, net growth of these forests has withdrawn carbon from the atmosphere at a rate equivalent, approximately, to 50% of the annual rise in atmospheric carbon. Various data inadequacies make this estimate probably no more precise than plus or minus half of the value. Analysis of growth and vegetation changes in New England and the southeastern United States shows that forest biomass has partly recovered since extensive clearing took place in the 18th and 19th centuries. This regrowth represents a net withdrawal of carbon (carbon sink) from the atmosphere in recent decades, although the difference in pool size between present and original forests means that, in the longer term, the two regions have functioned as carbon sources.

  12. A Facies Model for Temperate Continental Glaciers.

    Science.gov (United States)

    Ashley, Gail Mowry

    1987-01-01

    Discusses the presence and dynamics of continental glaciers in the domination of the physical processes of erosion and deposition in the mid-latitudes during the Pleistocene period. Describes the use of a sedimentary facies model as a guide to recognizing ancient temperate continental glacial deposits. (TW)

  13. The Temperance Movement and Social Work

    Science.gov (United States)

    Murdach, Allison D.

    2009-01-01

    This article examines a forgotten episode in social work history: the involvement of the profession in the temperance movement in the late 19th and early 20th centuries. Though some notable social workers such as Jane Addams, Robert A. Woods, and Representative Jeannette Rankin (the first woman elected to the U.S. Congress), championed the…

  14. Effects of a large wildfire on vegetation structure in a variable fire mosaic.

    Science.gov (United States)

    Foster, C N; Barton, P S; Robinson, N M; MacGregor, C I; Lindenmayer, D B

    2017-12-01

    Management guidelines for many fire-prone ecosystems highlight the importance of maintaining a variable mosaic of fire histories for biodiversity conservation. Managers are encouraged to aim for fire mosaics that are temporally and spatially dynamic, include all successional states of vegetation, and also include variation in the underlying "invisible mosaic" of past fire frequencies, severities, and fire return intervals. However, establishing and maintaining variable mosaics in contemporary landscapes is subject to many challenges, one of which is deciding how the fire mosaic should be managed following the occurrence of large, unplanned wildfires. A key consideration for this decision is the extent to which the effects of previous fire history on vegetation and habitats persist after major wildfires, but this topic has rarely been investigated empirically. In this study, we tested to what extent a large wildfire interacted with previous fire history to affect the structure of forest, woodland, and heath vegetation in Booderee National Park in southeastern Australia. In 2003, a summer wildfire burned 49.5% of the park, increasing the extent of recently burned vegetation (post-fire) to more than 72% of the park area. We tracked the recovery of vegetation structure for nine years following the wildfire and found that the strength and persistence of fire effects differed substantially between vegetation types. Vegetation structure was modified by wildfire in forest, woodland, and heath vegetation, but among-site variability in vegetation structure was reduced only by severe fire in woodland vegetation. There also were persistent legacy effects of the previous fire regime on some attributes of vegetation structure including forest ground and understorey cover, and woodland midstorey and overstorey cover. For example, woodland midstorey cover was greater on sites with higher fire frequency, irrespective of the severity of the 2003 wildfire. Our results show that even

  15. Impact of Climate Change on Temperate and Alpine Grasslands in China during 1982–2006

    Directory of Open Access Journals (Sweden)

    Xiangjin Shen

    2015-01-01

    Full Text Available Based on GIMMS NDVI and climate data from 1982 to 2006, this study analyzed the impact of climate change on grassland in China. During the growing season, there were significant effects of precipitation on the growth of all the grassland types (P<0.05, except for meadow vegetation. For the air temperatures, there existed asymmetrical effects of maximum temperature (Tmax and minimum temperature (Tmin on grassland vegetation, especially for the temperate grasslands and alpine steppe. The growing season NDVI correlated negatively with Tmax but positively with Tmin for temperate grasslands. Seasonally, these opposite effects were only observed in summer. For alpine steppe, the growing season NDVI correlated positively with Tmax but negatively with Tmin, and this pattern of asymmetrical responses was only obvious in spring and autumn. Under the background of global asymmetric warming, more attention should be paid to this asymmetric response of grassland vegetation to daytime and night-time warming, especially when we want to predict the productivity of China’s grasslands in the future.

  16. Seasonal pattern of anthropogenic salinization in temperate forested headwater streams.

    Science.gov (United States)

    Timpano, Anthony J; Zipper, Carl E; Soucek, David J; Schoenholtz, Stephen H

    2018-04-15

    Salinization of freshwaters by human activities is of growing concern globally. Consequences of salt pollution include adverse effects to aquatic biodiversity, ecosystem function, human health, and ecosystem services. In headwater streams of the temperate forests of eastern USA, elevated specific conductance (SC), a surrogate measurement for the major dissolved ions composing salinity, has been linked to decreased diversity of aquatic insects. However, such linkages have typically been based on limited numbers of SC measurements that do not quantify intra-annual variation. Effective management of salinization requires tools to accurately monitor and predict salinity while accounting for temporal variability. Toward that end, high-frequency SC data were collected within the central Appalachian coalfield over 4 years at 25 forested headwater streams spanning a gradient of salinity. A sinusoidal periodic function was used to model the annual cycle of SC, averaged across years and streams. The resultant model revealed that, on average, salinity deviated approximately ±20% from annual mean levels across all years and streams, with minimum SC occurring in late winter and peak SC occurring in late summer. The pattern was evident in headwater streams influenced by surface coal mining, unmined headwater reference streams with low salinity, and larger-order salinized rivers draining the study area. The pattern was strongly responsive to varying seasonal dilution as driven by catchment evapotranspiration, an effect that was amplified slightly in unmined catchments with greater relative forest cover. Evaluation of alternative sampling intervals indicated that discrete sampling can approximate the model performance afforded by high-frequency data but model error increases rapidly as discrete sampling intervals exceed 30 days. This study demonstrates that intra-annual variation of salinity in temperate forested headwater streams of Appalachia USA follows a natural seasonal

  17. Plants for passive cooling. A preliminary investigation of the use of plants for passive cooling in temperate humid climates

    Energy Technology Data Exchange (ETDEWEB)

    Spirn, A W; Santos, A N; Johnson, D A; Harder, L B; Rios, M W

    1981-04-01

    The potential of vegetation for cooling small, detached residential and commercial structures in temperate, humid climates is discussed. The results of the research are documented, a critical review of the literature is given, and a brief review of energy transfer processes is presented. A checklist of design objectives for passive cooling, a demonstration of design applications, and a palette of selected plant species suitable for passive cooling are included.

  18. Soil respiration and organic carbon dynamics with grassland conversions to woodlands in temperate china.

    Directory of Open Access Journals (Sweden)

    Wei Wang

    Full Text Available Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007-Dec. 2008 from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR, shrubland (SH, as well as in evergreen coniferous (EC, deciduous coniferous (DC and deciduous broadleaved forest (DB, to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China.

  19. Trichinella in arctic, subarctic and temperate regions

    DEFF Research Database (Denmark)

    Kapel, C. M O

    1997-01-01

    The transmission and occurrence of Trichinella spp according to the zoogeography of different climatic conditions, socioeconomy and human activity are discussed. Comparing arctic, subarctic and temperate regions, it appears that the species of Trichinella present, the composition of the fauna...... and the human activity are all very important interacting factors affecting epidemiology. In Greenland, where only sylvatic trichinellosis is present, the high prevalence in wildlife appears closely connected with polar bear hunting. In the Scandinavian countries, the prevalence of both sylvatic and domestic...

  20. Carbon density and distribution of six Chinese temperate forests

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Quantifying forest carbon(C) storage and distribution is important for forest C cycling studies and terrestrial ecosystem modeling.Forest inventory and allometric approaches were used to measure C density and allocation in six representative temperate forests of similar stand age(42-59 years old) and growing under the same climate in northeastern China.The forests were an aspen-birch forest,a hardwood forest,a Korean pine plantation,a Dahurian larch plantation,a mixed deciduous forest,and a Mongolian oak forest.There were no significant differences in the C densities of ecosystem components(except for detritus) although the six forests had varying vegetation compositions and site conditions.However,the differences were significant when the C pools were normalized against stand basal area.The total ecosystem C density varied from 186.9 tC hm-2 to 349.2 tC hm-2 across the forests.The C densities of vegetation,detritus,and soil ranged from 86.3-122.7 tC hm-2,6.5-10.5 tC hm-2,and 93.7-220.1 tC hm-2,respectively,which accounted for 39.7% ± 7.1%(mean ± SD),3.3% ± 1.1%,and 57.0% ± 7.9% of the total C densities,respectively.The overstory C pool accounted for > 99% of the total vegetation C pool.The foliage biomass,small root(diameter < 5mm) biomass,root-shoot ratio,and small root to foliage biomass ratio varied from 2.08-4.72 tC hm-2,0.95-3.24 tC hm-2,22.0%-28.3%,and 34.5%-122.2%,respectively.The Korean pine plantation had the lowest foliage production efficiency(total biomass/foliage biomass:22.6 g g-1) among the six forests,while the Dahurian larch plantation had the highest small root production efficiency(total biomass/small root biomass:124.7 g g-1).The small root C density decreased with soil depth for all forests except for the Mongolian oak forest,in which the small roots tended to be vertically distributed downwards.The C density of coarse woody debris was significantly less in the two plantations than in the four naturally regenerated forests.The variability

  1. World temperate fruit production: characteristics and challenges

    Directory of Open Access Journals (Sweden)

    Jorge B. Retamales

    2011-10-01

    Full Text Available In the last 30 years world population has increased 70% but per capita global fruit consumption is only 20% higher. Even though tropical and temperate fruit have similar contributions to the 50 kg/person/year of US consumption of fresh fruit, in the last 30 years this has been slightly greater for temperate fruit. Within fruit consumption, the largest expansion has been for organic fruit which increased more than 50% in the 2002-2006 period. The largest expansion of area planted in the 1996-2006 has been for kiwi (29% and blueberries (20%, while apples (-24% and sour cherries (-13% have had the largest reductions. Nearly 50% of the total global volume of fruit is produced by 5 countries: China, USA, Brazil, Italy and Spain. The main producer (China accounts for 23% of the total. While the main exporters are Spain, USA and Italy, the main importers are Germany, Russia and UK. Demands for the industry have evolved towards quality, food safety and traceability. The industry faces higher productions costs (labor, energy, agrichemicals. The retailers are moving towards consolidation while the customers are changing preferences (food for health. In this context there is greater pressure on growers, processors and retailers. Emerging issues are labor supply, climate change, water availability and sustainability. Recent developments in precision agriculture, molecular biology, phenomics, crop modelling and post harvest physiology should increase yields and quality, and reduce costs for temperate fruit production around the world.

  2. A review of the role of temperate forests in the global CO2 balance

    International Nuclear Information System (INIS)

    Musselman, R.C.; Fox, D.G.

    1991-01-01

    The role of temperate forests in the global carbon balance is difficult to determine because many uncertainties exist in the data, and many assumptions must be made in these determinations. Still, there is little doubt that increases in atmospheric CO 2 and global warming would have major effects on temperate forest ecosystems. Increases in atmospheric CO 2 may result in increases in photosynthesis, changes in water and nitrogen use efficiency, and changes in carbon allocation. Indirect effects of changes in global carbon balance on regional climate and on microenvironmental conditions, particularly temperature and moisture, may be more important then direct effects of increased CO 2 on vegetation. Increased incidence of forest perturbations might also be expected. The evidence suggests that conditions favorable to forest growth and development may exist in the northern latitudes, while southern latitude forests may undergo drought stress. Current harvest of temperate and world forests contributes substantial amounts of carbon to the atmosphere, possibly as much as 3 gigatons (Gt) per year. Return of this carbon to forest storage may require decades. Forest managers should be aware of the global as well as local impact their management decisions will have on the atmospheric carbon balance of the ecosystems they oversee

  3. The diversity and abundance of ground herbs in lowland mixed dipterocarp forest and heath forest in Brunei Darussalam

    Directory of Open Access Journals (Sweden)

    Nurul Hazlina Zaini

    2014-12-01

    Full Text Available Herbaceous plants are important components of total plant species richness in tropical forests. Ground herb diversity and abundance were studied in a lowland Mixed Dipterocarp forest (Andulau and a heath forest (Bukit Sawat in Brunei Darussalam, Borneo. At each site, all ground herbs in twenty randomly selected 10 × 10 m subplots within a one hectare permanent plot were censused and identified. The study recorded a total of 20 families and 32 genera of ground herbs, with the family Zingiberaceae as the most abundant at both sites. Thirteen genera were recorded only at Andulau and 7 genera were exclusive to Bukit Sawat, with twelve genera common to both sites. Ground herb species richness appear higher at Andulau than Bukit Sawat (37 vs. 29, but this difference was not statistically significant at the subplot level. However, ground herb abundance and density were significantly higher at Bukit Sawat than Andulau (n =  846 vs. 385; 4230 vs. 1925 individuals ha-1. The more open canopy at Bukit Sawat may provide higher light availability here than at Andulau, which is characterised by a closed canopy. We suggest that light availability is the most important environmental factor influencing ground herb density and abundance at these sites. 

  4. Disease risk in temperate amphibian populations is higher at closed-canopy sites.

    Directory of Open Access Journals (Sweden)

    C Guilherme Becker

    habitat modification and the resulting declines in temperate and tropical frogs, understanding how vegetation cover and disease interact is critical for predicting Bd spread and developing appropriate management tools for wild populations.

  5. Habitat selection of endemic birds in temperate forests in a biodiversity "Hotspot"

    Directory of Open Access Journals (Sweden)

    Roberto A. Moreno-García

    2014-08-01

    Full Text Available Aim of study: Our objective was to find habitat associations at a microhabitat level for two endemic birds in a Chilean temperate forest (biodiversity “hotspots”, in order to integrate biodiversity into forest planning.Area of study: Nahuelbuta Range, Chile.Material and methods: The two birds studied were Scelorchilus rubecula (Chucao Tapaculo and Scytalopus magellanicus (Magellanic Tapaculo, both belonging to the Rhinocryptidae family. Presence or absence of the two species was sampled in 57 census spots. Habitat was categorized according to presence/absence results. We assessed the influence of abiotic variables (altitude, exposure, slope and vegetation structure (percentage of understory cover, number of strata using a statistical cluster analysis.Main results: The two bird species selected the habitat. Most frequent presence was detected at a range of 600-1100 masl, but Magellanic Tapaculo was associated to more protected sites in terms of vegetation structure (50-75% for understory cover and 2-3 strata. Slope was the most relevant abiotic variable in habitat selection due to its linkage to vegetation traits in this area.Research highlights: Our results can help managers to integrate biodiversity (endemic fauna species into forest planning by preserving certain traits of the vegetation as part of a habitat (at a microhabitat level selected by the fauna species. That planning should be implemented with both an adequate wood harvesting cuts system and specific silvicultural treatments.Key words: Chile; Nahuelbuta; rhinocryptidae; cluster analysis; rorest planning; vegetation structure.

  6. Forests tend to cool the land surface in the temperate zone: An analysis of the mechanisms controlling radiometric surface temperature change in managed temperate ecosystems

    Science.gov (United States)

    Stoy, P. C.; Katul, G. G.; Juang, J.; Siqueira, M. B.; Novick, K. A.; Essery, R.; Dore, S.; Kolb, T. E.; Montes-Helu, M. C.; Scott, R. L.

    2010-12-01

    Vegetation is an important control on the surface energy balance and thereby surface temperature. Boreal forests and arctic shrubs are thought to warm the land surface by absorbing more radiation than the vegetation they replace. The surface temperatures of tropical forests tend to be cooler than deforested landscapes due to enhanced evapotranspiration. The effects of reforestation on surface temperature change in the temperate zone is less-certain, but recent modeling efforts suggest forests have a global warming effect. We quantified the mechanisms driving radiometric surface changes following landcover changes using paired ecosystem case studies from the Ameriflux database with energy balance models of varying complexity. Results confirm previous findings that deciduous and coniferous forests in the southeastern U.S. are ca. 1 °C cooler than an adjacent field on an annual basis because aerodynamic/ecophysiological cooling of 2-3 °C outweighs an albedo-related warming of stand-replacing ponderosa pine fire was ca. 1 °C warmer than unburned stands because a 1.5 °C aerodynamic warming offset a slight surface cooling due to greater albedo and soil heat flux. An ecosystem dominated by mesquite shrub encroachment was nearly 2 °C warmer than a native grassland ecosystem as aerodynamic and albedo-related warming outweighed a small cooling effect due to changes in soil heat flux. The forested ecosystems in these case studies are documented to have higher carbon uptake than the non-forested systems. Results suggest that temperate forests tend to cool the land surface and suggest that previous model-based findings that forests warm the Earth’s surface globally should be reconsidered.Changes to radiometric surface temperature (K) following changes in vegetation using paired ecosystem case studies C4 grassland and shrub ecosystem surface temperatures were adjusted for differences in air temperature across sites.

  7. PENGARUH VARIASI SUHU PADA PROSES SELF TEMPERING DAN VARIASI WAKTU TAHAN PADA PROSES TEMPERING TERHADAP SIFAT MEKANIS BAJA AISI 4140

    Directory of Open Access Journals (Sweden)

    Sunardi Sunardi

    2016-07-01

    Full Text Available Tujuan penelitian ini adalah untuk mengetahui sifat mekanis pada baja AISI 4140 dengan proses tempering dengan variasi waktu tahan dan variasi suhu pada proses self tempering. Material terlebih dahulu dipanaskan pada suhu 850°C, di tahan dengan waktu 14 dan 28 menit, media pendinginan adalah Oli SAE 20. Pada proses tempering baja dipanaskan kembali dengan suhu 200°C di tahan dengan waktu 30 dan 120 menit. Sedangkan untuk proses self tempering, baja di panaskan pada suhu 850°C di tahan dengan waktu 14 dan 28 menit kemudian didinginkan, suhu yang harus dicapai pada pendinginan adalah 200°C, 400°C dan 600°C. Proses tempering dengan variasi waktu tahan mempunyai nilai kekerasan terbesar 50,1 HRC dengan waktu tahan 120 menit, sedangkan nilai kekerasan terbesar pada proses self tempering dengan variasi suhu adalah 29,68 HRC pada suhu 200°C. Nilai ketangguhan terbesar pada saat proses tempering adalah 0,341 (J/mm2 dengan waktu tahan 120 menit, sedangkan pada saat proses self tempering ketangguhan terbesar pada suhu 600°C dengan nilai 0,375 (J/mm2. Laju korosi terbesar pada saat tempering adalah 0,055 (mpy dengan waktu tahan 30 menit, sedangkan pada saat proses self tempering laju korosi terbesar pada suhu 400°C dengan nilai 0,0388 (mpy. 

  8. Global vegetation change predicted by the modified Budyko model

    Energy Technology Data Exchange (ETDEWEB)

    Monserud, R.A.; Tchebakova, N.M.; Leemans, R. (US Department of Agriculture, Moscow, ID (United States). Intermountain Research Station, Forest Service)

    1993-09-01

    A modified Budyko global vegetation model is used to predict changes in global vegetation patterns resulting from climate change (CO[sub 2] doubling). Vegetation patterns are predicted using a model based on a dryness index and potential evaporation determined by solving radiation balance equations. Climate change scenarios are derived from predictions from four General Circulation Models (GCM's) of the atmosphere (GFDL, GISS, OSU, and UKMO). All four GCM scenarios show similar trends in vegetation shifts and in areas that remain stable, although the UKMO scenario predicts greater warming than the others. Climate change maps produced by all four GCM scenarios show good agreement with the current climate vegetation map for the globe as a whole, although over half of the vegetation classes show only poor to fair agreement. The most stable areas are Desert and Ice/Polar Desert. Because most of the predicted warming is concentrated in the Boreal and Temperate zones, vegetation there is predicted to undergo the greatest change. Most vegetation classes in the Subtropics and Tropics are predicted to expand. Any shift in the Tropics favouring either Forest over Savanna, or vice versa, will be determined by the magnitude of the increased precipitation accompanying global warming. Although the model predicts equilibrium conditions to which many plant species cannot adjust (through migration or microevolution) in the 50-100 y needed for CO[sub 2] doubling, it is not clear if projected global warming will result in drastic or benign vegetation change. 72 refs., 3 figs., 3 tabs.

  9. Transfer parameter values in temperate forest ecosystems: a review

    International Nuclear Information System (INIS)

    Calmon, Philippe; Thiry, Yves; Zibold, Gregor; Rantavaara, Aino; Fesenko, Sergei

    2009-01-01

    activity reduction, quantified as an ecological half-life, reflect the soil and pasture conditions at individual locations. Forests in temperate and boreal regions differ with respect to soil type and vegetation, and a faster decline of muscle activity concentrations in deer occurs in the temperate zone. However, in wild boar the caesium activity concentration shows no decline because of its special feeding habits. In the late phase, i.e. at least a few months since the external radionuclide contamination on feed plants has been removed, a T ag value of 0.01 m 2 kg -1 (fresh weight) is common for 137 Cs in the muscles of adult moose and terrestrial birds living in boreal forests, and 0.03 m 2 kg -1 (fresh weight) for arctic hare. Radiocaesium concentrations in reindeer muscle in winter may exceed the summer content by a factor of more than two, the mean T ag values for winter ranging from 0.02 to 0.8 m 2 kg -1 (fresh weight), and in summer from 0.04 to 0.4 m 2 kg -1 . The highest values are found in the year of initial contamination, followed by a gradual reduction. In waterfowl a relatively fast decline in uptake of 137 Cs has been found, with T ag values changing from 0.01 to 0.002 m 2 kg -1 (fresh weight) in the three years after the contaminating event, the rate being determined by the dynamics of 137 Cs in aquatic ecosystems.

  10. Transfer parameter values in temperate forest ecosystems: a review

    Energy Technology Data Exchange (ETDEWEB)

    Calmon, Philippe [Department of Radioecology, Institute of Radioprotection and Nuclear Safety, CE Cadarache, BP 3, 13115 Saint Paul-les-Durance Cedex (France)], E-mail: philippe.calmon@irsn.fr; Thiry, Yves [Biosphere Impact Studies, Belgian Nuclear Research Center (SCK.CEN, Foundation of Public Utility), 2400 Mol (Belgium); Zibold, Gregor [Hochschule Ravensburg-Weingarten, University of Applied Sciences, 88250 Weingarten (Germany); Rantavaara, Aino [Research and Environmental Surveillance, Radiation and Nuclear Safety Authority (STUK), BP 14, FIN-00881 Helsinki (Finland); Fesenko, Sergei [International Atomic Energy Agency (IAEA), 1400 Vienna (Austria)

    2009-09-15

    of radioactive caesium to game animals and reindeer and the rate of activity reduction, quantified as an ecological half-life, reflect the soil and pasture conditions at individual locations. Forests in temperate and boreal regions differ with respect to soil type and vegetation, and a faster decline of muscle activity concentrations in deer occurs in the temperate zone. However, in wild boar the caesium activity concentration shows no decline because of its special feeding habits. In the late phase, i.e. at least a few months since the external radionuclide contamination on feed plants has been removed, a T{sub ag} value of 0.01 m{sup 2} kg{sup -1} (fresh weight) is common for {sup 137}Cs in the muscles of adult moose and terrestrial birds living in boreal forests, and 0.03 m{sup 2} kg{sup -1} (fresh weight) for arctic hare. Radiocaesium concentrations in reindeer muscle in winter may exceed the summer content by a factor of more than two, the mean T{sub ag} values for winter ranging from 0.02 to 0.8 m{sup 2} kg{sup -1} (fresh weight), and in summer from 0.04 to 0.4 m{sup 2} kg{sup -1}. The highest values are found in the year of initial contamination, followed by a gradual reduction. In waterfowl a relatively fast decline in uptake of {sup 137}Cs has been found, with T{sub ag} values changing from 0.01 to 0.002 m{sup 2} kg{sup -1} (fresh weight) in the three years after the contaminating event, the rate being determined by the dynamics of {sup 137}Cs in aquatic ecosystems.

  11. Parallel tempering in full QCD with Wilson fermions

    International Nuclear Information System (INIS)

    Ilgenfritz, E.-M.; Kerler, W.; Mueller-Preussker, M.; Stueben, H.

    2002-01-01

    We study the performance of QCD simulations with dynamical Wilson fermions by combining the hybrid Monte Carlo algorithm with parallel tempering on 10 4 and 12 4 lattices. In order to compare tempered with standard simulations, covariance matrices between subensembles have to be formulated and evaluated using the general properties of autocorrelations of the parallel tempering algorithm. We find that rendering the hopping parameter κ dynamical does not lead to an essential improvement. We point out possible reasons for this observation and discuss more suitable ways of applying parallel tempering to QCD

  12. Lake Bathymetric Aquatic Vegetation

    Data.gov (United States)

    Minnesota Department of Natural Resources — Aquatic vegetation represented as polygon features, coded with vegetation type (emergent, submergent, etc.) and field survey date. Polygons were digitized from...

  13. Oceanic temperate forest versus warm temperate rainforest: a reply to Grubb et al. (2017)

    DEFF Research Database (Denmark)

    McGlone, Matt S.; Buitenwerf, Robert; Richardson, Sarah J.

    2017-01-01

    Grubb et al. (2017) point out that we (McGlone et al. 2016) erroneously stated that the definition of warm temperate rain forest (WTRF; Grubb et al. 2013) was based in part on climatic criteria. We apologise: their text made clear that this was not the case. However, they go on to say that they ‘...

  14. 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...

  15. Quantification of net carbon flux from plastic greenhouse vegetable cultivation: A full carbon cycle analysis

    International Nuclear Information System (INIS)

    Wang Yan; Xu Hao; Wu Xu; Zhu Yimei; Gu Baojing; Niu Xiaoyin; Liu Anqin; Peng Changhui; Ge Ying; Chang Jie

    2011-01-01

    Plastic greenhouse vegetable cultivation (PGVC) has played a vital role in increasing incomes of farmers and expanded dramatically in last several decades. However, carbon budget after conversion from conventional vegetable cultivation (CVC) to PGVC has been poorly quantified. A full carbon cycle analysis was used to estimate the net carbon flux from PGVC systems based on the combination of data from both field observations and literatures. Carbon fixation was evaluated at two pre-selected locations in China. Results suggest that: (1) the carbon sink of PGVC is 1.21 and 1.23 Mg C ha -1 yr -1 for temperate and subtropical area, respectively; (2) the conversion from CVC to PGVC could substantially enhance carbon sink potential by 8.6 times in the temperate area and by 1.3 times in the subtropical area; (3) the expansion of PGVC usage could enhance the potential carbon sink of arable land in China overall. - Highlights: → We used full carbon (C) cycle analysis to estimate the net C flux from cultivation. → The plastic greenhouse vegetable cultivation system in China can act as a C sink. → Intensified agricultural practices can generate C sinks. → Expansion of plastic greenhouse vegetable cultivation can enhance regional C sink. - The conversion from conventional vegetable cultivation to plastic greenhouse vegetable cultivation could substantially enhance carbon sink potential by 8.6 and 1.3 times for temperate and subtropical area, respectively.

  16. Adhesion and wear properties of boro-tempered ductile iron

    International Nuclear Information System (INIS)

    Kayali, Yusuf; Yalcin, Yilmaz; Taktak, Suekrue

    2011-01-01

    Highlights: → In this study, the wear and adhesion properties of BDI were investigated. → Boro-tempering process under several heat treatment conditions was examined. → Optical microscope, SEM and XRD analysis were carried out to investigate the microstructure. → It was observed that boro-tempering process improves micro-hardness and wear properties of ductile irons. -- Abstract: In this study, adhesion and wear properties of boro-tempered ductile iron (BDI) were investigated. Boro-tempering was carried out on two stage processes i.e. boronizing and tempering. At the first stage, ductile iron samples were boronized by using pack process at 900 o C for 1, 3, and 5 h and then, secondly tempered at 250, 300, 350, and 400 o C for 1 h. X-ray diffraction (XRD) analysis of boro-tempered samples showed that FeB and Fe 2 B phases were found on the surface of the samples. The Daimler-Benz Rockwell-C adhesion test was used to assess the adhesion of boride layer. Test result showed that adhesion decreased with increasing boriding time and increased with increasing tempering temperature. Dry sliding wear tests of these samples were performed against Al 2 O 3 ball at a constant sliding speed and loads of 5 and 10 N. Wear tests indicated that boro-tempering heat treatment increased wear resistance of ductile iron. In addition, it was found that while wear rate of boro-tempered samples decreased with increasing boriding time, there is no significant affect of tempering temperature on wear rate.

  17. Hardness of H13 Tool Steel After Non-isothermal Tempering

    Science.gov (United States)

    Nelson, E.; Kohli, A.; Poirier, D. R.

    2018-04-01

    A direct method to calculate the tempering response of a tool steel (H13) that exhibits secondary hardening is presented. Based on the traditional method of presenting tempering response in terms of isothermal tempering, we show that the tempering response for a steel undergoing a non-isothermal tempering schedule can be predicted. Experiments comprised (1) isothermal tempering, (2) non-isothermal tempering pertaining to a relatively slow heating to process-temperature and (3) fast-heating cycles that are relevant to tempering by induction heating. After establishing the tempering response of the steel under simple isothermal conditions, the tempering response can be applied to non-isothermal tempering by using a numerical method to calculate the tempering parameter. Calculated results are verified by the experiments.

  18. Dry matter intake and digestibility of temperate pastures ...

    African Journals Online (AJOL)

    The aim of this study was to evaluate the effect of sorghum grain supplementation on total and forage dry matter (DM) intake and digestibility of wethers and heifers consuming temperate pasture. Twenty four Corriedale x Milchschaf wethers and 24 crossbred heifers fed temperate pasture were non-supplemented or ...

  19. Simulation of Residual Stresses at Holes in Tempered Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Poulsen, Peter Noe

    2010-01-01

    This work presents a full 3D numerical study of the residual stresses in tempered (toughened) glass near holes using Narayanaswamy’s model for the tempering process. It is the objective of the paper to elucidate the influence on the minimal residual compressive stresses at holes from variations in...

  20. Recolonization and development of vegetation on mine spoils following brown coal mining in Lusatia

    International Nuclear Information System (INIS)

    Pietsch, W.H.O.

    1996-01-01

    A survey of primary colonization and succession of vegetation on various deposited substrates, littoral and shallow water areas of mining lakes and residual waters of the Lusatian lignite mining district is presented. Dumped substrates are characterized by a high acid potential which is caused by pyrite and marcasite of Tertiary origin. In the process of pyrite oxidation free mineral acids and large quantities of sulphate and bivalent iron are liberated. Residual waters are characterized by extreme acidity with pH values between 1.9 and 3.1 and by extremely high iron contents. Non-linear positive correlations are demonstrated between pH values and free mineral acids and between pH values and free carbonic acids (CO 2 ) and bivalent iron. In aquatic, semi-aquatic and in terrestrial areas the succession of vegetation can be described by the following five main stages: stage of primary colonization and spontaneous vegetation; stage of monodominant species stands; stage of the formation of vegetation mosaics; stage of the formation of plant associations; final stage of succession. Index species of the terrestrial colonization are Corynephorus canescens and Calamagrostis epigejos, while Juncus bulbosus is the indicator species of aquatic colonization. The succession of vegetation develops in the direction of close-to-nature vegetation conditions which are typical for the heath areas of the Lusatian Lowlands. 15 refs., 3 figs., 1 tab

  1. Biogenic emissions of volatile organic compounds from gorse (Ulex europaeus): Diurnal emission fluxes at Kelling Heath, England

    Science.gov (United States)

    Cao, X.-L.; Boissard, C.; Juan, A. J.; Hewitt, C. N.; Gallagher, M.

    1997-08-01

    Volatile organic compound (VOC) emission fluxes from Gorse (Ulex europaeus) were measured during May 30-31, 1995 at Kelling Heath in eastern England by using bag enclosure and gradient methods simultaneously. The enclosure measurements were made from branches at different stages of physiological development (flowering, after flowering, and mixed). Isoprene was found to represent 90% of the total VOC emissions, and its emission rates fluctuated from 6 ng (g dwt)-1 h-1 in the early morning to about 9700 ng(g dwt)-1 h-1 at midday. Averaged emission rates standardized to 20°C were 1625, 2120, and 3700 ng (g dwt)-1 h-1 for the new grown, "mixed," and flowering branch, respectively. Trans-ocimene and α-pinene were the main monoterpenes emitted and represented, on average, 47.6% and 36.9% of the total monoterpenes. Other monoterpenes, camphene, sabinene, β-pinene, myrcene, limonene and γ-terpinene, were positively identified but together represented less than 1.5% of the total VOC emissions from gorse. Maximum isoprene concentrations in air at the site were measured around midday at 2 m (174 parts per trillion by volume, or pptv) and 6 m (149 pptv), and minimum concentrations were measured during the night (8 pptv at both heights). Mean daytime α-pinene air concentrations of 141 and 60 pptv at 2 and 6 m height were determined, but trans-ocimene concentrations were less than the analytical detection limit (4 pptv), suggesting rapid chemical removal of this compound from air. The isoprene fluxes calculated by the micrometeorological gradient method showed a pattern similar to that of those calculated by the enclosure method, with isoprene emission rates maximum at midday (100 μg m-2 h-1) and not detectable during the nighttime. Assessment of the fraction of the site covered by gorse plants enabled an extrapolation of emission fluxes from the enclosure measurements. When averaged over the 2 day experiment, isoprene fluxes of 29.8 and 27.8 μg m-2 h-1 were obtained from

  2. Dynamic vegetation modeling of tropical biomes during Heinrich events

    Science.gov (United States)

    Handiani, Dian Noor; Paul, André; Dupont, Lydie M.

    2010-05-01

    changed from warm temperate forest during the last glacial maximum to the grassland and dry shrubland, suggesting a drier climate during Heinrich event 1. In south-western Africa savanna and dry woodland changed into boreal forest and boreal-temperate forest suggesting wetter conditions. The biomes diagnosed from the control-run, were compared to the modern vegetation reconstruction of BIOME 4 (http://www.bridge.bris.ac.uk/resources/Databases/BIOMES_data). Consistent biome patterns were simulated for the tropical forests of western and south-western Africa and the grasslands of northern Africa. On the other hand, in southern Europe, where the BIOME 4 vegetation reconstruction is dominated by warm temperate and temperate forest, our model shows a strong bias towards the grassland.

  3. The Heath Occupational Model.

    Science.gov (United States)

    Heath, William E.

    1990-01-01

    Career development programs must identify occupational needs of adults. A model based on Maslow's hierarchy develops occupational questions related to individual motivations (physiology, safety, love, esteem, and self-actualization). Individual needs are then compared with characteristics and benefits of proposed jobs, companies, or careers. (SK)

  4. Trace metal uptake by tropical vegetables grown on soil amended with urban sewage sludge

    International Nuclear Information System (INIS)

    Nabulo, G.; Black, C.R.; Young, S.D.

    2011-01-01

    Trace metal uptake was measured for tropical and temperate leafy vegetables grown on soil from an urban sewage disposal farm in the UK. Twenty-four leafy vegetables from East Africa and the UK were assessed and the five vegetable types that showed the greatest Cd concentrations were grown on eight soils differing in the severity of contamination, pH and other physico-chemical properties. The range of Cd concentrations in the edible shoots was greater for tropical vegetables than for temperate types. Metal uptake was modelled as a function of (i) total soil metal concentration, (ii) CaCl 2 -soluble metal, (iii) soil solution concentration and (iv) the activity of metal ions in soil pore water. Tropical vegetables were not satisfactorily modelled as a single generic 'green vegetable', suggesting that more sophisticated approaches to risk assessment may be required to assess hazard from peri-urban agriculture in developing countries. - Research highlights: → Cadmium uptake by tropical green vegetables varies greatly between types. → Modelling metal uptake works best for Ni, Cd and Zn but is poor for Cu, Ba and Pb. → Modelling with dilute CaCl 2 extraction is as good as metal ion activity in pore water. - Trace metal uptake by tropical leaf vegetables can be predicted from dilute CaCl 2 extraction of soil but model parameters are genotype-specific.

  5. Trace metal uptake by tropical vegetables grown on soil amended with urban sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Nabulo, G.; Black, C.R. [School of Biosciences, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom); Young, S.D., E-mail: scott.young@nottingham.ac.u [School of Biosciences, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom)

    2011-02-15

    Trace metal uptake was measured for tropical and temperate leafy vegetables grown on soil from an urban sewage disposal farm in the UK. Twenty-four leafy vegetables from East Africa and the UK were assessed and the five vegetable types that showed the greatest Cd concentrations were grown on eight soils differing in the severity of contamination, pH and other physico-chemical properties. The range of Cd concentrations in the edible shoots was greater for tropical vegetables than for temperate types. Metal uptake was modelled as a function of (i) total soil metal concentration, (ii) CaCl{sub 2}-soluble metal, (iii) soil solution concentration and (iv) the activity of metal ions in soil pore water. Tropical vegetables were not satisfactorily modelled as a single generic 'green vegetable', suggesting that more sophisticated approaches to risk assessment may be required to assess hazard from peri-urban agriculture in developing countries. - Research highlights: Cadmium uptake by tropical green vegetables varies greatly between types. Modelling metal uptake works best for Ni, Cd and Zn but is poor for Cu, Ba and Pb. Modelling with dilute CaCl{sub 2} extraction is as good as metal ion activity in pore water. - Trace metal uptake by tropical leaf vegetables can be predicted from dilute CaCl{sub 2} extraction of soil but model parameters are genotype-specific.

  6. Dams release methane even in temperate zoned

    International Nuclear Information System (INIS)

    Lemarchand, F.

    2010-01-01

    The Wohlen lake (near Bern) is a retaining dam built 90 years ago that has undergone a campaign to measure the quantity of methane released. The campaign lasted 1 year and the result was unexpected: 0.15 g/m 2 *day which one of the highest release rates in temperate zones. This result is all the more stunning since water stays only 2 days in average in the reservoir and that the drowned area is not important. In fact the river Aar that feeds the lake is loaded with organic matter coming from humane activities: agriculture and 3 sewage plants. This organic matter decays in the lake releasing methane. (A.C.)

  7. Moist temperate forest butterflies of western Bhutan

    Directory of Open Access Journals (Sweden)

    Arun P. Singh

    2016-03-01

    Full Text Available Random surveys were carried out in moist temperate forests (1,860–3,116 m around Bunakha Village and Dochula Pass, near Thimphu in western Bhutan, recording 65 species of butterflies.  Of these, 11 species, viz., Straightwing Blue Orthomiella pontis pontis Elwes, Slate Royal Maneca bhotea bhotea Moore, Dull Green Hairstreak Esakiozephyrus icana Moore, Yellow Woodbrown Lethe nicetas Hewitson, Small Silverfork Zophoessa jalaurida elwesi Moore, Scarce Labyrinth, Neope pulahina (Evans, Chumbi Wall Chonala masoni Elwes, Pale Hockeystick Sailer Neptis manasa manasa Moore and White Commodore Parasarpa dudu dudu Westwood, are restricted to the eastern Himalaya, northeastern India and Myanmar.  Two other species, Tawny Mime Chiasa agestor agestor (Gray and Himalayan Spotted Flat Celaenorrhinus munda Moore have been only rarely recorded from Bhutan and a few individuals of the rare Bhutan Glory Bhutanitis lidderdalei Atkinson were also recorded near Bunakha.  

  8. Study on tempering behaviour of AISI 410 stainless steel

    International Nuclear Information System (INIS)

    Chakraborty, Gopa; Das, C.R.; Albert, S.K.; Bhaduri, A.K.; Thomas Paul, V.; Panneerselvam, G.; Dasgupta, Arup

    2015-01-01

    Martensitic stainless steels find extensive applications due to their optimum combination of strength, hardness and wear-resistance in tempered condition. However, this class of steels is susceptible to embrittlement during tempering if it is carried out in a specific temperature range resulting in significant reduction in toughness. Embrittlement of as-normalised AISI 410 martensitic stainless steel, subjected to tempering treatment in the temperature range of 673–923 K was studied using Charpy impact tests followed by metallurgical investigations using field emission scanning electron and transmission electron microscopes. Carbides precipitated during tempering were extracted by electrochemical dissolution of the matrix and identified by X-ray diffraction. Studies indicated that temper embrittlement is highest when the steel is tempered at 823 K. Mostly iron rich carbides are present in the steel subjected to tempering at low temperatures of around 723 K, whereas chromium rich carbides (M 23 C 6 ) dominate precipitation at high temperature tempering. The range 773–823 K is the transition temperature range for the precipitates, with both Fe 2 C and M 23 C 6 types of carbides coexisting in the material. The nucleation of Fe 2 C within the martensite lath, during low temperature tempering, has a definite role in the embrittlement of this steel. Embrittlement is not observed at high temperature tempering because of precipitation of M 23 C 6 carbides, instead of Fe 2 C, preferentially along the lath and prior austenite boundaries. Segregation of S and P, which is widely reported as one of the causes for temper embrittlement, could not be detected in the material even through Auger electron spectroscopy studies. - Highlights: • Tempering behaviour of AISI 410 steel is studied within 673–923 K temperature range. • Temperature regime of maximum embrittlement is identified as 773–848 K. • Results show that type of carbide precipitation varies with

  9. Study on tempering behaviour of AISI 410 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Gopa, E-mail: gopa_mjs@igcar.gov.in [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Das, C.R.; Albert, S.K.; Bhaduri, A.K.; Thomas Paul, V. [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Panneerselvam, G. [Chemistry Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Dasgupta, Arup [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India)

    2015-02-15

    Martensitic stainless steels find extensive applications due to their optimum combination of strength, hardness and wear-resistance in tempered condition. However, this class of steels is susceptible to embrittlement during tempering if it is carried out in a specific temperature range resulting in significant reduction in toughness. Embrittlement of as-normalised AISI 410 martensitic stainless steel, subjected to tempering treatment in the temperature range of 673–923 K was studied using Charpy impact tests followed by metallurgical investigations using field emission scanning electron and transmission electron microscopes. Carbides precipitated during tempering were extracted by electrochemical dissolution of the matrix and identified by X-ray diffraction. Studies indicated that temper embrittlement is highest when the steel is tempered at 823 K. Mostly iron rich carbides are present in the steel subjected to tempering at low temperatures of around 723 K, whereas chromium rich carbides (M{sub 23}C{sub 6}) dominate precipitation at high temperature tempering. The range 773–823 K is the transition temperature range for the precipitates, with both Fe{sub 2}C and M{sub 23}C{sub 6} types of carbides coexisting in the material. The nucleation of Fe{sub 2}C within the martensite lath, during low temperature tempering, has a definite role in the embrittlement of this steel. Embrittlement is not observed at high temperature tempering because of precipitation of M{sub 23}C{sub 6} carbides, instead of Fe{sub 2}C, preferentially along the lath and prior austenite boundaries. Segregation of S and P, which is widely reported as one of the causes for temper embrittlement, could not be detected in the material even through Auger electron spectroscopy studies. - Highlights: • Tempering behaviour of AISI 410 steel is studied within 673–923 K temperature range. • Temperature regime of maximum embrittlement is identified as 773–848 K. • Results show that type of

  10. Estimation of vegetation cover resilience from satellite time series

    Directory of Open Access Journals (Sweden)

    T. Simoniello

    2008-07-01

    Full Text Available Resilience is a fundamental concept for understanding vegetation as a dynamic component of the climate system. It expresses the ability of ecosystems to tolerate disturbances and to recover their initial state. Recovery times are basic parameters of the vegetation's response to forcing and, therefore, are essential for describing realistic vegetation within dynamical models. Healthy vegetation tends to rapidly recover from shock and to persist in growth and expansion. On the contrary, climatic and anthropic stress can reduce resilience thus favouring persistent decrease in vegetation activity.

    In order to characterize resilience, we analyzed the time series 1982–2003 of 8 km GIMMS AVHRR-NDVI maps of the Italian territory. Persistence probability of negative and positive trends was estimated according to the vegetation cover class, altitude, and climate. Generally, mean recovery times from negative trends were shorter than those estimated for positive trends, as expected for vegetation of healthy status. Some signatures of inefficient resilience were found in high-level mountainous areas and in the Mediterranean sub-tropical ones. This analysis was refined by aggregating pixels according to phenology. This multitemporal clustering synthesized information on vegetation cover, climate, and orography rather well. The consequent persistence estimations confirmed and detailed hints obtained from the previous analyses. Under the same climatic regime, different vegetation resilience levels were found. In particular, within the Mediterranean sub-tropical climate, clustering was able to identify features with different persistence levels in areas that are liable to different levels of anthropic pressure. Moreover, it was capable of enhancing reduced vegetation resilience also in the southern areas under Warm Temperate sub-continental climate. The general consistency of the obtained results showed that, with the help of suited analysis

  11. Forecasting cyanobacteria dominance in Canadian temperate lakes.

    Science.gov (United States)

    Persaud, Anurani D; Paterson, Andrew M; Dillon, Peter J; Winter, Jennifer G; Palmer, Michelle; Somers, Keith M

    2015-03-15

    Predictive models based on broad scale, spatial surveys typically identify nutrients and climate as the most important predictors of cyanobacteria abundance; however these models generally have low predictive power because at smaller geographic scales numerous other factors may be equally or more important. At the lake level, for example, the ability to forecast cyanobacteria dominance is of tremendous value to lake managers as they can use such models to communicate exposure risks associated with recreational and drinking water use, and possible exposure to algal toxins, in advance of bloom occurrence. We used detailed algal, limnological and meteorological data from two temperate lakes in south-central Ontario, Canada to determine the factors that are closely linked to cyanobacteria dominance, and to develop easy to use models to forecast cyanobacteria biovolume. For Brandy Lake (BL), the strongest and most parsimonious model for forecasting % cyanobacteria biovolume (% CB) included water column stability, hypolimnetic TP, and % cyanobacteria biovolume two weeks prior. For Three Mile Lake (TML), the best model for forecasting % CB included water column stability, hypolimnetic TP concentration, and 7-d mean wind speed. The models for forecasting % CB in BL and TML are fundamentally different in their lag periods (BL = lag 1 model and TML = lag 2 model) and in some predictor variables despite the close proximity of the study lakes. We speculate that three main factors (nutrient concentrations, water transparency and lake morphometry) may have contributed to differences in the models developed, and may account for variation observed in models derived from large spatial surveys. Our results illustrate that while forecast models can be developed to determine when cyanobacteria will dominate within two temperate lakes, the models require detailed, lake-specific calibration to be effective as risk-management tools. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Photo series for quantifying forest fuels in Mexico: montane subtropical forests of the Sierra Madre del Sur and temperate forests and montane shrubland of the northern Sierra Madre Oriental

    Science.gov (United States)

    Jorge E. Morfin-Rios; Ernesto Alvarado-Celestino; Enrique J. Jardel-Pelaez; Robert E. Vihnanek; David K. Wright; Jose M. Michel-Fuentes; Clinton S. Wright; Roger D. Ottmar; David V. Sandberg; Andres Najera-Diaz

    2008-01-01

    Single wide-angle and stereo photographs display a range of forest ecosystems conditions and fuel loadings in montane subtropical forests of the Sierra Madre del Sur and temperate forests and montane shrubland of the northern Sierra Madre Oriental of Mexico. Each group of photographs includes inventory information summarizing overstory vegetation composition and...

  13. Vegetation dynamics and dynamic vegetation science

    NARCIS (Netherlands)

    Van der Maarel, E

    1996-01-01

    his contribution presents a review of the development of the study of vegetation dynamics since 1979, in the framework of a jubilee meeting on progress in the study of vegetation. However, an exhaustive review is both impossible and unnecessary. It is impossible within the few pages available

  14. 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

  15. 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

  16. 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

  17. Stress relaxation in tempered glass caused by heat soak testing

    DEFF Research Database (Denmark)

    Schneider, Jens; Hilcken, Jonas; Aronen, Antti

    2016-01-01

    Heat soak testing of tempered glass is a thermal process required after the tempering process itself to bring glasses of commercial soda-lime-silica-glass to failure that are contaminated with nickel sulphide inclusions, diameter 50 mm to 500 mm typically. Thus, the tests avoid a so-called "spont...... of commercial soda-lime-silica glass, it causes stress relaxation in tempered glass and the fracture pattern of the glass changes accordingly, especially thin glasses are affected. Based on the Tool-Narayanaswamy-Model, this paper comprises the theoretical background of the stress...

  18. Endemic shrubs in temperate arid and semiarid regions of northern China and their potentials for rangeland restoration.

    Science.gov (United States)

    Chu, Jianmin; Yang, Hongxiao; Lu, Qi; Zhang, Xiaoyan

    2015-06-03

    Some endemic shrubs in arid and semiarid ecosystems are in danger of extinction, and yet they can play useful roles in maintaining or restoring these ecosystems, thus practical efforts are needed to conserve them. The shrubs Amygdalus pedunculata Pall., Amygdalus mongolica (Maxim.) Ricker and Ammopiptanthus mongolicus (Maxim. ex Kom.) Cheng f. are endemic species in arid and semiarid regions of northern China, where rangeland desertification is pronounced due to chronic overgrazing. In this study, we tested the hypothesis that these endemic shrubs have developed adaptations to arid and semiarid environments and could play critical roles as nurse species to initiate the process of rangeland recovery. Based on careful vegetation surveys, we analysed the niches of these species in relation to precipitation, temperature and habitats. All sampling plots were categorized by these endemics and sorted by the non-metric multidimensional scaling method. Species ratios of each life form and species co-occurrence rates with the endemics were also evaluated. Annual average temperature and annual precipitation were found to be the key factors determining vegetation diversity and distributions. Amygdalus pedunculata prefers low hills and sandy land in temperate semiarid regions. Amygdalus mongolica prefers gravel deserts of temperate semiarid regions. Ammopiptanthus mongolicus prefers sandy land of temperate arid regions. Communities of A. pedunculata have the highest diversity and the largest ratios of long-lived grass species, whereas those of A. mongolicus have the lowest diversity but the largest ratios of shrub species. Communities of A. mongolica are a transition between the first two community types. These findings demonstrate that our focal endemic shrubs have evolved adaptations to arid and semiarid conditions, thus they can be nurse plants to stabilize sand ground for vegetation restoration. We suggest that land managers begin using these shrub species to restore

  19. Nitrogen deposition drives loss of moss cover in alpine moss-sedge heath via lowered C : N ratio and accelerated decomposition.

    Science.gov (United States)

    Britton, Andrea J; Mitchell, Ruth J; Fisher, Julia M; Riach, David J; Taylor, Andy F S

    2018-04-01

    In alpine ecosystems, nitrogen (N) deposition has been linked to plant community composition change, including loss of bryophytes and increase of graminoids. Since bryophyte growth is stimulated by increased N availability, it has been hypothesized that loss of bryophyte cover is driven by enhanced decomposition. As bryophyte mats are a significant carbon (C) store, their loss may impact C storage in these ecosystems. We used an N deposition gradient across 15 sites in the UK to examine effects of N deposition on bryophyte litter quality, decomposition and C and N stocks in Racomitrium moss-sedge heath. Increasing N deposition reduced C : N in bryophyte litter, which in turn enhanced decomposition. Soil N stocks increased significantly in response to increased N deposition, and soil C : N declined. However, depletion of the bryophyte mat and its replacement by graminoids under high N deposition was not associated with a change in total ecosystem C stocks. We conclude that decomposition processes in Racomitrium heath are very sensitive to N deposition and provide a mechanism by which N deposition drives depletion of the bryophyte mat. Nitrogen deposition did not measurably alter C stocks, but changes in soil N stocks and C : N suggest the ecosystem is becoming N saturated. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  20. Fruits and vegetables (image)

    Science.gov (United States)

    A healthy diet includes adding vegetables and fruit every day. Vegetables like broccoli, green beans, leafy greens, zucchini, cauliflower, cabbage, carrots, and tomatoes are low in calories and high in fiber, vitamins, and minerals. ...

  1. Vegetable Production System (Veggie)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Vegetable Production System (Veggie) was developed to be a simple, easily stowed, high growth volume, low resource facility capable of producing fresh vegetables...

  2. European Vegetation Archive (EVA)

    NARCIS (Netherlands)

    Chytrý, Milan; Hennekens, S.M.; Jiménez-Alfaro, Borja; Schaminée, J.H.J.; Haveman, Rense; Janssen, J.A.M.

    2016-01-01

    The European Vegetation Archive (EVA) is a centralized database of European vegetation plots developed by the IAVS Working Group European Vegetation Survey. It has been in development since 2012 and first made available for use in research projects in 2014. It stores copies of national and

  3. Relation between century-scale Holocene arid intervals in tropical and temperate zones

    Science.gov (United States)

    Lamb, H. F.; Gasse, F.; Benkaddour, A.; El Hamouti, N.; van der Kaars, S.; Perkins, W. T.; Pearce, N. J.; Roberts, C. N.

    1995-01-01

    CLIMATE records from lake sediments in tropical Africa, Central America and west Asia show several century-scale arid intervals during the Holocene1-10. These may have been caused by temporary weakening of the monsoonal circulation associated with reduced northward heat transport by the oceans7 or by feedback processes stimulated by changes in tropical land-surface conditions10. Here we use a lake-sediment record from the montane Mediterranean zone of Morocco to address the question of whether these events were also felt in temperate continental regions. We find evidence of arid intervals of similar duration, periodicity and possibly timing to those in the tropics. But our pollen data show that the forest vegetation was not substantially affected by these events, indicating that precipitation remained adequate during the summer growing season. Thus, the depletion of the groundwater aquifer that imprinted the dry events in the lake record must have resulted from reduced winter precipitation. We suggest that the occurrence of arid events during the summer in the tropics but during the winter at temperate latitudes can be rationalized if they are both associated with cooler sea surface temperatures in the North Atlantic.

  4. Environmental and Human Controls of Ecosystem Functional Diversity in Temperate South America

    Directory of Open Access Journals (Sweden)

    Domingo Alcaraz-Segura

    2013-01-01

    Full Text Available The regional controls of biodiversity patterns have been traditionally evaluated using structural and compositional components at the species level, but evaluation of the functional component at the ecosystem level is still scarce. During the last decades, the role of ecosystem functioning in management and conservation has increased. Our aim was to use satellite-derived Ecosystem Functional Types (EFTs, patches of the land-surface with similar carbon gain dynamics to characterize the regional patterns of ecosystem functional diversity and to evaluate the environmental and human controls that determine EFT richness across natural and human-modified systems in temperate South America. The EFT identification was based on three descriptors of carbon gain dynamics derived from seasonal curves of the MODIS Enhanced Vegetation Index (EVI: annual mean (surrogate of primary production, seasonal coefficient of variation (indicator of seasonality and date of maximum EVI (descriptor of phenology. As observed for species richness in the southern hemisphere, water availability, not energy, emerged as the main climatic driver of EFT richness in natural areas of temperate South America. In anthropogenic areas, the role of both water and energy decreased and increasing human intervention increased richness at low levels of human influence, but decreased richness at high levels of human influence.

  5. Summertime elemental mercury exchange of temperate grasslands on an ecosystem-scale

    Science.gov (United States)

    Fritsche, J.; Wohlfahrt, G.; Ammann, C.; Zeeman, M.; Hammerle, A.; Obrist, D.; Alewell, C.

    2013-01-01

    In order to estimate the air-surface mercury exchange of grasslands in temperate climate regions, fluxes of gaseous elemental mercury (GEM) were measured at two sites in Switzerland and one in Austria during summer 2006. Two classic micrometeorological methods (aerodynamic and modified Bowen ratio) have been applied to estimate net GEM exchange rates and to determine the response of the GEM flux to changes in environmental conditions (e.g. heavy rain, summer ozone) on an ecosystem-scale. Both methods proved to be appropriate to estimate fluxes on time scales of a few hours and longer. Average dry deposition rates up to 4.3 ng m−2 h−1 and mean deposition velocities up to 0.10 cm s−1 were measured, which indicates that during the active vegetation period temperate grasslands are a small net sink for atmospheric mercury. With increasing ozone concentrations depletion of GEM was observed, but could not be quantified from the flux signal. Night-time deposition fluxes of GEM were measured and seem to be the result of mercury co-deposition with condensing water. Effects of grass cuts could also be observed, but were of minor magnitude. PMID:24348525

  6. Summertime elemental mercury exchange of temperate grasslands on an ecosystem-scale

    Directory of Open Access Journals (Sweden)

    J. Fritsche

    2008-12-01

    Full Text Available In order to estimate the air-surface mercury exchange of grasslands in temperate climate regions, fluxes of gaseous elemental mercury (GEM were measured at two sites in Switzerland and one in Austria during summer 2006. Two classic micrometeorological methods (aerodynamic and modified Bowen ratio have been applied to estimate net GEM exchange rates and to determine the response of the GEM flux to changes in environmental conditions (e.g. heavy rain, summer ozone on an ecosystem-scale. Both methods proved to be appropriate to estimate fluxes on time scales of a few hours and longer. Average dry deposition rates up to 4.3 ng m−2 h−1 and mean deposition velocities up to 0.10 cm s−1 were measured, which indicates that during the active vegetation period temperate grasslands are a small net sink for atmospheric mercury. With increasing ozone concentrations depletion of GEM was observed, but could not be quantified from the flux signal. Night-time deposition fluxes of GEM were measured and seem to be the result of mercury co-deposition with condensing water. Effects of grass cuts could also be observed, but were of minor magnitude.

  7. Drilling in tempered glass – modelling and experiments

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    The present paper reports experimentally and numerically obtained results for the process of drilling in tempered glass. The experimental results are drilling depths on the edge in 19mm tempered glass with a known residual stress state measured by a scattered light polariscope. The experiments have...... been modelled using a state-of-the-art model and compared with satisfying result to the performed experiments. The numerical model has been used for a parametric study, investigating the redistribution of residual stresses during the process of drilling. This is done for investigating the possibility...... of applying forces in such holes and thereby being able to mechanically assemble tempered glass without the need of drilling holes before the tempering process. The paper is the result of currently ongoing research and the results should be treated as so....

  8. 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).

  9. Hot wire TIG temper bead welding for nuclear repairs

    International Nuclear Information System (INIS)

    Lambert, J.A.; Gilston, P.F.

    1989-08-01

    A preliminary assessment has been carried out to determine the suitability of the hot wire tungsten inert gas (TIG) welding process for the repair of thick section, ferritic steel nuclear pressure vessels. The objective has been to identify a hot wire TIG temper bead procedure, suitable for repairs without post weld heat treatment. This procedure involves depositing two weld layers with carefully selected welding parameters such that overlapping thermal cycles produce a refined and tempered heat affected zone, HAZ, microstructure. (author)

  10. Long-term effect of wildfires on temperate Pinus sylvestris forests: Vegetation dynamics and ecosystem resilience

    Czech Academy of Sciences Publication Activity Database

    Adámek, Martin; Hadincová, Věroslava; Wild, Jan

    2016-01-01

    Roč. 380, NOV 15 (2016), s. 285-295 ISSN 0378-1127 R&D Projects: GA ČR(CZ) GA14-22658S Institutional support: RVO:67985939 Keywords : Scots pine * succession * sandstone Subject RIV: EH - Ecology, Behaviour Impact factor: 3.064, year: 2016

  11. Long-term vegetation changes in a temperate forest impacted by climate change

    Science.gov (United States)

    Lauren E. Oakes; Paul E. Hennon; Kevin L. O' Hara; Rodolfo Dirzo

    2014-01-01

    Pervasive forest mortality is expected to increase in future decades as a result of increasing temperatures. Climate-induced forest dieback can have consequences on ecosystem services, potentially mediated by changes in forest structure and understory community composition that emerge in response to tree death. Although many dieback events around the world have been...

  12. Effect of Hummock-Forming Vegetation on Methane Emissions from a Temperate Sedge-Grass Marsh

    Czech Academy of Sciences Publication Activity Database

    Vítková, J.; Dušek, Jiří; Stellner, Stanislav; Moulisová, L.; Čížková, H.

    2017-01-01

    Roč. 37, č. 4 (2017), s. 675-686 ISSN 0277-5212 R&D Projects: GA MŠk(CZ) LO1415; GA MŠk(CZ) LM2015061; GA ČR(CZ) GAP504/11/1151 Institutional support: RVO:86652079 Keywords : Methane emissions * Chamber method * Carex acuta * Tussock * Water level * Wetland Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 1.573, year: 2016

  13. The tempered polymerization of human neuroserpin.

    Directory of Open Access Journals (Sweden)

    Rosina Noto

    Full Text Available Neuroserpin, a member of the serpin protein superfamily, is an inhibitor of proteolytic activity that is involved in pathologies such as ischemia, Alzheimer's disease, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB. The latter belongs to a class of conformational diseases, known as serpinopathies, which are related to the aberrant polymerization of serpin mutants. Neuroserpin is known to polymerize, even in its wild type form, under thermal stress. Here, we study the mechanism of neuroserpin polymerization over a wide range of temperatures by different techniques. Our experiments show how the onset of polymerization is dependent on the formation of an intermediate monomeric conformer, which then associates with a native monomer to yield a dimeric species. After the formation of small polymers, the aggregation proceeds via monomer addition as well as polymer-polymer association. No further secondary mechanism takes place up to very high temperatures, thus resulting in the formation of neuroserpin linear polymeric chains. Most interesting, the overall aggregation is tuned by the co-occurrence of monomer inactivation (i.e. the formation of latent neuroserpin and by a mechanism of fragmentation. The polymerization kinetics exhibit a unique modulation of the average mass and size of polymers, which might suggest synchronization among the different processes involved. Thus, fragmentation would control and temper the aggregation process, instead of enhancing it, as typically observed (e.g. for amyloid fibrillation.

  14. Influence of tempering temperature on mechanical properties of cast steels

    Directory of Open Access Journals (Sweden)

    G. Golański

    2008-12-01

    Full Text Available The paper presents results of research on the influence of tempering temperature on structure and mechanical properties of bainite hardened cast steel: G21CrMoV4 – 6 (L21HMF and G17CrMoV5 – 10 (L17HMF. Investigated cast steels were taken out from internal frames of steam turbines serviced for long time at elevated temperatures. Tempering of the investigated cast steel was carried out within the temperature range of 690 ÷ 730 C (G21CrMoV4 – 6 and 700 ÷ 740 C (G17CrMoV5 – 10. After tempering the cast steels were characterized by a structure of tempered lower bainite with numerous precipitations of carbides. Performed research of mechanical properties has shown that high temperatures of tempering of bainitic structure do not cause decrease of mechanical properties beneath the required minimum.oo It has also been proved that high-temperature tempering (>720 oC ensures high impact energy at the 20% decrease of mechanical properties.

  15. Regeneration complexities of Pinus gerardiana in dry temperate forests of Indian Himalaya.

    Science.gov (United States)

    Kumar, Raj; Shamet, G S; Mehta, Harsh; Alam, N M; Kaushal, Rajesh; Chaturvedi, O P; Sharma, Navneet; Khaki, B A; Gupta, Dinesh

    2016-04-01

    Pinus gerardiana is considered an important species in dry temperate forests of North-Western Indian Himalaya because of its influence on ecological processes and economic dependence of local people in the region. But, large numbers of biotic and abiotic factors have affected P. gerardiana in these forests; hence, there is a crucial need to understand the regeneration dynamics of this tree species. The present investigation was conducted in P. gerardiana forests to understand vegetation pattern and regeneration processes on different sites in the region. Statistical analysis was performed to know variability in growing stock and regeneration on sample plots, while correlation coefficients and regression models were developed to find the relationship between regeneration and site factors. The vegetation study showed dominance of P. gerardiana, which is followed by Cedrus deodara, Pinus wallichiana and Quercus ilex in the region. The growing stock of P. gerardiana showed steep increasing and then steadily declining trend from lower to higher diameter class. The distribution of seedling, sapling, pole and trees was not uniform at different sites and less number of plots in each site were observed to have effective conditions for continuous regeneration, but mostly showed extremely limited regeneration. Regeneration success ranging from 8.44 to 15.93 % was recorded in different sites of the region, which suggests that in different sites regeneration success is influenced by collection of cone for extracting seed, grazing/browsing and physico-chemical properties of soil. Regeneration success showed significant correlation and relationship with most of abiotic and biotic factors. The regeneration success is lower than the requirement of sustainable forest, but varies widely among sites in dry temperate forests of Himalaya. More forest surveys are required to understand the conditions necessary for greater success of P. gerardiana in the region.

  16. Vascular plant species richness along environmental gradients in a cool temperate to sub-alpine mountainous zone in central Japan.

    Science.gov (United States)

    Tsujino, Riyou; Yumoto, Takakazu

    2013-03-01

    In order to clarify how vegetation types change along the environmental gradients in a cool temperate to sub-alpine mountainous zone and the determinant factors that define plant species richness, we established 360 plots (each 4 × 10 m) within which the vegetation type, species richness, elevation, topographic position index (TPI), slope inclination, and ground light index (GLI) of the natural vegetation were surveyed. Mean elevation, TPI, slope inclination, and GLI differed across vegetation types. Tree species richness was negatively correlated with elevation, whereas fern and herb species richness were positively correlated. Tree species richness was greater in the upper slope area than the lower slope area, whereas fern and herb species richness were greater in the lower slope area. Ferns and trees species richness were smaller in the open canopy, whereas herb species richness was greater in the open canopy. Vegetation types were determined firstly by elevation and secondary by topographic configurations, such as topographic position, and slope inclination. Elevation and topography were the most important factors affecting plant richness, but the most influential variables differed among plant life-form groups. Moreover, the species richness responses to these environmental gradients greatly differed among ferns, herbs, and trees.

  17. Temperature and substrate controls on intra-annual variation in ecosystem respiration in two subarctic vegetation types

    DEFF Research Database (Denmark)

    Grogan, Paul; Jonasson, Sven Evert

    2005-01-01

    significantly to ecosystem respiration during most phases of winter and summer in the two vegetation types. Ecosystem respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76...... contributions of bulk soil organic matter and plant-associated carbon pools to ecosystem respiration is critical to predicting the response of arctic ecosystem net carbon balance to climate change. In this study, we determined the variation in ecosystem respiration rates from birch forest understory and heath......-92%) of the intra-annual variation in ecosystem respiration rates from these two common mesic subarctic ecosystems was explained using a first-order exponential equation relating respiration to substrate chemical quality and soil temperature. Removal of plants and their current year's litter significantly reduced...

  18. Vegetation cover in relation to socioeconomic factors in a tropical city assessed from sub-meter resolution imagery.

    Science.gov (United States)

    Martinuzzi, Sebastián; Ramos-González, Olga M; Muñoz-Erickson, Tischa A; Locke, Dexter H; Lugo, Ariel E; Radeloff, Volker C

    2018-04-01

    Fine-scale information about urban vegetation and social-ecological relationships is crucial to inform both urban planning and ecological research, and high spatial resolution imagery is a valuable tool for assessing urban areas. However, urban ecology and remote sensing have largely focused on cities in temperate zones. Our goal was to characterize urban vegetation cover with sub-meter (urban vegetation patterns in a tropical city, the San Juan Metropolitan Area, Puerto Rico. Our specific objectives were to (1) map vegetation cover using sub-meter spatial resolution (0.3-m) imagery, (2) quantify the amount of residential and non-residential vegetation, and (3) investigate the relationship between patterns of urban vegetation vs. socioeconomic and environmental factors. We found that 61% of the San Juan Metropolitan Area was green and that our combination of high spatial resolution imagery and object-based classification was highly successful for extracting vegetation cover in a moist tropical city (97% accuracy). In addition, simple spatial pattern analysis allowed us to separate residential from non-residential vegetation with 76% accuracy, and patterns of residential and non-residential vegetation varied greatly across the city. Both socioeconomic (e.g., population density, building age, detached homes) and environmental variables (e.g., topography) were important in explaining variations in vegetation cover in our spatial regression models. However, important socioeconomic drivers found in cities in temperate zones, such as income and home value, were not important in San Juan. Climatic and cultural differences between tropical and temperate cities may result in different social-ecological relationships. Our study provides novel information for local land use planners, highlights the value of high spatial resolution remote sensing data to advance ecological research and urban planning in tropical cities, and emphasizes the need for more studies in tropical

  19. Comparison of vegetable shortening and cocoa butter as vehicles for cortisol manipulation in Salmo trutta

    DEFF Research Database (Denmark)

    Birnie-Gauvin, Kim; Peiman, K. S.; Larsen, M. H.

    2018-01-01

    This study demonstrates that vegetable shortening and cocoa butter are two effective vehicles for intraperitoneal cortisol implants in juvenile teleosts, specifically brown trout Salmo trutta, residing in north temperate freshwater environments. Each vehicle showed a different pattern of cortisol...... elevation. Vegetable shortening was found to be a more suitable vehicle for long-term cortisol elevation [elevated at 3, 6 and 9 days post treatment (dpt)], while cocoa butter may be better suited for short-term cortisol elevation (only elevated at 3 dpt). Additionally, plasma cortisol levels were higher...... with cortisol–vegetable shortening than with cortisol–cocoa butter implants. Plasma glucose levels were elevated 6 and 9 dpt for fishes injected with cortisol–vegetable shortening, but did not change relative to controls and shams in cortisol–cocoa butter fishes. In conclusion, vegetable shortening and cocoa...

  20. Quantifying Vegetation Structure with Lightweight, Rapid-Scanning Terrestrial Lidar

    Science.gov (United States)

    Paynter, I.; Genest, D.; Saenz, E. J.; Strahler, A. H.; Li, Z.; Peri, F.; Schaaf, C.

    2016-12-01

    Light Detection and Ranging (lidar) is proving a competent technology for observing vegetation structure. Terrestrial laser scanners (TLS) are ground-based instruments which utilize hundreds of thousands to millions of lidar observations to provide detailed structural and reflective information of their surroundings. TLS has enjoyed initial success as a validation tool for satellite and airborne estimates of vegetation structure, and are producing independent estimates with increasing accuracy. Reconstruction techniques for TLS observations of vegetation have also improved rapidly, especially for trees. However, uncertainties and challenges still remain in TLS modelling of vegetation structure, especially in geometrically complex ecosystems such as tropical forests (where observation extent and density is hampered by occlusion) and highly temporally dynamic coastal ecosystems (such as saltmarshes and mangroves), where observations may be restricted to narrow microstates. Some of these uncertainties can be mitigated, and challenges met, through the use of lidar instruments optimized for favorable deployment logistics through low weight, rapid scanning, and improved durability. We have conducted studies of vegetation structure in temperate and tropical forests, saltmarshes and mangroves, utilizing a highly portable TLS with considerable deployment flexibility, the Compact Biomass Lidar (CBL). We show results from studies in the temperate Long Term Ecological Research site of Harvard Forest (MA, USA); the tropical forested long-term Carbono sites of La Selva Biological Station (Sarapiqui, Costa Rica); and the saltmarsh LTER of Plum Island (MA, USA). These results demonstrate the improvements to observations in these ecosystems which are facilitated by the specifications of the CBL (and similar TLS) which are optimized for favorable deployment logistics and flexibility. We show the benefits of increased numbers of scanning positions, and specialized deployment

  1. Narrowband Bio-Indicator Monitoring of Temperate Forest Carbon Fluxes in Northeastern China

    Directory of Open Access Journals (Sweden)

    Quanzhou Yu

    2014-09-01

    Full Text Available Developments in hyperspectral remote sensing techniques during the last decade have enabled the use of narrowband indices to evaluate the role of forest ecosystem variables in estimating carbon (C fluxes. In this study, narrowband bio-indicators derived from EO-1 Hyperion data were investigated to determine whether they could capture the temporal variation and estimate the spatial variability of forest C fluxes derived from eddy covariance tower data. Nineteen indices were divided into four categories of optical indices: broadband, chlorophyll, red edge, and light use efficiency. Correlation tests were performed between the selected vegetation indices, gross primary production (GPP, and ecosystem respiration (Re. Among the 19 indices, five narrowband indices (Chlorophyll Index RedEdge 710, scaled photochemical reflectance index (SPRI*enhanced vegetation index (EVI, SPRI*normalized difference vegetation index (NDVI, MCARI/OSAVI[705, 750] and the Vogelmann Index, and one broad band index (EVI had R-squared values with a good fit for GPP and Re. The SPRI*NDVI has the highest significant coefficients of determination with GPP and Re (R2 = 0.86 and 0.89, p < 0.0001, respectively. SPRI*NDVI was used in atmospheric inverse modeling at regional scales for the estimation of C fluxes. We compared the GPP spatial patterns inversed from our model with corresponding results from the Vegetation Photosynthesis Model (VPM, the Boreal Ecosystems Productivity Simulator model, and MODIS MOD17A2 products. The inversed GPP spatial patterns from our model of SPRI*NDVI had good agreement with the output from the VPM model. The normalized difference nitrogen index was well correlated with measured C net ecosystem exchange. Our findings indicated that narrowband bio-indicators based on EO-1 Hyperion images could be used to predict regional C flux variations for Northeastern China’s temperate broad-leaved Korean pine forest ecosystems.

  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. Irradiation of dehydrated vegetables

    International Nuclear Information System (INIS)

    Esterhuyse, A; Esterhuizen, T.

    1985-01-01

    The reason for radurization was to decreased the microbial count of dehydrated vegetables. The average absorbed irradiation dose range between 2kGy and 15kGy. The product catagories include a) Green vegetables b) White vegetables c) Powders of a) and b). The microbiological aspects were: Declining curves for the different products of T.P.C., Coliforms, E. Coli, Stap. areus, Yeast + Mold at different doses. The organoleptical aspects were: change in taste, flavour, texture, colour and moisture. The aim is the marketing of irradiated dehydrated vegetables national and international basis

  5. Evolution of Microsatellite Loci of Tropical and Temperate Anguilla Eels

    Directory of Open Access Journals (Sweden)

    Mei-Chen Tseng

    2012-04-01

    Full Text Available Anguilla eels are divided into temperate and tropical eels, based on their major distributions. The present study collected two temperate eels, Anguilla japonica and Anguilla anguilla, and two tropical eels, Anguilla marmorata and Anguilla bicolor pacifica, to examine two questions: do temperate and tropical Anguilla eels have different genetic polymorphic patterns?; and do temperate Anguilla japonica and Anguilla anguilla have a closer relationship to each other than to tropical eels? In total, 274 sequences were cloned and sequenced from six conserved microsatellite loci to examine polymorphic patterns of these four catadromous eels. Different mutational events, including substitutions, and repeat-unit deletions and insertions, appeared in major regions, while different point mutations were observed in flanking regions. The results implied that parallel patterns of microsatellite sequences occurred within both tropical and temperate freshwater eels. Consensus flanking sequences of six homologous loci from each of the four species were constructed. Genetic distances ranged from 0.044 (Anguilla bicolor pacifica vs. Anguilla marmorata to 0.061 (Anguilla marmorata vs. Anguilla anguilla. The tree topology suggests the hypothesis of Anguilla japonica and Anguilla anguilla being a sister group must be rejected.

  6. Effects of tempering on internal friction of carbon steels

    International Nuclear Information System (INIS)

    Hoyos, J.J.; Ghilarducci, A.A.; Salva, H.R.; Chaves, C.A.; Velez, J.M.

    2011-01-01

    Research highlights: → Time tempering dependent microstructure of two steels is studied by internal friction. → Internal friction indicates the interactions of dislocations with carbon and carbides. → Internal friction detects the first stage of tempering. → Precipitation hardening is detected by the decrease in the background. - Abstract: Two steels containing 0.626 and 0.71 wt.% carbon have been studied to determine the effects of tempering on the microstructure and the internal friction. The steels were annealed at 1093 K, quenched into water and tempered for 60 min at 423 K, 573 K and 723 K. The increase of the tempering time diminishes the martensite tetragonality due to the redistribution of carbon atoms from octahedrical interstitial sites to dislocations. Internal friction spectrum is decomposed into five peaks and an exponential background, which are attributed to the carbide precipitation and the dislocation relaxation process. Simultaneous presence of peaks P1 and P2 indicates the interaction of dislocations with the segregated carbon and carbide precipitate.

  7. Balkan Vegetation Database

    NARCIS (Netherlands)

    Vassilev, Kiril; Pedashenko, Hristo; Alexandrova, Alexandra; Tashev, Alexandar; Ganeva, Anna; Gavrilova, Anna; Gradevska, Asya; Assenov, Assen; Vitkova, Antonina; Grigorov, Borislav; Gussev, Chavdar; Filipova, Eva; Aneva, Ina; Knollová, Ilona; Nikolov, Ivaylo; Georgiev, Georgi; Gogushev, Georgi; Tinchev, Georgi; Pachedjieva, Kalina; Koev, Koycho; Lyubenova, Mariyana; Dimitrov, Marius; Apostolova-Stoyanova, Nadezhda; Velev, Nikolay; Zhelev, Petar; Glogov, Plamen; Natcheva, Rayna; Tzonev, Rossen; Boch, Steffen; Hennekens, Stephan M.; Georgiev, Stoyan; Stoyanov, Stoyan; Karakiev, Todor; Kalníková, Veronika; Shivarov, Veselin; Russakova, Veska; Vulchev, Vladimir

    2016-01-01

    The Balkan Vegetation Database (BVD; GIVD ID: EU-00-019; http://www.givd.info/ID/EU-00- 019) is a regional database that consists of phytosociological relevés from different vegetation types from six countries on the Balkan Peninsula (Albania, Bosnia and Herzegovina, Bulgaria, Kosovo, Montenegro

  8. Soil and vegetation surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, E.J.

    1995-06-01

    Soil sampling and analysis evaluates long-term contamination trends and monitors environmental radionuclide inventories. This section of the 1994 Hanford Site Environmental Report summarizes the soil and vegetation surveillance programs which were conducted during 1994. Vegetation surveillance is conducted offsite to monitor atmospheric deposition of radioactive materials in areas not under cultivation and onsite at locations adjacent to potential sources of radioactivity.

  9. Radiation processing of temperate fruits of Kashmir valley

    International Nuclear Information System (INIS)

    Hussain, Peerzada R.; Meena, Raghuveer S.; Dar, Mohd A.; Wani, Ali M.

    2011-01-01

    Kashmir valley is famous for its temperate horticulture. Main temperate fruits grown commercially in the valley include apple, pear, peach, plum, cherry, strawberry and apricot. These fruits being perishable and susceptible to microbial spoilage, have a short shelf-life. The short shelf-life in an impediment in their transportation and marketing and results in huge losses. Study was carried out at NRL, Srinagar to investigate the effect of gamma irradiation on the keeping quality of most of these fruits. The effect of gamma irradiation alone and in combination with other techniques like controlled low temperature storage, edible polysaccharide coating and calcium chloride treatment was studied in detail. The results revealed that there is a great potential for the use of radiation in extending the storage life of most of the temperate fruits produced in the valley of Kashmir. (author)

  10. Tempered stable distributions stochastic models for multiscale processes

    CERN Document Server

    Grabchak, Michael

    2015-01-01

    This brief is concerned with tempered stable distributions and their associated Levy processes. It is a good text for researchers interested in learning about tempered stable distributions.  A tempered stable distribution is one which takes a stable distribution and modifies its tails to make them lighter. The motivation for this class comes from the fact that infinite variance stable distributions appear to provide a good fit to data in a variety of situations, but the extremely heavy tails of these models are not realistic for most real world applications. The idea of using distributions that modify the tails of stable models to make them lighter seems to have originated in the influential paper of Mantegna and Stanley (1994). Since then, these distributions have been extended and generalized in a variety of ways. They have been applied to a wide variety of areas including mathematical finance, biostatistics,computer science, and physics.

  11. Resistance to small plastic strains during martensite tempering under tension

    Energy Technology Data Exchange (ETDEWEB)

    Zabil' skij, V.V.; Sarrak, V.I. (AN SSSR, Sverdlovsk. Inst. Fiziki Metallov)

    1982-11-01

    The mechanism of plastic deformation of martensite of a series of hardened steels (N18, 20KhG, 50KhFA and others) during tempering under tension and the role of residual internal microstresses and phase transformations are studied. It is shown that martensite low resistance to small plastic deformations during tempering under tension which is usually associated with phase transformations depends as well on the level of residual internal microstresses in the martensite structure. The decrease of resistance to deformation in the course of the decomposition of a solid solution is due to weakening of martensitic matrix because of carbon departure from the solid solution and carbide coarsening. An assumption is made that martensite plastic deformation during tempering under tension is realized at the expense of the directed microplastic deformation in the regions of higher concentration of internal stresses.

  12. Diversity and abundance of photosynthetic sponges in temperate Western Australia

    Directory of Open Access Journals (Sweden)

    Brümmer Franz

    2009-02-01

    Full Text Available Abstract Background Photosynthetic sponges are important components of reef ecosystems around the world, but are poorly understood. It is often assumed that temperate regions have low diversity and abundance of photosynthetic sponges, but to date no studies have investigated this question. The aim of this study was to compare the percentages of photosynthetic sponges in temperate Western Australia (WA with previously published data on tropical regions, and to determine the abundance and diversity of these associations in a range of temperate environments. Results We sampled sponges on 5 m belt transects to determine the percentage of photosynthetic sponges and identified at least one representative of each group of symbionts using 16S rDNA sequencing together with microscopy techniques. Our results demonstrate that photosynthetic sponges are abundant in temperate WA, with an average of 63% of sponge individuals hosting high levels of photosynthetic symbionts and 11% with low to medium levels. These percentages of photosynthetic sponges are comparable to those found on tropical reefs and may have important implications for ecosystem function on temperate reefs in other areas of the world. A diverse range of symbionts sometimes occurred within a small geographic area, including the three "big" cyanobacterial clades, Oscillatoria spongeliae, "Candidatus Synechococcus spongiarum" and Synechocystis species, and it appears that these clades all occur in a wide range of sponges. Additionally, spongin-permeating red algae occurred in at least 7 sponge species. This study provides the first investigation of the molecular phylogeny of rhodophyte symbionts in sponges. Conclusion Photosynthetic sponges are abundant and diverse in temperate WA, with comparable percentages of photosynthetic to non-photosynthetic sponges to tropical zones. It appears that there are three common generalist clades of cyanobacterial symbionts of sponges which occur in a wide

  13. Ultra low carbon bainitic (ULCB) steels after quenching and tempering

    International Nuclear Information System (INIS)

    Lis, A.K.; Lis, J.; Kolan, C.; Jeziorski, L.

    1998-01-01

    The mechanical and Charpy V impact strength properties of new advanced ultra low carbon bainitic (ULBC) steels after water quenching and tempering (WQT) have been investigated. Their chemical compositions are given. The nine continuous cooling transformation diagrams (CCT) of the new ULCB steel grades have been established. The CCT diagrams for ULCB N i steels containing 9% Ni - grade 10N9 and 5% Ni - grade HN5MVNb are given. The comparison between CCT diagrams of 3.5%Ni + 1.5%Cu containing steels grade HSLA 100 and HN3MCu is shown. The effect of the increase in carbon and titanium contents in the chemical composition of ULCB M n steels 04G3Ti, 06G3Ti and 09G3Ti on the kinetics of phase transformations during continuous cooling is presented by the shifting CCT diagrams. The Charpy V impact strength and brittle fracture occurence curves are shown. The effect of tempering temperature on tensile properties of WQT HN3MCu steel is shown and Charpy V impact strength curves after different tempering conditions are shown. The optimum tempering temperatures region of HN3MCu steel for high Charpy V impact toughness at law temperatures - 80 o C(193 K) and -120 o C(153 K) is estimated. The effect of tempering temperature on mechanical properties of HN5MVNb steel is given. The low temperature impact Charpy V toughness of HN5MVNb steel is shown. The optimum range of tempering temperature during 1 hour for high toughness of WQT HN5MVNb steel is given. HN3MCu and HN5MVNb steels after WQT have high yield strength YS≥690 MPa and high Charpy V impact toughness KV≥80 J at -100 o C (173K) and KCV≥50 J/cm 2 at - 120 o C (153K) so they may be used for cryogenic applications

  14. Method of producing vegetable puree

    DEFF Research Database (Denmark)

    2004-01-01

    A process for producing a vegetable puree, comprising the sequential steps of: a)crushing, chopping or slicing the vegetable into pieces of 1 to 30 mm; b) blanching the vegetable pieces at a temperature of 60 to 90°C; c) contacted the blanched vegetable pieces with a macerating enzyme activity; d......) blending the macerated vegetable pieces and obtaining a puree....

  15. Vegetation survey: a new focus for Applied Vegetation Science

    NARCIS (Netherlands)

    Chytry, M.; Schaminee, J.H.J.; Schwabe, A.

    2011-01-01

    Vegetation survey is an important research agenda in vegetation science. It defines vegetation types and helps understand differences among them, which is essential for both basic ecological research and applications in biodiversity conservation and environmental monitoring. In this editorial, we

  16. SWFSC/MMTD/CCE: Leatherback Use of Temperate Habitat (LUTH) 2008

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Leatherback Use of Temperate Habitat (LUTH) survey is an ecosystem assessment of temperate foraging habitats of endangered leatherback turtles off the coast of...

  17. Direct dating and identity of fiber temper in pre-contact Bushman (Masarwa) pottery

    CSIR Research Space (South Africa)

    Bollong, CA

    1993-01-01

    Full Text Available , ashed grass, or absorbed blood. Visual characteristics rule out the possibility of animal dung temper. Blood and fat residues absorbed by grass temper could be the combined cause of anomalous Q (13) C and high P values....

  18. Variation of biomass and carbon pools with forest type in temperate forests of Kashmir Himalaya, India.

    Science.gov (United States)

    Dar, Javid Ahmad; Sundarapandian, Somaiah

    2015-02-01

    influenced by vegetation type, stand structure, management history, and altitude. Our results reveal that a higher percentage (63 %) of C is stored in biomass and less in soil in these temperate forests except at the higher elevation broad-leaved BU forest. Results from this study will enhance our ability to evaluate the role of these forests in regional and global C cycles and have great implications for planning strategies for conservation. The study provides important data for developing and validating C cycling models for temperate forests.

  19. Predicting Changes in Arctic Tundra Vegetation: Towards an Understanding of Plant Trait Uncertainty

    Science.gov (United States)

    Euskirchen, E. S.; Serbin, S.; Carman, T.; Iversen, C. M.; Salmon, V.; Helene, G.; McGuire, A. D.

    2017-12-01

    Arctic tundra plant communities are currently undergoing unprecedented changes in both composition and distribution under a warming climate. Predicting how these dynamics may play out in the future is important since these vegetation shifts impact both biogeochemical and biogeophysical processes. More precise estimates of these future vegetation shifts is a key challenge due to both a scarcity of data with which to parameterize vegetation models, particularly in the Arctic, as well as a limited understanding of the importance of each of the model parameters and how they may vary over space and time. Here, we incorporate newly available field data from arctic Alaska into a dynamic vegetation model specifically developed to take into account a particularly wide array of plant species as well as the permafrost soils of the arctic tundra (the Terrestrial Ecosystem Model with Dynamic Vegetation and Dynamic Organic Soil, Terrestrial Ecosystem Model; DVM-DOS-TEM). We integrate the model within the Predicative Ecosystem Analyzer (PEcAn), an open-source integrated ecological bioinformatics toolbox that facilitates the flows of information into and out of process models and model-data integration. We use PEcAn to evaluate the plant functional traits that contribute most to model variability based on a sensitivity analysis. We perform this analysis for the dominant types of tundra in arctic Alaska, including heath, shrub, tussock and wet sedge tundra. The results from this analysis will help inform future data collection in arctic tundra and reduce model uncertainty, thereby improving our ability to simulate Arctic vegetation structure and function in response to global change.

  20. 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.

  1. Comparison of vegetable shortening and cocoa butter as vehicles for cortisol manipulation in Salmo trutta.

    Science.gov (United States)

    Birnie-Gauvin, K; Peiman, K S; Larsen, M H; Aarestrup, K; Gilmour, K M; Cooke, S J

    2018-01-01

    This study demonstrates that vegetable shortening and cocoa butter are two effective vehicles for intraperitoneal cortisol implants in juvenile teleosts, specifically brown trout Salmo trutta, residing in north temperate freshwater environments. Each vehicle showed a different pattern of cortisol elevation. Vegetable shortening was found to be a more suitable vehicle for long-term cortisol elevation [elevated at 3, 6 and 9 days post treatment (dpt)], while cocoa butter may be better suited for short-term cortisol elevation (only elevated at 3 dpt). Additionally, plasma cortisol levels were higher with cortisol-vegetable shortening than with cortisol-cocoa butter implants. Plasma glucose levels were elevated 6 and 9 dpt for fishes injected with cortisol-vegetable shortening, but did not change relative to controls and shams in cortisol-cocoa butter fishes. In conclusion, vegetable shortening and cocoa butter are both viable techniques for cortisol manipulation in fishes in temperate climates, providing researchers with different options depending on study objectives. © 2017 The Fisheries Society of the British Isles.

  2. State factor relationships of dissolved organic carbon and nitrogen losses from unpolluted temperate forest watersheds

    Science.gov (United States)

    Perakis, S.S.; Hedin, L.O.

    2007-01-01

    We sampled 100 unpolluted, old-growth forested watersheds, divided among 13 separate study areas over 5 years in temperate southern Chile and Argentina, to evaluate relationships among dominant soil-forming state factors and dissolved carbon and nitrogen concentrations in watershed streams. These watersheds provide a unique opportunity to examine broad-scale controls over carbon (C) and nitrogen (N) biogeochemistry in the absence of significant human disturbance from chronic N deposition and land use change. Variations in the ratio dissolved organic carbon (DOC) to nitrogen (DON) in watershed streams differed by underlying soil parent material, with average C:N = 29 for watersheds underlain by volcanic ash and basalt versus C:N = 73 for sedimentary and metamorphic parent materials, consistent with stronger adsorption of low C:N hydrophobic materials by amorphous clays commonly associated with volcanic ash and basalt weathering. Mean annual precipitation was related positively to variations in both DOC (range: 0.2-9.7 mg C/L) and DON (range: 0.008-0.135 mg N/L) across study areas, suggesting that variations in water volume and concentration may act synergistically to influence C and N losses across dry to wet gradients in these forest ecosystems. Dominance of vegetation by broadleaf versus coniferous trees had negligible effects on organic C and N concentrations in comparison to abiotic factors. We conclude that precipitation volume and soil parent material are important controls over chemical losses of dissolved organic C and N from unpolluted temperate forest watersheds. Our results raise the possibility that biotic imprints on watershed C and N losses may be less pronounced in naturally N-poor forests than in areas impacted by land use change and chronic N deposition. Copyright 2007 by the American Geophysical Union.

  3. δ15N constraints on long-term nitrogen balances in temperate forests

    Science.gov (United States)

    Perakis, S.S.; Sinkhorn, E.R.; Compton, J.E.

    2011-01-01

    Biogeochemical theory emphasizes nitrogen (N) limitation and the many factors that can restrict N accumulation in temperate forests, yet lacks a working model of conditions that can promote naturally high N accumulation. We used a dynamic simulation model of ecosystem N and δ15N to evaluate which combination of N input and loss pathways could produce a range of high ecosystem N contents characteristic of forests in the Oregon Coast Range. Total ecosystem N at nine study sites ranged from 8,788 to 22,667 kg ha−1 and carbon (C) ranged from 188 to 460 Mg ha−1, with highest values near the coast. Ecosystem δ15N displayed a curvilinear relationship with ecosystem N content, and largely reflected mineral soil, which accounted for 96–98% of total ecosystem N. Model simulations of ecosystem N balances parameterized with field rates of N leaching required long-term average N inputs that exceed atmospheric deposition and asymbiotic and epiphytic N2-fixation, and that were consistent with cycles of post-fire N2-fixation by early-successional red alder. Soil water δ15NO3 − patterns suggested a shift in relative N losses from denitrification to nitrate leaching as N accumulated, and simulations identified nitrate leaching as the primary N loss pathway that constrains maximum N accumulation. Whereas current theory emphasizes constraints on biological N2-fixation and disturbance-mediated N losses as factors that limit N accumulation in temperate forests, our results suggest that wildfire can foster substantial long-term N accumulation in ecosystems that are colonized by symbiotic N2-fixing vegetation.

  4. Drought impact on vegetation growth and mortality

    Science.gov (United States)

    Xu, C.; Wang, M.; Allen, C. D.; McDowell, N. G.; Middleton, R. S.

    2017-12-01

    Vegetation is a key regulator of the global carbon cycle via CO2 absorption through photosynthesis and subsequent growth; however, low water availability, heat stress, and disturbances associated with droughts could substantially reduce vegetation growth and increase vegetation mortality. As far as we know, there are few studies have assessed the drought impact on vegetation growth and mortality at regional and global scales. In this study, we analyzed 13 Earth System models (ESMs) to quantify the impact of drought on GPP and linked the remote-sensing based tree mortality to observed drought indices to assess the drought impact on tree mortality in continental US (CONUS). Our analysis of 13 Earth System models (ESMs) shows that the average global gross primary production (GPP) reduction per year associated with extreme droughts over years 2075-2099 is predicted to be 3-5 times larger than that over years 1850-1999. The annual drought-associated reduction in GPP over years 2075-2099 could be 52 and 74 % of annual fossil fuel carbon emission during years 2000-2007. Increasing drought impacts on GPP are driven primarily by the increasing drought frequency. The risks of drought-associated GPP reduction are particularly high for temperate and tropical regions. The consistent prediction of higher drought-associated reduction in NPP across 13 ESMs suggests increasing impacts of drought on the global carbon cycle with atmospheric warming. Our analysis of drought impact on tree mortality showed that drought-associated carbon loss accounts for 12% of forest carbon loss in CONUS for 2000-2014, which is about one-fifth of that resulting from timber harvesting and 1.35 % of average annual fossil fuel emissions in the U.S. for the same period. The carbon stock loss from natural disturbances for 2000-2014 is approximately 75% of the total carbon loss from anthropogenic disturbance (timber harvesting), suggesting that natural disturbances play a very important role on forest

  5. 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.

  6. Tempered fractional time series model for turbulence in geophysical flows

    Science.gov (United States)

    Meerschaert, Mark M.; Sabzikar, Farzad; Phanikumar, Mantha S.; Zeleke, Aklilu

    2014-09-01

    We propose a new time series model for velocity data in turbulent flows. The new model employs tempered fractional calculus to extend the classical 5/3 spectral model of Kolmogorov. Application to wind speed and water velocity in a large lake are presented, to demonstrate the practical utility of the model.

  7. Tempered fractional time series model for turbulence in geophysical flows

    International Nuclear Information System (INIS)

    Meerschaert, Mark M; Sabzikar, Farzad; Phanikumar, Mantha S; Zeleke, Aklilu

    2014-01-01

    We propose a new time series model for velocity data in turbulent flows. The new model employs tempered fractional calculus to extend the classical 5/3 spectral model of Kolmogorov. Application to wind speed and water velocity in a large lake are presented, to demonstrate the practical utility of the model. (paper)

  8. Joint measurement of risk aversion, prudence, and temperance

    NARCIS (Netherlands)

    Ebert, S.; Wiesen, D.

    Risk aversion—but also the higher-order risk preferences of prudence and temperance—are fundamental concepts in the study of economic decision making. We propose a method to jointly measure the intensity of risk aversion, prudence, and temperance. Our theoretical approach is to define risk

  9. The Fracture Process of Tempered Soda-Lime-Silica Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Stang, Henrik

    2009-01-01

    This work presents experimental observations of the characteristic fracture process of tempered glass. Square specimens with a side length of 300 mm, various thicknesses and a residual stress state characterized by photoelastic measurements were used. Fracture was initiated using a 2.5 mm diamond...

  10. Tempered orbital energies and the potential curve within a molecule

    International Nuclear Information System (INIS)

    Anno, T.; Sakai, Y.

    1979-01-01

    It is shown that the sum of the tempered orbital energies behaves much the same way as does the some of the Hartree--Fock orbital energies. The H 2 moluecule in its minimum basis set description is chosen as an example and comparison of orbital energies is carried out

  11. Significance of rate of work hardening in tempered martensite embrittlement

    International Nuclear Information System (INIS)

    Pietikainen, J.

    1995-01-01

    The main explanations for tempered martensite embrittlement are based on the effects of impurities and cementite precipitation on the prior austenite grain boundaries. There are some studies where the rate of work hardening is proposed as a potential reason for the brittleness. One steel was studied by means of a specially developed precision torsional testing device. The test steel had a high Si and Ni content so ε carbide and Fe 3 C appear in quite different tempering temperature ranges. The M S temperature is low enough so that self tempering does not occur. With the testing device it was possible to obtain the true stress - true strain curves to very high deformations. The minimum toughness was always associated with the minimum of rate of work hardening. The change of deformed steel volume before the loss of mechanical stability is proposed as at least one reason for tempered martensite embrittlement. The reasons for the minimum of the rate of work hardening are considered. (orig.)

  12. Tempered Water Lower Port Connector Structural Analysis Verification

    International Nuclear Information System (INIS)

    CREA, B.A.

    2000-01-01

    Structural analysis of the lower port connection of the Tempered Water System of the Cold Vacuum Drying Facility was performed. Subsequent detailed design changes to enhance operability resulted in the need to re-evaluate the bases of the original analysis to verify its continued validity. This evaluation is contained in Appendix A of this report. The original evaluation is contained in Appendix B

  13. Effects of temperate agriculture on neotropical migrant landbirds

    Science.gov (United States)

    Nicholas L. Rodenhouse; Louis B. Best; Raymond J. O' Connor; Eric K. Bollinger

    1993-01-01

    The ecology of Neotropical migrant landbirds in temperate farmland is reviewed to develop management recommendations for the conservation of migrants. Migrants constitute about 71% of bird species using farmland and 86% of bird species nesting there. The number and abundances of Neotropical migrants using farmland are greatest in uncultivated edges with trees and...

  14. Solid-wood production from temperate eucalypt plantations: a ...

    African Journals Online (AJOL)

    Since 1988, there has been a major focus in Tasmania on research for the management of temperate eucalypt plantations for solid wood. This coincided with the formal transfer of large areas of native forest that had previously been part of the production forest estate into reserves, a decision that triggered the establishment ...

  15. Vegetation Identification With LIDAR

    National Research Council Canada - National Science Library

    Helt, Michael F

    2005-01-01

    .... The specific terrain element of interest is vegetation, and in particular, tree type. Data taken on April 12th, 2005, were taken over a 10 km 20 km region which is mixed use agriculture and wetlands...

  16. Vegetation and soils

    Science.gov (United States)

    Burke, M.K.; King, S.L.; Eisenbies, M.H.; Gartner, D.

    2000-01-01

    Intro paragraph: Characterization of bottomland hardwood vegetation in relatively undisturbed forests can provide critical information for developing effective wetland creation and restoration techniques and for assessing the impacts of management and development. Classification is a useful technique in characterizing vegetation because it summarizes complex data sets, assists in hypothesis generation about factors influencing community variation, and helps refine models of community structure. Hierarchical classification of communities is particularly useful for showing relationships among samples (Gauche 1982).

  17. 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

  18. Bifurcation dynamics of the tempered fractional Langevin equation

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Caibin, E-mail: macbzeng@scut.edu.cn; Yang, Qigui, E-mail: qgyang@scut.edu.cn [School of Mathematics, South China University of Technology, Guangzhou 510640 (China); Chen, YangQuan, E-mail: ychen53@ucmerced.edu [MESA LAB, School of Engineering, University of California, Merced, 5200 N. Lake Road, Merced, California 95343 (United States)

    2016-08-15

    Tempered fractional processes offer a useful extension for turbulence to include low frequencies. In this paper, we investigate the stochastic phenomenological bifurcation, or stochastic P-bifurcation, of the Langevin equation perturbed by tempered fractional Brownian motion. However, most standard tools from the well-studied framework of random dynamical systems cannot be applied to systems driven by non-Markovian noise, so it is desirable to construct possible approaches in a non-Markovian framework. We first derive the spectral density function of the considered system based on the generalized Parseval's formula and the Wiener-Khinchin theorem. Then we show that it enjoys interesting and diverse bifurcation phenomena exchanging between or among explosive-like, unimodal, and bimodal kurtosis. Therefore, our procedures in this paper are not merely comparable in scope to the existing theory of Markovian systems but also provide a possible approach to discern P-bifurcation dynamics in the non-Markovian settings.

  19. Linking Well-Tempered Metadynamics Simulations with Experiments

    Science.gov (United States)

    Barducci, Alessandro; Bonomi, Massimiliano; Parrinello, Michele

    2010-01-01

    Abstract Linking experiments with the atomistic resolution provided by molecular dynamics simulations can shed light on the structure and dynamics of protein-disordered states. The sampling limitations of classical molecular dynamics can be overcome using metadynamics, which is based on the introduction of a history-dependent bias on a small number of suitably chosen collective variables. Even if such bias distorts the probability distribution of the other degrees of freedom, the equilibrium Boltzmann distribution can be reconstructed using a recently developed reweighting algorithm. Quantitative comparison with experimental data is thus possible. Here we show the potential of this combined approach by characterizing the conformational ensemble explored by a 13-residue helix-forming peptide by means of a well-tempered metadynamics/parallel tempering approach and comparing the reconstructed nuclear magnetic resonance scalar couplings with experimental data. PMID:20441734

  20. Reversible temper brittleness on tensile tests at room temperature

    International Nuclear Information System (INIS)

    Quadros, N.F. de; Cabral, U.Q.

    1976-01-01

    Tensile tests were carried out on unnotched test pieces at room temperature and three strain rates: 2,5x10 -4 , 2,5x10 -3 and 1,0x10 -2 s -1 in a low alloy No-Cr-Mo steel to observe the variation in its mechanical properties with the occurrence of reversible temper brittleness. The brittle samples showed a sensitivity of 50 0 C in a 48 hour heat treatment at 500 0 C. The tests showed that at the strain rate of 2,5x10 -4 s -1 there are statistically significant differences between the elongations of the material in the brittle and the nonbrittle and regenerated states. A short review of reversible temper brittleness is given and a theory suggested for the mechanism [pt

  1. The tempered stable process with infinitely divisible inverse subordinators

    International Nuclear Information System (INIS)

    Wyłomańska, Agnieszka

    2013-01-01

    In the last decade processes driven by inverse subordinators have become extremely popular. They have been used in many different applications, especially for data with observable constant time periods. However, the classical model, i.e. the subordinated Brownian motion, can be inappropriate for the description of observed phenomena that exhibit behavior not adequate for Gaussian systems. Therefore, in this paper we extend the classical approach and replace the Brownian motion by the tempered stable process. Moreover, on the other hand, as an extension of the classical model, we analyze the general class of inverse subordinators. We examine the main properties of the tempered stable process driven by inverse subordinators from the infinitely divisible class of distributions. We show the fractional Fokker–Planck equation of the examined process and the asymptotic behavior of the mean square displacement for two cases of subordinators. Additionally, we examine how an external force can influence the examined characteristics. (paper)

  2. Effect of tempering on corrosion resistance of cast aluminium bronzes

    International Nuclear Information System (INIS)

    Aaltonen, P.; Klemetti, K.; Haenninen, H.

    1985-01-01

    The subject of this study is corrosion resistance of aluminium bronzes, which are copper base alloys containing aluminium up to 12% with additions of nickel, iron and manganese. The main conclutions that can be drawn are: (1) The dealloying corrosion resistance of nickel-aluminium bronze is much better than that of aluminium bronze with iron and manganese additions, but it is not immune; (2) The dealloying corrosion resistance of aluminium bronzes can be improved by appropiate heat treatments. The best properties were obtained by temperering between 600 and 800 deg C, depending on the initial microstructure; (3) In crevice conditions, where local acidification can occur, dealloying of aluminium bronzes is a consequence of the preferential attack of aluminium-rich phases. By appropriate tempering, a uniform distribution of aluminium-rich phases is obtained and the continous path for selective corrosion is not formed

  3. Interspecific variation in total phenolic content in temperate brown algae

    Directory of Open Access Journals (Sweden)

    Anna Maria Mannino

    2017-09-01

    Full Text Available Marine algae synthesize secondary metabolites such as polyphenols that function as defense and protection mechanisms. Among brown algae, Fucales and Dictyotales (Phaeophyceae contain the highest levels of phenolic compounds, mainly phlorotannins, that play multiple roles. Four temperate brown algae (Cystoseira amentacea, Cystoseira compressa, Dictyopteris polypodioides and Padina pavonica were studied for total phenolic contents. Total phenolic content was determined colorimetrically with the Folin-Ciocalteu reagent. Significant differences in total phenolic content were observed between leathery and sheetlike algae and also within each morphological group. Among the four species, the sheet-like alga D. polypodioides, living in the upper infralittoral zone, showed the highest concentration of phenolic compounds. These results are in agreement with the hypothesis that total phenolic content in temperate brown algae is influenced by a combination of several factors, such as growth form, depth, and exposition to solar radiation.

  4. The Vegetables Turned:

    DEFF Research Database (Denmark)

    Carter, Dale

    2009-01-01

    in the relationship between creative artists and the Anglo-American popular music industry in the mid-1960s. Finally, and in retrospect, the figure of the vegetable cast into relief the counter-culture's utopian and dystopian dynamics as manifested in these song-writers' personal lives, now rendered as contemporary...... lyricist Van Dyke Parks, the incongruous, semantically complex figure of the vegetable came to illuminate aspects of psychedelic consciousness and - part by design, part by accident - the link between LSD and Anglo-American popular music. It threw light, too, on the scope and limits of changes...

  5. Altitudinal variation in soil organic carbon stock in coniferous subtropical and broadleaf temperate forests in Garhwal Himalaya

    Directory of Open Access Journals (Sweden)

    Kumar Munesh

    2009-08-01

    Full Text Available Abstract Background The Himalayan zones, with dense forest vegetation, cover a fifth part of India and store a third part of the country reserves of soil organic carbon (SOC. However, the details of altitudinal distribution of these carbon stocks, which are vulnerable to forest management and climate change impacts, are not well known. Results This article reports the results of measuring the stocks of SOC along altitudinal gradients. The study was carried out in the coniferous subtropical and broadleaf temperate forests of Garhwal Himalaya. The stocks of SOC were found to be decreasing with altitude: from 185.6 to 160.8 t C ha-1 and from 141.6 to 124.8 t C ha-1 in temperature (Quercus leucotrichophora and subtropical (Pinus roxburghii forests, respectively. Conclusion The results of this study lead to conclusion that the ability of soil to stabilize soil organic matter depends negatively on altitude and call for comprehensive theoretical explanation

  6. Hurricane Impacts to Tropical and Temperate Forest Landscapes

    OpenAIRE

    Boose, Emery Robert; Foster, David Russell; Fluet, Marcheterre

    1994-01-01

    Hurricanes represent an important natural disturbance process to tropical and temperate forests in many coastal areas of the world. The complex patterns of damage created in forests by hurricane winds result from the interaction of meteorological, physiographic, and biotic factors on a range of spatial scales. To improve our understanding of these factors and of the role of catastrophic hurricane wind as a disturbance process, we take an integrative approach. A simple meteorological model (HU...

  7. First description of underwater acoustic diversity in three temperate ponds

    Directory of Open Access Journals (Sweden)

    Camille Desjonquères

    2015-11-01

    Full Text Available The past decade has produced an increased ecological interest in sonic environments, or soundscapes. However, despite this rise in interest and technological improvements that allow for long-term acoustic surveys in various environments, some habitats’ soundscapes remain to be explored. Ponds, and more generally freshwater habitats, are one of these acoustically unexplored environments. Here we undertook the first long term acoustic monitoring of three temperate ponds in France. By aural and visual inspection of a selection of recordings, we identified 48 different sound types, and according to the rarefaction curves we calculated, more sound types are likely present in one of the three ponds. The richness of sound types varied significantly across ponds. Surprisingly, there was no pond-to-pond daily consistency of sound type richness variation; each pond had its own daily patterns of activity. We also explored the possibility of using six acoustic diversity indices to conduct rapid biodiversity assessments in temperate ponds. We found that all indices were sensitive to the background noise as estimated through correlations with the signal-to-noise ratio (SNR. However, we determined that the AR index could be a good candidate to measure acoustic diversities using partial correlations with the SNR as a control variable. Yet, research is still required to automatically compute the SNR in order to apply this index on a large data set of recordings. The results showed that these three temperate ponds host a high level of acoustic diversity in which the soundscapes were variable not only between but also within the ponds. The sources producing this diversity of sounds and the drivers of difference in daily song type richness variation both require further investigation. Such research would yield insights into the biodiversity and ecology of temperate ponds.

  8. 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

  9. 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

  10. Efficient assignment of the temperature set for Parallel Tempering

    International Nuclear Information System (INIS)

    Guidetti, M.; Rolando, V.; Tripiccione, R.

    2012-01-01

    We propose a simple algorithm able to identify a set of temperatures for a Parallel Tempering Monte Carlo simulation, that maximizes the probability that the configurations drift across all temperature values, from the coldest to the hottest ones, and vice versa. The proposed algorithm starts from data gathered from relatively short Monte Carlo simulations and is straightforward to implement. We assess its effectiveness on a test case simulation of an Edwards–Anderson spin glass on a lattice of 12 3 sites.

  11. Grain boundary diffusion in terms of the tempered fractional calculus

    Energy Technology Data Exchange (ETDEWEB)

    Sibatov, R.T., E-mail: ren_sib@bk.ru [Ulyanovsk State University, 432017, 42 Leo Tolstoy str., Ulyanovsk (Russian Federation); Svetukhin, V.V. [Ulyanovsk State University, 432017, 42 Leo Tolstoy str., Ulyanovsk (Russian Federation); Institute of Nanotechnology and Microelectronics of the Russian Academy of Sciences, 115487, 18 Nagatinskaya str., Moscow (Russian Federation)

    2017-06-28

    Mathematical treatment of grain-boundary diffusion based on the model first proposed by Fisher is usually formulated in terms of normal diffusion equations in a two-component nonhomogeneous medium. On the other hand, fractional equations of anomalous diffusion proved themselves to be useful in description of grain-boundary diffusion phenomena. Moreover, the most important propagation regime predicted by Fisher's model demonstrates subdiffusive behavior. However, the direct link between fractional approach and the Fisher model and its modifications has not found yet. Here, we fill this gap and show that solution of fractional subdiffusion equation offers general properties of classical solutions obtained by Whipple and Suzuoka. The tempered fractional approach is a convenient tool for studying precipitation in granular materials as the tempered subdiffusion limited process. - Highlights: • The link connected fractional diffusion approach and Fisher's model of grain-boundary diffusion is derived. • The subdiffusion exponent of grain-boundary diffusion can differ from 1/2. • Nucleation in granular materials is modeled by the process limited by tempered subdiffusion.

  12. Biochar boosts tropical but not temperate crop yields

    Science.gov (United States)

    Jeffery, Simon; Abalos, Diego; Prodana, Marija; Catarina Bastos, Ana; van Groenigen, Jan Willem; Hungate, Bruce A.; Verheijen, Frank

    2017-05-01

    Applying biochar to soil is thought to have multiple benefits, from helping mitigate climate change [1, 2], to managing waste [3] to conserving soil [4]. Biochar is also widely assumed to boost crop yield [5, 6], but there is controversy regarding the extent and cause of any yield benefit [7]. Here we use a global-scale meta-analysis to show that biochar has, on average, no effect on crop yield in temperate latitudes, yet elicits a 25% average increase in yield in the tropics. In the tropics, biochar increased yield through liming and fertilization, consistent with the low soil pH, low fertility, and low fertilizer inputs typical of arable tropical soils. We also found that, in tropical soils, high-nutrient biochar inputs stimulated yield substantially more than low-nutrient biochar, further supporting the role of nutrient fertilization in the observed yield stimulation. In contrast, arable soils in temperate regions are moderate in pH, higher in fertility, and generally receive higher fertilizer inputs, leaving little room for additional benefits from biochar. Our findings demonstrate that the yield-stimulating effects of biochar are not universal, but may especially benefit agriculture in low-nutrient, acidic soils in the tropics. Biochar management in temperate zones should focus on potential non-yield benefits such as lime and fertilizer cost savings, greenhouse gas emissions control, and other ecosystem services.

  13. Grain boundary diffusion in terms of the tempered fractional calculus

    International Nuclear Information System (INIS)

    Sibatov, R.T.; Svetukhin, V.V.

    2017-01-01

    Mathematical treatment of grain-boundary diffusion based on the model first proposed by Fisher is usually formulated in terms of normal diffusion equations in a two-component nonhomogeneous medium. On the other hand, fractional equations of anomalous diffusion proved themselves to be useful in description of grain-boundary diffusion phenomena. Moreover, the most important propagation regime predicted by Fisher's model demonstrates subdiffusive behavior. However, the direct link between fractional approach and the Fisher model and its modifications has not found yet. Here, we fill this gap and show that solution of fractional subdiffusion equation offers general properties of classical solutions obtained by Whipple and Suzuoka. The tempered fractional approach is a convenient tool for studying precipitation in granular materials as the tempered subdiffusion limited process. - Highlights: • The link connected fractional diffusion approach and Fisher's model of grain-boundary diffusion is derived. • The subdiffusion exponent of grain-boundary diffusion can differ from 1/2. • Nucleation in granular materials is modeled by the process limited by tempered subdiffusion.

  14. Comparative visual ecophysiology of mid-Atlantic temperate reef fishes

    Directory of Open Access Journals (Sweden)

    Andrij Z. Horodysky

    2013-11-01

    The absolute light sensitivities, temporal properties, and spectral sensitivities of the visual systems of three mid-Atlantic temperate reef fishes (Atlantic spadefish [Ephippidae: Chaetodipterus faber], tautog [Labridae: Tautoga onitis], and black sea bass [Serranidae: Centropristis striata] were studied via electroretinography (ERG. Pelagic Atlantic spadefish exhibited higher temporal resolution but a narrower dynamic range than the two more demersal foragers. The higher luminous sensitivities of tautog and black sea bass were similar to other benthic and demersal coastal mid-Atlantic fishes. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of the three species spanned 400–610 nm, with high likelihood of cone dichromacy providing the basis for color and contrast discrimination. Significant day-night differences in spectral responses were evident in spadefish and black sea bass but not tautog, a labrid with characteristic structure-associated nocturnal torpor. Atlantic spadefish responded to a wider range of wavelengths than did deeper-dwelling tautog or black sea bass. Collectively, these results suggest that temperate reef-associated fishes are well-adapted to their gradient of brighter to dimmer photoclimates, representative of their unique ecologies and life histories. Continuing anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may however impede visual foraging and reproductive signaling in temperate reef fishes.

  15. Carbon sequestration in managed temperate coniferous forests under climate change

    Science.gov (United States)

    Dymond, Caren C.; Beukema, Sarah; Nitschke, Craig R.; Coates, K. David; Scheller, Robert M.

    2016-03-01

    Management of temperate forests has the potential to increase carbon sinks and mitigate climate change. However, those opportunities may be confounded by negative climate change impacts. We therefore need a better understanding of climate change alterations to temperate forest carbon dynamics before developing mitigation strategies. The purpose of this project was to investigate the interactions of species composition, fire, management, and climate change in the Copper-Pine Creek valley, a temperate coniferous forest with a wide range of growing conditions. To do so, we used the LANDIS-II modelling framework including the new Forest Carbon Succession extension to simulate forest ecosystems under four different productivity scenarios, with and without climate change effects, until 2050. Significantly, the new extension allowed us to calculate the net sector productivity, a carbon accounting metric that integrates aboveground and belowground carbon dynamics, disturbances, and the eventual fate of forest products. The model output was validated against literature values. The results implied that the species optimum growing conditions relative to current and future conditions strongly influenced future carbon dynamics. Warmer growing conditions led to increased carbon sinks and storage in the colder and wetter ecoregions but not necessarily in the others. Climate change impacts varied among species and site conditions, and this indicates that both of these components need to be taken into account when considering climate change mitigation activities and adaptive management. The introduction of a new carbon indicator, net sector productivity, promises to be useful in assessing management effectiveness and mitigation activities.

  16. Climate change implications in the northern coastal temperate rainforest of North America

    Science.gov (United States)

    Shanley, Colin S.; Pyare, Sanjay; Goldstein, Michael I.; Alaback, Paul B.; Albert, David M.; Beier, Colin M.; Brinkman, Todd J.; Edwards, Rick T.; Hood, Eran; MacKinnon, Andy; McPhee, Megan V.; Patterson, Trista; Suring, Lowell H.; Tallmon, David; Wipfli, Mark S.

    2015-01-01

    We synthesized an expert review of climate change implications for hydroecological and terrestrial ecological systems in the northern coastal temperate rainforest of North America. Our synthesis is based on an analysis of projected temperature, precipitation, and snowfall stratified by eight biogeoclimatic provinces and three vegetation zones. Five IPCC CMIP5 global climate models (GCMs) and two representative concentration pathways (RCPs) are the basis for projections of mean annual temperature increasing from a current average (1961–1990) of 3.2 °C to 4.9–6.9 °C (5 GCM range; RCP4.5 scenario) or 6.4–8.7 °C (RCP8.5), mean annual precipitation increasing from 3130 mm to 3210–3400 mm (3–9 % increase) or 3320–3690 mm (6–18 % increase), and total precipitation as snow decreasing from 1200 mm to 940–720 mm (22–40 % decrease) or 720–500 mm (40–58 % decrease) by the 2080s (2071–2100; 30-year normal period). These projected changes are anticipated to result in a cascade of ecosystem-level effects including: increased frequency of flooding and rain-on-snow events; an elevated snowline and reduced snowpack; changes in the timing and magnitude of stream flow, freshwater thermal regimes, and riverine nutrient exports; shrinking alpine habitats; altitudinal and latitudinal expansion of lowland and subalpine forest types; shifts in suitable habitat boundaries for vegetation and wildlife communities; adverse effects on species with rare ecological niches or limited dispersibility; and shifts in anadromous salmon distribution and productivity. Our collaborative synthesis of potential impacts highlights the coupling of social and ecological systems that characterize the region as well as a number of major information gaps to help guide assessments of future conditions and adaptive capacity.

  17. leafy vegetable, Gnetum africanum

    African Journals Online (AJOL)

    A prerequisite for successful in vitro culture is the establishment of an aseptic technique, thus the experiment was to investigate suitable sterilization regimes for the leaf explants of Gnetum africanum, an endangered green leafy vegetable. Three sterilization regimes were tested to establish the best regime using three to four ...

  18. The possibility of tribopair lifetime extending by welding of quenched and tempered stainless steel with quenched and tempered carbon steel

    Directory of Open Access Journals (Sweden)

    V. Marušić

    2015-04-01

    Full Text Available In the conditions of tribocorrosion wear, extending of parts lifetime could be achieved by using stainless steel,which is hardened to sufficiently high hardness. In the tribosystem bolt/ bushing shell/link plate of the bucket elevator transporter conveyor machine, the previously quenched and tempered martensitic stainless steel for bolts is hardened at ≈47 HRC and welded with the quenched and tempered high yield carbon steel for bolts. Additional material, based on Cr-Ni-Mo (18/8/6 is used. The microstructure and hardness of welded samples are tested. On the tensile tester, resistance of the welded joint is tested with a simulated experiment. Dimensional control of worn tribosystem elements was performed after six months of service.

  19. Spent nuclear fuel project cold vacuum drying facility tempered water and tempered water cooling system design description

    International Nuclear Information System (INIS)

    IRWIN, J.J.

    1998-01-01

    This document provides the System Design Description (SDD) for the Cold Vacuum Drying Facility (CVDF) Tempered Water (TW) and Tempered Water Cooling (TWC) System . The SDD was developed in conjunction with HNF-SD-SNF-SAR-002, Safety Analysis Report for the Cold Vacuum Drying Facility, Phase 2, Supporting Installation of Processing Systems (Garvin 1998), The HNF-SD-SNF-DRD-O02, 1998, Cold Vacuum Drying Facility Design Requirements, and the CVDF Design Summary Report. The SDD contains general descriptions of the TW and TWC equipment, the system functions, requirements and interfaces. The SDD provides references for design and fabrication details, operation sequences and maintenance. This SOD has been developed for the SNFP Operations Organization and shall be updated, expanded, and revised in accordance with future design, construction and startup phases of the CVDF until the CVDF final ORR is approved

  20. Classification of Snowfall Events and Their Effect on Canopy Interception Efficiency in a Temperate Montane Forest.

    Science.gov (United States)

    Roth, T. R.; Nolin, A. W.

    2015-12-01

    Forest canopies intercept as much as 60% of snowfall in maritime environments, while processes of sublimation and melt can reduce the amount of snow transferred from the canopy to the ground. This research examines canopy interception efficiency (CIE) as a function of forest and event-scale snowfall characteristics. We use a 4-year dataset of continuous meteorological measurements and monthly snow surveys from the Forest Elevation Snow Transect (ForEST) network that has forested and open sites at three elevations spanning the rain-snow transition zone to the upper seasonal snow zone. Over 150 individual storms were classified by forest and storm type characteristics (e.g. forest density, vegetation type, air temperature, snowfall amount, storm duration, wind speed, and storm direction). The between-site comparisons showed that, as expected, CIE was highest for the lower elevation (warmer) sites with higher forest density compared with the higher elevation sites where storm temperatures were colder, trees were smaller and forests were less dense. Within-site comparisons based on storm type show that this classification system can be used to predict CIE.Our results suggest that the coupling of forest type and storm type information can improve estimates of canopy interception. Understanding the effects of temperature and storm type in temperate montane forests is also valuable for future estimates of canopy interception under a warming climate.

  1. Virtual water content of temperate cereals and maize: Present and potential future patterns

    Science.gov (United States)

    Fader, Marianela; Rost, Stefanie; Müller, Christoph; Bondeau, Alberte; Gerten, Dieter

    2010-04-01

    SummaryKnowledge of the virtual water content (VWC) of crops and especially its possible future developments is helpful for improvements in water productivity and water management, which are necessary at global scale due to rising demand for food, the necessity to ease present and future water scarcity, and the reduction of poverty. Using a dynamic global vegetation and water balance model (LPJmL), this study quantifies the VWC of two of the most important crop types worldwide, temperate cereals and maize, at high spatial resolution (0.5°). We analyzed present conditions (1999-2003) and also for the first time also for scenarios of future climate and increasing atmospheric CO 2 concentrations (2041-2070; HadCM3, ECHAM5 and CCSM3 climate models, A2 emissions scenario). VWC presently differs significantly among regions: highest values are common in large parts of Africa (>2 m 3 kg -1), and lowest values were found e.g. for Central Europe (Europe, South Africa, Argentina, Australia and South East Asia—are projected to become less water efficient (higher VWC) for at least one of the crop types. CO 2 fertilisation was simulated to generally reduce VWC, though realisation of this effect in the field will depend, for example, on the intensity of nutrient management in the future. The potentially adverse future changes in VWC found here pose a challenge to water management efforts and eventually global trade policies.

  2. Facilitation between woody and herbaceous plants that associate with arbuscular mycorrhizal fungi in temperate European forests.

    Science.gov (United States)

    Veresoglou, Stavros D; Wulf, Monika; Rillig, Matthias C

    2017-02-01

    In late-successional environments, low in available nutrient such as the forest understory, herbaceous plant individuals depend strongly on their mycorrhizal associates for survival. We tested whether in temperate European forests arbuscular mycorrhizal (AM) woody plants might facilitate the establishment of AM herbaceous plants in agreement with the mycorrhizal mediation hypothesis. We used a dataset spanning over 400 vegetation plots in the Weser-Elbe region (northwest Germany). Mycorrhizal status information was obtained from published resources, and Ellenberg indicator values were used to infer environmental data. We carried out tests for both relative richness and relative abundance of herbaceous plants. We found that the subset of herbaceous individuals that associated with AM profited when there was a high cover of AM woody plants. These relationships were retained when we accounted for environmental filtering effects using path analysis. Our findings build on the existing literature highlighting the prominent role of mycorrhiza as a coexistence mechanism in plant communities. From a nature conservation point of view, it may be possible to promote functional diversity in the forest understory through introducing AM woody trees in stands when absent.

  3. Linking root traits to nutrient foraging in arbuscular mycorrhizal trees in a temperate forest.

    Science.gov (United States)

    Eissenstat, David M; Kucharski, Joshua M; Zadworny, Marcin; Adams, Thomas S; Koide, Roger T

    2015-10-01

    The identification of plant functional traits that can be linked to ecosystem processes is of wide interest, especially for predicting vegetational responses to climate change. Root diameter of the finest absorptive roots may be one plant trait that has wide significance. Do species with relatively thick absorptive roots forage in nutrient-rich patches differently from species with relatively fine absorptive roots? We measured traits related to nutrient foraging (root morphology and architecture, root proliferation, and mycorrhizal colonization) across six coexisting arbuscular mycorrhizal (AM) temperate tree species with and without nutrient addition. Root traits such as root diameter and specific root length were highly correlated with root branching intensity, with thin-root species having higher branching intensity than thick-root species. In both fertilized and unfertilized soil, species with thin absorptive roots and high branching intensity showed much greater root length and mass proliferation but lower mycorrhizal colonization than species with thick absorptive roots. Across all species, fertilization led to increased root proliferation and reduced mycorrhizal colonization. These results suggest that thin-root species forage more by root proliferation, whereas thick-root species forage more by mycorrhizal fungi. In mineral nutrient-rich patches, AM trees seem to forage more by proliferating roots than by mycorrhizal fungi. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  4. Twenty-Two Years of Warming, Fertilisation and Shading of Subarctic Heath Shrubs Promote Secondary Growth and Plasticity but Not Primary Growth

    Science.gov (United States)

    Campioli, Matteo; Leblans, Niki; Michelsen, Anders

    2012-01-01

    Most manipulation experiments simulating global change in tundra were short-term or did not measure plant growth directly. Here, we assessed the growth of three shrubs (Cassiope tetragona, Empetrum hermaphroditum and Betula nana) at a subarctic heath in Abisko (Northern Sweden) after 22 years of warming (passive greenhouses), fertilisation (nutrients addition) and shading (hessian fabric), and compare this to observations from the first decade of treatment. We assessed the growth rate of current-year leaves and apical stem (primary growth) and cambial growth (secondary growth), and integrated growth rates with morphological measurements and species coverage. Primary- and total growth of Cassiope and Empetrum were unaffected by manipulations, whereas growth was substantially reduced under fertilisation and shading (but not warming) for Betula. Overall, shrub height and length tended to increase under fertilisation and warming, whereas branching increased mostly in shaded Cassiope. Morphological changes were coupled to increased secondary growth under fertilisation. The species coverage showed a remarkable increase in graminoids in fertilised plots. Shrub response to fertilisation was positive in the short-term but changed over time, likely because of an increased competition with graminoids. More erected postures and large, canopies (requiring enhanced secondary growth for stem reinforcement) likely compensated for the increased light competition in Empetrum and Cassiope but did not avoid growth reduction in the shade intolerant Betula. The impact of warming and shading on shrub growth was more conservative. The lack of growth enhancement under warming suggests the absence of long-term acclimation for processes limiting biomass production. The lack of negative effects of shading on Cassiope was linked to morphological changes increasing the photosynthetic surface. Overall, tundra shrubs showed developmental plasticity over the longer term. However, such plasticity

  5. Prediction of hardness in pieces of quenched and tempered steel

    International Nuclear Information System (INIS)

    Yanzon, Rodolfo Carlos; Rodriguez, Augusto; Sanchez, Arlington Ricardo

    2006-01-01

    This presentation describes the first stage of a work plan to obtain a simple software, for predicting properties at certain points of a quenched and tempered piece. In this first stage, this prediction is limited to cylindrical pieces made with steels whose chemical composition is within a certain range. The methodology basically consists of obtaining , from experimental data, a mathematical tool able to predict the hardness value, for Jominy test piece ends made with this type of steel. This meant beginning with the analysis of the usual forms of theoretical calculation of Jominy curves of quenched samples, which resulted in a proposal to modify the Just equation. Two different mathematical methods were then developed, that could predict hardness values in tempered Jominy test pieces. One, based on the determination of polynomic equations, that reproduces the loss of hardness at points along the test piece, base on the quenching value and as a function of the tempering temperature. The other one, which uses the lineal multidimensional interpolation method, because of its ease of application, has been selected as the mathematical tool to use in the software under development. At this stage of the work, the relationship between the points on the piece and those on the Jominy test pieces is carried out by the Lamont method and the representative variable of the temperature/time combination for the tempering process itself, is obtained with software based on the Hollomon and Jaffe expression. Data is needed to define: a) chemical composition and grain size of the steel used, b) diameter of the piece, c) 'H G ' severity of the quenching medium d) temperature and time of the tempering. The work's second stage continued with the addition of hardness values measured in Jominy test pieces made with other steels. The chemical composition and grain size data of each steel introduced are converted by the software into one more variable, using the concept of ideal critical

  6. 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.

  7. Canopy Modeling of Aquatic Vegetation: Construction of Submerged Vegetation Index

    Science.gov (United States)

    Ma, Z.; Zhou, G.

    2018-04-01

    The unique spectral characteristics of submerged vegetation in wetlands determine that the conventional terrestrial vegetation index cannot be directly employed to species identification and parameter inversion of submerged vegetation. Based on the Aquatic Vegetation Radiative Transfer model (AVRT), this paper attempts to construct an index suitable for submerged vegetation, the model simulated data and a scene of Sentinel-2A image in Taihu Lake, China are utilized for assessing the performance of the newly constructed indices and the existent vegetation indices. The results show that the angle index composed by 525 nm, 555 nm and 670 nm can resist the effects of water columns and is more sensitive to vegetation parameters such as LAI. Furthermore, it makes a well discrimination between submerged vegetation and water bodies in the satellite data. We hope that the new index will provide a theoretical basis for future research.

  8. Holocene stratigraphy and vegetation history in the Scoresby Sund area, East Greenland

    International Nuclear Information System (INIS)

    Funder, S.

    1978-01-01

    The Holocene stratigraphy in Scoresby Sund is based on climatic change reflected by fluctuations in fjord and valley glaciers, immigration and extinction of marine molluscs, and the vegetation history recorded in pollen diagrams from five lakes. The histories are dated by C-14, and indirectly by emergence curves showing the patterns of isostatic uplift. From c. 10100-10400 to 9400 yr BP the major fjord glaciers showed oscillatory retreat with abundant moraine formation, the period of the Milne Land Moraines. The vegetation in the ice free areas was a sparse type of fell field vetetation but with thermophilous elements indicating temperatures similar to the present. From 9400 yr BP the fjord glaciers retreated rapidly in the narrow fjords, the few moraines formed are referred to the Roedefjord stages and indicate topographically conditioned stillstands. At 8000 yr BP the low arctic Betula nana imigrated into the area, and in the period until 5000 yr BP dense dwarf shrub heat grew in areas where it is now absent. In the fjords the subarctic Mytilus edulis and Pecten islandia lived, suggesting a climate warmer than the present. From c. 5000 yr BP the dense dwarf shrub heath began to disappear in the coastal areas, and a ''poor'' heat dominated by the high arctic Salix Arctica and Cassiope tetragona expanded. These two species, which are now extremely common, apparently did not grow in the area until c. 6000 yr BP. In lakes in the coastal area minerogenic sedimentation at c. 2800 yr BP, reflecting the general climatic deterioration. (author)

  9. Review of Vegetable Market Development in China

    Institute of Scientific and Technical Information of China (English)

    Chaoping; LUO; Yuandong; NI; Qiong; ZHAI

    2013-01-01

    This paper has reviewed vegetable market development from vegetable circulation system, the develop history of the liberalize vegetable market and the growth of the vegetable wholesale market in China. From the development of vegetables market in China and its characteristics: the development of vegetable market in China is related to vegetable market system, the change of institution, some technology development and infrastructure. this paper has put forward some related measures to perfect the vegetable market and improve the vegetable circulation efficiency in China.

  10. The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts

    Science.gov (United States)

    Vergés, Adriana; Steinberg, Peter D.; Hay, Mark E.; Poore, Alistair G. B.; Campbell, Alexandra H.; Ballesteros, Enric; Heck, Kenneth L.; Booth, David J.; Coleman, Melinda A.; Feary, David A.; Figueira, Will; Langlois, Tim; Marzinelli, Ezequiel M.; Mizerek, Toni; Mumby, Peter J.; Nakamura, Yohei; Roughan, Moninya; van Sebille, Erik; Gupta, Alex Sen; Smale, Dan A.; Tomas, Fiona; Wernberg, Thomas; Wilson, Shaun K.

    2014-01-01

    Climate-driven changes in biotic interactions can profoundly alter ecological communities, particularly when they impact foundation species. In marine systems, changes in herbivory and the consequent loss of dominant habitat forming species can result in dramatic community phase shifts, such as from coral to macroalgal dominance when tropical fish herbivory decreases, and from algal forests to ‘barrens’ when temperate urchin grazing increases. Here, we propose a novel phase-shift away from macroalgal dominance caused by tropical herbivores extending their range into temperate regions. We argue that this phase shift is facilitated by poleward-flowing boundary currents that are creating ocean warming hotspots around the globe, enabling the range expansion of tropical species and increasing their grazing rates in temperate areas. Overgrazing of temperate macroalgae by tropical herbivorous fishes has already occurred in Japan and the Mediterranean. Emerging evidence suggests similar phenomena are occurring in other temperate regions, with increasing occurrence of tropical fishes on temperate reefs. PMID:25009065

  11. An investigation on high temperature fatigue properties of tempered nuclear-grade deposited weld metals

    Science.gov (United States)

    Cao, X. Y.; Zhu, P.; Yong, Q.; Liu, T. G.; Lu, Y. H.; Zhao, J. C.; Jiang, Y.; Shoji, T.

    2018-02-01

    Effect of tempering on low cycle fatigue (LCF) behaviors of nuclear-grade deposited weld metal was investigated, and The LCF tests were performed at 350 °C with strain amplitudes ranging from 0.2% to 0.6%. The results showed that at a low strain amplitude, deposited weld metal tempered for 1 h had a high fatigue resistance due to high yield strength, while at a high strain amplitude, the one tempered for 24 h had a superior fatigue resistance due to high ductility. Deposited weld metal tempered for 1 h exhibited cyclic hardening at the tested strain amplitudes. Deposited weld metal tempered for 24 h exhibited cyclic hardening at a low strain amplitude but cyclic softening at a high strain amplitude. Existence and decomposition of martensite-austenite (M-A) islands as well as dislocations activities contributed to fatigue property discrepancy among the two tempered deposited weld metal.

  12. Biogenic volatile organic compound emissions from vegetation fires.

    Science.gov (United States)

    Ciccioli, Paolo; Centritto, Mauro; Loreto, Francesco

    2014-08-01

    The aim of this paper was to provide an overview of the current state of the art on research into the emission of biogenic volatile organic compounds (BVOCs) from vegetation fires. Significant amounts of VOCs are emitted from vegetation fires, including several reactive compounds, the majority belonging to the isoprenoid family, which rapidly disappear in the plume to yield pollutants such as secondary organic aerosol and ozone. This makes determination of fire-induced BVOC emission difficult, particularly in areas where the ratio between VOCs and anthropogenic NOx is favourable to the production of ozone, such as Mediterranean areas and highly anthropic temperate (and fire-prone) regions of the Earth. Fire emissions affecting relatively pristine areas, such as the Amazon and the African savannah, are representative of emissions of undisturbed plant communities. We also examined expected BVOC emissions at different stages of fire development and combustion, from drying to flaming, and from heatwaves coming into contact with unburned vegetation at the edge of fires. We conclude that forest fires may dramatically change emission factors and the profile of emitted BVOCs, thereby influencing the chemistry and physics of the atmosphere, the physiology of plants and the evolution of plant communities within the ecosystem. © 2014 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

  13. Cruciferous Vegetables and Cancer Prevention

    Science.gov (United States)

    ... case-control studies have found that people who ate greater amounts of cruciferous vegetables had a lower ... Professionals’ Follow-up Study—showed that women who ate more than 5 servings of cruciferous vegetables per ...

  14. Effect of Tempering and Baking on the Charpy Impact Energy of Hydrogen-Charged 4340 Steel

    Science.gov (United States)

    Mori, K.; Lee, E. W.; Frazier, W. E.; Niji, K.; Battel, G.; Tran, A.; Iriarte, E.; Perez, O.; Ruiz, H.; Choi, T.; Stoyanov, P.; Ogren, J.; Alrashaid, J.; Es-Said, O. S.

    2015-01-01

    Tempered AISI 4340 steel was hydrogen charged and tested for impact energy. It was found that samples tempered above 468 °C (875 °F) and subjected to hydrogen charging exhibited lower impact energy values when compared to uncharged samples. No significant difference between charged and uncharged samples tempered below 468 °C (875 °F) was observed. Neither exposure nor bake time had any significant effect on impact energy within the tested ranges.

  15. On the evolution of Cu-Ni-rich bridges of Alnico alloys with tempering

    Energy Technology Data Exchange (ETDEWEB)

    Fan, M. [Department of Materials Science and Engineering, North Carolina State University, Campus Box 7907, Raleigh, NC 27695-7907 (United States); Liu, Y. [Department of Materials Science and Engineering, North Carolina State University, Campus Box 7907, Raleigh, NC 27695-7907 (United States); Analytical Instrumentation Facility, North Carolina State University, Raleigh, NC 27695 (United States); Jha, Rajesh; Dulikravich, George S. [Departments of Mechanical and Materials Engineering, MAIDROC, Florida International University, EC3462, 10555 West Flagler Street, Miami, FL 33174 (United States); Schwartz, J.; Koch, C.C. [Department of Materials Science and Engineering, North Carolina State University, Campus Box 7907, Raleigh, NC 27695-7907 (United States)

    2016-12-15

    Tempering is a critical step in Alnico alloy processing, yet the effects of tempering on microstructure have not been well studied. Here we report these effects, and in particular the effects on the Cu-Ni bridges. Energy-dispersive X-ray spectroscopy (EDS) maps and line scans show that tempering changes the elemental distribution in the Cu-Ni bridges, but not the morphology and distribution of Cu-bridges. The Cu concentration in the Cu-Ni bridges increases after tempering while other element concentrations decrease, especially Ni and Al. Furthermore, tempering sharpens the Cu bridge boundaries. These effects are primarily related to the large 2C{sub 44}/(C{sub 11}−C{sub 12}) ratio for Cu, largest of all elements in Alnico. In addition, the Ni-Cu loops around the α{sub 1} phases become inconspicuous with tempering. The diffusion of Fe and Co to the α{sub 1} phase during tempering, which increases the difference of saturation magnetization between the α{sub 1} and α{sub 2} phases, is observed by EDS. In summary, α{sub 1}, α{sub 2} and Cu-bridges are concentrated with their major elements during tempering which improves the magnetic properties. The formation of these features formed through elemental diffusion is discussed via energy theories. - Highlights: • Tempering changes the elemental distribution in the Cu-Ni bridges, but not morphology. • Cu concentration in the Cu-Ni bridges increases after tempering while others decrease. • These effects are related to the large 2C{sub 44}/(C{sub 11}−C{sub 12}) ratio for Cu. • The Ni-Cu loops around the α{sub 1} phases become inconspicuous with tempering. • The diffusion of Fe and Co to the α{sub 1} phase during tempering is observed by EDS.

  16. Method to Predict Tempering of Steels Under Non-isothermal Conditions

    Science.gov (United States)

    Poirier, D. R.; Kohli, A.

    2017-05-01

    A common way of representing the tempering responses of steels is with a "tempering parameter" that includes the effect of temperature and time on hardness after hardening. Such functions, usually in graphical form, are available for many steels and have been applied for isothermal tempering. In this article, we demonstrate that the method can be extended to non-isothermal conditions. Controlled heating experiments were done on three grades in order to verify the method.

  17. Comparison of vegetation roughness descriptions

    NARCIS (Netherlands)

    Augustijn, Dionysius C.M.; Huthoff, Freek; van Velzen, E.H.; Altinakar, M.S.; Kokpinar, M.A.; Aydin, I.; Cokgor, S.; Kirkgoz, S.

    2008-01-01

    Vegetation roughness is an important parameter in describing flow through river systems. Vegetation impedes the flow, which affects the stage-discharge curve and may increase flood risks. Roughness is often used as a calibration parameter in river models, however when vegetation is allowed to

  18. Time-dependent temper embrittlement of reactor pressure vessel steel: Correlation between microstructural evolution and mechanical properties during tempering at 650 °C

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanwei; Han, Lizhan; Yan, Guanghua; Liu, Qingdong; Luo, Xiaomeng; Gu, Jianfeng, E-mail: gujf@sjtu.edu.cn

    2016-11-15

    The microstructural evolution of reactor pressure vessel (RPV) steel and its effect on the mechanical properties during tempering at 650 °C were studied to reveal the time-dependent toughness and temper embrittlement. The results show that the toughening of the material should be attributed to the decomposition of the martensite/austenite constituents and uniform distribution of carbides. When the tempering duration was 5 h, the strength of the investigated steel decreased to strike a balance with the material impact toughness that reached a plateau. As the tempering duration was further increased, the material strength was slightly reduced but the material impact toughness deteriorated drastically. This time-dependent temper embrittlement is different from traditional temper embrittlement, and it can be partly attributed to the softening of the matrix and the broadening of the ferrite laths. Moreover, the dimensions and distribution of the grain carbides are the most important factors of the impact toughness. - Highlights: • The fracture mechanism of reactor pressure vessel (RPV) steels under impact load was investigated. • The Charpy V-notch impact test and the hinge model were employed for the study. • Grain boundary carbides play a key role in the impact toughness and fracture toughness. • The dependence of the deterioration of impact toughness on tempering time was analyzed for the first time.

  19. Mapping cropland GPP in the north temperate region with space measurements of chlorophyll fluorescence

    Science.gov (United States)

    Guanter, L.; Zhang, Y.; Jung, M.; Joiner, J.; Voigt, M.; Huete, A. R.; Zarco-Tejada, P.; Frankenberg, C.; Lee, J.; Berry, J. A.; Moran, S. M.; Ponce-Campos, G.; Beer, C.; Camps-Valls, G.; Buchmann, N. C.; Gianelle, D.; Klumpp, K.; Cescatti, A.; Baker, J. M.; Griffis, T.

    2013-12-01

    Monitoring agricultural productivity is important for optimizing management practices in a world under a continuous increase of food and biofuel demand. We used new space measurements of sun-induced chlorophyll fluorescence (SIF), a vegetation parameter intrinsically linked to photosynthesis, to capture photosynthetic uptake of the crop belts in the north temperate region. The following data streams and procedures have been used in this analysis: (1) SIF retrievals have been derived from measurements of the MetOp-A / GOME-2 instrument in the 2007-2011 time period; (2) ensembles of process-based and data-driven biogeochemistry models have been analyzed in order to assess the capability of global models to represent crop gross primary production (GPP); (3) flux tower-based GPP estimates covering the 2007-2011 time period have been extracted over 18 cropland and grassland sites in the Midwest US and Western Europe from the Ameriflux and the European Fluxes Database networks; (4) large-scale NPP estimates have been derived by the agricultural inventory data sets developed by USDA-NASS and Monfreda et al. The strong linear correlation between the SIF space retrievals and the flux tower-based GPP, found to be significantly higher than that between reflectance-based vegetation indices (EVI, NDVI and MTCI) and GPP, has enabled the direct upscaling of SIF to cropland GPP maps at the synoptic scale. The new crop GPP estimates we derive from the scaling of SIF space retrievals are consistent with both flux tower GPP estimates and agricultural inventory data. These new GPP estimates show that crop productivity in the US Western Corn Belt, and most likely also in the rice production areas in the Indo-Gangetic plain and China, is up to 50-75% higher than estimates by state-of-the-art data-driven and process-oriented biogeochemistry models. From our analysis we conclude that current carbon models have difficulties in reproducing the special conditions of those highly productive

  20. Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes

    Science.gov (United States)

    Hilt, Sabine; Alirangues Nuñez, Marta M.; Bakker, Elisabeth S.; Blindow, Irmgard; Davidson, Thomas A.; Gillefalk, Mikael; Hansson, Lars-Anders; Janse, Jan H.; Janssen, Annette B. G.; Jeppesen, Erik; Kabus, Timm; Kelly, Andrea; Köhler, Jan; Lauridsen, Torben L.; Mooij, Wolf M.; Noordhuis, Ruurd; Phillips, Geoff; Rücker, Jacqueline; Schuster, Hans-Heinrich; Søndergaard, Martin; Teurlincx, Sven; van de Weyer, Klaus; van Donk, Ellen; Waterstraat, Arno; Willby, Nigel; Sayer, Carl D.

    2018-01-01

    Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative

  1. Soil emission and uptake of carbonyl sulfide at a temperate mountain grassland

    Science.gov (United States)

    Kitz, Florian; Hammerle, Albin; Laterza, Tamara; Spielmann, Felix M.; Wohlfahrt, Georg

    2016-04-01

    Flux partitioning, i.e. inferring gross primary productivity (GPP) and ecosystem respiration from the measured net ecosystem carbon dioxide (CO2) exchange, is one uncertainty in modelling the carbon cycle and in times where robust models are needed to assess future global changes a persistent problem. A promising new approach is to derive GPP by measuring carbonyl sulfide (COS), the most abundant sulfur-containing trace gas in the atmosphere, with a mean concentration of about 500 pptv in the troposphere. This is possible because COS and CO2 enter the leaf via a similar pathway and are processed by the same enzyme (carbonic anhydrase). A prerequisite to use COS as a proxy for canopy photosynthesis is a robust estimation of COS sources and sinks in an ecosystem. Past studies described soils either as a sink or source, depending on properties like soil temperature and soil water content. The main aim of this study was to quantify the soil COS exchange and its drivers of a temperate mountain grassland in order to aid the use of COS as tracer for canopy CO2 and water vapor exchange. We conducted a field campaign with a Quantum cascade laser at a temperate mountain grassland to estimate the soil COS fluxes under ambient conditions and while simulating a drought. We used self-built fused silica (i.e. light-transparent) soil chambers to avoid COS emissions from built-in materials and to assess the impact of radiation. Vegetation was removed within the chambers, therefor more radiation reached the soil surface compared to natural conditions. This might be the reason for highly positive fluxes during daytime more similar to agricultural study sites. To further investigate this large soil COS source we conducted within canopy concentration measurements near the soil surface and still recorded fluxes confirming the soil as a COS source during daytime. Results from the drought experiment suggested a strong impact of incoming radiation on soil COS fluxes followed by soil

  2. Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes.

    Science.gov (United States)

    Hilt, Sabine; Alirangues Nuñez, Marta M; Bakker, Elisabeth S; Blindow, Irmgard; Davidson, Thomas A; Gillefalk, Mikael; Hansson, Lars-Anders; Janse, Jan H; Janssen, Annette B G; Jeppesen, Erik; Kabus, Timm; Kelly, Andrea; Köhler, Jan; Lauridsen, Torben L; Mooij, Wolf M; Noordhuis, Ruurd; Phillips, Geoff; Rücker, Jacqueline; Schuster, Hans-Heinrich; Søndergaard, Martin; Teurlincx, Sven; van de Weyer, Klaus; van Donk, Ellen; Waterstraat, Arno; Willby, Nigel; Sayer, Carl D

    2018-01-01

    Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative

  3. Nematode spatial and ecological patterns from tropical and temperate rainforests.

    Directory of Open Access Journals (Sweden)

    Dorota L Porazinska

    Full Text Available Large scale diversity patterns are well established for terrestrial macrobiota (e.g. plants and vertebrates, but not for microscopic organisms (e.g. nematodes. Due to small size, high abundance, and extensive dispersal, microbiota are assumed to exhibit cosmopolitan distributions with no biogeographical patterns. This assumption has been extrapolated from local spatial scale studies of a few taxonomic groups utilizing morphological approaches. Recent molecularly-based studies, however, suggest something quite opposite. Nematodes are the most abundant metazoans on earth, but their diversity patterns are largely unknown. We conducted a survey of nematode diversity within three vertical strata (soil, litter, and canopy of rainforests at two contrasting latitudes in the North American meridian (temperate: the Olympic National Forest, WA, U.S.A and tropical: La Selva Biological Station, Costa Rica using standardized sampling designs and sample processing protocols. To describe nematode diversity, we applied an ecometagenetic approach using 454 pyrosequencing. We observed that: 1 nematode communities were unique without even a single common species between the two rainforests, 2 nematode communities were unique among habitats in both rainforests, 3 total species richness was 300% more in the tropical than in the temperate rainforest, 4 80% of the species in the temperate rainforest resided in the soil, whereas only 20% in the tropics, 5 more than 90% of identified species were novel. Overall, our data provided no support for cosmopolitanism at both local (habitats and large (rainforests spatial scales. In addition, our data indicated that biogeographical patterns typical of macrobiota also exist for microbiota.

  4. Nematode Spatial and Ecological Patterns from Tropical and Temperate Rainforests

    Science.gov (United States)

    Porazinska, Dorota L.; Giblin-Davis, Robin M.; Powers, Thomas O.; Thomas, W. Kelley

    2012-01-01

    Large scale diversity patterns are well established for terrestrial macrobiota (e.g. plants and vertebrates), but not for microscopic organisms (e.g. nematodes). Due to small size, high abundance, and extensive dispersal, microbiota are assumed to exhibit cosmopolitan distributions with no biogeographical patterns. This assumption has been extrapolated from local spatial scale studies of a few taxonomic groups utilizing morphological approaches. Recent molecularly-based studies, however, suggest something quite opposite. Nematodes are the most abundant metazoans on earth, but their diversity patterns are largely unknown. We conducted a survey of nematode diversity within three vertical strata (soil, litter, and canopy) of rainforests at two contrasting latitudes in the North American meridian (temperate: the Olympic National Forest, WA, U.S.A and tropical: La Selva Biological Station, Costa Rica) using standardized sampling designs and sample processing protocols. To describe nematode diversity, we applied an ecometagenetic approach using 454 pyrosequencing. We observed that: 1) nematode communities were unique without even a single common species between the two rainforests, 2) nematode communities were unique among habitats in both rainforests, 3) total species richness was 300% more in the tropical than in the temperate rainforest, 4) 80% of the species in the temperate rainforest resided in the soil, whereas only 20% in the tropics, 5) more than 90% of identified species were novel. Overall, our data provided no support for cosmopolitanism at both local (habitats) and large (rainforests) spatial scales. In addition, our data indicated that biogeographical patterns typical of macrobiota also exist for microbiota. PMID:22984536

  5. Joints in Tempered Glass Using Glass Dowel Discs

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Poulsen, Peter Noe

    One of the major reasons for using glass in structures is its transparency; however, traditional mechanical joints such as friction joints and steel dowel pinned connections are compromising the transparency. The present paper describes a novel joint which is practically maintaining the complete...... transparency of the glass. This is achieved by using a dowel disc made entirely of tempered glass. The concept of the joint is proved by pilot tests and numerical models. From the work it is seen that the load-carrying capacity of such a connection is similar to what is found for traditionally in-plane loaded...

  6. Production of vegetal oil for energetic purposes; Producao de oleo vegetal com fins energeticos a partir de oleoginosas perenes

    Energy Technology Data Exchange (ETDEWEB)

    Andrade Pinto, R. de [Companhia Paranaense de Energia (COPEL), Curitiba, PQ (Brazil)

    1987-12-31

    The technology to obtain vegetable oil from trans esterification is already dominated. However, the oil grain`s cultures of annual cycle (soy-beans, peanuts, sunflowers) demand fertile and plain lands, which actually ought to be destined for food production, The utilization of slope wise areas, which are often destroyed by means of burning, for the reforestation with perennial oily trees which will be subject for further experimental researches, is studied. Particularly, the studies involves the cultivation of avocado`s varieties, which present pulps with a high oil concentration, in regions of temperate climates. It also involves an analysis of the high productivity and various difficulties to be surpassed, since the development of a simple procedure for thr oils and by-products extraction (in rural properties), until genetic developments of new avocado`s kinds, in order to achieve a better adaptation to the regions climate and to contain a higher oil concentration. 7 refs., 1 tab.

  7. Vegetation Response to Upper Pliocene Glacial/Interglacial Cyclicity in the Central Mediterranean

    Science.gov (United States)

    Combourieu-Nebout, Nathalie

    1993-09-01

    New detailed pollen analysis of the lower part of the Upper Pliocene Semaforo section (Crotone, Italy) documents cyclic behavior of vegetation at the beginning of the Northern Hemisphere glaciations. The competition between four vegetation units (subtropical humid forest, deciduous temperate forest, altitudinal coniferous forest, and open xeric assemblage) probably reflects modifications of vegetation belts at this montane site. Several increases in herbaceous open vegetation regularly alternate with subtropical humid forest, which expresses rapid climatic oscillations. The complete temporal succession—deciduous forest (rich in Quercus), followed by subtropical humid forest (Taxodiaceae and Cathaya), then altitudinal coniferous forest ( Tsuga, Cedrus, Abies, and Picea), and finally herbaceous open vegetation (Graminae, Compositae, and Artemisia )—displays the climatic evolution from warm and humid interglaciation to cold and dry glaciation. It also suggests an independent variation of temperature and humidity, the two main climatic parameters. The vegetation history of southern Calabria recorded in the Semaforo section have been correlated with the ∂ 18O signal established in the Atlantic Ocean.

  8. Comparative life history of the south temperate Cape Penduline Tit (Anthoscopus minutus) and north temperate Remizidae species

    Science.gov (United States)

    Lloyd, Penn; Frauenknecht, Bernhard D.; du Plessis, Morné A.; Martin, Thomas E.

    2017-01-01

    We studied the breeding biology of the south temperate Cape Penduline Tit (Anthoscopus minutus) in order to compare its life history traits with those of related north temperate members of the family Remizidae, namely the Eurasian Penduline Tit (Remiz pendulinus) and the Verdin (Auriparus flaviceps). We used this comparison to test key predictions of three hypotheses thought to explain latitudinal variation in life histories among bird species—the seasonality and food limitation hypothesis, nest predation hypothesis and adult mortality hypothesis. Contrary to the general pattern of smaller clutch size and lower adult mortality among south-temperate birds living in less seasonal environments, the Cape Penduline Tit has a clutch size larger than that of the Verdin and similar to that of the Eurasian Penduline Tit, and higher adult mortality than both of the other two species. The most notable difference between the Cape Penduline Tit and the two other species is in parental behavioural strategy, with the former exhibiting bi-parental care at all stages of nesting together with facultative cooperative breeding, whereas the Eurasian Penduline Tit has uni-parental care and the Verdin has a combination of female-only incubation but bi-parental nestling care. Consequently, in comparison to the other two species, the Cape Penduline Tit exhibits greater nest attentiveness during incubation, a similar per-nestling feeding rate and greater post-fledging survival. Its relatively large clutch size, high parental investment and associated high adult mortality in a less seasonal environment are consistent with key predictions of the adult mortality hypothesis but not with key predictions of the seasonality and food limitation hypothesis in explaining life history variation among Remizidae species. These results add to a growing body of evidence of the importance of age-specific mortality in shaping life history evolution.

  9. Growth responses of five desert plants as influenced by biological soil crusts from a temperate desert, China

    Science.gov (United States)

    Zhang, Yuanming; Belnap, Jayne

    2015-01-01

    In almost all dryland systems, biological soil crusts (biocrusts) coexist alongside herbaceous and woody vegetation, creating landscape mosaics of vegetated and biocrusted patches. Results from past studies on the interaction between biocrusts and vascular plants have been contradictory. In the Gurbantunggut desert, a large temperate desert in northwestern China, well-developed lichen-dominated crusts dominate the areas at the base and between the sand dunes. We examined the influence of these lichen-dominated biocrusts on the germination, growth, biomass accumulation, and elemental content of five common plants in this desert: two shrubs (Haloxylon persicum, Ephedra distachya) and three herbaceous plants (Ceratocarpus arenarius, Malcolmia africana and Lappula semiglabra) under greenhouse conditions. The influence of biocrusts on seed germination was species-specific. Biocrusts did not affect percent germination in plants with smooth seeds, but inhibited germination of seeds with appendages that reduced or eliminated contact with the soil surface or prevented seeds from slipping into soil cracks. Once seeds had germinated, biocrusts had different influences on growth of shrub and herbaceous plants. The presence of biocrusts increased concentrations of nitrogen but did not affect phosphorus or potassium in tissue of all tested species, while the uptake of the other tested nutrients was species-specific. Our study showed that biocrusts can serve as a biological filter during seed germination and also can influence growth and elemental uptake. Therefore, they may be an important trigger for determining desert plant diversity and community composition in deserts.

  10. Biodiversity in temperate European grasslands: origin and conservation.

    OpenAIRE

    Pärtel, Meelis; Bruun, Hans Henrik; Sammul, Marek

    2005-01-01

    Northern Europe is in the forest zone, but wild megaherbivores have maintained grass-dominated vegetation here for the last 1.8 million years. Continuity of the grassland biome through glacialinterglacial cycles and connection to steppe vegetation has resulted in the evolution, immigration, and survival of a large number of grassland species. During the last millennia the effect of wild ungulates has been replaced by domestic grazers and hay making, and the persistence of grasslan...

  11. Phenolation of vegetable oils

    Directory of Open Access Journals (Sweden)

    ZORAN S. PETROVIĆ

    2011-04-01

    Full Text Available Novel bio-based compounds containing phenols suitable for the syn­thesis of polyurethanes were prepared. The direct alkylation of phenols with different vegetable oils in the presence of superacids (HBF4, triflic acid as ca­talysts was studied. The reaction kinetics was followed by monitoring the de­crease of the double bond content (iodine value with time. In order to under­stand the mechanism of the reaction, phenol was alkylated with model com­pounds. The model compounds containing one internal double bond were 9-oc­tadecene and methyl oleate and those with three double bonds were triolein and high oleic safflower oil (82 % oleic acid. It was shown that the best structures for phenol alkylation are fatty acids with only one double bond (oleic acid. Fatty acids with two double bonds (linoleic acid and three double bonds (lino­lenic acid lead to polymerized oils by a Diels–Alder reaction, and to a lesser extent to phenol alkylated products. The reaction product of direct alkylation of phenol with vegetable oils is a complex mixture of phenol alkylated with poly­merized oil (30–60 %, phenyl esters formed by transesterification of phenol with triglyceride ester bonds (<10 % and unreacted oil (30 %. The phenolated vegetable oils are new aromatic–aliphatic bio-based raw materials suitable for the preparation of polyols (by propoxylation, ethoxylation, Mannich reactions for the preparation of polyurethanes, as intermediates for phenolic resins or as bio-based antioxidants.

  12. Beneficial Effects of Temperate Forage Legumes that Contain Condensed Tannins

    Directory of Open Access Journals (Sweden)

    Jennifer W. MacAdam

    2015-07-01

    Full Text Available The two temperate forage legumes containing condensed tannins (CT that promote ruminant production are birdsfoot trefoil (Lotus corniculatus L.; BFT and sainfoin (Onobrychis viciifolia Scop.; SF. Both are well-adapted to the cool-temperate climate and alkaline soils of the Mountain West USA. Condensed tannins comprise a diverse family of bioactive chemicals with multiple beneficial functions for ruminants, including suppression of internal parasites and enteric methane. Birdsfoot trefoil contains 10 to 40 g·CT·kg−1 dry matter (DM, while SF contains 30 to 80 g·CT·kg−1 DM. Our studies have focused on these two plant species and have demonstrated consistently elevated rates of gain for beef calves grazing both BFT and SF. Novel results from our BFT research include carcass dressing percentages and consumer sensory evaluations equivalent to feedlot-finished steers and significantly greater than grass-finished steers, but with omega-3 fatty acid concentrations equal to grass-finished beef. We have further demonstrated that ruminants fed BFT or SF will consume more endophyte-infected tall fescue (Schedonorus arundinaceus (Schreb. Dumort. forage or seed than ruminants fed a non-CT forage legume. There is great potential value for sustainable livestock production in the use of highly digestible, nitrogen-fixing legumes containing tannins demonstrated to improve ruminant productivity.

  13. Chilling and heat requirements for flowering in temperate fruit trees.

    Science.gov (United States)

    Guo, Liang; Dai, Junhu; Ranjitkar, Sailesh; Yu, Haiying; Xu, Jianchu; Luedeling, Eike

    2014-08-01

    Climate change has affected the rates of chilling and heat accumulation, which are vital for flowering and production, in temperate fruit trees, but few studies have been conducted in the cold-winter climates of East Asia. To evaluate tree responses to variation in chill and heat accumulation rates, partial least squares regression was used to correlate first flowering dates of chestnut (Castanea mollissima Blume) and jujube (Zizyphus jujube Mill.) in Beijing, China, with daily chill and heat accumulation between 1963 and 2008. The Dynamic Model and the Growing Degree Hour Model were used to convert daily records of minimum and maximum temperature into horticulturally meaningful metrics. Regression analyses identified the chilling and forcing periods for chestnut and jujube. The forcing periods started when half the chilling requirements were fulfilled. Over the past 50 years, heat accumulation during tree dormancy increased significantly, while chill accumulation remained relatively stable for both species. Heat accumulation was the main driver of bloom timing, with effects of variation in chill accumulation negligible in Beijing’s cold-winter climate. It does not seem likely that reductions in chill will have a major effect on the studied species in Beijing in the near future. Such problems are much more likely for trees grown in locations that are substantially warmer than their native habitats, such as temperate species in the subtropics and tropics.

  14. Chilling and heat requirements for flowering in temperate fruit trees

    Science.gov (United States)

    Guo, Liang; Dai, Junhu; Ranjitkar, Sailesh; Yu, Haiying; Xu, Jianchu; Luedeling, Eike

    2014-08-01

    Climate change has affected the rates of chilling and heat accumulation, which are vital for flowering and production, in temperate fruit trees, but few studies have been conducted in the cold-winter climates of East Asia. To evaluate tree responses to variation in chill and heat accumulation rates, partial least squares regression was used to correlate first flowering dates of chestnut ( Castanea mollissima Blume) and jujube ( Zizyphus jujube Mill.) in Beijing, China, with daily chill and heat accumulation between 1963 and 2008. The Dynamic Model and the Growing Degree Hour Model were used to convert daily records of minimum and maximum temperature into horticulturally meaningful metrics. Regression analyses identified the chilling and forcing periods for chestnut and jujube. The forcing periods started when half the chilling requirements were fulfilled. Over the past 50 years, heat accumulation during tree dormancy increased significantly, while chill accumulation remained relatively stable for both species. Heat accumulation was the main driver of bloom timing, with effects of variation in chill accumulation negligible in Beijing's cold-winter climate. It does not seem likely that reductions in chill will have a major effect on the studied species in Beijing in the near future. Such problems are much more likely for trees grown in locations that are substantially warmer than their native habitats, such as temperate species in the subtropics and tropics.

  15. Nitrous oxide emission reduction in temperate biochar-amended soils

    Science.gov (United States)

    Felber, R.; Hüppi, R.; Leifeld, J.; Neftel, A.

    2012-01-01

    Biochar, a pyrolysis product of organic residues, is an amendment for agricultural soils to improve soil fertility, sequester CO2 and reduce greenhouse gas (GHG) emissions. In highly weathered tropical soils laboratory incubations of soil-biochar mixtures revealed substantial reductions for nitrous oxide (N2O) and carbon dioxide (CO2). In contrast, evidence is scarce for temperate soils. In a three-factorial laboratory incubation experiment two different temperate agricultural soils were amended with green waste and coffee grounds biochar. N2O and CO2 emissions were measured at the beginning and end of a three month incubation. The experiments were conducted under three different conditions (no additional nutrients, glucose addition, and nitrate and glucose addition) representing different field conditions. We found mean N2O emission reductions of 60 % compared to soils without addition of biochar. The reduction depended on biochar type and soil type as well as on the age of the samples. CO2 emissions were slightly reduced, too. NO3- but not NH4+ concentrations were significantly reduced shortly after biochar incorporation. Despite the highly significant suppression of N2O emissions biochar effects should not be transferred one-to-one to field conditions but need to be tested accordingly.

  16. Temperate marine protected area provides recruitment subsidies to local fisheries.

    Science.gov (United States)

    Le Port, A; Montgomery, J C; Smith, A N H; Croucher, A E; McLeod, I M; Lavery, S D

    2017-10-25

    The utility of marine protected areas (MPAs) as a means of protecting exploited species and conserving biodiversity within MPA boundaries is supported by strong empirical evidence. However, the potential contribution of MPAs to fished populations beyond their boundaries is still highly controversial; empirical measures are scarce and modelling studies have produced a range of predictions, including both positive and negative effects. Using a combination of genetic parentage and relatedness analysis, we measured larval subsidies to local fisheries replenishment for Australasian snapper ( Chrysophrys auratus : Sparidae) from a small (5.2 km 2 ), well-established, temperate, coastal MPA in northern New Zealand. Adult snapper within the MPA contributed an estimated 10.6% (95% CI: 5.5-18.1%) of newly settled juveniles to surrounding areas (approx. 400 km 2 ), with no decreasing trend in contributions up to 40 km away. Biophysical modelling of larval dispersal matched experimental data, showing larvae produced inside the MPA dispersed over a comparable distance. These results demonstrate that temperate MPAs have the potential to provide recruitment subsidies at magnitudes and spatial scales relevant to fisheries management. The validated biophysical model provides a cost-efficient opportunity to generalize these findings to other locations and climate conditions, and potentially informs the design of MPA networks for enhancing fisheries management. © 2017 The Author(s).

  17. Linking vegetation structure, function and physiology through spectroscopic remote sensing

    Science.gov (United States)

    Serbin, S.; Singh, A.; Couture, J. J.; Shiklomanov, A. N.; Rogers, A.; Desai, A. R.; Kruger, E. L.; Townsend, P. A.

    2015-12-01

    Terrestrial ecosystem process models require detailed information on ecosystem states and canopy properties to properly simulate the fluxes of carbon (C), water and energy from the land to the atmosphere and assess the vulnerability of ecosystems to perturbations. Current models fail to adequately capture the magnitude, spatial variation, and seasonality of terrestrial C uptake and storage, leading to significant uncertainties in the size and fate of the terrestrial C sink. By and large, these parameter and process uncertainties arise from inadequate spatial and temporal representation of plant traits, vegetation structure, and functioning. With increases in computational power and changes to model architecture and approaches, it is now possible for models to leverage detailed, data rich and spatially explicit descriptions of ecosystems to inform parameter distributions and trait tradeoffs. In this regard, spectroscopy and imaging spectroscopy data have been shown to be invaluable observational datasets to capture broad-scale spatial and, eventually, temporal dynamics in important vegetation properties. We illustrate the linkage of plant traits and spectral observations to supply key data constraints for model parameterization. These constraints can come either in the form of the raw spectroscopic data (reflectance, absorbtance) or physiological traits derived from spectroscopy. In this presentation we highlight our ongoing work to build ecological scaling relationships between critical vegetation characteristics and optical properties across diverse and complex canopies, including temperate broadleaf and conifer forests, Mediterranean vegetation, Arctic systems, and agriculture. We focus on work at the leaf, stand, and landscape scales, illustrating the importance of capturing the underlying variability in a range of parameters (including vertical variation within canopies) to enable more efficient scaling of traits related to functional diversity of ecosystems.

  18. 46 CFR 54.25-25 - Welding of quenched and tempered steels (modifies UHT-82).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Welding of quenched and tempered steels (modifies UHT-82... ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-25 Welding of quenched and tempered steels (modifies UHT-82). (a) The qualification of welding procedures, welders, and...

  19. Rumen pH and NH3-N concentration of sheep fed temperate ...

    African Journals Online (AJOL)

    The aim of this study was to evaluate the effect of sorghum grain supplementation on ruminal pH and NH. 3-N concentration of wethers consuming a fresh temperate pasture (Lotus corniculatus) in metabolism cages. Sixteen Corriedale x Milchschaf wethers were fed temperate pastures ad libitum and were ...

  20. The effects of boro-tempering heat treatment on microstructural properties of ductile iron

    International Nuclear Information System (INIS)

    Kayali, Yusuf; Yalcin, Yilmaz

    2011-01-01

    In this study, the effects of boro-tempering heat treatment on microstructural properties of ductile iron were investigated. Test samples with dimensions of 10 x 10 x 55 mm were boronized at 900 o C for 1, 3 and 5 h and then tempered at four different temperatures (250, 300, 350 and 450 o C) for 1 h. Both optical microscopy and scanning electron microscopy were used to reveal the microstructural details of coating and matrix of boro-tempered ductile iron. X-ray diffraction was used to determine the constituents of the coating layer. The boride layer formed on the surface of boro-tempered ductile cast iron is tooth shape form and consisted of FeB and Fe 2 B phases. The thickness of boride layer increases as the boronizing time increases and tempering temperature decreases. Tempering temperature is more effective than boronizing time on the matrix structure. Boro-tempering heat treatment reduces the formation of lower and upper ausferritic matrix temperature according to classical austempering. This causes formation of upper ausferritic matrix in the sample when tempered at 300 o C. This is in contrast to general case which is the formation of lower ausferritic matrix via austempering at this temperature.

  1. Investigation on tempering of granular bainite in an offshore platform steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yanlei; Jia, Tao; Zhang, Xiangjun [The State Key Laboratory of Rolling and Automation, Northeastern University, P.O. Box 105, No. 11, Lane 3, Wenhua Road, HePing District, Shenyang 110819 (China); Liu, Zhenyu, E-mail: zyliu@mail.neu.edu.cn [The State Key Laboratory of Rolling and Automation, Northeastern University, P.O. Box 105, No. 11, Lane 3, Wenhua Road, HePing District, Shenyang 110819 (China); Misra, R.D.K. [Department of Metallurgical and Materials Engineering, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0521 (United States)

    2015-02-25

    Granular bainite, where M-A constituents dispersed in bainitic ferrite matrix usually presents at the half thickness region in thermo-mechanically processed heavy gauge offshore platform steel. In the present work, the decomposition of M-A constituents during tempering at 600 °C was firstly revealed by transmission electron microscopy (TEM) analysis, which primarily involves the precipitation of cementite, recovery and recrystallization of highly dislocated ferrite matrix. Then, the effect of tempering on mechanical properties was investigated by tempering at different temperature for 60 min. Results indicated that, at tempering temperature of 500–600 °C, large quantity of micro-alloying carbides precipitated and partially compensated the loss of strength mainly due to the decomposition of M-A constituents. Compared with the as-rolled state, the decomposition of M-A constituents and softening of bainitic ferrite matrix after tempering have resulted in higher density of microvoids and substantial plastic deformation before impact failure.

  2. Wear behavior of tempered and borided tool steels under various conditions

    International Nuclear Information System (INIS)

    Al-Haidary, T. J.; Faleh, M. N.

    2000-01-01

    . Tool steel 61CrV5, 50 NiCr13 and X1000Cr MoV51 were used in the first stage of this investigation. They have been treated as follows: boriding, boriding and tempering and hardening and tempering. The wear tests were conducted under fixed conditions (150 N/mm 2 , 0.48m/sec) with and without lubricant. The wear rate and coefficient of friction of 61Cr Si V5 steel have been studied in the second stage hoping to find the influence of working conditions on these parameters and then to compare these results with the case of hardening and tempering which is the usual case in the actual working field. The study gives a good indication about the improvement achieved in boriding and tempering cases (∼ 30%) as compared with hardening tempering cases in dry sliding conditions -∼5% with lubricating ones. (authors). 13 refs., 19 figs., 1 table

  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. Quantitative consideration for the tempering effect during multi-pass thermal cycle in HAZ of low-alloy steel

    International Nuclear Information System (INIS)

    Yu, Lina; Nakabayashi, Yuma; Saida, Kazuyoshi; Mochizuki, Masahito; Nishimoto, Kazutoshi; Kameyama, Masashi; Hirano, Shinro; Chigusa, Naoki

    2011-01-01

    A new Thermal Cycle Tempering Parameter (TCTP) to deal with the tempering effect during multi-pass thermal cycles has been proposed by extending Larson-Miller parameter (LMP). Experimental result revealed that the hardness in synthetic HAZ of the low alloy steel subjected to multi tempering thermal cycles has a good linear relationship with TCTP. By using this relationship, the hardness of the low-alloy steel reheated with tempering thermal cycles can be predicted when the original hardness is known. (author)

  5. Effects of metals on vegetation

    Energy Technology Data Exchange (ETDEWEB)

    Press, N P

    1972-01-01

    Prospectors have long known that abnormal concentrations of metals in the soil overlying an ore deposit can affect the vegetation rooting in this soil; mineral deposits have even been discovered because of such vegetation changes. Recently, many people have become interested in the possibility of remote sensing such vegetation changes, and perhaps using the results in conjunction with airborne geophysics and photogeological interpretation in integrated prospecting programs.

  6. Vegetation and acidification, Chapter 5

    Science.gov (United States)

    David R. DeWalle; James N. Kochenderfer; Mary Beth Adams; Gary W. Miller

    2006-01-01

    In this chapter, the impact of watershed acidification treatments on WS3 at the Fernow Experimental Forest (FEF) and at WS9 on vegetation is presented and summarized in a comprehensive way for the first time. WS7 is used as a vegetative reference basin for WS3, while untreated plots within WS9 are used as a vegetative reference for WS9. Bioindicators of acidification...

  7. Soil warming and CO2 enrichment induce biomass shifts in alpine tree line vegetation.

    Science.gov (United States)

    Dawes, Melissa A; Philipson, Christopher D; Fonti, Patrick; Bebi, Peter; Hättenschwiler, Stephan; Hagedorn, Frank; Rixen, Christian

    2015-05-01

    Responses of alpine tree line ecosystems to increasing atmospheric CO2 concentrations and global warming are poorly understood. We used an experiment at the Swiss tree line to investigate changes in vegetation biomass after 9 years of free air CO2 enrichment (+200 ppm; 2001-2009) and 6 years of soil warming (+4 °C; 2007-2012). The study contained two key tree line species, Larix decidua and Pinus uncinata, both approximately 40 years old, growing in heath vegetation dominated by dwarf shrubs. In 2012, we harvested and measured biomass of all trees (including root systems), above-ground understorey vegetation and fine roots. Overall, soil warming had clearer effects on plant biomass than CO2 enrichment, and there were no interactive effects between treatments. Total plant biomass increased in warmed plots containing Pinus but not in those with Larix. This response was driven by changes in tree mass (+50%), which contributed an average of 84% (5.7 kg m(-2) ) of total plant mass. Pinus coarse root mass was especially enhanced by warming (+100%), yielding an increased root mass fraction. Elevated CO2 led to an increased relative growth rate of Larix stem basal area but no change in the final biomass of either tree species. Total understorey above-ground mass was not altered by soil warming or elevated CO2 . However, Vaccinium myrtillus mass increased with both treatments, graminoid mass declined with warming, and forb and nonvascular plant (moss and lichen) mass decreased with both treatments. Fine roots showed a substantial reduction under soil warming (-40% for all roots soil depth) but no change with CO2 enrichment. Our findings suggest that enhanced overall productivity and shifts in biomass allocation will occur at the tree line, particularly with global warming. However, individual species and functional groups will respond differently to these environmental changes, with consequences for ecosystem structure and functioning. © 2014 John Wiley & Sons Ltd.

  8. Managed grassland alters soil N dynamics and N2O emissions in temperate steppe.

    Science.gov (United States)

    Xu, Lijun; Xu, Xingliang; Tang, Xuejuan; Xin, Xiaoping; Ye, Liming; Yang, Guixia; Tang, Huajun; Lv, Shijie; Xu, Dawei; Zhang, Zhao

    2018-04-01

    Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen (N) dynamics and nitrous oxide (N 2 O) emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N2O emissions by field experiments in Hulunber in northern China. Soil (0-10cm), nitrate (NO 3 - ), ammonium (NH 4 + ), and microbial N were measured in plots in a temperate steppe (Leymus chinensis grassland) and two managed grasslands (Medicago sativa and Bromus inermis grasslands) in 2011 and 2012. The results showed conversion of L. chinensis grassland to M. sativa or B. inermis grasslands decreased concentrations of NO 3 - -N, but did not change NH 4 + -N. Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M. sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa (i.e., a legume grass) increased N 2 O emissions by 26.2%, while the conversion to the B. inermis (i.e., a non-legume grass) reduced N 2 O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO 3 - -N and NH 4 + -N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N 2 O emissions. Copyright © 2017. Published by Elsevier B.V.

  9. Abiotic and biotic control of methanol exchanges in a temperate mixed forest

    Directory of Open Access Journals (Sweden)

    Q. Laffineur

    2012-01-01

    Full Text Available Methanol exchanges over a mixed temperate forest in the Belgian Ardennes were measured for more than one vegetation season using disjunct eddy-covariance by a mass scanning technique and Proton Transfer Reaction Mass Spectrometry (PTR-MS. Half-hourly methanol fluxes were measured in the range of −0.6 μg m−2 s−1 to 0.6 μg m−2 s−1, and net daily methanol fluxes were generally negative in summer and autumn and positive in spring. On average, the negative fluxes dominated (i.e. the site behaved as a net sink, in contrast to what had been found in previous studies.

    An original model describing the adsorption/desorption of methanol in water films present in the forest ecosystem and the methanol degradation process was developed. Its calibration, based on field measurements, predicted a mean methanol degradation rate of −0.0074 μg m−2 s−1 and a half lifetime for methanol in water films of 57.4 h. Biogenic emissions dominated the exchange only in spring, with a standard emission factor of 0.76 μg m−2 s−1.

    The great ability of the model to reproduce the long-term evolution, as well as the diurnal variation of the fluxes, suggests that the adsorption/desorption and degradation processes play an important role in the global methanol budget. This result underlines the need to conduct long-term measurements in order to accurately capture these processes and to better estimate methanol fluxes at the ecosystem scale.

  10. Chlorophyll fluorescence tracks seasonal variations of photosynthesis from leaf to canopy in a temperate forest.

    Science.gov (United States)

    Yang, Hualei; Yang, Xi; Zhang, Yongguang; Heskel, Mary A; Lu, Xiaoliang; Munger, J William; Sun, Shucun; Tang, Jianwu

    2017-07-01

    Accurate estimation of terrestrial gross primary productivity (GPP) remains a challenge despite its importance in the global carbon cycle. Chlorophyll fluorescence (ChlF) has been recently adopted to understand photosynthesis and its response to the environment, particularly with remote sensing data. However, it remains unclear how ChlF and photosynthesis are linked at different spatial scales across the growing season. We examined seasonal relationships between ChlF and photosynthesis at the leaf, canopy, and ecosystem scales and explored how leaf-level ChlF was linked with canopy-scale solar-induced chlorophyll fluorescence (SIF) in a temperate deciduous forest at Harvard Forest, Massachusetts, USA. Our results show that ChlF captured the seasonal variations of photosynthesis with significant linear relationships between ChlF and photosynthesis across the growing season over different spatial scales (R 2  = 0.73, 0.77, and 0.86 at leaf, canopy, and satellite scales, respectively; P chlorophyll content (R 2  = 0.65 for canopy GPP SIF and chlorophyll content; P < 0.0001), leaf area index (LAI) (R 2  = 0.35 for canopy GPP SIF and LAI; P < 0.0001), and normalized difference vegetation index (NDVI) (R 2  = 0.36 for canopy GPP SIF and NDVI; P < 0.0001). Our results suggest that ChlF can be a powerful tool to track photosynthetic rates at leaf, canopy, and ecosystem scales. © 2016 John Wiley & Sons Ltd.

  11. Abiotic and biotic control of methanol exchanges in a temperate mixed forest

    Science.gov (United States)

    Laffineur, Q.; Aubinet, M.; Schoon, N.; Amelynck, C.; Müller, J.-F.; Dewulf, J.; van Langenhove, H.; Steppe, K.; Heinesch, B.

    2012-01-01

    Methanol exchanges over a mixed temperate forest in the Belgian Ardennes were measured for more than one vegetation season using disjunct eddy-covariance by a mass scanning technique and Proton Transfer Reaction Mass Spectrometry (PTR-MS). Half-hourly methanol fluxes were measured in the range of -0.6 μg m-2 s-1 to 0.6 μg m-2 s-1, and net daily methanol fluxes were generally negative in summer and autumn and positive in spring. On average, the negative fluxes dominated (i.e. the site behaved as a net sink), in contrast to what had been found in previous studies. An original model describing the adsorption/desorption of methanol in water films present in the forest ecosystem and the methanol degradation process was developed. Its calibration, based on field measurements, predicted a mean methanol degradation rate of -0.0074 μg m-2 s-1 and a half lifetime for methanol in water films of 57.4 h. Biogenic emissions dominated the exchange only in spring, with a standard emission factor of 0.76 μg m-2 s-1. The great ability of the model to reproduce the long-term evolution, as well as the diurnal variation of the fluxes, suggests that the adsorption/desorption and degradation processes play an important role in the global methanol budget. This result underlines the need to conduct long-term measurements in order to accurately capture these processes and to better estimate methanol fluxes at the ecosystem scale.

  12. Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient.

    Directory of Open Access Journals (Sweden)

    Yizhao Chen

    Full Text Available Water-use efficiency (WUE, defined as the ratio of net primary productivity (NPP to evapotranspiration (ET, is an important indicator to represent the trade-off pattern between vegetation productivity and water consumption. Its dynamics under climate change are important to ecohydrology and ecosystem management, especially in the drylands. In this study, we modified and used a late version of Boreal Ecosystem Productivity Simulator (BEPS, to quantify the WUE in the typical dryland ecosystems, Temperate Eurasian Steppe (TES. The Aridity Index (AI was used to specify the terrestrial water availability condition. The regional results showed that during the period of 1999-2008, the WUE has a clear decreasing trend in the spatial distribution from arid to humid areas. The highest annual average WUE was in dry and semi-humid sub-region (DSH with 0.88 gC mm-1 and the lowest was in arid sub-region (AR with 0.22 gC mm-1. A two-stage pattern of WUE was found in TES. That is, WUE would enhance with lower aridity stress, but decline under the humid environment. Over 65% of the region exhibited increasing WUE. This enhancement, however, could not indicate that the grasslands were getting better because the NPP even slightly decreased. It was mainly attributed to the reduction of ET over 70% of the region, which is closely related to the rainfall decrease. The results also suggested a similar negative spatial correlation between the WUE and the mean annual precipitation (MAP at the driest and the most humid ends. This regional pattern reflected the different roles of water in regulating the terrestrial ecosystems under different aridity levels. This study could facilitate the understanding of the interactions between terrestrial carbon and water cycles, and thus contribute to a sustainable management of nature resources in the dryland ecosystems.

  13. Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient.

    Science.gov (United States)

    Chen, Yizhao; Li, Jianlong; Ju, Weimin; Ruan, Honghua; Qin, Zhihao; Huang, Yiye; Jeelani, Nasreen; Padarian, José; Propastin, Pavel

    2017-01-01

    Water-use efficiency (WUE), defined as the ratio of net primary productivity (NPP) to evapotranspiration (ET), is an important indicator to represent the trade-off pattern between vegetation productivity and water consumption. Its dynamics under climate change are important to ecohydrology and ecosystem management, especially in the drylands. In this study, we modified and used a late version of Boreal Ecosystem Productivity Simulator (BEPS), to quantify the WUE in the typical dryland ecosystems, Temperate Eurasian Steppe (TES). The Aridity Index (AI) was used to specify the terrestrial water availability condition. The regional results showed that during the period of 1999-2008, the WUE has a clear decreasing trend in the spatial distribution from arid to humid areas. The highest annual average WUE was in dry and semi-humid sub-region (DSH) with 0.88 gC mm-1 and the lowest was in arid sub-region (AR) with 0.22 gC mm-1. A two-stage pattern of WUE was found in TES. That is, WUE would enhance with lower aridity stress, but decline under the humid environment. Over 65% of the region exhibited increasing WUE. This enhancement, however, could not indicate that the grasslands were getting better because the NPP even slightly decreased. It was mainly attributed to the reduction of ET over 70% of the region, which is closely related to the rainfall decrease. The results also suggested a similar negative spatial correlation between the WUE and the mean annual precipitation (MAP) at the driest and the most humid ends. This regional pattern reflected the different roles of water in regulating the terrestrial ecosystems under different aridity levels. This study could facilitate the understanding of the interactions between terrestrial carbon and water cycles, and thus contribute to a sustainable management of nature resources in the dryland ecosystems.

  14. Corrosion fatigue in nitrocarburized quenched and tempered steels

    Science.gov (United States)

    Khani, M. Karim; Dengel, D.

    1996-05-01

    In order to investigate the fatigue strength and fracture mechanism of salt bath nitrocarburized steels, specimens of the steels SAE 4135 and SAE 4140, in a quenched and tempered state, and additionally in a salt bath nitrocarburized and oxidizing cooled state as well as in a polished (after the oxidizing cooling) and renewed oxidized state, were subjected to comparative rotating bending fatigue tests in inert oil and 5 pct NaCl solution. In addition, some of the quenched and tempered specimens of SAE 4135 material were provided with an approximately 50-μm-thick electroless Ni-P layer, in order to compare corrosion fatigue behavior between the Ni-P layer and the nitride layers. Long-life corrosion fatigue tests of SAE 4135 material were carried out under small stresses in the long-life range up to 108 cycles with a test frequency of 100 Hz. Fatigue tests of SAE 4140 material were carried out in the range of finite life (low-cycle range) with a test frequency of 13 Hz. The results show that the 5 pct NaCl environment drastically reduced fatigue life, but nitrocarburizing plus oxidation treatment was found to improve the corrosion fatigue life over that of untreated and Ni-P coated specimens. The beneficial effect of nitrocarburizing followed by oxidation treatment on cor-rosion fatigue life results from the protection rendered by the compound layer by means of a well-sealed oxide layer, whereby the pores present in the compound layer fill up with oxides. The role of inclusions in initiating fatigue cracks was investigated. It was found that under corrosion fatigue conditions, the fatigue cracks started at cavities along the interfaces of MnS inclusions and matrix in the case of quenched and tempered specimens. The nitrocarburized specimens, however, showed a superposition of pitting corrosion and corrosion fatigue in which pores and nonmetallic inclusions in the compound layer play a predominant role concerning the formation of pits in the substrate.

  15. Combined Use of Airborne Lidar and DBInSAR Data to Estimate LAI in Temperate Mixed Forests

    Directory of Open Access Journals (Sweden)

    Ross F. Nelson

    2012-06-01

    Full Text Available The objective of this study was to determine whether leaf area index (LAI in temperate mixed forests is best estimated using multiple-return airborne laser scanning (lidar data or dual-band, single-pass interferometric synthetic aperture radar data (from GeoSAR alone, or both in combination. In situ measurements of LAI were made using the LiCor LAI-2000 Plant Canopy Analyzer on 61 plots (21 hardwood, 36 pine, 4 mixed pine hardwood; stand age ranging from 12-164 years; mean height ranging from 0.4 to 41.2 m in the Appomattox-Buckingham State Forest, Virginia, USA. Lidar distributional metrics were calculated for all returns and for ten one meter deep crown density slices (a new metric, five above and five below the mode of the vegetation returns for each plot. GeoSAR metrics were calculated from the X-band backscatter coefficients (four looks as well as both X- and P-band interferometric heights and magnitudes for each plot. Lidar metrics alone explained 69% of the variability in LAI, while GeoSAR metrics alone explained 52%. However, combining the lidar and GeoSAR metrics increased the R2 to 0.77 with a CV-RMSE of 0.42. This study indicates the clear potential for X-band backscatter and interferometric height (both now available from spaceborne sensors, when combined with small-footprint lidar data, to improve LAI estimation in temperate mixed forests.

  16. Relishes: The new pickled vegetables

    Directory of Open Access Journals (Sweden)

    Tepić Aleksandra N.

    2006-01-01

    Full Text Available There have been an increasing interest of consumers for a ide variety of pickled vegetable products worldwide. Regarding the regional vegetable supplies and relatively poor assortment of ready-to-use products, the need to broaden the offer of domestic pickled vegetables at the market came out. In this work recipes for different vegetables, spices and condiments were developed. The best graded samples were analyzed for their main chemical composition (dry matter, proteins, oils and fats, total acidity, total sugars, sucrose, starch, cellulose, pH and energy- values.

  17. Crestridge Vegetation Map [ds211

    Data.gov (United States)

    California Natural Resource Agency — This layer represents vegetation communities in the Department of Fish and Game's Crestridge Ecological Reserve. The County of San Diego, the Conservation Biology...

  18. Encouraging children to eat vegetables

    OpenAIRE

    Buh, Alenka

    2014-01-01

    It is important for children to maintain a healthy and balanced diet throughout their childhood and youth. Children tend to skip vegetables in their meals as they are not much liked; the tastes of vegetables are also highly specific and each individual has to get used to them by repeated tasting. The aim of this undergraduate thesis was to analyse how often children eat vegetables, which types of vegetables they like and which they do not, to determine if the executed method of pedagogica...

  19. A vegetal Geiger counter

    International Nuclear Information System (INIS)

    Anon.

    1999-01-01

    In order to study the Chernobyl accident impact on ecosystems, Ukrainian and Swiss scientists have used a plant: the Arabidopsis thaliana. They have introduced in its genome a gene coding an enzyme called β-glucuronidase. This substance, when it is expressed, colours vegetal cells blue. In fact the introduced gene is divided between 2 paired chromosomes. When the plant is placed on a nuclear contaminated soil, radiation damaged chromosomes exchange fragments and the 2 parts of the enzyme gene may recombine, the enzyme can then be expressed. For low and medium contamination ( 2 ) biologists have found a correlation between the number of blue spots on the plant and the irradiation rate. (A.C.)

  20. Genetic improvement of vegetables

    International Nuclear Information System (INIS)

    Jaramillo Vasquez, J.G.

    2001-01-01

    Some genetic bases of the improvement of vegetables are given. The objectives of the genetic improvement and the fundamental stages of this process are done. The sources of genetic variation are indicated and they are related the reproduction systems of the main horticultural species. It is analyzed the concept of genetic inheritance like base to determine the procedures more appropriate of improvement. The approaches are discussed, has more than enough phenotypic value, genetic action and genotypic variance; Equally the heredability concepts and value of improvement. The conventional methods of improvement are described, like they are: the introduction of species or varieties, the selection, the pure line, the pedigree method, the selection for families, the recurrent selection, the selection for unique seed, the haploids method, the selection for heterosis and the synthetic varieties

  1. Fruits and vegetables dehydration

    International Nuclear Information System (INIS)

    De Ita, A; Flores, G; Franco, F

    2015-01-01

    Dehydration diagrams were determined by means of Differential Thermal Analysis, DTA, and Thermo Gravimetric Analysis, TGA, curves of several simultaneous fruits and vegetables, all under the same conditions. The greater mass loss is associated with water containing in the structure of the investigated materials at low temperature. In poblano chile water is lost in a single step. The banana shows a very sharply two stages, while jicama can be observed although with a little difficulty three stages. The major mass loss occurs in the poblano chile and the lower in banana. The velocity and temperature of dehydration vary within a small range for most materials investigated, except for banana and cactus how are very different

  2. Fruits and vegetables dehydration

    Science.gov (United States)

    de Ita, A.; Flores, G.; Franco, F.

    2015-01-01

    Dehydration diagrams were determined by means of Differential Thermal Analysis, DTA, and Thermo Gravimetric Analysis, TGA, curves of several simultaneous fruits and vegetables, all under the same conditions. The greater mass loss is associated with water containing in the structure of the investigated materials at low temperature. In poblano chile water is lost in a single step. The banana shows a very sharply two stages, while jicama can be observed although with a little difficulty three stages. The major mass loss occurs in the poblano chile and the lower in banana. The velocity and temperature of dehydration vary within a small range for most materials investigated, except for banana and cactus how are very different.

  3. Heavy metals in green vegetables and soils from vegetable gardens ...

    African Journals Online (AJOL)

    Edible portions of five varieties of green vegetables, namely amaranth, chinese cabbage, cowpea leaves, leafy cabbage and pumpkin leaves, collected from several areas in Dar es Salaam, were analyzed for lead, cadmium, chromium, zinc, nickel and copper. Except for zinc, the levels of heavy metals in the vegetables ...

  4. Microevolution of European temperate oaks in response to environmental changes.

    Science.gov (United States)

    Kremer, Antoine

    2016-01-01

    This review reconstructs microevolutionary processes that allowed long-lived species as temperate oaks (Quercus petraea and Q. robur) to cope with climate change since the last glacial maximum, by assembling insights from complementary synchronic and allochronic approaches. Paleobotanical and genetic investigations show that oaks migrated at larger velocities than expected, thanks to long-distance rare events and most likely human interferences. Hybridization was a key mechanism accelerating migration and enhancing species succession. Common garden experiments and genome wide association studies demonstrated that diversifying selection across large environmental gradients contributed to rapid local adaptation. Finally the review explores how lessons taken from past evolutionary scenarios may help to predict future responses of oaks to ongoing climate change. Copyright © 2016. Published by Elsevier SAS.

  5. Nitrogen Deposition Effects on Soil Carbon Dynamics in Temperate Forests

    DEFF Research Database (Denmark)

    Ginzburg Ozeri, Shimon

    Soils contain the largest fraction of terrestrial carbon (C). Understanding the factors regulating the decomposition and storage of soil organic matter (SOM) is essential for predictions of the C sink strength of the terrestrial environment in the light of global change. Elevated long-term nitrog...... implications for modelling the carbon sink-strength of temperate forests under global change.......Soils contain the largest fraction of terrestrial carbon (C). Understanding the factors regulating the decomposition and storage of soil organic matter (SOM) is essential for predictions of the C sink strength of the terrestrial environment in the light of global change. Elevated long-term nitrogen...... (N) deposition into forest ecosystems has been increasing globally and was hypothesized to raise soil organic C (SOC) stocks by increasing forest productivity and by reducing SOM decomposition. Yet, these effects of N deposition on forest SOC stocks are uncertain and largely based on observations...

  6. Temperance internationalism: Guy Hayler and the World Prohibition Federation.

    Science.gov (United States)

    Fahey, David M

    2006-01-01

    The World Prohibition Federation, organized in 1909, and the International Record, published from 1917 to 1968, sought to internationalize the temperance movement by collecting and disseminating anti-drink news from around the globe. The Federation was based in London, and most of its activities were English-speakers. A British reformer named Guy Hayler served as its honorary president for thirty years and edited the "International Record" until his death in 1943. The Federation emphasized that prohibitionists comprised a moral community, united regardless of race, religion, nationality, or politics. Poorly funded, the Federation had difficulty competing with the World League against Alcoholism after the Anti-Saloon League of America organized this rival propaganda society in 1919.

  7. Influence of titanium on the tempering structure of austenitic steels

    International Nuclear Information System (INIS)

    Ghuezaiel, M.J.

    1985-10-01

    The microstructure of titanium-stabilized and initially deformed (approximately 20%) austenitic stainless steels used in structures of fast neutrons reactors has been studied after one hour duration annealings (500 0 C) by X-ray diffraction, optical microscopy, microhardness and transmission electron microscopy. The studied alloys were either of industrial type CND 17-13 (0.23 to 0.45 wt% Ti) or pure steels (18% Cr, 14% Ni, 0 or 0.3 wt% Ti). During tempering, the pure steels presented some restauration before recristallization. In the industrial steels, only recristallization occurred, and this only in the most deformed steel. Precipitation does not occur in the titanium-free pure steel. In industrial steels, many intermetallic phases are formed when recristallization starts [fr

  8. 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

  9. THE CLASS QUERCO-FAGETEA SYLVATICAE IN SICILY: AN EXAMPLE OF BOREO-TEMPERATE VEGETATION IN THE CENTRAL MEDITERRANEAN REGION

    Directory of Open Access Journals (Sweden)

    C. Brullo

    2012-04-01

    Full Text Available A syntaxonomical revision of the class Querco-Fagetea sylvaticae in Sicily, based on literature data and unpublished relevés, is presented. This class groups the mesophilous woods characterized by the dominance of deciduous trees (e.g. Fagus sylvatica, Quercus sp. pl., Acer sp. pl., and more rarely by conifers (Taxus baccata, Pinus nigra subsp. calabrica, as well as by other broadleaved trees, such as Betula aetnensis, Populus tremula, Castanea sativa. In Sicily, these woody communities are widespread in the northern and north-eastern districts of the island, chiefly on the highest peaks (Madonie, Nebrodi, Peloritani, and Etna. This class is represented in Sicily by two, both floristically and ecologically well differentiated orders: Fagetalia sylvaticae, with the sole alliance Geranio versicoloris-Fagion sylvaticae, and Quercetalia pubescenti-petraeae, with the endemic alliance Pino calabricae-Quercion congestae. On the whole, 22 associations have been recognized within the class Querco-Fagetea and for each of them nomenclature, floristic assessment, ecology, syndinamic relationships, and chorology are examined.

  10. Diversity patterns of ground beetles and understory vegetation in mature, secondary, and plantation forest regions of temperate northern China

    NARCIS (Netherlands)

    Zou, Yi; Sang, Weiguo; Wang, Shunzhong; Warren-Thomas, Eleanor; Liu, Yunhui; Yu, Zhenrong; Wang, Changliu; Axmacher, Jan Christoph

    2015-01-01

    Plantation and secondary forests form increasingly important components of the global forest cover, but our current knowledge about their potential contribution to biodiversity conservation is limited. We surveyed understory plant and carabid species assemblages at three distinct regions in

  11. Contributions of large wood to the initial establishment and diversity of riparian vegetation in a bar-braided temperate river

    OpenAIRE

    Nakamura, Futoshi; Fuke, Nao; Kubo, Mayumi

    2012-01-01

    The purpose of this study was to examine the effects of large wood (LW) on the physical environment and the initial establishment of vascular plant species in the Rekifune River, a large bar-braided monsoonal river in Japan. The physical environment and the diversity and composition of plant species were compared in relation to the orientation of LW pieces. We found that shading effects were more prevalent in the immediate vicinity of LW pieces than in quadrats distant from LW. The effect was...

  12. Altitudinal changes in composition and structure of mountain-temperate vegetation: a case study from the Western Carpathians

    Czech Academy of Sciences Publication Activity Database

    Doležal, J.; Šrůtek, Miroslav

    2003-01-01

    Roč. 158, - (2003), s. 201-221 ISSN 1385-0237 R&D Projects: GA AV ČR KSK6005114 Keywords : floristic calssification * gradient analysis * tree spatial pattern Subject RIV: EF - Botanics Impact factor: 1.000, year: 2003

  13. Application of Hyperspectral Vegetation Indices to Detect Variations in High Leaf Area Index Temperate Shrub Thicket Canopies

    Science.gov (United States)

    2011-01-01

    litter was collected after leaf fall in November 2008. Litter was dried at 70 °C for 4–5 days, separated into leaf, woody and reproductive (i.e. fruits ...115 (2011) 514–523 Davis, C., Bowles, J., Leathers , R., Korwan, D., Downes, T. V., Snyder, W., et al. (2002). Ocean PHILLS hyperspectral imager

  14. Disentangling the effects of climate, topography, soil and vegetation on stand-scale species richness in temperate forests

    OpenAIRE

    Zellweger Florian; Braunisch Veronika; Morsdorf Felix; Baltensweiler Andri; Abegg Meinrad; Roth Tobias; Bugmann Harald; Bollmann Kurt

    2015-01-01

    The growing awareness of biodiversity by forest managers has fueled the demand for information on abiotic and biotic factors that determine spatial biodiversity patterns. Detailed and area wide environmental data on potential predictors and site specific habitat characteristics however are usually not available across large spatial extents. Recent developments in environmental data acquisition such as the advent of Light Detection And Ranging (LiDAR) remote sensing provide opportunities to ch...

  15. Temporal flexibility of reproduction in temperate-breeding dabbling ducks

    Science.gov (United States)

    Krapu, Gary L.

    2000-01-01

    I compared nesting intervals during three consecutive years in five species of temperate-nesting dabbling ducks (Mallard [Anas platyrhynchos], Northern Pintail [Anas acuta], Northern Shoveler [Anas clypeata], Blue-winged Teal [Anas discors], Gadwall [Anas strepera]) and assessed whether differences existed in timing of refractoriness. Most nesting by females of all five species ended by the summer solstice. Nesting ended earliest for Northern Shovelers and Northern Pintails and latest for Gadwalls. Some Mallards, Blue-winged Teal, and Gadwalls continued to nest into mid- and late summer, whereas Northern Shovelers and Northern pintails did not. Mallards, Blue-winged Teal, and Gadwalls accounted for 99% (81 of 82) of flightless broods resulting from nests initiated during mid- or late summer in North Dakota and 98% (58 of 59) of flightless juveniles shot on or after 1 October by a random sample of duck hunters from across the United States. Early cessation of breeding by Northern Shovelers may have evolved in response to the species' limited flexibility in diet. Photorefractory mechanisms that limit most breeding to spring presumably evolved in response to severe constraints on reproductive success when nesting continued through summer(e.g. mortality of late-hatched young and molting females due to low temperatures). Interspecific differences in photosensitivity may account for variation in timing of cessation of nesting in late spring, but controlled experiments are needed to assess the possible role of non-photic influences. My results suggest that the refractory mechanisms controlling length of the breeding in temperate-nesting dabbling ducks are more varied and complex than previously thought, with non-photic influences (e.g. water conditions, food availability, food quality) having a larger role than indicated by earlier research.

  16. Influence of tempering on mechanical properties of ferritic martensitic steels

    International Nuclear Information System (INIS)

    Chun, Y. B.; Han, C. H.; Choi, B. K.; Lee, D. W.; Kim, T. K.; Jeong, Y. H.; Cho, S.

    2012-01-01

    In the mid-1980s research programs for development of low activation materials began. This is based on the US Nuclear Regulatory Commission Guidelines (10CFR part 61) that were developed to reduce long-lived radioactive isotopes, which allows nuclear reactor waste to be disposed of by shallow land burial when removed from service. Development of low activation materials is also key issue in nuclear fusion systems, as the structural components can became radioactive due to nuclear transmutation caused by exposure to high dose neutron irradiation. Reduced-activation ferritic martensitic (RAFM) steels have been developed in the leading countries in nuclear fusion technology, and are now being considered as primary candidate material for the test blanket module (TBM) in the international thermonuclear experiment reactor (ITER). RAFM steels developed so far (e.g., EUROFER 97 and F82H) meet the requirement for structural application in the ITER. However, if such alloys are used in the DEMO or commercial fusion reactor is still unclear, as the reactors are designed to operate under much severe conditions (i.e., higher outlet coolant temperature and neutron fluences). Such harsh operating conditions lead to development of RAFM steels with better creep and irradiation resistances. Mechanical properties of RAFM steels are strongly affected by microstructural features including the distribution, size and type of precipitates, dislocation density and grain size. For a given composition, such microstructural characteristics are determined mainly by thermo-mechanical process employed to fabricate the final product, and accordingly a final heat treatment, i.e., tempering is the key step to control the microstructure and mechanical properties. In the present work, we investigated mechanical properties of the RAFM steels with a particular attention being paid to effects of tempering on impact and creep properties

  17. Seasonality of temperate forest photosynthesis and daytime respiration.

    Science.gov (United States)

    Wehr, R; Munger, J W; McManus, J B; Nelson, D D; Zahniser, M S; Davidson, E A; Wofsy, S C; Saleska, S R

    2016-06-30

    Terrestrial ecosystems currently offset one-quarter of anthropogenic carbon dioxide (CO2) emissions because of a slight imbalance between global terrestrial photosynthesis and respiration. Understanding what controls these two biological fluxes is therefore crucial to predicting climate change. Yet there is no way of directly measuring the photosynthesis or daytime respiration of a whole ecosystem of interacting organisms; instead, these fluxes are generally inferred from measurements of net ecosystem-atmosphere CO2 exchange (NEE), in a way that is based on assumed ecosystem-scale responses to the environment. The consequent view of temperate deciduous forests (an important CO2 sink) is that, first, ecosystem respiration is greater during the day than at night; and second, ecosystem photosynthetic light-use efficiency peaks after leaf expansion in spring and then declines, presumably because of leaf ageing or water stress. This view has underlain the development of terrestrial biosphere models used in climate prediction and of remote sensing indices of global biosphere productivity. Here, we use new isotopic instrumentation to determine ecosystem photosynthesis and daytime respiration in a temperate deciduous forest over a three-year period. We find that ecosystem respiration is lower during the day than at night-the first robust evidence of the inhibition of leaf respiration by light at the ecosystem scale. Because they do not capture this effect, standard approaches overestimate ecosystem photosynthesis and daytime respiration in the first half of the growing season at our site, and inaccurately portray ecosystem photosynthetic light-use efficiency. These findings revise our understanding of forest-atmosphere carbon exchange, and provide a basis for investigating how leaf-level physiological dynamics manifest at the canopy scale in other ecosystems.

  18. Social implications of residential demand response in cool temperate climates

    International Nuclear Information System (INIS)

    Darby, Sarah J.; McKenna, Eoghan

    2012-01-01

    Residential electrical demand response (DR) offers the prospect of reducing the environmental impact of electricity use, and also the supply costs. However, the relatively small loads and numerous actors imply a large effort: response ratio. Residential DR may be an essential part of future smart grids, but how viable is it in the short to medium term? This paper reviews some DR concepts, then evaluates the propositions that households in cool temperate climates will be in a position to contribute to grid flexibility within the next decade, and that that they will allow some automated load control. Examples of demand response from around the world are discussed in order to assess the main considerations for cool climates. Different tariff types and forms of control are assessed in terms of what is being asked of electricity users, with a focus on real-time pricing and direct load control in energy systems with increasingly distributed resources. The literature points to the significance of thermal loads, supply mix, demand-side infrastructure, market regulation, and the framing of risks and opportunities associated with DR. In concentrating on social aspects of residential demand response, the paper complements the body of work on technical and economic potential. - Highlights: ► Demand response implies major change in governance of electricity systems. ► Households in cool temperate climates can be flexible, mainly with thermal loads. ► DR requires simple tariffs, appropriate enabling technology, education, and feedback. ► Need to test consumer acceptance of DR in specific conditions. ► Introduce tariffs with technologies e.g., TOU tariff plus DLC with electric vehicles.

  19. Vegetable Genetic Resources in China

    Directory of Open Access Journals (Sweden)

    Haiping WANG

    2018-03-01

    Full Text Available China is recognized as an important region for plant biodiversity based on its vast and historical collection of vegetable germplasm. The aim of this review is to describe the exploration status of vegetable genetic resources in China, including their collection, preservation, evaluation, and utilization. China has established a number of national-level vegetable genetic resources preservation units, including the National Mid-term Genebank for Vegetable Germplasm Resources, the National Germplasm Repository for Vegetatively-Propagated Vegetables, and the National Germplasm Repository for Aquatic Vegetables. In 2015, at least 36 000 accessions were collected and preserved in these units. In the past decade, 44 descriptors and data standards for different species have been published, and most accessions have been evaluated for screening the germplasms for specific important traits such as morphological characteristics, disease resistance, pest resistance, and stress tolerance. Moreover, the genetic diversity and evolution of some vegetable germplasms have been evaluated at the molecular level. Recently, more than 1 000 accessions were distributed to researchers and breeders each year by various means for vegetable research and production. However, additional wild-relative and abroad germplasms from other regions need to be collected and preserved in the units to expand genetic diversity. Furthermore, there is a need to utilize advanced techniques to better understand the background and genetic diversity of a wide range of vegetable genetic resources. This review will provide agricultural scientists’ insights into the genetic diversity in China and provide information on the distribution and potential utilization of these valuable genetic resources. Keywords: vegetable, genetic resource, preservation, evaluation, utilization

  20. Vegetation resurvey is robust to plot location uncertainty

    Science.gov (United States)

    Kopecký, Martin; Macek, Martin

    2017-01-01

    Aim Resurveys of historical vegetation plots are increasingly used for the assessment of decadal changes in plant species diversity and composition. However, historical plots are usually relocated only approximately. This potentially inflates temporal changes and undermines results. Location Temperate deciduous forests in Central Europe. Methods To explore if robust conclusions can be drawn from resurvey studies despite location uncertainty, we compared temporal changes in species richness, frequency, composition and compositional heterogeneity between exactly and approximately relocated plots. We hypothesized that compositional changes should be lower and changes in species richness should be less variable on exactly relocated plots, because pseudo-turnover inflates temporal changes on approximately relocated plots. Results Temporal changes in species richness were not more variable and temporal changes in species composition and compositional heterogeneity were not higher on approximately relocated plots. Moreover, the frequency of individual species changed similarly on both plot types. Main conclusions The resurvey of historical vegetation plots is robust to uncertainty in original plot location and, when done properly, provides reliable evidence of decadal changes in plant communities. This provides important background for other resurvey studies and opens up the possibility for large-scale assessments of plant community change. PMID:28503083

  1. Establishment of vegetation on mined sites by management of mycorrhizae

    International Nuclear Information System (INIS)

    Marrs, L.F.; Marx, D.H.; Cordell, C.E.

    1999-01-01

    Plant ecosystems, including those in the tropical, temperate, boreal, and desert zones, began evolving more than 400 million years ago. Trees and other land plants in these environments were faced with many natural stresses including extreme temperature changes, fluctuating levels of available water, soil infertility, catastrophic fires and storms, poor soil physical conditions and competition. Basically, these plants evolved by genetic selection and developed many physical, chemical, and biological requirements necessary to survive these periodically stressed environments. Survivors were those that could form extensive lateral root systems to occupy soil volumes sufficiently large for them to obtain enough essential mineral elements and water to support their above and below ground growth needs. The most competitive plants in these stressed ecosystems were those with the largest root systems. One major biological requirement that evolved was the association of plants with mycorrhizal fungi. This is still true today for land that has been disturbed by mining, construction, and other activities. Successful vegetation establishment on these lands has been achieved by using the biological tools; native tree seedlings, shrubs, forbs, and grasses inoculated with specific, beneficial mycorrhizal fungi. Trees and shrubs are custom grown in nurseries with selected mycorrhizal fungi, such as Pisolithus tinctorius (Pt) and other fungi, provide significant benefits to the plants through increased water and mineral adsorption, decreased toxin absorption and overall reduction of plant stress. This has resulted in significant increases in plant growth and survival rates, density and sustainable vegetation

  2. Advanced remote sensing to quantify temperate peatland capacity for belowground carbon capture

    Science.gov (United States)

    Byrd, K. B.; Blanchard, S.; Schile, L. M.; Kolding, S.; Kelly, M.; Windham-Myers, L.; Miller, R.

    2011-12-01

    Temperate peatlands typically dominated by grasses and sedges generate among the greatest annual rates of net primary productivity (NPP, up to 4 kg C m-2) and soil carbon storage (up to 1 kg C m-2) for natural ecosystems. Belowground tissues represent 20-80% of total NPP, thus understanding the controls on belowground NPP (BNPP) in these wetland ecosystems is particularly important to quantifying peatland carbon balances. In addition, there is a growing need to quantify large-scale belowground C sequestration rates in wetlands to better understand marsh resilience to sea level rise and to help define eligibility for carbon offset credits. Since plant productivity influences wetland C budgets, combining field and remote sensing techniques for estimating above and belowground productivity of wetland vegetation over a large spatial extent will help to address these needs. We are working in a USGS long-term experimental wetland restoration site on drained peatland in the Sacramento-San Joaquin River Delta. Using the spatial variability in water depth and residence time across the 7 ha wetland, our goal is to develop practical methods to quantify and map BNPP of emergent marsh vegetation from remotely sensed estimates of aboveground plant characteristics and aboveground NPP. Field data collected on wetland plants hardstem bulrush (Schoenoplectus acutus) and cattail (Typha spp.) were coupled with reflectance data from a field spectrometer (range 350-2500 nm) every two to three weeks during the summer of 2011. We are analyzing reflectance data to develop hyperspectral indices that predict the biophysical characteristics of wetland vegetation - biomass, leaf area index (LAI), and the fraction of absorbed photosynthetically active radiation (fAPAR) - which may be used to infer belowground biomass and productivity. Soil cores and root in-growth bags were used to calculate root biomass and productivity rates. Existing allometric relationships were used to calculate

  3. Deciphering the Costs of Reproduction in Mango – Vegetative Growth Matters

    Science.gov (United States)

    Capelli, Mathilde; Lauri, Pierre-Éric; Normand, Frédéric

    2016-01-01

    Irregular fruit production across successive years is a major issue that limits the profitability of most temperate and tropical fruit crops. It is particularly affected by the reciprocal relationships between vegetative and reproductive growth. The concept of the costs of reproduction is defined in terms of losses in the potential future reproductive success caused by current investment in reproduction. This concept, developed in ecology and evolutionary biology, could provide a methodological framework to analyze irregular bearing in fruit crops, especially in relation to the spatial scale at which studies are done. The objective of this study was to investigate the direct effects of reproduction during a growing cycle on reproduction during the following growing cycle and the indirect effects through vegetative growth between these two reproductive events, for four mango cultivars and during two growing cycles. Two spatial scales were considered: the growth unit (GU) and the scaffold branch. Costs of reproduction were detected between two successive reproductive events and between reproduction and vegetative growth. These costs were scale-dependent, generally detected at the GU scale and infrequently at the scaffold branch scale, suggesting partial branch autonomy with respect to processes underlying the effects of reproduction on vegetative growth. In contrast, the relationships between vegetative growth and reproduction were positive at the GU scale and at the scaffold branch scale in most cases, suggesting branch autonomy for the processes, mainly local, underlying flowering and fruiting. The negative effect of reproduction on vegetative growth prevailed over the positive effect of vegetative growth on the subsequent reproduction. The costs of reproduction were also cultivar-dependent. Those revealed at the GU scale were related to the bearing behavior of each cultivar. Our results put forward the crucial role of vegetative growth occurring between two

  4. Toxicología Vegetal

    OpenAIRE

    García Fernández, Antonio Juan

    2010-01-01

    Presentaciones de clase de los temas de Toxicología Vegetal de la licenciatura de Veterinaria de la Universidad de Murcia del curso 2011/12. Presentaciones de Toxicología Vegetal de la asignatura de Toxicología de la Licenciatura de Veterinaria del curso 2011/12

  5. Effect of tempering upon the tensile properties of a nanostructured bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, H.S. [University of Technology, Baghdad (Iraq); Peet, M.J., E-mail: mjp54@cam.ac.uk [Department of Materials Science and Metallurgy, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Avettand-Fènoël, M-N. [Unité Matériaux Et Transformations (UMET) UMR CNRS 8207, Université, Lille 1, 59655 Villeneuve D' ASCQ (France); Bhadeshia, H.K.D.H. [Department of Materials Science and Metallurgy, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2014-10-06

    The tensile properties of a nanostructured carbide-free bainitic steel formed at 200–250 °C are compared against those after tempering sufficiently to remove the retained austenite. Although significant ductility is observed following tempering, a comparison of tempered and untempered samples shows that it is in fact reduced when a comparison is made at identical strength. The shape of the stress–strain curves shows clear evidence that the capacity for work hardening is reduced with the loss of austenite. The nanostructure of the steel transformed at 250 °C is examined by transmission electron microscopy, to compare the as-transformed to the tempered structure. In this case after tempering at 500 °C the energy absorbed during the tensile test is lower, due to the lower strength. Reduction of strength is caused by the slight coarsening of the bainite plates, and lower dislocation density after tempering. Considering the formation of carbide particles in high strength steel, impressive ductility is exhibited even in the tempered condition.

  6. Effect of tempering upon the tensile properties of a nanostructured bainitic steel

    International Nuclear Information System (INIS)

    Hasan, H.S.; Peet, M.J.; Avettand-Fènoël, M-N.; Bhadeshia, H.K.D.H.

    2014-01-01

    The tensile properties of a nanostructured carbide-free bainitic steel formed at 200–250 °C are compared against those after tempering sufficiently to remove the retained austenite. Although significant ductility is observed following tempering, a comparison of tempered and untempered samples shows that it is in fact reduced when a comparison is made at identical strength. The shape of the stress–strain curves shows clear evidence that the capacity for work hardening is reduced with the loss of austenite. The nanostructure of the steel transformed at 250 °C is examined by transmission electron microscopy, to compare the as-transformed to the tempered structure. In this case after tempering at 500 °C the energy absorbed during the tensile test is lower, due to the lower strength. Reduction of strength is caused by the slight coarsening of the bainite plates, and lower dislocation density after tempering. Considering the formation of carbide particles in high strength steel, impressive ductility is exhibited even in the tempered condition

  7. DETERMINATION OF THE OPTIMAL TEMPERING TEMPERATURE IN HARD FACING OF THE FORGING DIES

    Directory of Open Access Journals (Sweden)

    Milan Mutavdžić

    2012-06-01

    Full Text Available Here is analyzed selection of the optimal technology for heat treatment during the reparation of the damaged forging dies. Those tools are manufactured from alloyed tool steels for operation at elevated temperatures. Those steels are prone to self-hardening, so in reparatory hard-facing they must be preheated, additionally heated and tempered. During the tempering, in temperature interval 500-600°C, a secondary increase of hardness and decrease of impact toughness occurs, the so-called reversible tempering brittleness. Here is shown that it can be avoided by application of metallurgical and technological measures. Metallurgical measures assume adequate selection of steels. Since the considered steels are per se prone to tempering brittleness, we conducted experimental investigations to define the technological measures to avoid it. Tests on models were conducted: tempering from different temperatures, slow heating and cooling in still air. Hardness measurements showed that at 520°C, the secondary increase of hardness occurs, with drop of the impact toughness. Additional hard-facing tests included samples tempered at various regimes. Samples were prepared for mechanical and metallographic investigations. Results presented illustrate influence of additional heat treatment on structure, hardness and mechanical properties of the hard-faced layers. This enabled establishing the possibility of avoiding the tempering brittleness through technological measures.

  8. Determination of the optimal tempering temperature in hard facing of the forging dies

    Directory of Open Access Journals (Sweden)

    Milan Mutavdžić

    2012-05-01

    Full Text Available Here is analyzed selection of the optimal technology for heat treatment during the reparation of the damaged forging dies. Those tools are manufactured from alloyed tool steels for operation at elevated temperatures. Those steels are prone to self-hardening, so in reparatory hard-facing they must be preheated, additionally heated and tempered. During the tempering, in temperature interval 500-600°C, a secondary increase of hardness and decrease of impact toughness occurs, the so-called reversible tempering brittleness. Here is shown that it can be avoided by application of metallurgical and technological measures. Metallurgical measures assume adequate selection of steels. Since the considered steels are per se prone to tempering brittleness, we conducted experimental investigations to define the technological measures to avoid it. Tests on models were conducted: tempering from different temperatures, slow heating and cooling in still air. Hardness measurements showed that at 520°C, the secondary increase of hardness occurs, with drop of the impact toughness. Additional hard-facing tests included samples tempered at various regimes. Samples were prepared for mechanical and metallographic investigations. Results presented illustrate influence of additional heat treatment on structure, hardness and mechanical properties of the hard-faced layers. This enabled establishing the possibility of avoiding the tempering brittleness through technological measures. 

  9. Effect of tempering on the microstructure and mechanical properties of a medium carbon bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Kang, J. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, F.C., E-mail: zfc@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China); Yang, X.W. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Lv, B. [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Wu, K.M. [International Research Institute for Steel Technology, Wuhan University of Science and Technology, Wuhan 430081 (China); Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

    2017-02-16

    The effect of tempering on the microstructure and mechanical properties of a medium carbon bainitic steel has been investigated through optical microscopy, electron back-scattered diffraction, transmission electron microscopy and X-ray diffraction analyses. A nano-level microstructure containing plate-like bainitic ferrite and film-like retained austenite is obtained by isothermal transformation at Ms+10 °C followed by tempering within 240–450 °C. Results show that the sample tempered at 340 °C occupies the optimal balance of strength and toughness by maintaining a certain level of plasticity; samples tempered at 320 °C and 360 °C with low and high yield ratio come second. The microstructure of the steel is not sensitive to tempering temperatures before 360 °C. When the temperature is increased to 450 °C, the significantly coarsened bainitic ferrite plate and the occurrence of a small quantity of carbide precipitation account for its low toughness. The amount of retained austenite increases with the tempering temperature before 400 °C, followed by decreasing with further increase in the temperature. This behavior is related to the competition between retained austenite further transforming into bainite and decomposing into carbide during tempering.

  10. Palynological evidence for vegetation patterns in the Transvaal (South Africa during the late Pleistocene and Holocene

    Directory of Open Access Journals (Sweden)

    L. Scott

    1983-11-01

    Full Text Available Palynological evidence relating to the nature of Late Quaternary vegetation types and plant migrations in the Transvaal is briefly summarized. It is suggested that, after an early temperate, relatively moist phase and a subsequent relatively dry phase lasting until about 25 000 yr B.P., a vegetation-type with ericaceous elements developed. It resembled belts presently occurring above the treeline and was possibly widespread over the plains of the Transvaal during the last glacial maximum period. In the central parts of the province, warm semi-arid savanna subsequently expanded during the early Holocene and was followed by a more broad-leafed type of woodland in the late Holocene. This change probably resulted from slightly wetter and, at times, also slightly warmer and cooler conditions.

  11. 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

  12. Effect of microalloying elements on microstructure and properties of quenched and tempered constructional steel

    Science.gov (United States)

    Ma, Qingshen; Huang, Leqing; Di, Guobiao; Wang, Yanfeng; Yang, Yongda; Ma, Changwen

    2017-09-01

    The effects of microalloying elements Nb, V and Ti on microstructure and properties of quenched and tempered steel were studied. Results showed that the addition of microalloying elements led to the formation of bainite and increased strength, while the austenization and ferrite transformation temperature was barely affected, i.e. 10°C. Microalloying elements shortened the incubation time for bainite transformation by refinement of austenite grain, and decreased the hardenability by forming carbides and therefore reducing the carbon content of super-cooled austenite. Either of them promoted the bainite transformation. The better tempering stability was ascribed to the as hot-rolled bainite microstructure and secondary carbide precipitation during tempering.

  13. Internal strains after recovery of hardness in tempered martensitic steels for fusion reactors

    Science.gov (United States)

    Brunelli, L.; Gondi, P.; Montanari, R.; Coppola, R.

    1991-03-01

    After tempering, with recovery of hardness, MANET steels present internal strains; these residual strains increase with quenching rate prior to tempering, and they remain after prolonged tempering times. On account of their persistence, after thermal treatments which lead to low dislocation and sub-boundary densities, the possibility has been considered that the high swelling resistance of MANET is connected with these centres of strain, probably connected with the formation, in ferrite, of Cr-enriched and contiguous Cr-depleted zones which may act as sinks for interstitials. Comparative observations on the internal strain behaviour of cold worked 316L stainless steel appear consistent with this possibility.

  14. On the tempered martensite embrittlement in AISI 4140 low alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, F.A. (Dept. of Materials Science and Metallurgy, Catholic Univ., Rio de Janeiro, RJ (Brazil)); Pereira, L.C.; Gatts, C. (Dept. of Metallurgy and Materials Engineering, Federal Univ., Rio de Janeiro, RJ (Brazil)); Graca, M.L. (Materials Div., Technical Aerospace Center, Sao Jose dos Campos, SP (Brazil))

    1991-02-01

    In the present investigation the Auger electron spectroscopy (AES) technique was used to determine local carbon and phosphorus concentrations on the fracture surfaces of as-quenched and quenched-and-tempered (at 350deg C) AISI 4140 steel specimens austenitized at low and high temperatures. The AES results were rationalized to conclude that, although carbide growth as well as phosphorus segregation are expected to contribute to tempered martensite embrittlement, carbide precipitation on prior austenite grain boundaries during tempering is seen to be the microstructural change directly responsible for the occurrence of the referred embrittlement phenomenon. (orig.).

  15. Effect of tempering time on the ballistic performance of a high strength armour steel

    OpenAIRE

    Jena, Pradipta Kumar; Senthil P., Ponguru; K., Siva Kumar

    2016-01-01

    The investigation describes and analyses the effect of tempering time on the mechanical and ballistic performance of a high strength armour steel. The steel is subjected to tempering at 300 °C for 2, 24 and 48 h. A marginal variation in strength and hardness is observed with increase in tempering time, whereas ductility and Charpy impact values are found to be decreasing. Ballistic performance of the samples are evaluated by impacting 7.62 mm and 12.7 mm armour piercing projectiles at 0° angl...

  16. Ecosystem CO2 production during winter in a Swedish subarctic region: the relative importance of climate and vegetation type

    DEFF Research Database (Denmark)

    Grogan, Paul; Jonasson, Sven Evert

    2006-01-01

    General circulation models consistently predict that regional warming will be most rapid in the Arctic, that this warming will be predominantly in the winter season, and that it will often be accompanied by increasing snowfall. Paradoxically, despite the strong cold season emphasis in these predi...... will respond to climate change during winter because they indicate a threshold (~1 m) above which there would be little effect of increased snow accumulation on wintertime biogeochemical cycling....... in these predictions, we know relatively little about the plot and landscape-level controls on tundra biogeochemical cycling in wintertime as compared to summertime. We investigated the relative influence of vegetation type and climate on CO2 production rates and total wintertime CO2 release in the Scandinavian...... subarctic. Ecosystem respiration rates and a wide range of associated environmental and substrate pool size variables were measured in the two most common vegetation types of the region (birch understorey and heath tundra) at four paired sites along a 50 km transect through a strong snow depth gradient...

  17. Synchrotron micro-diffraction analysis of the microstructure of cryogenically treated high performance tool steels prior to and after tempering

    Energy Technology Data Exchange (ETDEWEB)

    Xu, N.; Cavallaro, G.P. [Applied Centre for Structural and Synchrotron Studies, Mawson Lakes Blvd, University of South Australia, Mawson Lakes, South Australia 5095 (Australia); Gerson, A.R., E-mail: Andrea.Gerson@unisa.edu.au [Applied Centre for Structural and Synchrotron Studies, Mawson Lakes Blvd, University of South Australia, Mawson Lakes, South Australia 5095 (Australia)

    2010-10-15

    The phase transformation and strain changes within cryogenically (-196 deg. C) treated high performance tool steels (AISI H13) before and after tempering have been examined using both laboratory XRD and synchrotron micro-diffraction. The martensitic unit cell was found to have very low tetragonality as expected for low carbon steel. Tempering resulted in the diffusion of excess carbon out of the martensite phase and consequent unit cell shrinkage. In addition on tempering the martensite became more homogeneous as compared to the same samples prior to tempering. For cryogenically treated samples, the effect was most pronounced for the rapidly cooled sample which was the least homogenous sample prior to tempering but was the most homogenous sample after tempering. This suggests that the considerable degree of disorder resulting from rapid cryogenic cooling results in the beneficial release of micro-stresses on tempering thus possibly resulting in the improved wear resistance and durability observed for cryogenically treated tool steels.

  18. Synchrotron micro-diffraction analysis of the microstructure of cryogenically treated high performance tool steels prior to and after tempering

    International Nuclear Information System (INIS)

    Xu, N.; Cavallaro, G.P.; Gerson, A.R.

    2010-01-01

    The phase transformation and strain changes within cryogenically (-196 deg. C) treated high performance tool steels (AISI H13) before and after tempering have been examined using both laboratory XRD and synchrotron micro-diffraction. The martensitic unit cell was found to have very low tetragonality as expected for low carbon steel. Tempering resulted in the diffusion of excess carbon out of the martensite phase and consequent unit cell shrinkage. In addition on tempering the martensite became more homogeneous as compared to the same samples prior to tempering. For cryogenically treated samples, the effect was most pronounced for the rapidly cooled sample which was the least homogenous sample prior to tempering but was the most homogenous sample after tempering. This suggests that the considerable degree of disorder resulting from rapid cryogenic cooling results in the beneficial release of micro-stresses on tempering thus possibly resulting in the improved wear resistance and durability observed for cryogenically treated tool steels.

  19. Deriving Vegetation Dynamics of Natural Terrestrial Ecosystems from MODIS NDVI/EVI Data over Turkey.

    Science.gov (United States)

    Evrendilek, Fatih; Gulbeyaz, Onder

    2008-09-01

    The 16-day composite MODIS vegetation indices (VIs) at 500-m resolution for the period between 2000 to 2007 were seasonally averaged on the basis of the estimated distribution of 16 potential natural terrestrial ecosystems (NTEs) across Turkey. Graphical and statistical analyses of the time-series VIs for the NTEs spatially disaggregated in terms of biogeoclimate zones and land cover types included descriptive statistics, correlations, discrete Fourier transform (DFT), time-series decomposition, and simple linear regression (SLR) models. Our spatio-temporal analyses revealed that both MODIS VIs, on average, depicted similar seasonal variations for the NTEs, with the NDVI values having higher mean and SD values. The seasonal VIs were most correlated in decreasing order for: barren/sparsely vegetated land > grassland > shrubland/woodland > forest; (sub)nival > warm temperate > alpine > cool temperate > boreal = Mediterranean; and summer > spring > autumn > winter. Most pronounced differences between the MODIS VI responses over Turkey occurred in boreal and Mediterranean climate zones and forests, and in winter (the senescence phase of the growing season). Our results showed the potential of the time-series MODIS VI datasets in the estimation and monitoring of seasonal and interannual ecosystem dynamics over Turkey that needs to be further improved and refined through systematic and extensive field measurements and validations across various biomes.

  20. Special study on vegetative covers

    International Nuclear Information System (INIS)

    1988-11-01

    This report describes the findings of a special study on the use of vegetative covers to stabilize tailings piles for the Uranium Mill Tailings Remedial Action (UMTRA) Project. The principal rationale for using plants would be to establish a dynamic system for controlling water balance. Specifically, vegetation would be used to intercept and transpire precipitation to the atmosphere, rather than allowing water to drain into the tailings and mobilize contaminants. This would facilitate compliance with groundwater standards proposed for the UMTRA Project by the Environmental Protection Agency. The goals of the study were to evaluate the feasibility of using vegetative covers on UMTRA Project piles, define the advantages and disadvantages of vegetative covers, and develop general guidelines for their use when such use seems reasonable. The principal method for the study was to analyze and apply to the UMTRA Project the results of research programs on vegetative covers at other US Department of Energy (DOE) waste management facilities. The study also relied upon observations made of existing stabilized piles at UMTRA Project sites where natural vegetation is growing on the rock-covered surfaces. Water balance and erosion models were also used to quantify the long-term performance of vegetative covers planned for the topslopes of stabilized piles at Grand Junction and Durango, Colorado, two UMTRA Project sites where the decision was made during the course of this special study to use vegetative covers. Elements in the design and construction of the vegetative covers at these two sites are discussed in the report, with explanations of the differing features that reflect differing environmental conditions. 28 refs., 18 figs., 9 tabs

  1. Significant impacts of nutrient enrichment on High Arctic vegetation and soils despite two decades of recovery

    Science.gov (United States)

    Street, L. E.; Burns, N. R.; Woodin, S. J.

    2012-04-01

    We re-visit a unique field manipulation study in Svalbard to assess the long-term recovery of plant species composition, leaf tissue chemistry and total ecosystem carbon storage from nutrient enrichment. The experiment was established in 1991. The original aim was to quantify the 'critical load' of nitrogen (N) for tundra; that is, the minimum rate of N deposition affecting ecosystem structure and function. Dissolved N was applied to heath vegetation, both alone and in combination with phosphorous (P), during the growing season over three years. The rates of N addition were lower than in most other nutrient manipulation studies, and were designed to represent typical rates of deposition in the Scottish highlands (50 kg N ha-1 yr-1) and maximum deposition rates experienced in the Arctic (10 kg N ha-1 yr-1). Significant changes in shrub cover, the greenness and N content of the moss layer, and the extent of ecosystem N saturation had occurred by the end of the treatment period. After 18 years of recovery without further treatment, we assessed primary productivity using CO2 flux measurements, and the 'greenness' of vegetation using the Normalised Difference Vegetation Index. We made destructive measurements of above- and below-ground carbon and nutrient stocks, quantified species composition and sampled leaf tissue for chemical analysis. Total carbon storage in organic soils and vegetation was c. 40 % lower in the plots treated with 50 kg N ha-1 yr-1 compared to controls. Species composition in N treated plots also differed significantly, but there was no clear treatment effect on primary productivity. Where 50 kg N ha-1 yr-1 was applied in combination with P (at 5 kg P ha-1 yr-1 ), organic carbon storage was c. 70 % greater than controls, the vegetation was greener, and primary productivity higher. Effects of the treatments were also still clearly apparent in moss tissue nutrient status, even at the lower nitrogen application rate. Our results imply that the effects

  2. Radiation and the vegetable industry

    International Nuclear Information System (INIS)

    Roberts, P.B.

    1984-01-01

    The possible uses of irradiation in the vegetable industry are considered. Interest has been increasing because of possible bans on chemical fumigants and clearance of irradiation as an acceptable process, up to certain dose limits, by Codex Alimentarius and the US FDA. Inhibition of sprouting in potatoes and onions would be one possibility for exploitation. However, the main incentive for vegetable irradiation would be as a quarantine treatment for exported products. The shelf-life of a few vegetables could also be increased by combining radiation with heat treatments. Costs in New Zealand and consumer attitudes are briefly considered

  3. In Situ Study of Phase Transformations during Non-Isothermal Tempering of Bainitic and Martensitic Microstructures

    Directory of Open Access Journals (Sweden)

    S. Hesamodin Talebi

    2017-09-01

    Full Text Available Phase transformations during non-isothermal tempering of bainitic or martensitic microstructures obtained after quenching of a medium-carbon low-alloy steel was studied. The microstructures correspond to different locations of an as-quenched large-sized forged ingot used as a die material in the automotive industry. High-resolution dilatometry experiments were conducted to simulate the heat treatment process, as well as to investigate different phenomena occurring during non-isothermal tempering. The microstructures were characterized using optical and scanning electron microscopy. Dilatometry analyses demonstrated that tempering behavior varied significantly from bainitic to martensitic microstructures. Retained austenite, which exists between bainitic ferrite sheaves, decomposes to lower bainite causing a remarkable volume increase. It was found that this decomposition finishes below 386 °C. By contrast, martensite tempering was accompanied with a volume decrease due to the decomposition of medium-carbon martensite to low carbon martensite and carbides.

  4. A common framework for greenhouse gas assessment protocols in temperate agroforestry systems: Connecting via GRACEnet

    Science.gov (United States)

    Agroforestry systems offer many ecosystem benefits, but such systems have previously been marginalized in temperate environments due to overriding economic goals and perceived management complexity. In view of adaptation to a changing climate, agroforestry systems offer advantages that require quan...

  5. Understanding seagrass resilience in temperate systems: the importance of timing of the disturbance

    NARCIS (Netherlands)

    Soissons, L.M.; Li, B.; Han, Q.; van Katwijk, M.M.; Ysebaert, T.; Herman, P.M.J.; Bouma, T.J.

    2016-01-01

    Temperate seagrass meadows form valuable ecosystems in coastal environments and present a distinctseasonal growth. They are threatened by an increasing amount of stressors, potentially affecting theircapacity to recover from disturbances. We hypothesized that their resilience to disturbances is

  6. Understanding seagrass resilience in temperate systems: the importance of timing of the disturbance

    NARCIS (Netherlands)

    Soissons, L.M.; Li, B.Q.; Han, Q.Y.; Katwijk, M.M. van; Ysebaert, T.; Herman, P.M.J.; Bouma, T.J.

    2016-01-01

    Temperate seagrass meadows form valuable ecosystems in coastal environments and present a distinct seasonal growth. They are threatened by an increasing amount of stressors, potentially affecting their capacity to recover from disturbances. We hypothesized that their resilience to disturbances is

  7. Studies on growth and age of bivalves from temperate and tropical estuarine ecosystems

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    Comparison of growth progression and age composition of Abra alba and Nuculana minuta from temperate estuarine ecosystem with Meretrix casta and Paphia malabarica from tropical estuarine environment, revealed that the annual growth rate in tropical...

  8. Analysis of mechanical properties of steel 1045 plasma nitriding: with and without tempering

    International Nuclear Information System (INIS)

    Machado, N.T.B.; Passos, M.L.M. dos; Riani, J.C.; Recco, A.A.C.

    2014-01-01

    The purpose of this study was to evaluate the possibility of tempering during the nitriding of AISI 1045 steel. The objective was to evaluate the possibility of eliminating this phase, with the nitriding properties remaining unaltered. For this, three parameter samples were compared: quenched, tempered and nitrided for 2h; quenching and nitrided for 2h and quenching and nitrided for 4h. The analysis techniques used for characterizing the samples before and after nitriding were optical microscopy, hardness Rockwell C (HRC), scanning electron microscopy (SEM), X-ray diffraction (XRD). Results showed that phase γ is the most favorable of all parameters tested. The hardness assays showed that samples with different initial hardness (with and without tempering) and even nitriding time showed similar mechanical properties. This fact suggests that the tempering process occurred parallel to the nitriding process. (author)

  9. Evolutionary and ecological differentiation in the pantropical to warm-temperate seaweed Digenea simplex (Rhodophyta)

    NARCIS (Netherlands)

    Pakker, H; Klerk, H; vanCampen, JH; Olsen, JL; Breeman, AM

    Genetic differentiation among geographic isolates of the pantropical to warm-temperate red alga Digenea simplex (Wulfen) C. Agardh was investigated using random amplified polymorphic DNA (RAPD) markers, crossing studies, and temperature tolerances experiments. Eleven isolates representing

  10. Can Detectability Analysis Improve the Utility of Point Counts for Temperate Forest Raptors?

    Science.gov (United States)

    Temperate forest breeding raptors are poorly represented in typical point count surveys because these birds are cryptic and typically breed at low densities. In recent years, many new methods for estimating detectability during point counts have been developed, including distanc...

  11. Comparison of the segregation behavior between tempered martensite and tempered bainite in Ni-Cr-Mo high strength low alloy RPV steel

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang Gyu; Kim, Min Chul; Kim, Hyung Jun; Lee, Bong Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    SA508 Gr.4N Ni-Cr-Mo low alloy steel has an superior fracture toughness and strength, compared to commercial Mn-Mo-Ni low alloy RPV steel SA508 Gr.3. Higher strength and fracture toughness of low alloy steels could be obtained by adding Ni and Cr. So several were performed on researches on SA508 Gr.4N low alloy steel for a RPV application. The operation temperature and term of a reactor pressure vessel is more than 300 .deg. C and over 40 years. Therefore, in order to apply the SA508 Gr.4N low alloy steel for a reactor pressure vessel, the resistance of thermal embrittlement in the high temperature range including temper embrittlement is required. S. Raoul reported that the susceptibility to temper embrittlement was increasing a function of the cooling rate in SA533 steel, which suggests the martensitic microstructures resulting from increased cooling rates are more susceptible to temper embrittlement. However, this result has not been proved yet. So the comparison of temper embrittlement behavior was made between martensitic microstructure and bainitic microstructure with a viewpoint of boundary features in SA508 Gr.4N, which have mixture of tempered bainite/martensite. We have compared temper embrittlement behaviors of SA508 Gr.4N low alloy steel with changing volume fraction of martensite. The mechanical properties of these low alloy steels were evaluated after a long-term heat treatment. Then, the the segregated boundaries were observed and segregation behavior was analyzed by AES. In order to compare the misorientation distributions of model alloys, grain boundary structures were measured with EBSD

  12. COMPARISON OF THREE METHODS TO PROJECT FUTURE BASELINE CARBON EMISSIONS IN TEMPERATE RAINFOREST, CURINANCO, CHILE

    Energy Technology Data Exchange (ETDEWEB)

    Patrick Gonzalez; Antonio Lara; Jorge Gayoso; Eduardo Neira; Patricio Romero; Leonardo Sotomayor

    2005-07-14

    Deforestation of temperate rainforests in Chile has decreased the provision of ecosystem services, including watershed protection, biodiversity conservation, and carbon sequestration. Forest conservation can restore those ecosystem services. Greenhouse gas policies that offer financing for the carbon emissions avoided by preventing deforestation require a projection of future baseline carbon emissions for an area if no forest conservation occurs. For a proposed 570 km{sup 2} conservation area in temperate rainforest around the rural community of Curinanco, Chile, we compared three methods to project future baseline carbon emissions: extrapolation from Landsat observations, Geomod, and Forest Restoration Carbon Analysis (FRCA). Analyses of forest inventory and Landsat remote sensing data show 1986-1999 net deforestation of 1900 ha in the analysis area, proceeding at a rate of 0.0003 y{sup -1}. The gross rate of loss of closed natural forest was 0.042 y{sup -1}. In the period 1986-1999, closed natural forest decreased from 20,000 ha to 11,000 ha, with timber companies clearing natural forest to establish plantations of non-native species. Analyses of previous field measurements of species-specific forest biomass, tree allometry, and the carbon content of vegetation show that the dominant native forest type, broadleaf evergreen (bosque siempreverde), contains 370 {+-} 170 t ha{sup -1} carbon, compared to the carbon density of non-native Pinus radiata plantations of 240 {+-} 60 t ha{sup -1}. The 1986-1999 conversion of closed broadleaf evergreen forest to open broadleaf evergreen forest, Pinus radiata plantations, shrublands, grasslands, urban areas, and bare ground decreased the carbon density from 370 {+-} 170 t ha{sup -1} carbon to an average of 100 t ha{sup -1} (maximum 160 t ha{sup -1}, minimum 50 t ha{sup -1}). Consequently, the conversion released 1.1 million t carbon. These analyses of forest inventory and Landsat remote sensing data provided the data to

  13. Vegetation - McKenzie Preserve [ds703

    Data.gov (United States)

    California Natural Resource Agency — The California Native Plant Society (CNPS) Vegetation Program produced a vegetation map and classification for approximately 11,600 acres primarily within Millerton...

  14. Physico-chemical protection, rather than biochemical composition, governs the responses of soil organic carbon decomposition to nitrogen addition in a temperate agroecosystem.

    Science.gov (United States)

    Tan, Wenbing; Wang, Guoan; Huang, Caihong; Gao, Rutai; Xi, Beidou; Zhu, Biao

    2017-11-15

    The heterogeneous responses of soil organic carbon (SOC) decomposition in different soil fractions to nitrogen (N) addition remain elusive. In this study, turnover rates of SOC in different aggregate fractions were quantified based on changes in δ 13 C following the conversion of C 3 to C 4 vegetation in a temperate agroecosystem. The turnover of both total organic matter and specific organic compound classes within each aggregate fraction was inhibited by N addition. Moreover, the intensity of inhibition increases with decreasing aggregate size and increasing N addition level, but does not vary among chemical compound classes within each aggregate fraction. Overall, the response of SOC decomposition to N addition is dependent on the physico-chemical protection of SOC by aggregates and minerals, rather than the biochemical composition of organic substrates. The results of this study could help to understand the fate of SOC in the context of increasing N deposition. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Sorption of pesticides in tropical and temperate soils from Australia and the Philippines.

    Science.gov (United States)

    Oliver, Danielle P; Kookana, Rai S; Quintana, Belen

    2005-08-10

    The sorption behavior of diuron, imidacloprid, and thiacloprid was investigated using 22 soils collected in triplicate from temperate environments in Australia and tropical environments in Australia and the Philippines. Within the temperate environment in Australia, the soils were selected from a range of land uses. The average KOC values (L/kg) for imidacloprid were 326, 322, and 336; for thiacloprid, the values were 915, 743, and 842; and for diuron, the values were 579, 536, and 618 for the Ord (tropical), Mt. Lofty (temperate), and Philippines (tropical) soils, respectively. For all soils, the sorption coefficients decreased in the following order: thiacloprid > diuron > imidacloprid. There were no significant differences in sorption behavior between the tropical soils from the Philippines and the temperate soils from Australia. Sorption was also not significantly related with soil characteristics, namely, organic carbon (OC) content, clay content, and pH, for any of the three chemicals studied. When the data were sorted into separate land uses, the sorption of all three chemicals was highly correlated (P soils from the Philippines. Sorption coefficients for all three chemicals were highly correlated with OC in temperate, native soils only when one extreme value was removed. The relationships between sorption of all three chemicals and OC in temperate, pasture soils were best described by a polynomial. Sorption coefficients for imidacloprid and thiacloprid determined in the temperate pasture soils remained fairly consistent as the OC content increased from 3.3 to 5.3%, indicating that, although the total OC in the pasture soils was increasing, the component of OC involved with sorption of these two compounds may have been remaining constant. This study demonstrated that the origin of the soils (i.e., temperate vs tropical) had no significant effect on the sorption behavior, but in some cases, land use significantly affected the sorption behavior of the three

  16. Clonal and bud bank traits: patterns across temperate plant communities

    Czech Academy of Sciences Publication Activity Database

    Klimešová, Jitka; Herben, Tomáš

    2015-01-01

    Roč. 26, č. 2 (2015), s. 243-253 ISSN 1100-9233 R&D Projects: GA ČR GB14-36079G; GA ČR GA13-17118S; GA ČR GAP505/12/1007 Institutional support: RVO:67985939 Keywords : clonal and bud bank traits * vegetation * central Europe Subject RIV: EH - Ecology, Behaviour Impact factor: 3.151, year: 2015

  17. Vegetation - Lassen Foothills [ds564

    Data.gov (United States)

    California Natural Resource Agency — In 2007 Aerial Information Systems, Inc. (AIS) was contracted by the California Native Plant Society (CNPS) to produce a vegetation map for approximately 100,000...

  18. in Leafy Vegetable and Pharmaceutical

    African Journals Online (AJOL)

    Bheema

    successfully employed for the determination of copper (II) in leafy vegetable and pharmaceutical samples. ... Our previous studies of transition metal ions such as zinc, cobalt and ..... A new method for extractive photometric determination of.

  19. Buffers and vegetative filter strips

    Science.gov (United States)

    Matthew J. Helmers; Thomas M. Isenhart; Michael G. Dosskey; Seth M. Dabney

    2008-01-01

    This chapter describes the use of buffers and vegetative filter strips relative to water quality. In particular, we primarily discuss the herbaceous components of the following NRCS Conservation Practice Standards.

  20. Nitrogen acquisition by plants and microorganisms in a temperate grassland.

    Science.gov (United States)

    Liu, Qianyuan; Qiao, Na; Xu, Xingliang; Xin, Xiaoping; Han, Jessie Yc; Tian, Yuqiang; Ouyang, Hua; Kuzyakov, Yakov

    2016-03-10

    Nitrogen (N) limitation is common in most terrestrial ecosystems, often leading to strong competition between microorganisms and plants. The mechanisms of niche differentiation to reduce this competition remain unclear. Short-term (15)N experiments with NH4(+), NO3(-), and glycine were conducted in July, August and September in a temperate grassland to evaluate the chemical, spatial and temporal niche differentiation by competition between plants and microorganisms for N. Microorganisms preferred NH4(+) and NO3(-), while plants preferred NO3(-). Both plants and microorganisms acquired more N in August and September than in July. The soil depth had no significant effects on microbial uptake, but significantly affected plant N uptake. Plants acquired 67% of their N from the 0-5 cm soil layer and 33% from the 5-15 cm layer. The amount of N taken up by microorganisms was at least seven times than plants. Although microorganisms efficiently compete for N with plants, the competition is alleviated through chemical partitioning mainly in deeper soil layer. In the upper soil layer, neither chemical nor temporal niche separation is realized leading to strong competition between plants and microorganisms that modifies N dynamics in grasslands.

  1. Synchronous dynamics of zooplankton competitors prevail in temperate lake ecosystems.

    Science.gov (United States)

    Vasseur, David A; Fox, Jeremy W; Gonzalez, Andrew; Adrian, Rita; Beisner, Beatrix E; Helmus, Matthew R; Johnson, Catherine; Kratina, Pavel; Kremer, Colin; de Mazancourt, Claire; Miller, Elizabeth; Nelson, William A; Paterson, Michael; Rusak, James A; Shurin, Jonathan B; Steiner, Christopher F

    2014-08-07

    Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset. Synchronous dynamics were far more prevalent at all scales and times and were ubiquitous at the annual scale. Although we found compensatory dynamics in approximately 14% of all combinations of time period/scale/lake, there were no consistent scales or time periods during which compensatory dynamics were apparent across different regions. Our results suggest that the processes driving compensatory dynamics may be local in their extent, while those generating synchronous dynamics operate at much larger scales. This highlights an important gap in our understanding of the interaction between environmental and biotic forces that structure communities. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  2. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    Full Text Available Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2.s(-1 and clipping (2.06 μmol.m(-2.s(-1 than under grazing (1.65 μmol.m-(2.s(-1 over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP. Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content and biotic (ANPP and BNPP factors regulate soil respiration in the semiarid temperate grassland of northern China.

  3. Seasonal sediment dynamics shape temperate bedrock reef communities

    Science.gov (United States)

    Figurski, Jared D.; Freiwald, Jan; Lonhart, Steve I.; Storlazzi, Curt

    2016-01-01

    Mobilized seafloor sediment can impact benthic reef communities through burial, scour, and turbidity. These processes are ubiquitous in coastal oceans and, through their influence on the survival, fitness, and interactions of species, can alter the structure and function of benthic communities. In northern Monterey Bay, California, USA, as much as 30% of the seafloor is buried or exposed seasonally, making this an ideal location to test how subtidal temperate rocky reef communities vary in the presence and absence of chronic sediment-based disturbances. Designated dynamic plots were naturally inundated by sediment in summer (50 to 100% cover) and swept clean in winter, whereas designated stable plots remained free of sediment during our study. Multivariate analyses indicated significant differences in the structure of sessile and mobile communities between dynamic and stable reef habitats. For sessile species, community structure in disturbed plots was less variable in space and time than in stable plots due to the maintenance of an early successional state. In contrast, community structure of mobile species varied more in disturbed plots than in stable plots, reflecting how mobile species distribute in response to sediment dynamics. Some species were found only in these disturbed areas, suggesting that the spatial mosaic of disturbance could increase regional diversity. We discuss how the relative ability of species to tolerate disturbance at different life history stages and their ability to colonize habitat translate into community-level differences among habitats, and how this response varies between mobile and sessile communities.

  4. Winter habitat occurrence patterns of temperate migrant birds in Belize

    Science.gov (United States)

    Dawson, D.K.; Robbins, C.S.; Sauer, J.R.

    1992-01-01

    We used mist nets and point counts to sample bird populations in 61 sites in Belize during January-March of 1987-1991. Sites were classified as forest, second growth, woody agricultural crops (citrus, mango, cacao, and cashew), or non-woody agricultural crops (rice and sugar cane). We evaluated patterns of occurence of wintering temperate migrant bird species in these habitats. Mist net captures of 22 of 31 migrant species differed significantly among habitats. Of these, 13 species were captured more frequently in the agricultural habitats. American Redstart (Setophaga ruticilla), Black-and-white Warbler (Mniotilta varia), and Magnolia Warbler (Dendroica magnolia) were among the species captured most frequently in woody agricultural habitats; captures of Common Yellowthroat (Geothlypis trichas), Indigo Bunting (Passerina cyanea), and Northern (lcterus galbula) and Orchard orioles (I. spur/anus) were highest in the non-woody agricultural sites. We relate these occurrence patterns to trends in breeding populations in North America. While count data provide a wide picture of winter habitat distribution of migrants, more intensive work is necessary to assess temporal and geographic variation of migrant bird use of agricultural habitats.

  5. Reasons to temper enthusiasm about open access nursing journals.

    Science.gov (United States)

    de Jong, Gideon

    2017-04-01

    Open access is a relatively new phenomenon within nursing science. Several papers from various nursing journals have been published recently on the disadvantages of the traditional model of purchasing proprietary fee-based databases to access scholarly information. Just few nursing scholars are less optimistic about the possible benefits of open access nursing journals. A critical reflection on the merits and pitfalls of open access journals along insights from the literature and personal opinion. Two arguments are discussed, providing justification for tempering enthusiasm about open access journals. First, only research groups with sufficient financial resources can publish in open access journals. Second, open access has conflicting incentives, where the aim is to expand production at the expense of publishing quality articles; a business model that fits well into a neoliberal discourse. There are valid reasons to criticise the traditional publishers for the excessive costs of a single article, therefore preventing the dissemination of scholarly nursing information. On the contrary, the business model of open access publishers is no less imbued with the neoliberal tendency of lining the pockets.

  6. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Science.gov (United States)

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China.

  7. Mercury emission from a temperate lake during autumn turnover

    International Nuclear Information System (INIS)

    Wollenberg, Jennifer L.; Peters, Stephen C.

    2009-01-01

    Lakes in temperate regions stratify during summer and winter months, creating distinct layers of water differentiated by their physical and chemical characteristics. When lakes mix in autumn and spring, mercury cycling may be affected by the chemical changes that occur during mixing. Sampling was conducted in Lake Lacawac, Eastern Pennsylvania, USA, throughout the autumn of 2007 to characterize changes in emission of gaseous elemental mercury (Hg 0 ) from the lake surface and dissolved mercury profiles in the water column during mixing. Water chemistry and weather parameters were also measured, including dissolved organic carbon (DOC), iron, and solar radiation which have been shown to interact with mercury species. Results indicate that emission of Hg 0 from the lake to the atmosphere during turnover was controlled both by solar radiation and by surface water mercury concentration. As autumn turnover progressed through the months of October and November, higher mercury concentration water from the hypolimnion mixed with epilimnetic water, increasing mercury concentration in epilimnetic waters. Dissolved absorbance was significantly correlated with mercury concentrations and with iron, but DOC concentrations were essentially constant throughout the study period and did not exhibit a relationship with either dissolved mercury concentrations or emission rates. Positive correlations between dissolved mercury and iron and manganese also suggest a role for these elements in mercury transport within the lake, but iron and manganese did not demonstrate a relationship with emission rates. This research indicates that consideration of seasonal processes in lakes is important when evaluating mercury cycling in aquatic systems

  8. Growth mindset tempers the effects of poverty on academic achievement.

    Science.gov (United States)

    Claro, Susana; Paunesku, David; Dweck, Carol S

    2016-08-02

    Two largely separate bodies of empirical research have shown that academic achievement is influenced by structural factors, such as socioeconomic background, and psychological factors, such as students' beliefs about their abilities. In this research, we use a nationwide sample of high school students from Chile to investigate how these factors interact on a systemic level. Confirming prior research, we find that family income is a strong predictor of achievement. Extending prior research, we find that a growth mindset (the belief that intelligence is not fixed and can be developed) is a comparably strong predictor of achievement and that it exhibits a positive relationship with achievement across all of the socioeconomic strata in the country. Furthermore, we find that students from lower-income families were less likely to hold a growth mindset than their wealthier peers, but those who did hold a growth mindset were appreciably buffered against the deleterious effects of poverty on achievement: students in the lowest 10th percentile of family income who exhibited a growth mindset showed academic performance as high as that of fixed mindset students from the 80th income percentile. These results suggest that students' mindsets may temper or exacerbate the effects of economic disadvantage on a systemic level.

  9. Elevation alters ecosystem properties across temperate treelines globally

    Science.gov (United States)

    Mayor, Jordan R.; Sanders, Nathan J.; Classen, Aimée T.; Bardgett, Richard D.; Clément, Jean-Christophe; Fajardo, Alex; Lavorel, Sandra; Sundqvist, Maja K.; Bahn, Michael; Chisholm, Chelsea; Cieraad, Ellen; Gedalof, Ze'Ev; Grigulis, Karl; Kudo, Gaku; Oberski, Daniel L.; Wardle, David A.

    2017-01-01

    Temperature is a primary driver of the distribution of biodiversity as well as of ecosystem boundaries. Declining temperature with increasing elevation in montane systems has long been recognized as a major factor shaping plant community biodiversity, metabolic processes, and ecosystem dynamics. Elevational gradients, as thermoclines, also enable prediction of long-term ecological responses to climate warming. One of the most striking manifestations of increasing elevation is the abrupt transitions from forest to treeless alpine tundra. However, whether there are globally consistent above- and belowground responses to these transitions remains an open question. To disentangle the direct and indirect effects of temperature on ecosystem properties, here we evaluate replicate treeline ecotones in seven temperate regions of the world. We find that declining temperatures with increasing elevation did not affect tree leaf nutrient concentrations, but did reduce ground-layer community-weighted plant nitrogen, leading to the strong stoichiometric convergence of ground-layer plant community nitrogen to phosphorus ratios across all regions. Further, elevation-driven changes in plant nutrients were associated with changes in soil organic matter content and quality (carbon to nitrogen ratios) and microbial properties. Combined, our identification of direct and indirect temperature controls over plant communities and soil properties in seven contrasting regions suggests that future warming may disrupt the functional properties of montane ecosystems, particularly where plant community reorganization outpaces treeline advance.

  10. Quantifying the effects of tempering on individual phase properties of DP980 steel with nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, G.; Zhang, F.; Ruimi, A.; Field, D. P.; Sun, X.

    2016-06-01

    We conduct a series of thermal and mechanical testing on a commercial dual phase (DP) 980 steel in order to quantify the effects of tempering on its individual phase properties. Tempering treatment is conducted at 250 °C and 400 °C for 60 minutes each. Ferrite and martensite grains are distinguished using electron backscatter diffraction (EBSD) and scanning probe microscopy (SPM), and the martensite volume fractions (MVF) are determined based on the image quality (IQ) map. Multi-scale indentation tests combined with a newly developed inverse method are used to obtain the individual phase flow properties in each tempered DP980 sample. The results show that, i) tempering significantly reduces martensite yield strength, while it only slightly reduces the ferrite yield strength; ii) tempering temperature has a more significant influence on the work hardening exponent of ferrite than that of martensite; iii) the elastic modulus of martensite is consistently higher than that of ferrite. As a validation, a simple rule of mixtures is used to verify the above-predicted individual phase flow stresses with the experimentally obtained overall true stress vs. true strain curves. The methodology and the corresponding results shown in this study can help guide the selection of tempering parameters in optimizing the mechanical properties of DP steels for their intended applications.

  11. Influence of Mo addition on the tempered properties of 13Cr martensitic stainless steel

    International Nuclear Information System (INIS)

    Jung, Byong Ho; Ahn, Yong Sik

    1998-01-01

    In order to investigate the effect of Mo addition on the mechanical properties of 13Cr-0.2C martensitic stainless steel, tensile test and Charpy V-notch test were performed after tempering at the temperature range of 200∼700 .deg. C following austenitizing at 1100 .deg. C. The yield strength and hardness of the steel were increased with the increase of Mo content at all tempering conditions, because Mo causes retardation of precipitation and coarsening of carbides and solid solution strengthening of matrix. Except 500 .deg. C of tempering temperature, the Charpy impact energy was significantly increased with Mo content and showed the highest value at 1.5 wt% addition. The increase of impact energy of the steel containing Mo is thought to be caused by δ-ferrite formed in the tempered martensitic matrix. At 500 .deg. C tempering, Charpy impact energy was decreased drastically due to temper embrittlement and it was not possible to prevent it even though Mo was added up to 1.5 wt%

  12. A Novel Methods for Fracture Toughness Evaluation of Tool Steels with Post-Tempering Cryogenic Treatment

    Directory of Open Access Journals (Sweden)

    Ramona Sola

    2017-02-01

    Full Text Available Cryogenic treatments are usually carried out immediately after quenching, but their use can be extended to post tempering in order to improve their fracture toughness. This research paper focuses on the influence of post-tempering cryogenic treatment on the microstructure and mechanical properties of tempered AISI M2, AISI D2, and X105CrCoMo18 steels. The aforementioned steels have been analysed after tempering and tempering + cryogenic treatment with scanning electron microscopy, X-ray diffraction for residual stress measurements, and micro- and nano-indentation to determine Young’s modulus and plasticity factor measurement. Besides the improvement of toughness, a further aim of the present work is the investigation of the pertinence of a novel technique for characterizing the fracture toughness via scratch experiments on cryogenically-treated steels. Results show that the application of post-tempering cryogenic treatment on AISI M2, AISI D2, and X105CrCoMo18 steels induce precipitation of fine and homogeneously dispersed sub-micrometric carbides which do not alter hardness and Young’s modulus values, but reduce residual stresses and increase fracture toughness. Finally, scratch test proved to be an alternative simple technique to determine the fracture toughness of cryogenically treated steels.

  13. Mechanism of Secondary Hardening in Rapid Tempering of Dual-Phase Steel

    Science.gov (United States)

    Saha, Dulal Chandra; Nayak, Sashank S.; Biro, Elliot; Gerlich, Adrian P.; Zhou, Y.

    2014-12-01

    Dual-phase steel with ferrite-martensite-bainite microstructure exhibited secondary hardening in the subcritical heat affected zone during fiber laser welding. Rapid isothermal tempering conducted in a Gleeble simulator also indicated occurrence of secondary hardening at 773 K (500 °C), as confirmed by plotting the tempered hardness against the Holloman-Jaffe parameter. Isothermally tempered specimens were characterized by analytic transmission electron microscopy and high-angle annular dark-field imaging. The cementite (Fe3C) and TiC located in the bainite phase of DP steel decomposed upon rapid tempering to form needle-shaped Mo2C (aspect ratio ranging from 10 to 25) and plate-shaped M4C3 carbides giving rise to secondary hardening. Precipitation of these thermodynamically stable and coherent carbides promoted the hardening phenomenon. However, complex carbides were only seen in the tempered bainite and were not detected in the tempered martensite. The martensite phase decomposed into ferrite and spherical Fe3C, and interlath-retained austenite decomposed into ferrite and elongated carbide.

  14. Tempering of Mn and Mn-Si-V dual-phase steels

    Science.gov (United States)

    Speich, G. R.; Schwoeble, A. J.; Huffman, G. P.

    1983-06-01

    Changes in the yield behavior, strength, and ductility of a Mn and a Mn-Si-V d11Al-phase (ferrite-martensite) steel were investigated after tempering one hour at 200 to 600 °C. The change in yield behavior was complex in both steels with the yield strength first increasing and then decreasing as the tempering temperature was increased. This complex behavior is attributed to a combination of factors including carbon segregation to dislocations, a return of discontinuous yielding, and the relief of resid11Al stresses. In contrast, the tensile strength decreased continuously as the tempering temperature was increased in a manner that could be predicted from the change in hardness of the martensite phase using a simple composite strengthening model. The initial tensile ductility (total elongation) of the Mn-Si-V steel was much greater than that of the Mn steel. However, upon tempering up to 400 °C, the ductility of the Mn-Si-V decreased whereas that of the Mn steel increased. As a result, both steels had similar ductilities after tempering at 400 °C or higher temperatures. These results are attributed to the larger amounts of retained austenite in the Mn-Si-V steel (9 pct) compared to the Mn steel (3 pct) and its contribution to tensile ductility by transforming to martensite during plastic straining. Upon tempering at 400 °C, the retained austenite decomposes to bainite and its contribution to tensile ductility is eliminated.

  15. Fledgling survival increases with development time and adult survival across north and south temperate zones

    Science.gov (United States)

    Lloyd, Penn; Martin, Thomas E.

    2016-01-01

    Slow life histories are characterized by high adult survival and few offspring, which are thought to allow increased investment per offspring to increase juvenile survival. Consistent with this pattern, south temperate zone birds are commonly longer-lived and have fewer young than north temperate zone species. However, comparative analyses of juvenile survival, including during the first few weeks of the post-fledging period when most juvenile mortality occurs, are largely lacking. We combined our measurements of fledgling survival for eight passerines in South Africa with estimates from published studies of 57 north and south temperate zone songbird species to test three predictions: (1) fledgling survival increases with length of development time in the nest; (2) fledgling survival increases with adult survival and reduced brood size controlled for development time; and (3) south temperate zone species, with their higher adult survival and smaller brood sizes, exhibit higher fledgling survival than north temperate zone species controlled for development time. We found that fledgling survival was higher among south temperate zone species and generally increased with development time and adult survival within and between latitudinal regions. Clutch size did not explain additional variation, but was confounded with adult survival. Given the importance of age-specific mortality to life history evolution, understanding the causes of these geographical patterns of mortality is important.

  16. Riparian vegetation in the alpine connectome: Terrestrial-aquatic and terrestrial-terrestrial interactions.

    Science.gov (United States)

    Zaharescu, Dragos G; Palanca-Soler, Antonio; Hooda, Peter S; Tanase, Catalin; Burghelea, Carmen I; Lester, Richard N

    2017-12-01

    Alpine regions are under increased attention worldwide for their critical role in early biogeochemical cycles, their high sensitivity to environmental change, and as repositories of natural resources of high quality. Their riparian ecosystems, at the interface between aquatic and terrestrial environments, play important geochemical functions in the watershed and are biodiversity hotspots, despite a harsh climate and topographic setting. With climate change rapidly affecting the alpine biome, we still lack a comprehensive understanding of the extent of interactions between riparian surface, lake and catchment environments. A total of 189 glacial - origin lakes were surveyed in the Central Pyrenees to test how key elements of the lake and terrestrial environments interact at different scales to shape riparian plant composition. Secondly, we evaluated how underlying ecotope features drive the formation of natural communities potentially sensitive to environmental change and assessed their habitat distribution. At the macroscale, vegetation composition responded to pan-climatic gradients altitude and latitude, which captured in a narrow geographic area the transition between large European climatic zones. Hydrodynamics was the main catchment-scale factor connecting riparian vegetation with major water fluxes, followed by topography and geomorphology. Lake sediment Mg and Pb, and water Mn and Fe contents reflected local influences from mafic bedrock and soil water saturation. Community analysis identified four keystone ecosystems: (i) damp ecotone, (ii) snow bed-silicate bedrock, (iii) wet heath, and (iv) calcareous substrate. These communities and their connections with ecotope elements could be at risk from a number of environmental change factors including warmer seasons, snow line and lowland species advancement, increased nutrient/metal input and water level fluctuations. The results imply important natural terrestrial-aquatic linkages in the riparian environment

  17. Connecting long term species changes and their water competitions in temperate forest Mt. Baegun, Rep. of Korea using hydrogen and oxygen stable isotope analysis

    Science.gov (United States)

    Jeon, J.; Lee, H.; Lee, M.; Song, W.; Byeon, S.; Lee, B.; Cho, S.; Park, J.; Kim, H. S.

    2017-12-01

    Many dynamic vegetation model simulations have predicted dramatic changes in species composition of temperate forests due to climate changes and successional reasons. Especially, conifer species are expected to lose their habitats and to be replaced by broadleaf species. Similarly, our more than 15-years-long 880 permenant plots tree survey data in Mt. Baegun, Rep. of Korea, showed substantial decrease of conifer species and their productivities and increase of broadleaved species. One of main reasons for these changes in species could be attributed to the water competition among tree species in the same stand. Therefore, we investigated the differences in water uptake scheme between conifer and broadleaf species from the temperate forests of Korea using stable isotopes. Six study plots showing high competition (conifers vs. broadleaf species) based on previous vegetation survey were chosen and the species-specific water uptake depth was estimated by measuring hydrogen(δ2H) and oxygen(δ18O) ratio from the xylem sap and leaves of individual species and by comparing them with those of soil water from 5 depths, (10, 30, 50, 100 and 120 cm), which extracted by lysimeter. The collection was conducted from April 2016 to Nov 2017. The conifer species included Pinus densiflora and Chamaecyparis obtusa vs. broadleaved species included Carpinus laxiflora, Prunus sargentii, Styrax obassia, Lindera erythrocarpa and Quercus species such as Q. mongolica, Q. serrata, Q. accuticima. Preliminary results showed the stable isotope signatures of soil water was increased from 10 cm to 30 cm, and then decreased gradually until 120 cm. In addition, current dominant canopy species, Chamaecyparis obtusa absorbed majority of their water from 10 to 30 cm depth. In comparison, current mid canopy but one of upcoming dominant species, Styrax obassia's major water source was 30 cm and deeper of soil. Our results could be essential for the prediction of species composition under climate change

  18. Tropical forest biomass and successional age class relationships to a vegetation index derived from Landsat TM data

    Science.gov (United States)

    Sader, Steven A.; Waide, Robert B.; Lawrence, William T.; Joyce, Armond T.

    1989-01-01

    Forest stand structure and biomass data were collected using conventional forest inventory techniques in tropical, subtropical, and warm temperate forest biomes. The feasibility of detecting tropical forest successional age class and total biomass differences using Landsat-Thematic mapper (TM) data, was evaluated. The Normalized Difference Vegetation Index (NDVI) calculated from Landsat-TM data were not significantly correlated with forest regeneration age classes in the mountain terrain of the Luquillo Experimental Forest, Puerto Rico. The low sun angle and shadows cast on steep north and west facing slopes reduced spectral reflectance values recorded by TM orbital altitude. The NDVI, calculated from low altitude aircraft scanner data, was significatly correlated with forest age classes. However, analysis of variance suggested that NDVI differences were not detectable for successional forests older than approximately 15-20 years. Also, biomass differences in young successional tropical forest were not detectable using the NDVI. The vegetation index does not appear to be a good predictor of stand structure variables (e.g., height, diameter of main stem) or total biomass in uneven age, mixed broadleaf forest. Good correlation between the vegetation index and low biomass in even age pine plantations were achieved for a warm temperate study site. The implications of the study for the use of NDVI for forest structure and biomass estimation are discussed.

  19. Surface soil phytoliths as vegetation and altitude indicators: a study from the southern Himalaya.

    Science.gov (United States)

    An, Xiaohong; Lu, Houyuan; Chu, Guoqiang

    2015-10-26

    Phytoliths represent one of the few available altitudinal vegetation proxies for mountain ecosystems. This study analyzed 41 topsoil phytolith samples collected from five altitudinal zones in the southern Himalaya as far as, and beyond, the timberline, from tropical forest (up to 1,000 m a.s.l.) to subtropical forest (1,000-2,000 m a.s.l.), to temperate forest (2,000-3,000 m a.s.l.), to subalpine forest (3,000-4,100 m a.s.l.) and finally to alpine scrub (4,100-5,200 m a.s.l.). The statistical results show a good correlation between phytolith assemblages and these five altitudinal vegetation zones: the five phytolith assemblages identified effectively differentiated these five altitudinal vegetation zones. In particular, coniferous phytoliths accurately indicated the timberline. Additionally, we tested the phytolith index Ic (a proxy for estimating the percentage of Pooideae vis-à-vis the total grass content) as a quantifier of phytolith variety versus altitude. Ic increased along altitude, as expected. An investigation of phytoliths provided an initial basis for the analysis of the composition of gramineous vegetation. Furthermore, redundancy analysis and discriminant analysis also suggested a significant correlation between phytolith assemblages and altitude. Our research therefore provides an up-to-date analogue for the reconstruction of changes to palaeovegetation and palaeoaltitude in mountainous areas.

  20. Biological Control of Diseases of Vegetables Grown Hydroponically in Thailand: Challenge and Opportunity.

    Science.gov (United States)

    Kanjanamaneesathian, Mana

    2015-01-01

    In Thailand, yield loss due to plant diseases in vegetables grown hydroponically is very high as a result of the growers` lack of knowledge for controlling diseases and their un- willingness to invest in setting-up the proper hydroponic system from the beginning. Severe root rot disease caused by Pythium spp. is frequent and can be anticipated in the hot climate in Thailand. This review focuses on the diseases in temperate lettuces which have been produced hydroponically and have been attacked by plant pathogens, particularly Pythium spp. Biological control of vegetable diseases grown hydroponically has been investigated in Thailand. Research is being carried out to identify effective strains of the antagonists, formulating the applicable products and delivering them appropriately to control the disease. Products of Bacillus subtilis, Chaetomium globosom and Trichoderma harzianum have been recommended for use to control diseases in vegetables grown hydroponically. Control efficacy of these products is varied as the biological products have been used by the growers in the paradigm of using chemical fungicide for disease control in hydroponic production system, overlooking the intrinsic characteristics of the biological control products. The recent patent, which minimizes the effects of sunlight and heat on the nutrient solution without the use of an external energy for cooling the nutrient, should be applied in producing hydroponic vegetables to mitigate poor plant growth and root rot disease outbreak in Thailand.

  1. Does food store access modify associations between intrapersonal factors and fruit and vegetable consumption?

    Science.gov (United States)

    Thornton, L E; Lamb, K E; Tseng, M; Crawford, D A; Ball, K

    2015-08-01

    Existing theoretical frameworks suggest that healthy eating is facilitated by an individual's ability, motivation and environmental opportunities. It is plausible, although largely untested, that the importance of factors related to ability and motivation differ under varied environmental conditions. This study aimed to determine whether the magnitude of associations between fruit and vegetable consumption and intrapersonal factors (ability and motivation) were modified by differences in access to stores selling these items (environmental opportunities). Cross-sectional analysis of 4335 women from socioeconomically disadvantaged neighbourhoods in the state of Victoria, Australia. Self-reported fruit and vegetable consumption was assessed against a number of ability- and motivation-related factors. To examine whether associations were modified by store access, interactions with access to supermarkets and greengrocers within 2 km of participants' households were tested. Of the two factors related to ability and seven factors related to motivation, almost all were associated with fruit and vegetable consumption. In general, associations were not modified by store access suggesting that these factors were not tempered by environmental opportunities. This study provides little support for the hypothesis that the importance of intra-personal factors to fruit and vegetable consumption is modified by food store access. Further research on this topic is required to inform behaviour change interventions.

  2. Handling Procedures of Vegetable Crops

    Science.gov (United States)

    Perchonok, Michele; French, Stephen J.

    2004-01-01

    The National Aeronautics and Space Administration (NASA) is working towards future long duration manned space flights beyond low earth orbit. The duration of these missions may be as long as 2.5 years and will likely include a stay on a lunar or planetary surface. The primary goal of the Advanced Food System in these long duration exploratory missions is to provide the crew with a palatable, nutritious, and safe food system while minimizing volume, mass, and waste. Vegetable crops can provide the crew with added nutrition and variety. These crops do not require any cooking or food processing prior to consumption. The vegetable crops, unlike prepackaged foods, will provide bright colors, textures (crispy), and fresh aromas. Ten vegetable crops have been identified for possible use in long duration missions. They are lettuce, spinach, carrot, tomato, green onion, radish, bell pepper, strawberries, fresh herbs, and cabbage. Whether these crops are grown on a transit vehicle (e.g., International Space Station) or on the lunar or planetary surface, it will be necessary to determine how to safely handle the vegetables while maintaining acceptability. Since hydrogen peroxide degrades into water and oxygen and is generally recognized as safe (GRAS), hydrogen peroxide has been recommended as the sanitizer. The objective of th is research is to determine the required effective concentration of hydrogen peroxide. In addition, it will be determined whether the use of hydrogen peroxide, although a viable sanitizer, adversely affects the quality of the vegetables. Vegetables will be dipped in 1 % hydrogen peroxide, 3% hydrogen peroxide, or 5% hydrogen peroxide. Treated produce and controls will be stored in plastic bags at 5 C for up to 14 days. Sensory, color, texture, and total plate count will be measured. The effect on several vegetables including lettuce, radish, tomato and strawberries has been completed. Although each vegetable reacts to hydrogen peroxide differently, the

  3. Uncertainty analysis of a coupled ecosystem response model simulating greenhouse gas fluxes from a temperate grassland

    Science.gov (United States)

    Liebermann, Ralf; Kraft, Philipp; Houska, Tobias; Breuer, Lutz; Müller, Christoph; Kraus, David; Haas, Edwin; Klatt, Steffen

    2015-04-01

    Among anthropogenic greenhouse gas emissions, CO2 is the dominant driver of global climate change. Next to its direct impact on the radiation budget, it also affects the climate system by triggering feedback mechanisms in terrestrial ecosystems. Such mechanisms - like stimulated photosynthesis, increased root exudations and reduced stomatal transpiration - influence both the input and the turnover of carbon and nitrogen compounds in the soil. The stabilization and decomposition of these compounds determines how increasing CO2 concentrations change the terrestrial trace gas emissions, especially CO2, N2O and CH4. To assess the potential reaction of terrestrial greenhouse gas emissions to rising tropospheric CO2 concentration, we make use of a comprehensive ecosystem model integrating known processes and fluxes of the carbon-nitrogen cycle in soil, vegetation and water. We apply a state-of-the-art ecosystem model with measurements from a long term field experiment of CO2 enrichment. The model - a grassland realization of LandscapeDNDC - simulates soil chemistry coupled with plant physiology, microclimate and hydrology. The data - comprising biomass, greenhouse gas emissions, management practices and soil properties - has been attained from a FACE (Free Air Carbon dioxide Enrichment) experiment running since 1997 on a temperate grassland in Giessen, Germany. Management and soil data, together with weather records, are used to drive the model, while cut biomass as well as CO2 and N2O emissions are used for calibration and validation. Starting with control data from installations without CO2 enhancement, we begin with a GLUE (General Likelihood Uncertainty Estimation) assessment using Latin Hypercube to reduce the range of the model parameters. This is followed by a detailed sensitivity analysis, the application of DREAM-ZS for model calibration, and an estimation of the effect of input uncertainty on the simulation results. Since first results indicate problems with

  4. East African Cenozoic vegetation history.

    Science.gov (United States)

    Linder, Hans Peter

    2017-11-01

    The modern vegetation of East Africa is a complex mosaic of rainforest patches; small islands of tropic-alpine vegetation; extensive savannas, ranging from almost pure grassland to wooded savannas; thickets; and montane grassland and forest. Here I trace the evolution of these vegetation types through the Cenozoic. Paleogene East Africa was most likely geomorphologically subdued and, as the few Eocene fossil sites suggest, a woodland in a seasonal climate. Woodland rather than rainforest may well have been the regional vegetation. Mountain building started with the Oligocene trap lava flows in Ethiopia, on which rainforest developed, with little evidence of grass and none of montane forests. The uplift of the East African Plateau took place during the middle Miocene. Fossil sites indicate the presence of rainforest, montane forest and thicket, and wooded grassland, often in close juxtaposition, from 17 to 10 Ma. By 10 Ma, marine deposits indicate extensive grassland in the region and isotope analysis indicates that this was a C 3 grassland. In the later Miocene rifting, first of the western Albertine Rift and then of the eastern Gregory Rift, added to the complexity of the environment. The building of the high strato-volcanos during the later Mio-Pliocene added environments suitable for tropic-alpine vegetation. During this time, the C 3 grassland was replaced by C 4 savannas, although overall the extent of grassland was reduced from the mid-Miocene high to the current low level. Lake-level fluctuations during the Quaternary indicate substantial variation in rainfall, presumably as a result of movements in the intertropical convergence zone and the Congo air boundary, but the impact of these fluctuations on the vegetation is still speculative. I argue that, overall, there was an increase in the complexity of East African vegetation complexity during the Neogene, largely as a result of orogeny. The impact of Quaternary climatic fluctuation is still poorly understood

  5. Chapter 3: Status and trends of vegetation

    Science.gov (United States)

    James M. Guldin; Frank R. Thompson; Lynda L. Richards; Kyra C. Harper

    1999-01-01

    This chapter provides information about the vegetation cover of the Assessment area. The types and areal extent of vegetation in the Highlands are of interest for many reasons. Vegetation cover largely determines the availability of habitat for terrestrial animals, plants, and other organisms. Vegetation cover strongly influences what uses {e.g., timber, forage,...

  6. Vegetables and other core food groups

    NARCIS (Netherlands)

    Poelman, Astrid A.M.; Delahunty, Conor M.; Graaf, de Kees

    2017-01-01

    Vegetables are the food category least liked by children. This research investigated the sensory properties of vegetables vis-a-vis other core foods that comprise children's diets, to determine to what degree low acceptance of vegetables can be attributed to sensory properties. Vegetables (n =

  7. 18 CFR 1304.203 - Vegetation management.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Vegetation management...-Owned Residential Access Shoreland § 1304.203 Vegetation management. No vegetation management shall be approved on TVA-owned Residential Access Shoreland until a Vegetation Management Plan meeting the...

  8. Anthropogenic impact on amorphous silica pools in temperate soils

    Directory of Open Access Journals (Sweden)

    W. Clymans

    2011-08-01

    Full Text Available Human land use changes perturb biogeochemical silica (Si cycling in terrestrial ecosystems. This directly affects Si mobilisation and Si storage and influences Si export from the continents, although the magnitude of the impact is unknown. A major reason for our lack of understanding is that very little information exists on how land use affects amorphous silica (ASi storage in soils. We have quantified and compared total alkali-extracted (PSia and easily soluble (PSie Si pools at four sites along a gradient of anthropogenic disturbance in southern Sweden. Land use clearly affects ASi pools and their distribution. Total PSia and PSie for a continuous forested site at Siggaboda Nature Reserve (66 900 ± 22 800 kg SiO2 ha−1 and 952 ± 16 kg SiO2 ha−1 are significantly higher than disturbed land use types from the Råshult Culture Reserve including arable land (28 800 ± 7200 kg SiO2 ha−1 and 239 ± 91 kg SiO2 ha−1, pasture sites (27 300 ± 5980 kg SiO2 ha−1 and 370 ± 129 kg SiO2 ha−1 and grazed forest (23 600 ± 6370 kg SiO2 ha−1 and 346 ± 123 kg SiO2 ha−1. Vertical PSia and PSie profiles show significant (p < 0.05 variation among the sites. These differences in size and distribution are interpreted as the long-term effect of reduced ASi replenishment, as well as changes in ecosystem specific pedogenic processes and increased mobilisation of the PSia in disturbed soils. We have also made a first, though rough, estimate of the magnitude of change in temperate continental ASi pools due to human disturbance. Assuming that our data are representative, we estimate that total ASi storage in soils has declined by ca. 10 % since the onset of agricultural development (3000 BCE

  9. Are all temperate lakes eutrophying in a warmer world?

    Science.gov (United States)

    Paltsev, A.; Creed, I. F.

    2017-12-01

    Freshwater lakes are at risk of eutrophication due to climate change and intensification of human activities on the planet. In relatively undisturbed areas of the temperate forest biome, lakes are "sentinels" of the effects of rising temperatures. We hypothesise that rising temperatures are driving a shift from nutrient-poor oligotrophic states to nutrient-rich eutrophic states. To test this hypothesis, we examined a time series of satellite based chlorophyll-a (a proxy of algal biomass) of 12,000+ lakes over 30 years in the Canadian portion of the Laurentian Great Lakes basin. From the time series, non-stationary trends (detected by Mann-Kendall analysis) and stationary cycles (revealed through Morlet wavelet analysis) were removed, and the standard deviation (SD) of the remaining residuals was used as an indicator of lake stability. Four classes of lake stability were identified: (1) stable (SD is consistently low); (2) destabilizing (SD increases over time); (3) unstable (SD is consistently high); and (4) stabilizing lakes (SD decreases over time). Stable lakes were either oligotrophic or eutrophic indicating the presence of two stable states in the region. Destabilizing lakes were shifting from oligotrophic to lakes with a higher trophic status (indicating eutrophication), unstable lakes were mostly mesotrophic, and stabilizing lakes were shifting from eutrophic to the lakes with lower trophic status (indicating oligotrophication). In contrast to common expectations, while many lakes (2142) were shifting from oligotrophic to eutrophic states, more lakes (3199) were showing the opposite trend and shifting from eutrophic to oligotrophic states. This finding reveals a complexity of lake responses to rising temperatures and the need to improve understanding of why some lakes shift while others do not. Future work is focused on exploring the interactive effects of global, regional, and local drivers of lake trophic states.

  10. Production of fermentables and biomass by six temperate fuelcrops

    Energy Technology Data Exchange (ETDEWEB)

    Parrish, D.J.; Gammon, T.C.; Graves, B.

    1985-12-01

    Several potential fuelcrops have been studied individually, but relatively little work has been done to compare the various temperate species in side-by-side trials. The production has been examined of readily fermentable carbohydrates and biomass by six fuelcrop candidates: grain sorghum (Sorghum bicolor), Jerusalem articoke (Helianthus tuberosus), maize (Zea Mays), sugarbeet (Beta vulgaris), sweet potato (Ipomoea batatas) and sweet sorghum (Sorghum bicolor). A randomized complete block design with four replicates was employed at each of three locations that were somewhat diverse in soil type, elevation, growing season length, and 1980 rainfall distribution. Fermentables in the harvestable dry matter were determined colorimetrically following dilute acid plus enzymatic hydrolysis. Overall, sugarbeet was the most prolific producer of fermentables (7.4 Mg/ha); Jerusalem artichoke (5.8 Mg/ha), maize (4.8 Mg/ha) and sweet sorghum stems (5.8 Mg/ha) were statistically equivalent, while sweet potato (4.0 Mg/ha) and grain sorghum (3.8 Mg/ha) were less productive than the other candidates. The crops performed somewhat differently at each location, but the most striking site-specific differences were seen at the site with the coarsest textured soil and driest season. At that location, maize produced the least fermentables (0.6 Mg/ha). Biomass production generally reflected either the amount of time each species was actively growing or limiations to growth associated with drought. No general recommendations are made concerning a preferred temperature fuelcrop. Based on the studies, however, maize may not always be the fuelcrop of choice; others, especially sugarbeet and sweet sorghum (when harvested for grain also), may be superior to maize in productivity of fermentable substrates. 6 tabs., 13 refs.

  11. Analysis of ecological thresholds in a temperate forest undergoing dieback.

    Directory of Open Access Journals (Sweden)

    Philip Martin

    Full Text Available Positive feedbacks in drivers of degradation can cause threshold responses in natural ecosystems. Though threshold responses have received much attention in studies of aquatic ecosystems, they have been neglected in terrestrial systems, such as forests, where the long time-scales required for monitoring have impeded research. In this study we explored the role of positive feedbacks in a temperate forest that has been monitored for 50 years and is undergoing dieback, largely as a result of death of the canopy dominant species (Fagus sylvatica, beech. Statistical analyses showed strong non-linear losses in basal area for some plots, while others showed relatively gradual change. Beech seedling density was positively related to canopy openness, but a similar relationship was not observed for saplings, suggesting a feedback whereby mortality in areas with high canopy openness was elevated. We combined this observation with empirical data on size- and growth-mediated mortality of trees to produce an individual-based model of forest dynamics. We used this model to simulate changes in the structure of the forest over 100 years under scenarios with different juvenile and mature mortality probabilities, as well as a positive feedback between seedling and mature tree mortality. This model produced declines in forest basal area when critical juvenile and mature mortality probabilities were exceeded. Feedbacks in juvenile mortality caused a greater reduction in basal area relative to scenarios with no feedback. Non-linear, concave declines of basal area occurred only when mature tree mortality was 3-5 times higher than rates observed in the field. Our results indicate that the longevity of trees may help to buffer forests against environmental change and that the maintenance of old, large trees may aid the resilience of forest stands. In addition, our work suggests that dieback of forests may be avoidable providing pressures on mature and juvenile trees do

  12. Radiation budget changes with dry forest clearing in temperate Argentina.

    Science.gov (United States)

    Houspanossian, Javier; Nosetto, Marcelo; Jobbágy, Esteban G

    2013-04-01

    Land cover changes may affect climate and the energy balance of the Earth through their influence on the greenhouse gas composition of the atmosphere (biogeochemical effects) but also through shifts in the physical properties of the land surface (biophysical effects). We explored how the radiation budget changes following the replacement of temperate dry forests by crops in central semiarid Argentina and quantified the biophysical radiative forcing of this transformation. For this purpose, we computed the albedo and surface temperature for a 7-year period (2003-2009) from MODIS imagery at 70 paired sites occupied by native forests and crops and calculated the radiation budget at the tropopause and surface levels using a columnar radiation model parameterized with satellite data. Mean annual black-sky albedo and diurnal surface temperature were 50% and 2.5 °C higher in croplands than in dry forests. These contrasts increased the outgoing shortwave energy flux at the top of the atmosphere in croplands by a quarter (58.4 vs. 45.9 W m(-2) ) which, together with a slight increase in the outgoing longwave flux, yielded a net cooling of -14 W m(-2) . This biophysical cooling effect would be equivalent to a reduction in atmospheric CO2 of 22 Mg C ha(-1) , which involves approximately a quarter to a half of the typical carbon emissions that accompany deforestation in these ecosystems. We showed that the replacement of dry forests by crops in central Argentina has strong biophysical effects on the energy budget which could counterbalance the biogeochemical effects of deforestation. Underestimating or ignoring these biophysical consequences of land-use changes on climate will certainly curtail the effectiveness of many warming mitigation actions, particularly in semiarid regions where high radiation load and smaller active carbon pools would increase the relative importance of biophysical forcing. © 2012 Blackwell Publishing Ltd.

  13. Holocene Dynamics of Temperate Rainforests in West-Central Patagonia

    Directory of Open Access Journals (Sweden)

    Virginia Iglesias

    2018-01-01

    Full Text Available Analyses of long-term ecosystem dynamics offer insights into the conditions that have led to stability vs. rapid change in the past and the importance of disturbance in regulating community composition. In this study, we (1 used lithology, pollen, and charcoal data from Mallín Casanova (47°S to reconstruct the wetland, vegetation, and fire history of west-central Patagonia; and (2 compared the records with independent paleoenvironmental and archeological information to assess the effects of past climate and human activity on ecosystem dynamics. Pollen data indicate that Nothofagus-Pilgerodendron forests were established by 9,000 cal yr BP. Although the biodiversity of the understory increased between 8,480 and 5,630 cal yr BP, forests remained relatively unchanged from 9,000 to 2,000 cal yr BP. The charcoal record registers high fire-episode frequency in the early Holocene followed by low biomass burning between 6,500 and 2,000 cal yr BP. Covarying trends in charcoal, bog development, and Neoglacial advances suggest that climate was the primary driver of these changes. After 2,000 cal yr BP, the proxy data indicate (a increased fire-episode frequency; (b centennial-scale shifts in bog and forest composition; (c the emergence of vegetation-fire linkages not recorded in previous times; and (d paludification in the last 500 years possibly associated with forest loss. Our results therefore suggest that Nothofagus-Pilgerodendron dominance was maintained through much of the Holocene despite long-term changes in climate and fire. Unparalleled fluctuations in local ecosystems during the last two millennia were governed by disturbance-vegetation-hydrology feedbacks likely triggered by greater climate variability and deforestation.

  14. Functional Trait Changes, Productivity Shifts and Vegetation Stability in Mountain Grasslands during a Short-Term Warming.

    Science.gov (United States)

    Debouk, Haifa; de Bello, Francesco; Sebastià, Maria-Teresa

    2015-01-01

    Plant functional traits underlie vegetation responses to environmental changes such as global warming, and consequently influence ecosystem processes. While most of the existing studies focus on the effect of warming only on species diversity and productivity, we further investigated (i) how the structure of community plant functional traits in temperate grasslands respond to experimental warming, and (ii) whether species and functional diversity contribute to a greater stability of grasslands, in terms of vegetation composition and productivity. Intact vegetation turves were extracted from temperate subalpine grassland (highland) in the Eastern Pyrenees and transplanted into a warm continental, experimental site in Lleida, in Western Catalonia (lowland). The impacts of simulated warming on plant production and diversity, functional trait structure, and vegetation compositional stability were assessed. We observed an increase in biomass and a reduction in species and functional diversity under short-term warming. The functional structure of the grassland communities changed significantly, in terms of functional diversity and community-weighted means (CWM) for several traits. Acquisitive and fast-growing species with higher SLA, early flowering, erect growth habit, and rhizomatous strategy became dominant in the lowland. Productivity was significantly positively related to species, and to a lower extent, functional diversity, but productivity and stability after warming were more dependent on trait composition (CWM) than on diversity. The turves with more acquisitive species before warming changed less in composition after warming. Results suggest that (i) the short-term warming can lead to the dominance of acquisitive fast growing species over conservative species, thus reducing species richness, and (ii) the functional traits structure in grassland communities had a greater influence on the productivity and stability of the community under short-term warming

  15. Functional Trait Changes, Productivity Shifts and Vegetation Stability in Mountain Grasslands during a Short-Term Warming.

    Directory of Open Access Journals (Sweden)

    Haifa Debouk

    Full Text Available Plant functional traits underlie vegetation responses to environmental changes such as global warming, and consequently influence ecosystem processes. While most of the existing studies focus on the effect of warming only on species diversity and productivity, we further investigated (i how the structure of community plant functional traits in temperate grasslands respond to experimental warming, and (ii whether species and functional diversity contribute to a greater stability of grasslands, in terms of vegetation composition and productivity. Intact vegetation turves were extracted from temperate subalpine grassland (highland in the Eastern Pyrenees and transplanted into a warm continental, experimental site in Lleida, in Western Catalonia (lowland. The impacts of simulated warming on plant production and diversity, functional trait structure, and vegetation compositional stability were assessed. We observed an increase in biomass and a reduction in species and functional diversity under short-term warming. The functional structure of the grassland communities changed significantly, in terms of functional diversity and community-weighted means (CWM for several traits. Acquisitive and fast-growing species with higher SLA, early flowering, erect growth habit, and rhizomatous strategy became dominant in the lowland. Productivity was significantly positively related to species, and to a lower extent, functional diversity, but productivity and stability after warming were more dependent on trait composition (CWM than on diversity. The turves with more acquisitive species before warming changed less in composition after warming. Results suggest that (i the short-term warming can lead to the dominance of acquisitive fast growing species over conservative species, thus reducing species richness, and (ii the functional traits structure in grassland communities had a greater influence on the productivity and stability of the community under short

  16. Microstructural, mechanical and electrochemical behaviour of a 7017 Al–Zn–Mg alloy of different tempers

    Energy Technology Data Exchange (ETDEWEB)

    Rout, Prasanta Kumar, E-mail: prasantonnet55@yahoo.com; Ghosh, M.M.; Ghosh, K.S., E-mail: ksghosh2001@yahoo.co.uk

    2015-06-15

    The aim of the investigation is to assess the microstructural features and associated physical, mechanical and electrochemical properties of a 7017 Al–Zn–Mg alloy of various tempers. A 7017 Al–Zn–Mg alloy was subjected to different ageing schedules to produce under-(T4), peak-(T6), over-(T7) and highly over-aged tempers. Optical microscopy, hardness measurement, electrical conductivity measurement, tensile testing and SEM fractographs, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electrochemical polarization studies have been used to characterize the alloy tempers. Hardness measurement and tensile testing showed the characteristic age hardening phenomenon of aluminium alloys. Optical and TEM micrographs have revealed the variation in size of matrix strengthening η′ (MgZn{sub 2}) and also the size and distribution of grain boundary η (MgZn{sub 2}) precipitate with ageing time. DSC thermograms exhibiting exothermic and endothermic peaks indicated the characteristic solid state reaction sequence of the 7017 alloy. Potentiodynamic polarization study of the 7017 alloy of various tempers in 3.5 wt.% NaCl solution at near neutral pH showed typical active metal dissolution behaviour, but at pH 12 an active–passive–transpassive transition behaviour has been observed. - Graphical abstract: TEM micrograph of the 7017 aluminium alloy of various tempers (a, b) under aged (T4), (c, d) peak aged (T6), (e, f) over aged (T7) and (g, h) highly over-aged. Display Omitted - Highlights: • 7017 Al-Zn-Mg alloy was subjected to different artificial ageing treatments. • Characterization of 7017 alloy tempers by hardness, tensile, DSC, TEM and electrochemical behaviour. • Structure-properties relationship of the 7017 Al-Zn-Mg alloy of various tempers.

  17. Cellular metabolic rate is influenced by life-history traits in tropical and temperate birds.

    Science.gov (United States)

    Jimenez, Ana Gabriela; Van Brocklyn, James; Wortman, Matthew; Williams, Joseph B

    2014-01-01

    In general, tropical birds have a "slow pace of life," lower rates of whole-animal metabolism and higher survival rates, than temperate species. A fundamental challenge facing physiological ecologists is the understanding of how variation in life-history at the whole-organism level might be linked to cellular function. Because tropical birds have lower rates of whole-animal metabolism, we hypothesized that cells from tropical species would also have lower rates of cellular metabolism than cells from temperate species of similar body size and common phylogenetic history. We cultured primary dermal fibroblasts from 17 tropical and 17 temperate phylogenetically-paired species of birds in a common nutritive and thermal environment and then examined basal, uncoupled, and non-mitochondrial cellular O2 consumption (OCR), proton leak, and anaerobic glycolysis (extracellular acidification rates [ECAR]), using an XF24 Seahorse Analyzer. We found that multiple measures of metabolism in cells from tropical birds were significantly lower than their temperate counterparts. Basal and uncoupled cellular metabolism were 29% and 35% lower in cells from tropical birds, respectively, a decrease closely aligned with differences in whole-animal metabolism between tropical and temperate birds. Proton leak was significantly lower in cells from tropical birds compared with cells from temperate birds. Our results offer compelling evidence that whole-animal metabolism is linked to cellular respiration as a function of an animal's life-history evolution. These findings are consistent with the idea that natural selection has uniquely fashioned cells of long-lived tropical bird species to have lower rates of metabolism than cells from shorter-lived temperate species.

  18. Cellular metabolic rate is influenced by life-history traits in tropical and temperate birds.

    Directory of Open Access Journals (Sweden)

    Ana Gabriela Jimenez

    Full Text Available In general, tropical birds have a "slow pace of life," lower rates of whole-animal metabolism and higher survival rates, than temperate species. A fundamental challenge facing physiological ecologists is the understanding of how variation in life-history at the whole-organism level might be linked to cellular function. Because tropical birds have lower rates of whole-animal metabolism, we hypothesized that cells from tropical species would also have lower rates of cellular metabolism than cells from temperate species of similar body size and common phylogenetic history. We cultured primary dermal fibroblasts from 17 tropical and 17 temperate phylogenetically-paired species of birds in a common nutritive and thermal environment and then examined basal, uncoupled, and non-mitochondrial cellular O2 consumption (OCR, proton leak, and anaerobic glycolysis (extracellular acidification rates [ECAR], using an XF24 Seahorse Analyzer. We found that multiple measures of metabolism in cells from tropical birds were significantly lower than their temperate counterparts. Basal and uncoupled cellular metabolism were 29% and 35% lower in cells from tropical birds, respectively, a decrease closely aligned with differences in whole-animal metabolism between tropical and temperate birds. Proton leak was significantly lower in cells from tropical birds compared with cells from temperate birds. Our results offer compelling evidence that whole-animal metabolism is linked to cellular respiration as a function of an animal's life-history evolution. These findings are consistent with the idea that natural selection has uniquely fashioned cells of long-lived tropical bird species to have lower rates of metabolism than cells from shorter-lived temperate species.

  19. Cellular Metabolic Rate Is Influenced by Life-History Traits in Tropical and Temperate Birds

    Science.gov (United States)

    Jimenez, Ana Gabriela; Van Brocklyn, James; Wortman, Matthew; Williams, Joseph B.

    2014-01-01

    In general, tropical birds have a “slow pace of life,” lower rates of whole-animal metabolism and higher survival rates, than temperate species. A fundamental challenge facing physiological ecologists is the understanding of how variation in life-history at the whole-organism level might be linked to cellular function. Because tropical birds have lower rates of whole-animal metabolism, we hypothesized that cells from tropical species would also have lower rates of cellular metabolism than cells from temperate species of similar body size and common phylogenetic history. We cultured primary dermal fibroblasts from 17 tropical and 17 temperate phylogenetically-paired species of birds in a common nutritive and thermal environment and then examined basal, uncoupled, and non-mitochondrial cellular O2 consumption (OCR), proton leak, and anaerobic glycolysis (extracellular acidification rates [ECAR]), using an XF24 Seahorse Analyzer. We found that multiple measures of metabolism in cells from tropical birds were significantly lower than their temperate counterparts. Basal and uncoupled cellular metabolism were 29% and 35% lower in cells from tropical birds, respectively, a decrease closely aligned with differences in whole-animal metabolism between tropical and temperate birds. Proton leak was significantly lower in cells from tropical birds compared with cells from temperate birds. Our results offer compelling evidence that whole-animal metabolism is linked to cellular respiration as a function of an animal’s life-history evolution. These findings are consistent with the idea that natural selection has uniquely fashioned cells of long-lived tropical bird species to have lower rates of metabolism than cells from shorter-lived temperate species. PMID:24498080

  20. Mutation breeding in vegetable crops

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Takashi

    1984-03-01

    Vegetables breed by seeds and vegetative organs. In main vegetables, the differentiation of clopping types, the adoption of monoculture and year-round production and shipment are carried out, adapting to various socio-economic and cultivation conditions. Protected agriculture has advanced mainly for fruit vegetables, and the seeds for sale have become almost hybrid varieties. Reflecting this situation, the demand for breeding is diversified and characteristic. The present status of mutation breeding of vegetables is not yet well under way, but reports of about 40 raised varieties have been published in the world. The characters introduced by induced mutation and irradiation are compact form, harvesting aptitude, the forms and properties of stems and leaves, anti-lodging property, the size, form and uniformity of fruits, male sterility and so on. The radiation sources used were mostly gamma ray or X-ray, but sometimes, combined irradiation was used. Results obtained in Japan include: burdocks as an example to gamma ray irradiation of seeds; tomatoes as an example of inducing compound resistance against disease injury; and lettuce as an example of internal beta irradiation. (Kako, I.).

  1. Mutation breeding in vegetable crops

    International Nuclear Information System (INIS)

    Yamaguchi, Takashi

    1984-01-01

    Vegetables breed by seeds and vegetative organs. In main vegetables, the differentiation of clopping types, the adoption of monoculture and year-round production and shipment are carried out, adapting to various socio-economic and cultivation conditions. Protected agriculture has advanced mainly for fruit vegetables, and the seeds for sale have become almost hybrid varieties. Reflecting the situation like this, the demand for breeding is diversified and characteristic, and the case of applying mutation breeding seems to be many. The present status of the mutation breeding of vegetables is not yet well under way, but about 40 raised varieties have been published in the world. The characters introduced by induced mutation and irradiation were compact form, harvesting aptitude, the forms and properties of stems and leaves, anti-lodging property, the size, form and uniformity of fruits, male sterility and so on. The radiation sources used were mostly gamma ray or X-ray, but sometimes, combined irradiation was used. As the results obtained in Japan, burdocks as an example of gamma ray irradiation to seeds, tomatoes as an example of inducing the compound resistance against disease injury and lettuces as an example of internal beta irradiation are reported. (Kako, I.)

  2. Temporal reflectance changes in vegetables

    DEFF Research Database (Denmark)

    Dissing, Bjørn Skovlund; Clemmensen, Line Katrine Harder; Ersbøll, Bjarne Kjær

    2009-01-01

    Quality control in the food industry is often performed by measuring various chemical compounds of the food involved. We propose an imaging concept for acquiring high quality multispectral images to evaluate changes of carrots and celeriac over a period of 14 days. Properties originating...... in the surface chemistry of vegetables may be captured in an integrating sphere illumination which enables the creation of detailed surface chemistry maps with a good combination of spectral and spatial resolutions. Prior to multispectral image recording, the vegetables were prefried and frozen at -30Â......°C for four months. During the 14 days of image recording, the vegetables were kept at +5°C in refrigeration. In this period, surface changes and thereby reflectance properties were very subtle. To describe this small variation we employed advanced statistical techniques to search a large featurespace...

  3. ROOT VEGETABLES, BREEDING TRENDS, RESULTS

    Directory of Open Access Journals (Sweden)

    M. I. Fedorova

    2017-01-01

    Full Text Available The main advantage of root vegetables is their unique specificity and high economic importance. The benefits and medicinal properties of root vegetables being highly demanded by the market requirements to the commodity are highlighted in the article. The main directions of breeding program for root vegetable crops, including species of Apiaceae family with carrot, parsnips; Chenopodioideae family with red beet; Brassicaceae family with radish, Daikon, Raphanus sativus L. var. lobo Sazonova & Stank, turnip and rutabaga. Initial breeding accessions of carrot, red beet, radish, Daikon, Raphanus sativus L. var. lobo Sazonova & Stank, turnip and rutabaga have been selected out to be used for breeding program for heterosis. The mf and ms breeding lines were developed, and with the use of them the new gene pool was created. Variety supporting breeding program and methods were also proposed. 

  4. An instrument design and sample strategy for measuring soil respiration in the coastal temperate rain forest

    Science.gov (United States)

    Nay, S. M.; D'Amore, D. V.

    2009-12-01

    The coastal temperate rainforest (CTR) along the northwest coast of North America is a large and complex mosaic of forests and wetlands located on an undulating terrain ranging from sea level to thousands of meters in elevation. This biome stores a dynamic portion of the total carbon stock of North America. The fate of the terrestrial carbon stock is of concern due to the potential for mobilization and export of this store to both the atmosphere as carbon respiration flux and ocean as dissolved organic and inorganic carbon flux. Soil respiration is the largest export vector in the system and must be accurately measured to gain any comprehensive understanding of how carbon moves though this system. Suitable monitoring tools capable of measuring carbon fluxes at small spatial scales are essential for our understanding of carbon dynamics at larger spatial scales within this complex assemblage of ecosystems. We have adapted instrumentation and developed a sampling strategy for optimizing replication of soil respiration measurements to quantify differences among spatially complex landscape units of the CTR. We start with the design of the instrument to ease the technological, ergonomic and financial barriers that technicians encounter in monitoring the efflux of CO2 from the soil. Our sampling strategy optimizes the physical efforts of the field work and manages for the high variation of flux measurements encountered in this difficult environment of rough terrain, dense vegetation and wet climate. Our soil respirometer incorporates an infra-red gas analyzer (LiCor Inc. LI-820) and an 8300 cm3 soil respiration chamber; the device is durable, lightweight, easy to operate and can be built for under $5000 per unit. The modest unit price allows for a multiple unit fleet to be deployed and operated in an intensive field monitoring campaign. We use a large 346 cm2 collar to accommodate as much micro spatial variation as feasible and to facilitate repeated measures for tracking

  5. Local vegetables in Cameroon: Corchorus species used as a vegetable.

    NARCIS (Netherlands)

    Westphal-Stevels, J.M.C.

    1986-01-01

    An agro-botanical study of local vegetables in Cameroon is in preparation, including the taxonomy, identity, morphology, agronomy and nutritional value of about 70 species. Corchorus olitorius L. and other edible species of the genus Corchorus L. (Tiliaceae) are part of this study. The wide

  6. Mitigating Uncertainty from Vegetation Spatial Complexity with Highly Portable Lidar

    Science.gov (United States)

    Paynter, I.; Schaaf, C.; Peri, F.; Saenz, E. J.; Genest, D.; Strahler, A. H.; Li, Z.

    2015-12-01

    To fully utilize the excellent spatial coverage and temporal resolution offered by satellite resources for estimating ecological variables, fine-scale observations are required for comparison, calibration and validation. Lidar instruments have proved effective in estimating the properties of vegetation components of ecosystems, but they are often challenged by occlusion, especially in structurally complex and spatially fragmented ecosystems such as tropical forests. Increasing the range of view angles, both horizontally and vertically, by increasing the number of scans, can mitigate occlusion. However these scans must occur within the window of temporal stability for the ecosystem and vegetation property being measured. The Compact Biomass Lidar (CBL) is a TLS optimized for portability and scanning speed, developed and operated by University of Massachusetts Boston. This 905nm wavelength scanner achieves an angular resolution of 0.25 degrees at a rate of 33 seconds per scan. The ability to acquire many scans within narrow windows of temporal stability for ecological variables has facilitated the more complete investigation of ecosystem structural characteristics, and their expression as a function of view angle. The lightweight CBL has facilitated the use of alternative deployment platforms including towers, trams and masts, allowing analysis of the vertical structure of ecosystems, even in highly enclosed environments such as the sub-canopy of tropical forests where aerial vehicles cannot currently operate. We will present results from view angle analyses of lidar surveys of tropical rainforest in La Selva, Costa Rica where the CBL was deployed at heights up to 10m in Carbono long-term research plots utilizing a portable mast, and on a 25m stationary tower; and temperate forest at Harvard Forest, Massachusetts, USA, where the CBL has been deployed biannually at long-term research plots of hardwood and hemlock, as well as at heights of up to 25m utilizing a

  7. Reference of Temperature and Time during tempering process for non-stoichiometric FTO films

    Science.gov (United States)

    Yang, J. K.; Liang, B.; Zhao, M. J.; Gao, Y.; Zhang, F. C.; Zhao, H. L.

    2015-10-01

    In order to enhance the mechanical strength of Low-E glass, Fluorine-doped tin oxide (FTO) films have to be tempered at high temperatures together with glass substrates. The effects of tempering temperature (600 °C ~ 720 °C) and time (150 s ~ 300 s) on the structural and electrical properties of FTO films were investigated. The results show all the films consist of non-stoichiometric, polycrystalline SnO2 without detectable amounts of fluoride. 700 °C and 260 s may be the critical tempering temperature and time, respectively. FTO films tempered at 700 °C for 260 s possesses the resistivity of 7.54 × 10-4 Ω•cm, the average transmittance in 400 ~ 800 nm of ~80%, and the calculated emissivity of 0.38. Hall mobility of FTO films tempered in this proper condition is mainly limited by the ionized impurity scattering. The value of [O]/[Sn] at the film surface is much higher than the stoichiometric value of 2.0 of pure crystalline SnO2.

  8. Effect of land use change on methane oxidation in temperate forest and grassland soils

    Energy Technology Data Exchange (ETDEWEB)

    Ojima, D.S.; Valentine, D.W.; Mosier, A.R.; Parton, W.J.; Schimel, D.S. (Colorado State University, Fort Collins, CO (USA). Natural Resources Ecology Lab.)

    Evidence is accumulating that land use changes and other human activity during the past 100 to 200 years have contributed to decreased CH[sub 4] oxidation in the soil. Increased N additions to temperate forest soils in the northeastern United States decreased CH[sub 4] uptake by 30 to 60%, and increased N fertilization and conversion to cropland in temperate grasslands decreased CH[sub 4] uptake by 30 to 75%. Using these data, a series of calculations were made to estimate the impact of land use and management changes which have altered soil, the CH[sub 4] sink in temperate forest and grassland ecosystems. As the atmospheric mixing ratio of CH[sub 4] has increased during the past 150 y, the temperate CH[sub 4] sink has risen from approximately 8 Tg y[sup -1] to 27 Tg y[sup -1], assuming no loss of land cover to cropland conversion. The net effect of intensive land cover changes and extensive chronic disturbance (i.e., increased atmospheric N deposition) to these ecosystems have resulted in about 30% reduction in the CH[sub 4] budget even more as atmospheric CH[sub 4] concentrations increase and as a result of further disturbance to other biomes. Without accounting for this approximately 20 Tg y[sup -1] temperate soil sink, the atmospheric CH[sub 4] concentration would be increasing about 1.5 times the current rate. 39 refs., 2 figs., 1 tab.

  9. Methane Ebullition in Temperate Hydropower Reservoirs and Implications for US Policy on Greenhouse Gas Emissions.

    Science.gov (United States)

    Miller, Benjamin L; Arntzen, Evan V; Goldman, Amy E; Richmond, Marshall C

    2017-10-01

    The United States is home to 2198 dams actively used for hydropower production. With the December 2015 consensus adoption of the United Nations Framework Convention on Climate Change Paris Agreement, it is important to accurately quantify anthropogenic greenhouse gas emissions. Methane ebullition, or methane bubbles originating from river or lake sediments, has been shown to account for nearly all methane emissions from tropical hydropower reservoirs to the atmosphere. However, distinct ebullitive methane fluxes have been studied in comparatively few temperate hydropower reservoirs globally. This study measures ebullitive and diffusive methane fluxes from two eastern Washington reservoirs, and synthesizes existing studies of methane ebullition in temperate, boreal, and tropical hydropower reservoirs. Ebullition comprises nearly all methane emissions (>97%) from this study's two eastern Washington hydropower reservoirs to the atmosphere. Summer methane ebullition from these reservoirs was higher than ebullition in six southeastern U.S. hydropower reservoirs, however it was similar to temperate reservoirs in other parts of the world. Our literature synthesis suggests that methane ebullition from temperate hydropower reservoirs can be seasonally elevated compared to tropical climates, however annual emissions are likely to be higher within tropical climates, emphasizing the possible range of methane ebullition fluxes and the need for the further study of temperate reservoirs. Possible future changes to the Intergovernmental Panel on Climate Change and UNFCCC guidelines for national greenhouse gas inventories highlights the need for accurate assessment of reservoir emissions.

  10. Methane Ebullition in Temperate Hydropower Reservoirs and Implications for US Policy on Greenhouse Gas Emissions

    Science.gov (United States)

    Miller, Benjamin L.; Arntzen, Evan V.; Goldman, Amy E.; Richmond, Marshall C.

    2017-10-01

    The United States is home to 2198 dams actively used for hydropower production. With the December 2015 consensus adoption of the United Nations Framework Convention on Climate Change Paris Agreement, it is important to accurately quantify anthropogenic greenhouse gas emissions. Methane ebullition, or methane bubbles originating from river or lake sediments, has been shown to account for nearly all methane emissions from tropical hydropower reservoirs to the atmosphere. However, distinct ebullitive methane fluxes have been studied in comparatively few temperate hydropower reservoirs globally. This study measures ebullitive and diffusive methane fluxes from two eastern Washington reservoirs, and synthesizes existing studies of methane ebullition in temperate, boreal, and tropical hydropower reservoirs. Ebullition comprises nearly all methane emissions (>97%) from this study's two eastern Washington hydropower reservoirs to the atmosphere. Summer methane ebullition from these reservoirs was higher than ebullition in six southeastern U.S. hydropower reservoirs, however it was similar to temperate reservoirs in other parts of the world. Our literature synthesis suggests that methane ebullition from temperate hydropower reservoirs can be seasonally elevated compared to tropical climates, however annual emissions are likely to be higher within tropical climates, emphasizing the possible range of methane ebullition fluxes and the need for the further study of temperate reservoirs. Possible future changes to the Intergovernmental Panel on Climate Change and UNFCCC guidelines for national greenhouse gas inventories highlights the need for accurate assessment of reservoir emissions.

  11. Appropriate welding conditions of temper bead weld repair for SQV2A pressure vessel steel

    International Nuclear Information System (INIS)

    Mizuno, R.; Matsuda, F.; Brziak, P.; Lomozik, M.

    2004-01-01

    Temper bead welding technique is one of the most important repair welding methods for large structures for which it is difficult to perform the specified post weld heat treatment. In this study, appropriate temper bead welding conditions to improve the characteristics of heat affected zone (HAZ) are studied using pressure vessel steel SQV2A corresponding to ASTM A533 Type B Class 1. Thermal/mechanical simulator is employed to give specimens welding thermal cycles from single to quadruple cycle. Charpy absorbed energy and hardness of simulated CGHAZ by first cycle were degraded as compared with base metal. Improvability of these degradations by subsequent cycles is discussed and appropriate temper bead thermal cycles are clarified. When the peak temperature lower than Ac1 and near Ac1 in the second thermal cycle is applied to CGAHZ by first thermal cycle, the characteristics of CGHAZ improve enough. When the other peak temperatures (that is, higher than Ac1) in the second thermal cycle are applied to the CGHAZ, third or more thermal cycle temper bead process should be applied to improve the properties. Appropriate weld condition ranges are selected based on the above results. The validity of the selected ranges is verified by the temper bead welding test. (orig.)

  12. The Kinetics of Phase Transformations During Tempering in Laser Melted High Chromium Cast Steel

    Science.gov (United States)

    Li, M. Y.; Wang, Y.; Han, B.

    2012-06-01

    The precipitation of secondary carbides in the laser melted high chromium cast steels during tempering at 300-650 °C for 2 h in air furnace was characterized and the present phases was identified, by using transmission electron microscopy. Laser melted high chromium cast steel consists of austenitic dendrites and interdendritic M23C6 carbides. The austenite has such a strong tempering stability that it remains unchanged at temperature below 400 °C and the secondary hardening phenomenon starts from 450 °C to the maximum value of 672 HV at 560 °C. After tempering at 450 °C fine M23C6 carbides precipitate from the supersaturated austenite preferentially. In addition, the dislocation lines and slip bands still exist inside the austenite. While tempering at temperature below 560 °C, the secondary hardening simultaneously results from the martensite phase transformation and the precipitation of carbides as well as dislocation strengthening within a refined microstructure. Moreover, the formation of the ferrite matrix and large quality of coarse lamellar M3C carbides when the samples were tempered at 650 °C contributes to the decrease of hardness.

  13. Spatiotemporal changes in vegetation net primary productivity in the arid region of Northwest China, 2001 to 2012

    Science.gov (United States)

    Li, Zhen; Pan, Jinghu

    2018-03-01

    Net primary productivity (NPP) is recognized as an important index of ecosystem conditions and a key variable of the terrestrial carbon cycle. It also represents the comprehensive effects of climate change and anthropogenic activity on terrestrial vegetation. In this study, the temporal-spatial pattern of NPP for the period 2001-2012 was analyzed using a remote sensing-based carbon model (i.e., the Carnegie-Ames-Stanford Approach, CASA) in addition to other methods, such as linear trend analysis, standard deviation, and the Hurst index. Temporally, NPP showed a significant increasing trend for the arid region of Northwest China (ARNC), with an annual increase of 2.327 g C. Maximum and minimum productivity values appeared in July and December, respectively. Spatially, the NPP was relatively stable in the temperate and warm-temperate desert regions of Northwest China, while temporally, it showed an increasing trend. However, some attention should be given to the northwestern warm-temperate desert region, where there is severe continuous degradation and only a slight improvement trend.

  14. Multiyear greenhouse gas balances at a rewetted temperate peatland.

    Science.gov (United States)

    Wilson, David; Farrell, Catherine A; Fallon, David; Moser, Gerald; Müller, Christoph; Renou-Wilson, Florence

    2016-12-01

    Drained peat soils are a significant source of greenhouse gas (GHG) emissions to the atmosphere. Rewetting these soils is considered an important climate change mitigation tool to reduce emissions and create suitable conditions for carbon sequestration. Long-term monitoring is essential to capture interannual variations in GHG emissions and associated environmental variables and to reduce the uncertainty linked with GHG emission factor calculations. In this study, we present GHG balances: carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) calculated for a 5-year period at a rewetted industrial cutaway peatland in Ireland (rewetted 7 years prior to the start of the study); and compare the results with an adjacent drained area (2-year data set), and with ten long-term data sets from intact (i.e. undrained) peatlands in temperate and boreal regions. In the rewetted site, CO 2 exchange (or net ecosystem exchange (NEE)) was strongly influenced by ecosystem respiration (R eco ) rather than gross primary production (GPP). CH 4 emissions were related to soil temperature and either water table level or plant biomass. N 2 O emissions were not detected in either drained or rewetted sites. Rewetting reduced CO 2 emissions in unvegetated areas by approximately 50%. When upscaled to the ecosystem level, the emission factors (calculated as 5-year mean of annual balances) for the rewetted site were (±SD) -104 ± 80 g CO 2 -C m -2  yr -1 (i.e. CO 2 sink) and 9 ± 2 g CH 4 -C m -2  yr -1 (i.e. CH 4 source). Nearly a decade after rewetting, the GHG balance (100-year global warming potential) had reduced noticeably (i.e. less warming) in comparison with the drained site but was still higher than comparative intact sites. Our results indicate that rewetted sites may be more sensitive to interannual changes in weather conditions than their more resilient intact counterparts and may switch from an annual CO 2 sink to a source if triggered by slightly drier

  15. Bed-Deformation Experiments Beneath a Temperate Glacier

    Science.gov (United States)

    Iverson, N. R.; Hooyer, T. S.; Fischer, U. H.; Cohen, D.; Jackson, M.; Moore, P. L.; Lappegard, G.; Kohler, J.

    2002-12-01

    Fast flow of glaciers and genesis of glacial landforms are commonly attributed to shear deformation of subglacial sediment. Although models of this process abound, data gathered subglacially on the kinematics and mechanics of such deformation are difficult to interpret. Major difficulties stem from the necessity of either measuring deformation near glacier margins, where conditions may be abnormal, or at the bottoms of boreholes, where the scope of instrumentation is limited, drilling disturbs sediment, and local boundary conditions are poorly known. A different approach is possible at the Svartisen Subglacial Laboratory, where tunnels melted in the ice provide temporary human access to the bed of Engabreen, a temperate outlet glacier of the Svartisen Ice Cap in Norway. A trough (2 m x 1.5 m x 0.5 m deep) was blasted in the rock bed, where the glacier is 220 m thick and sliding at 0.1-0.2 m/d. During two spring field seasons, this trough was filled with 2.5 tons of simulated till. Instruments in the till recorded shear (tiltmeters), volume change, total normal stress, and pore-water pressure as ice moved across the till surface. Pore pressure was brought to near the total normal stress by feeding water to the base of the till with a high-pressure pump, operated in a rock tunnel 4 m below the bed surface. Results illustrate some fundamental aspects of bed deformation. Permanent shear deformation requires low effective normal stress and hence high pore-water pressure, owing to the frictional nature of till. Shear strain generally increases upward in the bed toward the glacier sole, consistent with previous measurements beneath thinner ice at glacier margins. At low effective normal stresses, ice sometimes decouples from underlying till. Overall, bed deformation accounts for 10-35 % of basal motion, although this range excludes shear in the uppermost 0.05 m of till where shear was not measured. Pump tests with durations ranging from seconds to hours highlight the need

  16. A minimal model of fire-vegetation feedbacks and disturbance stochasticity generates alternative stable states in grassland–shrubland–woodland systems

    International Nuclear Information System (INIS)

    Batllori, Enric; Ackerly, David D; Moritz, Max A

    2015-01-01

    Altered disturbance regimes in the context of global change are likely to have profound consequences for ecosystems. Interactions between fire and vegetation are of particular interest, as fire is a major driver of vegetation change, and vegetation properties (e.g., amount, flammability) alter fire regimes. Mediterranean-type ecosystems (MTEs) constitute a paradigmatic example of temperate fire-prone vegetation. Although these ecosystems may be heavily impacted by global change, disturbance regime shifts and the implications of fire-vegetation feedbacks in the dynamics of such biomes are still poorly characterized. We developed a minimal modeling framework incorporating key aspects of fire ecology and successional processes to evaluate the relative influence of extrinsic and intrinsic factors on disturbance and vegetation dynamics in systems composed of grassland, shrubland, and woodland mosaics, which characterize many MTEs. In this theoretical investigation, we performed extensive simulations representing different background rates of vegetation succession and disturbance regime (fire frequency and severity) processes that reflect a broad range of MTE environmental conditions. Varying fire-vegetation feedbacks can lead to different critical points in underlying processes of disturbance and sudden shifts in the vegetation state of grassland–shrubland–woodland systems, despite gradual changes in ecosystem drivers as defined by the environment. Vegetation flammability and disturbance stochasticity effectively modify system behavior, determining its heterogeneity and the existence of alternative stable states in MTEs. Small variations in system flammability and fire recurrence induced by climate or vegetation changes may trigger sudden shifts in the state of such ecosystems. The existence of threshold dynamics, alternative stable states, and contrasting system responses to environmental change has broad implications for MTE management. (letter)

  17. Classification and ordination of understory vegetation using multivariate techniques in the Pinus wallichiana forests of Swat Valley, northern Pakistan

    Science.gov (United States)

    Rahman, Inayat Ur; Khan, Nasrullah; Ali, Kishwar

    2017-04-01

    An understory vegetation survey of the Pinus wallichiana-dominated temperate forests of Swat District was carried out to inspect the structure, composition and ecological associations of the forest vegetation. A quadrat method of sampling was used to record the floristic and phytosociological data necessary for the analysis using 300 quadrats of 10 × 10 m each. Some vegetation parameters viz. frequency and density for trees (overstory vegetation) as well as for the understory vegetation were recorded. The results revealed that in total, 92 species belonging to 77 different genera and 45 families existed in the area. The largest families were Asteraceae, Rosaceae and Lamiaceae with 12, ten and nine species, respectively. Ward's agglomerative cluster analysis for tree species resulted in three floristically and ecologically distinct community types along different topographic and soil variables. Importance value indices (IVI) were also calculated for understory vegetation and were subjected to ordination techniques, i.e. canonical correspondence analysis (CCA) and detrended correspondence analysis (DCA). DCA bi-plots for stands show that most of the stands were scattered around the centre of the DCA bi-plot, identified by two slightly scattered clusters. DCA for species bi-plot clearly identified three clusters of species revealing three types of understory communities in the study area. Results of the CCA were somewhat different from the DCA showing the impact of environmental variables on the understory species. CCA results reveal that three environmental variables, i.e. altitude, slope and P (mg/kg), have a strong influence on distribution of stands and species. Impact of tree species on the understory vegetation was also tested by CCA which showed that four tree species, i.e. P. wallichiana A.B. Jackson, Juglans regia Linn., Quercus dilatata Lindl. ex Royle and Cedrus deodara (Roxb. ex Lamb.) G. Don, have strong influences on associated understory vegetation. It

  18. Buffers for biomass production in temperate European agriculture

    DEFF Research Database (Denmark)

    Christen, Benjamin; Dalgaard, Tommy

    2013-01-01

    , environmental pressures from intensive agriculture and policy developments. Use of conservation buffers by farmers outside of designated schemes is limited to date, but the increasing demand for bioenergy and the combination of agricultural production with conservation calls for a much wider implementation....... This paper reviews the biophysical knowledge on buffer functioning and associated ecosystem services. It describes how a three-zone buffer design, with arable fields buffered in combination by grassland, short rotation forestry (SRF) or coppice (SRC) and undisturbed vegetation along water courses, can...... be incorporated into farming landscapes as productive conservation elements and reflects on the potential for successful implementation. Land use plays a much greater role in determining catchment hydrology than soil type: shelterbelts or buffer strips have markedly higher infiltration capacity than arable...

  19. Vegetables, Coctails & Reflections / Marco Laimre

    Index Scriptorium Estoniae

    Laimre, Marko, 1968-

    2006-01-01

    Pealkirja "Vegetables, Coctails & Reflections" kandis Tallinna Kunstihoones 8.04.-28.05.2006 avatud Elin Kardi, Marko Mäetamme, Marco Laimre ja Andres Tali ühisnäitusel "Vägivald ja propaganda" Marco Laimre installatsioon. Marco Laimre esinemine raadiosaates "kunst.er" Klassikaraadios 16.04.2006

  20. Vegetable Crop Pests. MEP 311.

    Science.gov (United States)

    Kantzes, James G.; And Others

    As part of a cooperative extension service series by the University of Maryland, this publication introduces the identification and control of common agricultural pests of vegetable crops. The first of the five sections defines "pest" and "weed" and generally introduces different kinds of pests in the categories of insects,…

  1. Self-crafting vegetable snacks

    NARCIS (Netherlands)

    Raghoebar, Sanne; Kleef, van Ellen; Vet, de Emely

    2017-01-01

    Purpose: The purpose of this paper is to test whether the IKEA-effect (Norton et al., 2012) – better liking for self-crafted products than for identical products crafted by others – can be exploited to increase liking and consumption of vegetable snacks in children. Design/methodology/approach: A

  2. Flavour release from dried vegetables

    NARCIS (Netherlands)

    Ruth, van S.M.

    1995-01-01

    The research described in this thesis was focused on the development of an in vitro model system for isolation of volatile compounds from dried vegetables under mouth conditions, such as volume of the mouth, temperature, salivation and mastication. Instrumental analysis of these

  3. Assessing stream bank condition using airborne LiDAR and high spatial resolution image data in temperate semirural areas in Victoria, Australia

    Science.gov (United States)

    Johansen, Kasper; Grove, James; Denham, Robert; Phinn, Stuart

    2013-01-01

    Stream bank condition is an important physical form indicator for streams related to the environmental condition of riparian corridors. This research developed and applied an approach for mapping bank condition from airborne light detection and ranging (LiDAR) and high-spatial resolution optical image data in a temperate forest/woodland/urban environment. Field observations of bank condition were related to LiDAR and optical image-derived variables, including bank slope, plant projective cover, bank-full width, valley confinement, bank height, bank top crenulation, and ground vegetation cover. Image-based variables, showing correlation with the field measurements of stream bank condition, were used as input to a cumulative logistic regression model to estimate and map bank condition. The highest correlation was achieved between field-assessed bank condition and image-derived average bank slope (R2=0.60, n=41), ground vegetation cover (R=0.43, n=41), bank width/height ratio (R=0.41, n=41), and valley confinement (producer's accuracy=100%, n=9). Cross-validation showed an average misclassification error of 0.95 from an ordinal scale from 0 to 4 using the developed model. This approach was developed to support the remotely sensed mapping of stream bank condition for 26,000 km of streams in Victoria, Australia, from 2010 to 2012.

  4. Survival rates of birds of tropical and temperate forests: will the dogma survive?

    Science.gov (United States)

    Karr, J.R.; Nichols, J.D.; Klimkiewicz, M.K.; Brawn, J.D.

    1990-01-01

    Survival rates of tropical forest birds are widely assumed to be high relative to the survival rates of temperate forest birds. Much life-history theory is based on this assumption despite the lack of empirical data to support it. We provide the first detailed comparison of survival rates of tropical and temperate forest birds based on extensive data bases and modern capture-recapture models. We find no support for the conventional wisdom. Because clutch size is only one component of reproductive rate, the frequently assumed, simple association between clutch size and adult survival rates should not necessarily be expected. Our results emphasize the need to consider components of fecundity in addition to clutch size when comparing the life histories of tropical and temperate birds and suggest similar considerations in the development of vertebrate life-history theory.

  5. Microstructural characteristics of steel rebar submitted to the process of self - tempering

    International Nuclear Information System (INIS)

    Barreto, M.F.O.

    2014-01-01

    Every day the construction industry seeks new alternatives to maximize use of the materials provided new tools for structural design of the new techniques in welding rods. In this sense, this work proposes to study the mechanical properties of steel rebar self-tempering for civil construction, choosing the bars from 6.3 to 25.4 mm in diameter for the study. The cooling process of rebar, after rolling, known as self-tempering produces a rebar with excellent mechanical properties and low cost to the plant, they put the rebar shall be composed of concentric layers with different mechanical properties among themselves. To study the influence of these layers on the mechanical behavior of rebar microstructural characterization was made by means of electron microscopy analysis of transmitted light and scanning of all samples. From the results it was found that only the bars 20 and 25mm diameter had a heat treatment for self-tempering relevant. (author)

  6. Evaluation of temper embrittlement of martensitic and ferritic-martensitic steels by acoustic emission

    International Nuclear Information System (INIS)

    Lu, Yusho; Takahashi, Hideaki; Shoji, Tetsuo

    1987-01-01

    Martensitic (HT-9) and ferritic-martensitic steels (9Cr-2Mo) are considered as fusion first wall materials. In this investigation in order to understand the sensitivity of temper embrittlement in these steels under actual service condition, fracture toughness testing was made by use of acoustic emission technique. The temper embrittlement was characterized in terms of fracture toughness. The fracture toughness of these steels under 500 deg C, 100 hrs, and 1000 hrs heat treatment was decreased and their changes in micro-fracture process have been observed. The fracture toughness changes by temper embrittlement was discussed by the characteristic of AE, AE spectrum analysis and fractographic investigation. The relation between micro-fracture processes and AE has been clarified. (author)

  7. Quantifying the effects of tempering on individual phase properties of DP980 steel with nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, G. [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA (United States); Zhang, F. [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA (United States); Ruimi, A. [Department of Mechanical Engineering, Texas A& M University, Doha (Qatar); Field, D.P. [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA (United States); Sun, X., E-mail: xin.sun@pnnl.gov [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA (United States)

    2016-06-14

    Tempering treatment is conducted on a commercial dual phase (DP) 980 steel at 250 °C and 400 °C for 60 min each. Ferrite and martensite grains are distinguished using electron backscatter diffraction (EBSD) and scanning probe microscopy (SPM), and the martensite volume fractions (MVF) are determined based on the image quality (IQ) map. Indentation tests combined with a newly developed inverse method are used to obtain the individual phase flow properties in each sample. The results show that, i) tempering significantly reduces martensite yield strength, while it slightly reduces the ferrite yield strength; ii) tempering temperature has a more significant influence on the work hardening exponent of ferrite than that of martensite. As a validation, a simple rule-of-mixtures is used to verify the above-predicted individual phase flow stresses with the experimentally obtained overall true stress vs. true strain curves.

  8. Testing the correlation of fragmented pollen records of the middle and late Pleistocene temperate stages

    DEFF Research Database (Denmark)

    Kuneš, Petr; Odgaard, Bent Vad

    Quaternary temperate stages have long been described based on changing pollen abundances of various tree taxa in lacustrine sediments. Later, attempts have been made to assign such biostratigraphic units to distinct marine isotope stages (MIS). Existing continuous chronosequences from Southern...... records depends on site-to-site correlations. This comparison has often been performed on a visual basis, lacking clearly defined protocols and statements of underlying assumptions. Here I test the correlation of well and poorly known pollen records of the middle- and late-Pleistocene temperate stages...... from Northern-Central Europe and evaluate the usefulness of several numerical techniques. TWINSPAN analysis identifies groups of temperate stages based on presence/absence of their indicative taxa and may be useful for distinguishing between older and younger interglacials. Site-to-site sequence...

  9. Electromagnetic nondestructive evaluation of tempering process in AISI D2 tool steel

    Science.gov (United States)

    Kahrobaee, Saeed; Kashefi, Mehrdad

    2015-05-01

    The present paper investigates the potential of using eddy current technique as a reliable nondestructive tool to detect microstructural changes during the different stages of tempering treatment in AISI D2 tool steel. Five stages occur in tempering of the steel: precipitation of ɛ carbides, formation of cementite, retained austenite decomposition, secondary hardening effect and spheroidization of carbides. These stages were characterized by destructive methods, including dilatometry, differential scanning calorimetry, X-ray diffraction, scanning electron microscopic observations, and hardness measurements. The microstructural changes alter the electrical resistivity/magnetic saturation, which, in turn, influence the eddy current signals. Two EC parameters, induced voltage sensed by pickup coil and impedance point detected by excitation coil, were evaluated as a function of tempering temperature to characterize the microstructural features, nondestructively. The study revealed that a good correlation exists between the EC parameters and the microstructural changes.

  10. Investigation of the self tempering effect of martensite by means of atom probe tomography

    International Nuclear Information System (INIS)

    Sackl, Stephanie; Clemens, Helmut; Primig, Sophie

    2015-01-01

    Self-tempering effects can be observed in steels with relatively high martensite start temperatures. After the formation of the first martensitic laths, carbon is able to diffuse in these laths during cooling, which can be attributed to sufficiently high temperatures. This effect cannot be observed in laths formed at lower temperatures. In steels containing up to 0.2 m.-% carbon, up to 90 % of the carbon atoms in the martensite segregate to dislocations during quenching. Due to its atomic resolution and sensitivity with respect to light elements, atom probe tomography is very well suited for the investigation of this phenomenon. In this study, the self-tempering effect in a quenched and tempered steel 42CrMo4 with a martensite start temperature of 310 C is investigated by means of atom probe tomography.

  11. Resonant behavior of the generalized Langevin system with tempered Mittag–Leffler memory kernel

    Science.gov (United States)

    Chen, Yao; Wang, Xudong; Deng, Weihua

    2018-05-01

    The generalized Langevin equation describes anomalous dynamics. Noise is not only the origin of uncertainty but also plays a positive role in helping to detect signals with information, termed stochastic resonance (SR). This paper analyzes the anomalous resonant behaviors of the generalized Langevin system with a multiplicative dichotomous noise and an internal tempered Mittag–Leffler noise. For a system with a fluctuating harmonic potential, we obtain the exact expressions of several types of SR such as the first moment, the amplitude and autocorrelation function for the output signal as well as the signal–noise ratio. We analyze the influence of the tempering parameter and memory exponent on the bona fide SR and the general SR. Moreover, it is detected that the critical memory exponent changes regularly with the increase of the tempering parameter. Almost all the theoretical results are validated by numerical simulations.

  12. Remaining stress-state and strain-energy in tempered glass fragments

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2016-01-01

    to the fragmentation process and some authors e.g. Barsom (J Am Ceram Soc 51(2):75, 1968), Gulati (Glass processing days, Tamglass Engineering Oy, Tampere, 1997), Warren (Fractography of glasses and ceramics IV, Alfred University, Alfred, 2001) and Tandon and Glass (Fracture mechanics of ceramics—active materials......When tempered glass breaks, it shatters into relatively small pieces depending on the residual stress state in the glass. This has been known for centuries and is currently used in standards for classifying whether a piece of glass is tempered or not. However, the process of fragmentation...... is complex and only a few, relatively simple, models have been suggested for predicting the fragment size. The full theoretical explanation is still to be found and this work aims at providing another brick to the puzzle. The strain-energy present in tempered glass is obviously contributing...

  13. Tempering response to different morphologies of martensite in tensile deformation of dual-phase steel

    International Nuclear Information System (INIS)

    Ahmad, E.; Manzoor, T.; Sarwar, M.; Arif, M.; Hussain, N.

    2011-01-01

    A low alloy steel containing 0.2% C was heat treated with three cycles of heat treatments with the aim to acquire different morphologies of martensite in dual phase microstructure. Microscopic examination revealed that the morphologies consisting of grain boundary growth, scattered laths and bulk form of martensite were obtained. These morphologies have their distinct patterns of distribution in the matrix (ferrite). In tensile properties observations the dual phase steel with bulk morphology of martensite showed minimum of ductility but high tensile strength as compared to other two morphologies. This may be due to poor alignments of bulk martensite particles along tensile axes during deformation. Tempering was employed with various holding times at 550 deg. C to induce ductility in the heat treated material. The tempering progressively increased the ductility by increasing holding time. However, tempering response to strengths and ductilities was different to all three morphologies of martensite. (author)

  14. Localization and Ballistic Diffusion for the Tempered Fractional Brownian-Langevin Motion

    Science.gov (United States)

    Chen, Yao; Wang, Xudong; Deng, Weihua

    2017-10-01

    This paper discusses the tempered fractional Brownian motion (tfBm), its ergodicity, and the derivation of the corresponding Fokker-Planck equation. Then we introduce the generalized Langevin equation with the tempered fractional Gaussian noise for a free particle, called tempered fractional Langevin equation (tfLe). While the tfBm displays localization diffusion for the long time limit and for the short time its mean squared displacement (MSD) has the asymptotic form t^{2H}, we show that the asymptotic form of the MSD of the tfLe transits from t^2 (ballistic diffusion for short time) to t^{2-2H}, and then to t^2 (again ballistic diffusion for long time). On the other hand, the overdamped tfLe has the transition of the diffusion type from t^{2-2H} to t^2 (ballistic diffusion). The tfLe with harmonic potential is also considered.

  15. T6 and T78 tempers of AA6065 alloy: a quantitative TEM study

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, M.; Warner, T. [Compagnie de Produits Chimiques et Electrometallurgiques Pechiney, Centre de Recherches de Voreppe, 38 (France)

    2000-07-01

    Quantitative transmission electron microscopy is used to characterize the microstructure of an industrial Al-Mg-Si-Cu alloy (AA6056) in a state (T78 temper) desensitized to intergranular corrosion in comparison with the peak aged state (T6 temper). Analysis of dark-field images and of zero-loss filtered selected-area-diffraction patterns, along with EDX spectroscopy, indicates an advanced precipitation of the quaternary phase containing Si and Cu in the T78-tempered alloy compared to the T6 one. This supports the current theory of the desensitization of AA6056 alloy. However, the application of EDX analysis to provide direct evidence of the chemical composition variation in the solid solution across the grain boundary appears less satisfactory. (orig.)

  16. Serving vegetables first: A strategy to increase vegetable consumption in elementary school cafeterias.

    Science.gov (United States)

    Elsbernd, S L; Reicks, M M; Mann, T L; Redden, J P; Mykerezi, E; Vickers, Z M

    2016-01-01

    Vegetable consumption in the United States is low despite the wealth of evidence that vegetables play an important role in reducing risk of various chronic diseases. Because eating patterns developed in childhood continue through adulthood, we need to form healthy eating habits in children. The objective of this study was to determine if offering vegetables before other meal components would increase the overall consumption of vegetables at school lunch. We served kindergarten through fifth-grade students a small portion (26-33 g) of a raw vegetable (red and yellow bell peppers) while they waited in line to receive the rest of their lunch meal. They then had the options to take more of the bell peppers, a different vegetable, or no vegetable from the lunch line. We measured the amount of each vegetable consumed by each child. Serving vegetables first greatly increased the number of students eating vegetables. On intervention days most of the vegetables consumed came from the vegetables-first portions. Total vegetable intake per student eating lunch was low because most students chose to not eat vegetables, but the intervention significantly increased this value. Serving vegetables first is a viable strategy to increase vegetable consumption in elementary schools. Long-term implementation of this strategy may have an important impact on healthy eating habits, vegetable consumption, and the health consequences of vegetable intake. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Plasmodium vivax populations revisited: mitochondrial genomes of temperate strains in Asia suggest ancient population expansion

    Directory of Open Access Journals (Sweden)

    Miao Miao

    2012-02-01

    Full Text Available Abstract Background Plasmodium vivax is the most widely distributed human malaria parasite outside of Africa, and its range extends well into the temperate zones. Previous studies provided evidence for vivax population differentiation, but temperate vivax parasites were not well represented in these analyses. Here we address this deficit by using complete mitochondrial (mt genome sequences to elucidate the broad genetic diversity and population structure of P. vivax from temperate regions in East and Southeast Asia. Results From the complete mtDNA sequences of 99 clinical samples collected in China, Myanmar and Korea, a total of 30 different haplotypes were identified from 26 polymorphic sites. Significant differentiation between different East and Southeast Asian parasite populations was observed except for the comparison between populations from Korea and southern China. Haplotype patterns and structure diversity analysis showed coexistence of two different groups in East Asia, which were genetically related to the Southeast Asian population and Myanmar population, respectively. The demographic history of P. vivax, examined using neutrality tests and mismatch distribution analyses, revealed population expansion events across the entire P. vivax range and the Myanmar population. Bayesian skyline analysis further supported the occurrence of ancient P. vivax population expansion. Conclusions This study provided further resolution of the population structure and evolution of P. vivax, especially in temperate/warm-temperate endemic areas of Asia. The results revealed divergence of the P. vivax populations in temperate regions of China and Korea from other populations. Multiple analyses confirmed ancient population expansion of this parasite. The extensive genetic diversity of the P. vivax populations is consistent with phenotypic plasticity of the parasites, which has implications for malaria control.

  18. Tempering Behavior of TiC-Reinforced SKD11 Steel Matrix Composite

    Science.gov (United States)

    Hwang, Ji-In; Kim, Seong Hoon; Heo, Yoon-Uk; Kim, Dae Ha; Hwang, Keum-Cheol; Suh, Dong-Woo

    2018-03-01

    TiC-reinforced SKD11 steel matrix composite, fabricated by a pressure infiltration casting, undergoes monotonic decrease in hardness as tempering temperature increases. Element mappings by TEM-EDS and thermodynamic calculation indicate that remarkable redistribution of V between the reinforcement and the steel matrix occurs by partial dissolution and re-precipitation of MC carbides upon casting process. The absence of secondary hardening is led by the enrichment of V in the reinforcement that reduces the V content in the steel matrix; this reduction in V content makes the precipitation of fine VC sluggish during the tempering.

  19. X-ray residual stress analysis on machined and tempered HPSN-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Immelmann, S.; Welle, E.; Reimers, W. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1997-11-15

    The residual stress state induced by grinding and tempering of hot pressed silicon nitride (HPSN) samples is studied by X-ray diffraction. The results reveal that the residual stress values at the surface of the samples as well as their gradient within the penetration depth of the X-rays depend on the sintering aid and thus, on the glassy phase content of the HPSN. Tempering of the ground HPSN reduces the residual stress values due to microplastic deformation, whereas an oxidation of the glassy phase leads to the formation of compressive residual stresses. (orig.) 35 refs.

  20. Use of the integration elements encoded by the temperate lactococcal bacteriophage TP901-1

    DEFF Research Database (Denmark)

    Brøndsted, Lone; Hammer, Karin

    1999-01-01

    Previously we showed that only one phage-expressed protein (Orf1), a 425-bp region upstream of the orf1 gene (presumably encoding a promoter), and the attP region are necessary and also sufficient for integration of the bacteriophage TP901-1 genome into the chromosome of Lactococcus lactis subsp......P region seem to be necessary for site-specific integration of the temperate bacteriophage TP901-1. By use of the integrative elements (attP and orf1) expressed by the temperate lactococcal bacteriophage TP901-1, a system for obtaining stable chromosomal single-copy transcriptional fusions in L. lactis...

  1. Managing Understory Vegetation for Maintaining Productivity in Black Spruce Forests: A Synthesis within a Multi-Scale Research Model

    Directory of Open Access Journals (Sweden)

    Gilles Joanisse

    2013-07-01

    Full Text Available Sustainable management of boreal ecosystems involves the establishment of vigorous tree regeneration after harvest. However, two groups of understory plants influence regeneration success in eastern boreal Canada. Ericaceous shrubs are recognized to rapidly dominate susceptible boreal sites after harvest. Such dominance reduces recruitment and causes stagnant conifer growth, lasting decades on some sites. Additionally, peat accumulation due to Sphagnum growth after harvest forces the roots of regenerating conifers out of the relatively nutrient rich and warm mineral soil into the relatively nutrient poor and cool organic layer, with drastic effects on growth. Shifts from once productive black spruce forests to ericaceous heaths or paludified forests affect forest productivity and biodiversity. Under natural disturbance dynamics, fires severe enough to substantially reduce the organic layer thickness and affect ground cover species are required to establish a productive regeneration layer on such sites. We succinctly review how understory vegetation influences black spruce ecosystem dynamics in eastern boreal Canada, and present a multi-scale research model to understand, limit the loss and restore productive and diverse ecosystems in this region. Our model integrates knowledge of plant-level mechanisms in the development of silvicultural tools to sustain productivity. Fundamental knowledge is integrated at stand, landscape, regional and provincial levels to understand the distribution and dynamics of ericaceous shrubs and paludification processes and to support tactical and strategic forest management. The model can be adapted and applied to other natural resource management problems, in other biomes.

  2. Effect of tempering on microstructure and tensile properties of niobium modified martensitic 9Cr heat resistant steel

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, A., E-mail: anupmetal@gmail.com; Bandyopadhay, T.K.

    2015-01-03

    The effect of tempering on the microstructure of niobium modified 8.8 wt% chromium steel has been evaluated. Steel has been prepared using the conventional melting and casting route. Homogenization and forging is done at 1100 °C. Dilatometric study shows that the Ac{sub 1}, Ac{sub 3} and M{sub s} temperatures are 800, 855, and 131 °C, respectively. Initial cast and forged microstructures consist of martensite/ferrite. The samples are subsequently tempered at 500–800 °C for various intervals of time (1–5 h). The microstructure of the tempered sample is analyzed using optical microscopy, scanning electron microscopy, and X-ray diffraction. High Resolution Transmission Electron Microscopy (HRTEM) is used to identify the precipitate. Nanometer-sized precipitates (50–200 nm) are observed after tempering at 700 °C for 1 h. Niobium rich MC type carbide precipitates and chromium rich M{sub 23}C{sub 6} type precipitates are observed after tempering at 700 °C. Tensile strength decreases with increasing tempering temperature. Maximum tensile strength of 920 MPa is observed after tempering at 700 °C and maximum elongation of ∼11% is observed after tempering at 750 °C.

  3. Effect of tempering temperature on microstructure and sliding wear property of laser quenched 4Cr13 steel

    NARCIS (Netherlands)

    Ouyang, J.H.; Pei, Y.T.; Li, X.D.; Lei, T.C.

    1994-01-01

    4Cr13 martensite stainless steel was quenched by a CO2 laser and tempered for 2 h at different temperatures in the range 200 °C to 550 °C. The microstructure of treated layer was observed by SEM, XRD and TEM. Tempering leads to the decomposition of a large number of retained austenites in laser

  4. Carbon isotope characterization of vegetation and soil organic matter in subtropical forests in Luquillo, Puerto Rico

    International Nuclear Information System (INIS)

    Fischer, J.C. von; Tieszen, L.L.

    1995-01-01

    We examined natural abundances of 13 C in vegetation and soil organic maner (SOM) of subtropical wet and rain forests to characterize the isotopic enrichment through decomposition that has been reported for temperate forests. Soil cores and vegetative samples from the decomposition continuum (leaves, new litter, old liner, wood, and roots) were taken from each of four forest types in the Luquillo Experimental Forest, Puerto Rico. SOM δ 13 C was enriched 1.60/00 relative to aboveground litter. We found no further enrichment within the soil profile. The carbon isotope ratios of vegetation varied among forests, ranging from -28.20/00 in the Colorado forest to -26.90/00 in the Palm forest. Isotope ratios of SOM differed between forests primarily in the top 20 em where the Colorado forest was again most negative at -28.00/00, and the Palm forest was most positive at -26.50/00. The isotopic differences between forests are likely attributable to differences in light regimes due to canopy density variation, soil moisture regimes, and/or recycling of CO 2 . Our data suggest that recalcitrant SOM is not derived directly from plant lignin since plant lignin is even more 13 C depleted than the bulk vegetation. We hypothesize that the anthropogenic isotopic depletion of atmospheric CO 2 , (ca 1.50/00 in the last 150 years) accounts for some of the enrichment observed in the SOM relative to the more modern vegetation in this study and others. This study also supports other observations that under wet or anaerobic soil environments there is no isotopic enrichment during decomposition or with depth in the active profile. (author)

  5. 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.

  6. Carbon isotope characterization of vegetation and soil organic matter in subtropical forests in Luquillo, Puerto Rico

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J.C. von [Cornell University, Ithaca, NY (United States); Tieszen, L. L.

    1995-06-15

    We examined natural abundances of {sup 13}C in vegetation and soil organic maner (SOM) of subtropical wet and rain forests to characterize the isotopic enrichment through decomposition that has been reported for temperate forests. Soil cores and vegetative samples from the decomposition continuum (leaves, new litter, old liner, wood, and roots) were taken from each of four forest types in the Luquillo Experimental Forest, Puerto Rico. SOM δ{sup 13}C was enriched 1.60/00 relative to aboveground litter. We found no further enrichment within the soil profile. The carbon isotope ratios of vegetation varied among forests, ranging from -28.20/00 in the Colorado forest to -26.90/00 in the Palm forest. Isotope ratios of SOM differed between forests primarily in the top 20 em where the Colorado forest was again most negative at -28.00/00, and the Palm forest was most positive at -26.50/00. The isotopic differences between forests are likely attributable to differences in light regimes due to canopy density variation, soil moisture regimes, and/or recycling of CO{sub 2}. Our data suggest that recalcitrant SOM is not derived directly from plant lignin since plant lignin is even more {sup 13}C depleted than the bulk vegetation. We hypothesize that the anthropogenic isotopic depletion of atmospheric CO{sub 2}, (ca 1.50/00 in the last 150 years) accounts for some of the enrichment observed in the SOM relative to the more modern vegetation in this study and others. This study also supports other observations that under wet or anaerobic soil environments there is no isotopic enrichment during decomposition or with depth in the active profile. (author)

  7. Seasonal changes in nitrogen availability, and root and microbial uptake of 15N13C9-phenylalanine and 15N-ammonium in situ at a temperate heath

    DEFF Research Database (Denmark)

    Andresen, Louise C.; Michelsen, Anders; Jonasson, Sven Evert

    2011-01-01

    In the plant biosynthesis of secondary compounds, phenylalanine is a precursor of condensed tannins. Tannins are deposited into the soil in plant root exudates and dead plant material and have been suggested to precipitate some soil nutrients and hence reduce nutrient availability for plants. Free...... amino acid,inorganic and microbial N concentration during the growing season was investigated in an ecosystem with a natural tannin chemosphere. The influence of tannins on the uptake of nitrogen in plants and microbes was followed by injecting tannic acid (TA), ammonium-15N and phenylalanine-15N/13C9...

  8. Unexpectedly large impact of forest management and grazing on global vegetation biomass

    Science.gov (United States)

    Erb, Karl-Heinz; Kastner, Thomas; Plutzar, Christoph; Bais, Anna Liza S.; Carvalhais, Nuno; Fetzel, Tamara; Gingrich, Simone; Haberl, Helmut; Lauk, Christian; Niedertscheider, Maria; Pongratz, Julia; Thurner, Martin; Luyssaert, Sebastiaan

    2018-01-01

    Carbon stocks in vegetation have a key role in the climate system. However, the magnitude, patterns and uncertainties of carbon stocks and the effect of land use on the stocks remain poorly quantified. Here we show, using state-of-the-art datasets, that vegetation currently stores around 450 petagrams of carbon. In the hypothetical absence of land use, potential vegetation would store around 916 petagrams of carbon, under current climate conditions. This difference highlights the massive effect of land use on biomass stocks. Deforestation and other land-cover changes are responsible for 53-58% of the difference between current and potential biomass stocks. Land management effects (the biomass stock changes induced by land use within the same land cover) contribute 42-47%, but have been underestimated in the literature. Therefore, avoiding deforestation is necessary but not sufficient for mitigation of climate change. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for the mitigation of climate change. Efforts to raise biomass stocks are currently verifiable only in temperate forests, where their potential is limited. By contrast, large uncertainties hinder verification in the tropical forest, where the largest potential is located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement.

  9. Unexpectedly large impact of forest management and grazing on global vegetation biomass.

    Science.gov (United States)

    Erb, Karl-Heinz; Kastner, Thomas; Plutzar, Christoph; Bais, Anna Liza S; Carvalhais, Nuno; Fetzel, Tamara; Gingrich, Simone; Haberl, Helmut; Lauk, Christian; Niedertscheider, Maria; Pongratz, Julia; Thurner, Martin; Luyssaert, Sebastiaan

    2018-01-04

    Carbon stocks in vegetation have a key role in the climate system. However, the magnitude, patterns and uncertainties of carbon stocks and the effect of land use on the stocks remain poorly quantified. Here we show, using state-of-the-art datasets, that vegetation currently stores around 450 petagrams of carbon. In the hypothetical absence of land use, potential vegetation would store around 916 petagrams of carbon, under current climate conditions. This difference highlights the massive effect of land use on biomass stocks. Deforestation and other land-cover changes are responsible for 53-58% of the difference between current and potential biomass stocks. Land management effects (the biomass stock changes induced by land use within the same land cover) contribute 42-47%, but have been underestimated in the literature. Therefore, avoiding deforestation is necessary but not sufficient for mitigation of climate change. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for the mitigation of climate change. Efforts to raise biomass stocks are currently verifiable only in temperate forests, where their potential is limited. By contrast, large uncertainties hinder verification in the tropical forest, where the largest potential is located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement.

  10. Ecosystem properties self-organize in response to a directional fog-vegetation interaction.

    Science.gov (United States)

    Stanton, Daniel E; Armesto, Juan J; Hedin, Lars O

    2014-05-01

    Feedbacks between vegetation and resource inputs can lead to the local, self-organization of ecosystem properties. In particular, feedbacks in response to directional resources (e.g., coastal fog, slope runoff) can create complex spatial patterns, such as vegetation banding. Although similar feedbacks are thought to be involved in the development of ecosystems, clear empirical examples are rare. We created a simple model of a fog-influenced, temperate rainforest in central Chile, which allows the comparison of natural banding patterns to simulations of various putative mechanisms. We show that only feedbacks between plants and fog were able to replicate the characteristic distributions of vegetation, soil water, and soil nutrients observed in field transects. Other processes, such as rainfall, were unable to match these diagnostic distributions. Furthermore, fog interception by windward trees leads to increased downwind mortality, leading to progressive extinction of the leeward edge. This pattern of ecosystem development and decay through self-organized processes illustrates, on a relatively small spatial and temporal scale, the patterns predicted for ecosystem evolution.

  11. Biologically active matters in soy vegetative mass

    OpenAIRE

    GNOEVYY I.V.

    2013-01-01

    Maintenance of row of bioactive matters of phenic nature in particular, isoflavonoids is investigational at to soy-bean cakes to vegetative mass of soy in the phases of vegetation of 8 the most widespread sorts of soy in Ukraine.

  12. Vegetation - San Felipe Valley [ds172

    Data.gov (United States)

    California Natural Resource Agency — This Vegetation Map of the San Felipe Valley Wildlife Area in San Diego County, California is based on vegetation samples collected in the field in 2002 and 2005 and...

  13. Biota - 2009 Vegetation Inventory - Lake Ashtabula, ND

    Data.gov (United States)

    Army Corps of Engineers, Department of the Army, Department of Defense — 2009 Vegetation Classification for Lake Ashtabula, ND Vegetation Project Report, OMBIL Environmental Stewardship - Level 1 Inventory, U.S. Army Corps of Engineers...

  14. Ecosystems past: prehistory of California vegetation

    Science.gov (United States)

    C.I. Millar; W.B. Woolfenden

    2016-01-01

    The history of California's vegetation, from origins in the Mesozoic through Quaternary is outlined. Climatic and geologic history and the processes driving changes in vegetation over time are also described. 

  15. Marketing African Leafy Vegetables: Challenges and Opportunities ...

    African Journals Online (AJOL)

    Marketing African Leafy Vegetables: Challenges and Opportunities in the Kenyan Context. ... The market share of ALVs vis-à-vis other vegetable species, particularly kales, cabbages and ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  16. Biota - 2011 Vegetation Inventory - Marsh Lake, MN

    Data.gov (United States)

    Army Corps of Engineers, Department of the Army, Department of Defense — 2011 Vegetation Classification for Marsh Lake, MN Vegetation Project Report, OMBIL Environmental Stewardship - Level 1 Inventory. Marsh Lake is located on the...

  17. Effect of quenching and tempering process on sulfide stress cracking susceptibility in API-5CT-C110 casing steel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, M.; Wang, C.H.; Dai, Y.C.; Li, X.; Cao, G.H. [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, 149 Yanchang Road, Shanghai 200072 (China); Russell, A.M. [Division of Materials Science and Engineering, Ames Laboratory of the U.S.D.O.E., and Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-2300 (United States); Liu, Y.H.; Dong, X.M. [Tube & Pipe Department, Baosteel Research Institute, Baoshan Iron & Steel Co., Ltd, Shanghai 201900 (China); Zhang, Z.H., E-mail: zhzhang@baosteel.com [Tube & Pipe Department, Baosteel Research Institute, Baoshan Iron & Steel Co., Ltd, Shanghai 201900 (China)

    2017-03-14

    Three quenching and tempering processes performed on API-5CT-C110 casing steel produced tempered martensite structures and similar mechanical properties but distinct sulfide stress cracking (SSC) behavior as evaluated by Double Cantilever Beam (DCB) testing. An as-quenched specimen tempered at 690 °C for two hours showed superior SSC behavior compared to another specimen tempered at 715 °C for one hour. The latter contained a larger fraction of low-angle boundaries (LABs) and higher values of kernel average misorientation (KAM) than those in the former. Moreover, one more quenching and tempering on the former specimen would produce better SSC resistance with a decrease in the fraction of LABs and the values of KAM. Since dislocations trap hydrogen more strongly than grain boundaries, the specimen with higher KAM values, as well as higher dislocation density, would trap more hydrogen atoms and lead to greater SSC.

  18. Contribution of fine tree roots to the silicon cycle in a temperate forest ecosystem developed on three soil types

    Science.gov (United States)

    Turpault, Marie-Pierre; Calvaruso, Christophe; Kirchen, Gil; Redon, Paul-Olivier; Cochet, Carine

    2018-04-01

    The role of forest vegetation in the silicon (Si) cycle has been widely examined. However, to date, little is known about the specific role of fine roots. The main objective of our study was to assess the influence of fine roots on the Si cycle in a temperate forest in north-eastern France. Silicon pools and fluxes in vegetal solid and solution phases were quantified within each ecosystem compartment, i.e. in the atmosphere, above-ground and below-ground tree tissues, forest floor and different soil layers, on three plots, each with different soil types, i.e. Dystric Cambisol (DC), Eutric Cambisol (EC) and Rendzic Leptosol (RL). In this study, we took advantage of a natural soil gradient, from shallow calcic soil to deep moderately acidic soil, with similar climates, atmospheric depositions, species compositions and management. Soil solutions were measured monthly for 4 years to study the seasonal dynamics of Si fluxes. A budget of dissolved Si (DSi) was also determined for the forest floor and soil layers. Our study highlighted the major role of fine roots in the Si cycle in forest ecosystems for all soil types. Due to the abundance of fine roots mainly in the superficial soil layers, their high Si concentration (equivalent to that of leaves and 2 orders higher than that of coarse roots) and their rapid turnover rate (approximately 1 year), the mean annual Si fluxes in fine roots in the three plots were 68 and 110 kg ha-1 yr-1 for the RL and the DC, respectively. The turnover rates of fine roots and leaves were approximately 71 and 28 % of the total Si taken up by trees each year, demonstrating the importance of biological recycling in the Si cycle in forests. Less than 1 % of the Si taken up by trees each year accumulated in the perennial tissues. This study also demonstrated the influence of soil type on the concentration of Si in the annual tissues and therefore on the Si fluxes in forests. The concentrations of Si in leaves and fine roots were approximately 1

  19. An automatic approach for rice mapping in temperate region using time series of MODIS imagery: first results for Mediterranean environment

    Science.gov (United States)

    Boschetti, M.; Nelson, A.; Manfrom, G.; Brivio, P. A.

    2012-04-01

    Timely and accurate information on crop typology and status are required to support suitable action to better manage agriculture production and reduce food insecurity. More specifically, regional crop masking and phenological information are important inputs for spatialized crop growth models for yield forecasting systems. Digital cartographic data available at global/regional scale, such as GLC2000, GLOBCOVER or MODIS land cover products (MOD12), are often not adequate for this crop modeling application. For this reason, there is a need to develop and test methods that can provide such information for specific cropsusing automated classification techniques.. In this framework we focused our analysis on the rice cultivation area detection due to the importance of this crop. Rice is a staple food for half of the world's population (FAO 2004). Over 90% of the world's rice is produced and consumed in Asia and the region is home to 70% of the world's poor, most of whom depend on rice for their livelihoods andor food security. Several initiatives are being promoted at the international level to provide maps of rice cultivated areas in South and South East Asia using different approaches available in literature for rice mapping in tropical regions. We contribute to these efforts by proposing an automatic method to detect rice cultivated areas in temperate regions exploiting MODIS 8-Day composite of Surface Reflectance at 500m spatial resolution (MOD09A1product). Temperate rice is cultivated worldwide in more than 20 countries covering around 16M ha for a total production of about 65M tons of paddy per year. The proposed method is based on a common approach available in literature that first identifies flood condition that can be related to rice agronomic practice and then checks for vegetation growth. The method presents innovative aspects related both to the flood detection, exploiting Short Wave Infrared spectral information, and to the crop grow monitoring analyzing

  20. Piping dynamics in mid-altitude mountains under a temperate climate: the Bieszczady Mts., the Eastern Carpathians

    Science.gov (United States)

    Bernatek-Jakiel, Anita; Jakiel, Michał; Krzemień, Kazimierz

    2017-04-01

    Soil erosion is caused not only by overland flow, but also by subsurface flow. Piping which is a process of mechanical removal of soil particles by concentrated subsurface flow is frequently being overlooked and not accounted for in soil erosion studies. However, it seems that it is far more widespread than it has often been supposed. Furthermore, our knowledge about piping dynamics and its quantification currently relies on a limited number of data available for mainly loess-mantled areas and marl badlands. Therefore, this research aims to recognize piping dynamics in mid-altitude mountains under a temperate climate, where piping occurs in Cambisols, not previously considered as piping-prone soils. The survey was carried out in the Bereźnica Wyżna catchment (305 ha), in the Bieszczady Mts. (the Eastern Carpathians, Poland), where 188 collapsed pipes were mapped. The research was based on the monitoring of selected piping systems located within grasslands (1971-1974, 2013-2016). The development of piping systems is mainly induced by the elongation of pipes and creation of new collapses (closed depressions and sinkholes), rather than by the enlargement of existing piping forms, or the deepening of pipes. It draws attention to the role of dense vegetation (grasslands) in the delay of pipe collapses and, also, to the boundary of pipe development (soil-bedrock interface). The obtained results reveal an episodic, and even stochastic nature of piping activity, expressed by varied one-year and short-term (3 years) erosion rates, and pipe elongation. Changes in soil loss vary significantly between different years (up to 27.36 t ha-1 y-1), reaching the rate of 1.34 t ha-1 y-1 for the 45-year study period. The elongation of pipes also differs, from no changes to 36 m during one year. The results indicate that soil loss due to piping can cause high soil loss even in highly vegetated lands (grasslands), which are generally considered as areas without a significant erosion

  1. Late Glacial-Holocene Pollen-Based Vegetation History from Pass Lake, Prince of Wales Island, Southeastern Alaska

    Science.gov (United States)

    Ager, Thomas A.; Rosenbaum, Joseph G.

    2009-01-01

    A radiocarbon-dated history of vegetation development since late Wisconsin deglaciation has been reconstructed from pollen evidence preserved in a sediment core from Pass Lake on Prince of Wales Island, southeastern Alaska. The shallow lake is in the south-central part of the island and occupies a low pass that was filled by glacial ice of local origin during the late Wisconsin glaciation. The oldest pollen assemblages indicate that pine woodland (Pinus contorta) had developed in the area by ~13,715 cal yr B.P. An abrupt decline in the pine population, coinciding with expansion of alder (Alnus) and ferns (mostly Polypodiaceae) began ~12,875 yr B.P., and may have been a response to colder, drier climates during the Younger Dryas climatic interval. Mountain hemlock (Tsuga mertensiana) began to colonize central Prince of Wales Island by ~11,920 yr B.P. and was soon followed by Sitka spruce (Picea sitchensis). Pollen of western hemlock (Tsuga heterophylla) began to appear in Pass Lake sediments soon after 11,200 yr B.P. The abundance of western hemlock pollen in the Pass Lake core during most of the Holocene appears to be the result of wind transport from trees growing at lower altitudes on the island. The late Holocene pollen record from Pass Lake is incomplete because of one or more unconformities, but the available record suggests that a vegetation change occurred during the late Holocene. Increases in pollen percentages of pine, cedar (probably yellow cedar, Chamaecyparis nootkatensis), and heaths (Ericales) suggest an expansion of muskeg vegetation occurred in the area during the late Holocene. This vegetation change may be related to the onset of cooler, wetter climates that began as early as ~3,774 yr B.P. in the region. This vegetation history provides the first radiocarbon-dated Late Glacial-Holocene terrestrial paleoecological framework for Prince of Wales Island. An analysis of magnetic properties of core sediments from Pass Lake suggests that unconformities

  2. Irradiation of fruit and vegetables

    International Nuclear Information System (INIS)

    O'Beirne, David

    1987-01-01

    There is likely to be less economic incentive to irradiate fruits and vegetables compared with applications which increase the safety of foods such as elimination of Salmonella or decontamination of food ingredients. Of the fruit and vegetable applications, irradiation of mushrooms may offer the clearest economic benefits in North-Western Europe. The least likely application appears to be sprout inhibition in potatoes and onions, because of the greater efficiency and flexibility of chemical sprout inhibitors. In the longer-term, combinations between irradiation/MAP/other technologies will probably be important. Research in this area is at an early stage. Consumer attitudes to food irradiation remain uncertain. This will be a crucial factor in the commercial application of the technology and in the determining the balance between utilisation of irradiation and of technologies which compete with irradiation. (author)

  3. Hyperspectral remote sensing of vegetation

    Science.gov (United States)

    Thenkabail, Prasad S.; Lyon, John G.; Huete, Alfredo

    2011-01-01

    Hyperspectral narrow-band (or imaging spectroscopy) spectral data are fast emerging as practical solutions in modeling and mapping vegetation. Recent research has demonstrated the advances in and merit of hyperspectral data in a range of applications including quantifying agricultural crops, modeling forest canopy biochemical properties, detecting crop stress and disease, mapping leaf chlorophyll content as it influences crop production, identifying plants affected by contaminants such as arsenic, demonstrating sensitivity to plant nitrogen content, classifying vegetation species and type, characterizing wetlands, and mapping invasive species. The need for significant improvements in quantifying, modeling, and mapping plant chemical, physical, and water properties is more critical than ever before to reduce uncertainties in our understanding of the Earth and to better sustain it. There is also a need for a synthesis of the vast knowledge spread throughout the literature from more than 40 years of research.

  4. Phenolic Compounds in Brassica Vegetables

    Directory of Open Access Journals (Sweden)

    Pablo Velasco

    2010-12-01

    Full Text Available Phenolic compounds are a large group of phytochemicals widespread in the plant kingdom. Depending on their structure they can be classified into simple phenols, phenolic acids, hydroxycinnamic acid derivatives and flavonoids. Phenolic compounds have received considerable attention for being potentially protective factors against cancer and heart diseases, in part because of their potent antioxidative properties and their ubiquity in a wide range of commonly consumed foods of plant origin. The Brassicaceae family includes a wide range of horticultural crops, some of them with economic significance and extensively used in the diet throughout the world. The phenolic composition of Brassica vegetables has been recently investigated and, nowadays, the profile of different Brassica species is well established. Here, we review the significance of phenolic compounds as a source of beneficial compounds for human health and the influence of environmental conditions and processing mechanisms on the phenolic composition of Brassica vegetables.

  5. Clearing and vegetation management issues

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    Clearing and continued management of incompatible plant species is critical to maintaining safe and reliable transmission and distribution lines at British Columbia Hydro. As part of a general review of policies regarding rights-of-way, the clearing of BC Hydro rights-of-way was studied by a task team in order to formulate a set of recommended policies and procedures to guide employees in all rights-of-way decisions, and to provide clear direction for resolution of all rights-of-way issues in a cost-effective manner. Issues reviewed were: clearing standards and line security standardization for transmission circuits; clearing rights for removal of trees or management of vegetation beyond the statutory right-of-way; clearing and vegetation management procedures; tree replacement; arboricultural techniques; periodic reviewing of clearing practices; compensation for tree removal; herbicide use; and heritage and wildlife trees. Justification for the recommendation is provided along with alternate options and costs of compliance

  6. Biodiversity of Terrestrial Ecosystems in Tropical to Temperate Australia

    Directory of Open Access Journals (Sweden)

    Raymond L. Specht

    2012-01-01

    Full Text Available During the short period of annual foliage growth in evergreen plant communities, aerodynamic fluxes (frictional, thermal, evaporative in the atmosphere as it flows over and through a plant community determine the Foliage Projective Covers and leaf attributes in overstorey and understorey strata. The number of leaves produced on each vertical foliage shoot depends on available soil water and nutrients during this growth period. The area of all leaves exposed to solar radiation determines net photosynthetic fixation of the plant community throughout the year. In turn, the species richness (number of species per hectare of both plants and resident vertebrates is determined. The species richness of unicellular algae and small multicellular isopods in permanent freshwater lagoons in Northern Australia may possibly have been increased by radiation released from nearby uranium deposits. Evolution of new angiosperms probably occurred in refugia during periods of extreme drought. When favourable climates were restored, the vegetation expanded to result in high Gamma Biodiversity (number of plant species per region but with each major plant community having essentially the same species richness (number of plant species per hectare. The probable effects of pollution and Global Warming on biodiversity in Australian ecosystems, that experience seasonal drought, are discussed.

  7. The role of vegetation dynamics in the control of atmospheric CO{sub 2} content

    Energy Technology Data Exchange (ETDEWEB)

    Sitch, Stephen

    2000-04-01

    the terrestrial biosphere to store additional carbon diminishes. At the end of the forcing period, vegetation is no longer in equilibrium, justifying the need for dynamic models in global change research. LPJ predicts the abundance of woody vegetation to increase everywhere, except in regions facing large reductions in precipitation. The tree-line extends northwards and temperate woody plants expand into the present-day boreal forest.

  8. Ecophysiological Remote Sensing of Leaf-Canopy Photosynthetic Characteristics in a Cool-Temperate Deciduous Forest in Japan

    Science.gov (United States)

    Noda, H. M.; Muraoka, H.

    2014-12-01

    Satellite remote sensing of structure and function of canopy is crucial to detect temporal and spatial distributions of forest ecosystems dynamics in changing environments. The spectral reflectance of the canopy is determined by optical properties (spectral reflectance and transmittance) of single leaves and their spatial arrangements in the canopy. The optical properties of leaves reflect their pigments contents and anatomical structures. Thus detailed information and understandings of the consequence between ecophysiological traits and optical properties from single leaf to canopy level are essential for remote sensing of canopy ecophysiology. To develop the ecophysiological remote sensing of forest canopy, we have been promoting multiple and cross-scale measurements in "Takayama site" belonging to AsiaFlux and JaLTER networks, located in a cool-temperate deciduous broadleaf forest on a mountainous landscape in Japan. In this forest, in situ measurement of canopy spectral reflectance has been conducted continuously by a spectroradiometer as part of the "Phenological Eyes Network (PEN)" since 2004. To analyze the canopy spectral reflectance from leaf ecophysiological viewpoints, leaf mass per area, nitrogen content, chlorophyll contents, photosynthetic capacities and the optical properties have been measured for dominant canopy tree species Quercus crispla and Betula ermanii throughout the seasons for multiple years.Photosynthetic capacity was largely correlated with chlorophyll contents throughout the growing season in both Q. crispla and B. ermanii. In these leaves, the reflectance at "red edge" (710 nm) changed by corresponding to the changes of chlorophyll contents throughout the seasons. Our canopy-level examination showed that vegetation indices obtained by red edge reflectance have linear relationship with leaf chlorophyll contents and photosynthetic capacity. Finally we apply this knowledge to the Rapid Eye satellite imagery around Takayama site to scale

  9. Role of forest conservation in lessening land degradation in a temperate region: the Monarch Butterfly Biosphere Reserve, Mexico.

    Science.gov (United States)

    Manzo-Delgado, Lilia; López-García, José; Alcántara-Ayala, Irasema

    2014-06-01

    With international concern about the rates of deforestation worldwide, particular attention has been paid to Latin America. Forest conservation programmes in Mexico include Payment for Environmental Services (PES), a scheme that has been successfully introduced in the Monarch Butterfly Biosphere Reserve. To seek further evidence of the role of PES in lessening land degradation processes in a temperate region, the conservation state of the Cerro Prieto ejido within the Reserve was assessed by an analysis of changes in vegetation cover and land-use between 1971 and 2013. There were no changes in the total forest surface area, but the relative proportions of the different classes of cover density had changed. In 1971, closed and semi-closed forest occupied 247.81 ha and 5.38 ha, 82.33% and 1.79% of the total area of the ejido, respectively. By 2013, closed forest had decreased to 230.38 ha (76.54% of the ejido), and semi-closed cover was 17.23 ha (5.72% of the ejido), suggesting that some semi-closed forest had achieved closed status. The final balance between forest losses and recovery was: 29.63 ha were lost, whereas 13.72 ha were recovered. Losses were mainly linked to a sanitation harvest programme to control the bark beetle Scolytus mundus. Ecotourism associated with forest conservation in the Cerro Prieto ejido has been considered by inhabitants as a focal alternative for economic development. Consequently, it is essential to develop a well-planned and solidly structured approach based on social cohesion to foster a community-led sustainable development at local level. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Mapping the spatial pattern of temperate forest above ground biomass by integrating airborne lidar with Radarsat-2 imagery via geostatistical models

    Science.gov (United States)

    Li, Wang; Niu, Zheng; Gao, Shuai; Wang, Cheng

    2014-11-01

    Light Detection and Ranging (LiDAR) and Synthetic Aperture Radar (SAR) are two competitive active remote sensing techniques in forest above ground biomass estimation, which is important for forest management and global climate change study. This study aims to further explore their capabilities in temperate forest above ground biomass (AGB) estimation by emphasizing the spatial auto-correlation of variables obtained from these two remote sensing tools, which is a usually overlooked aspect in remote sensing applications to vegetation studies. Remote sensing variables including airborne LiDAR metrics, backscattering coefficient for different SAR polarizations and their ratio variables for Radarsat-2 imagery were calculated. First, simple linear regression models (SLR) was established between the field-estimated above ground biomass and the remote sensing variables. Pearson's correlation coefficient (R2) was used to find which LiDAR metric showed the most significant correlation with the regression residuals and could be selected as co-variable in regression co-kriging (RCoKrig). Second, regression co-kriging was conducted by choosing the regression residuals as dependent variable and the LiDAR metric (Hmean) with highest R2 as co-variable. Third, above ground biomass over the study area was estimated using SLR model and RCoKrig model, respectively. The results for these two models were validated using the same ground points. Results showed that both of these two methods achieved satisfactory prediction accuracy, while regression co-kriging showed the lower estimation error. It is proved that regression co-kriging model is feasible and effective in mapping the spatial pattern of AGB in the temperate forest using Radarsat-2 data calibrated by airborne LiDAR metrics.

  11. Structural and functional responses of plant communities to climate change-mediated alterations in the hydrology of riparian areas in temperate Europe.

    Science.gov (United States)

    Baattrup-Pedersen, Annette; Garssen, Annemarie; Göthe, Emma; Hoffmann, Carl Christian; Oddershede, Andrea; Riis, Tenna; van Bodegom, Peter M; Larsen, Søren E; Soons, Merel

    2018-04-01

    The hydrology of riparian areas changes rapidly these years because of climate change-mediated alterations in precipitation patterns. In this study, we used a large-scale in situ experimental approach to explore effects of drought and flooding on plant taxonomic diversity and functional trait composition in riparian areas in temperate Europe. We found significant effects of flooding and drought in all study areas, the effects being most pronounced under flooded conditions. In near-stream areas, taxonomic diversity initially declined in response to both drought and flooding (although not significantly so in all years) and remained stable under drought conditions, whereas the decline continued under flooded conditions. For most traits, we found clear indications that the functional diversity also declined under flooded conditions, particularly in near-stream areas, indicating that fewer strategies succeeded under flooded conditions. Consistent changes in community mean trait values were also identified, but fewer than expected. This can have several, not mutually exclusive, explanations. First, different adaptive strategies may coexist in a community. Second, intraspecific variability was not considered for any of the traits. For example, many species can elongate shoots and petioles that enable them to survive shallow, prolonged flooding but such abilities will not be captured when applying mean trait values. Third, we only followed the communities for 3 years. Flooding excludes species intolerant of the altered hydrology, whereas the establishment of new species relies on time-dependent processes, for instance the dispersal and establishment of species within the areas. We expect that altered precipitation patterns will have profound consequences for riparian vegetation in temperate Europe. Riparian areas will experience loss of taxonomic and functional diversity and, over time, possibly also alterations in community trait responses that may have cascading effects

  12. Waste vegetable oil survey report

    Energy Technology Data Exchange (ETDEWEB)

    MacLeod, R. [Science enterprise Algoma seA, Sault Ste. Marie, ON (Canada)

    2009-02-06

    This study was conducted to estimate potential sources of feedstock waste oils for biodiesel production in the Sault Ste. Marie region of Ontario. Two feedstocks were investigated over a period of several months, notably cooking oil and waste vegetable oil. The study was conducted to examine oil throughput, collection practices, and to gauge interest in local initiatives. A distribution list of commercial restaurant listings was developed, and surveys were conducted with members of private enterprises, city government, and non-profit stakeholders in the region. Average volumes of waste vegetable oil were presented for different types of restaurants. The various types of oil used in the restaurants were also quantified. Results of the study showed a positive public response to the idea of a local biodiesel initiative. Steak house, fast food, and Italian establishments generated the largest portion of waste vegetable oil amongst survey respondents. However, the highest response rates came from establishments with little or no oil consumption. Many franchise fast food restaurants are already in contracts with waste oil removal companies. 3 tabs., 3 figs.

  13. The northern flying squirrel as an indicator species of temperate rain forest: test of an hypothesis.

    Science.gov (United States)

    Winston P. Smith; Scott M. Gende; Jeffrey V. Nichols

    2005-01-01

    Management indicator species (MIS) often are selected because their life history and demographics are thought to reflect a suite of ecosystem conditions that are too difficult or costly to measure directly. The northern flying squirrel (Glaucomys sabrinus) has been proposed as an MIS of temperate rain forest of southeastern Alaska based on previous...

  14. Restoration of a boulder reef in temperate waters: Strategy, methodology and lessons learnt

    DEFF Research Database (Denmark)

    Støttrup, Josianne Gatt; Dahl, Karsten; Niemann, Sanne

    2017-01-01

    Anthropogenic impacts on marine habitats are a global problem, particularly in coastal areas. While boulder reefs in temperate waters hold high biomass and biodiversity, and may be unable to recover from anthropogenic stressors without restoration efforts, little is known about how to restore and...

  15. Characterization of Nanometric-Sized Carbides Formed During Tempering of Carbide-Steel Cermets

    Directory of Open Access Journals (Sweden)

    Matus K.

    2016-06-01

    Full Text Available The aim of this article of this paper is to present issues related to characterization of nanometric-sized carbides, nitrides and/or carbonitrides formed during tempering of carbide-steel cermets. Closer examination of those materials is important because of hardness growth of carbide-steel cermet after tempering. The results obtained during research show that the upswing of hardness is significantly higher than for high-speed steels. Another interesting fact is the displacement of secondary hardness effect observed for this material to a higher tempering temperature range. Determined influence of the atmosphere in the sintering process on precipitations formed during tempering of carbide-steel cermets. So far examination of carbidesteel cermet produced by powder injection moulding was carried out mainly in the scanning electron microscope. A proper description of nanosized particles is both important and difficult as achievements of nanoscience and nanotechnology confirm the significant influence of nanocrystalline particles on material properties even if its mass fraction is undetectable by standard methods. The following research studies have been carried out using transmission electron microscopy, mainly selected area electron diffraction and energy dispersive spectroscopy. The obtained results and computer simulations comparison were made.

  16. Modification of Low-Alloy Steel Surface by High-Temperature Gas Nitriding Plus Tempering

    Science.gov (United States)

    Jiao, Dongling; Li, Minsong; Ding, Hongzhen; Qiu, Wanqi; Luo, Chengping

    2018-02-01

    The low-alloy steel was nitrided in a pure NH3 gas atmosphere at 640 660 °C for 2 h, i.e., high-temperature gas nitriding (HTGN), followed by tempering at 225 °C, which can produce a high property surface coating without brittle compound (white) layer. The steel was also plasma nitriding for comparison. The composition, microstructure and microhardness of the nitrided and tempered specimens were examined, and their tribological behavior investigated. The results showed that the as-gas-nitrided layer consisted of a white layer composed of FeN0.095 phase (nitrided austenite) and a diffusional zone underneath the white layer. After tempering, the white layer was decomposed to a nano-sized (α-Fe + γ'-Fe4N + retained austenite) bainitic microstructure with a high hardness of 1150HV/25 g. Wear test results showed that the wear resistance and wear coefficient yielded by the complex HTGN plus tempering were considerably higher and lower, respectively, than those produced by the conventional plasma nitriding.

  17. Effect of microstructure on the susceptibility of a 533 steel to temper embrittlement

    International Nuclear Information System (INIS)

    Raoul, S.; Marini, B.; Pineau, A.

    1998-01-01

    In ferritic steels, brittle fracture usually occurs at low temperature by cleavage. However the segregation of impurities (P, As, Sn etc..) along prior γ grain boundaries can change the brittle fracture mode from transgranular to intergranular. In quenched and tempered steels, this segregation is associated with what is called the temper-embrittlement phenomenon. The main objective of the present study is to investigate the influence of the as-quenched microstructure (lower bainite or martensite) on the susceptibility of a low alloy steel (A533 cl.1) to temper-embrittlement. Dilatometric tests were performed to determine the continous-cooling-transformation (CCT) diagram of the material and to measure the critical cooling rate (V c ) for a martensitic quench. Then subsized Charpy V-notched specimens were given various cooling rates from the austenitization temperature to obtain a wide range of as-quenched microstructures, including martensite and bainite. These specimens were subsequently given a heat treatment to develop temper embrittlement and tested to measure the V-notch fracture toughness at -50 C. The fracture surfaces were examined by SEM. It is shown that martensitic microstructures are more susceptible to intergranular embrittlement than bainitic microstructures. These observed microstructural influences are briefly discussed. (orig.)

  18. Finite Element Implementation of a Glass Tempering Model in Three Dimensions

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Poulsen, Peter Noe

    2010-01-01

    The present paper develops and validates a 3D model for the simulation of glass tempering. It is assembled from well-known models of temperature dependent viscoelasticity and structural relaxation and predicts both transient and steady-state stresses in complex 3D glass geometries. The theory and...

  19. Effect of microstructure on the susceptibility of a 533 steel to temper embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    Raoul, S.; Marini, B. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Service de Recherches Metallurgiques Appliquees; Pineau, A. [CNRS, Evry (France). Centre de Materiaux

    1998-11-01

    In ferritic steels, brittle fracture usually occurs at low temperature by cleavage. However the segregation of impurities (P, As, Sn etc..) along prior {gamma} grain boundaries can change the brittle fracture mode from transgranular to intergranular. In quenched and tempered steels, this segregation is associated with what is called the temper-embrittlement phenomenon. The main objective of the present study is to investigate the influence of the as-quenched microstructure (lower bainite or martensite) on the susceptibility of a low alloy steel (A533 cl.1) to temper-embrittlement. Dilatometric tests were performed to determine the continous-cooling-transformation (CCT) diagram of the material and to measure the critical cooling rate (V{sub c}) for a martensitic quench. Then subsized Charpy V-notched specimens were given various cooling rates from the austenitization temperature to obtain a wide range of as-quenched microstructures, including martensite and bainite. These specimens were subsequently given a heat treatment to develop temper embrittlement and tested to measure the V-notch fracture toughness at -50 C. The fracture surfaces were examined by SEM. It is shown that martensitic microstructures are more susceptible to intergranular embrittlement than bainitic microstructures. These observed microstructural influences are briefly discussed. (orig.) 11 refs.

  20. Forest dynamics in the temperate rainforests of Alaska: from individual tree to regional scales

    Science.gov (United States)

    Tara M. Barrett

    2015-01-01

    Analysis of remeasurement data from 1079 Forest Inventory and Analysis (FIA) plots revealed multi-scale change occurring in the temperate rainforests of southeast Alaska. In the western half of the region, including Prince William Sound, aboveground live tree biomass and carbon are increasing at a rate of 8 ( ± 2 ) percent per decade, driven by an increase in Sitka...