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Your Yukon is a weekly column about environmental issues and research, from Canada's Yukon. This column discusses how climate change, especially drought stress, may be affecting the boreal forest.--Includes text from publisher's website.
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Native grasslands have been altered to a greater extent than any other biome in North America. The habitats and resources needed to support breeding performance of grassland birds endemic to prairie ecosystems are currently threatened by land management practices and impending climate change. Climate models for the Great Plains prairie region predict a future of hotter and drier summers with strong multiyear droughts and more frequent and severe precipitation events. We examined how fluctuations in weather conditions in eastern Colorado influenced nest survival of an avian species that has experienced recent population declines, the Mountain Plover (Charadrius montanus). Nest survival averaged 27.2% over a 7-yr...
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Unprecedented rates of climate warming over the past century have resulted in increased forest stress and mortality worldwide. Decreased tree growth in association with increasing temperatures is generally accepted as a signal of temperature-induced drought stress. However, variations in tree growth alone do not reveal the physiological mechanisms behind recent changes in tree growth. Examining stable carbon isotope composition of tree rings in addition to tree growth can provide a secondary line of evidence for physiological drought stress. In this study, we examined patterns of black spruce growth and carbon isotopic composition in tree rings in response to climate warming and drying in the boreal forest of interior...
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Owing to large climatic and orographic variation, British Columbia covers a variety of ecosystems extending from temperate rainforests on the Pacific coast to boreal forests in the north-east. The aim of this study is to investigate the spatial variation of trends in wildfire activity and their relationship to summer drought for the entire province of British Columbia. Time series of annual wildfire extent and occurrence, summer self-calibrating Palmer Drought Severity Index and summer Aridity Index were derived from spatially explicit data. Sixteen landscape regions according to the provincial Biogeoclimatic Ecosystem Classification system served as spatial reference. The regional series for 1920-2000 were subjected...
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Increment cores from the boreal forest have long been used to reconstruct past climates. However, in recent years, numerous studies have revealed a deterioration of the correlation between temperature and tree growth that is commonly referred to as "divergence". In the Brooks Range of northern Alaska, studies of white spruce (Picea glauca) revealed that trees in the west generally showed positive growth trends, while trees in the central and eastern Brooks Range showed mixed and negative trends during late 20th century warming. The growing season climate of the eastern Brooks Range is thought to be drier than the west. On this basis, divergent tree growth in the eastern Brooks Range has been attributed to drought...
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High latitude trees are increasingly showing mixed growth responses to climate warming. Recent studies of white spruce (Picea glauca ) in the Brooks Range of Alaska have revealed that trees in the west have generally shown positive growth responses, while trees in the central and eastern Brooks Range have shown mixed and negative growth responses, respectively. An earlier study suggested that the growing season climate of the eastern Brooks Range is warmer and drier than in the west. On this basis, growth declines in the eastern Brooks Range were attributed to drought stress, caused by rising temperature and increasing evaporative demand. I investigated the hypothesis that drought stress can explain white spruce...
We assessed tropical montane cloud forest (TMCF) sensitivity to natural disturbance by drought, fire, and dieback with a 7300-year-long paleorecord. We analyzed pollen assemblages, charcoal accumulation rates, and higher plant biomarker compounds (average chain length [ACL] of n-alkanes) in sediments from Wai’ānapanapa, a small lake near the upper forest limit and the mean trade wind inversion (TWI) in Hawai‘i. The paleorecord of ACL suggests increased drought frequency and a lower TWI elevation from 2555–1323 cal yr B.P. and 606–334 cal yr B.P. Charcoal began to accumulate and a novel fire regime was initiated ca. 880 cal yr B.P., followed by a decreased fire return interval at ca. 550 cal yr B.P. Diebacks occurred...
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Climate has warmed substantially in interior Alaska and several remote sensing studies have documented a decadal-scale decline in the normalized difference vegetation index (NDVI) termed a ‘browning trend’. Reduced summer soil moisture due to changing climatic factors such as earlier springs, less snowpack, and summer drought may reduce boreal productivity and NDVI. However, the relative importance of these climatic factors is poorly understood in boreal interior Alaska. In this study, I used the remotely sensed peak summer NDVI as an index of boreal productivity at 250 m pixel size from 2000 to 2014. Maximum summer NDVI was related to last day of spring snow, early spring snow water equivalent (SWE), and a...
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Trends of summer precipitation and summer temperature and their influence on trends in summer drought and area burned in British Columbia (BC) were investigated for the period 1920–2000. The complexity imposed by topography was taken into account by incorporating high spatial resolution climate and fire data. Considerable regional variation in trends and in climate–fire relationships was observed. A weak but significant increase in summer temperature was detected in northeastern and coastal BC, whereas summer precipitation increased significantly in all regions—by up to 45.9 %. A significant decrease in province-wide area burned and at the level of sub-units was strongly related to increasing precipitation, more...
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Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. While drylands as a whole are expected to increase in distribution and aridity in coming decades, temperature and precipitation forecasts vary by latitude and geographic region suggesting different trajectories for tropical, subtropical, and temperate drylands. Uncertainty in the future of tropical and subtropical drylands is well constrained, whereas soil moisture and ecological droughts, which drive vegetation productivity and composition, remain poorly understood in temperate drylands. Here we show that, over the 21st century, temperate drylands may contract by a third, primarily converting to subtropical drylands,...
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Developing conservation strategies for threatened species increasingly requires understanding vulnerabilities to climate change, in terms of both demographic sensitivities to climatic and other environmental factors, and exposure to variability in those factors over time and space. Weconducted a range-wide, spatially explicit climate change vulnerability assessment for Eastern Massasauga (Sistrurus catenatus), a declining endemic species in a region showing strong environmental change. Using active season and winter adult survival estimates derived from 17 data sets throughout the species’ range, we identified demographic sensitivities to winter drought, maximum precipitation during the summer, and the proportion...
Growing evidence suggests short-duration climate events may drive community structure and composition more directly than long-term climate means, particularly at ecotones where taxa are close to their physiological limits. Here we use an empirical habitat model to evaluate the role of microclimate during a strong El Niño in structuring a tropical montane cloud forest’s upper limit and composition in Hawai‘i. We interpolate climate surfaces, derived from a high-density network of climate stations, to permanent vegetation plots. Climatic predictor variables include (1) total rainfall, (2) mean relative humidity, and (3) mean temperature representing non-El Niño periods and a strong El Niño drought. Habitat models...
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The northern treeline is generally limited by available warmth. However, in recent years, more and more studies have identified drought stress as an additional limiting factor for tree growth in northern boreal forests and at treelines. Three growth responses to warming have been identified: increase in growth, decrease in growth, and nonsignificant correlation of tree growth with climate. Here we investigate the effect of drought stress on radial growth of white spruce at northern treelines along a longitudinal gradient spanning the entire Brooks Range in Alaska. We systematically sampled 687 white spruce at seven treeline sites. Where possible, we sampled three site types at a given site: high-density forest,...
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The potential ecological and economic effects of climate change for tropical islands were studied using output from 12 statistically downscaled general circulation models (GCMs) taking Puerto Rico as a test case. Two model selection/model averaging strategies were used: the average of all available GCMs and the average of the models that are able to reproduce the observed large-scale dynamics that control precipitation over the Caribbean. Five island-wide and multidecadal averages of daily precipitation and temperature wereestimated by way of a climatology-informed interpolation of the site-specific downscaled climate model output. Annual cooling degree-days (CDD) were calculated as a proxy index for air-conditioning...
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Executive summary: Tamarisk control and removal has become a priority of riparian ecosystem management, due in part to its potential negative impacts on stream flow and groundwater recharge. Among the most controversial, and potentially most effective tamarisk control approaches is the introduction of the tamarisk leaf beetle, Diorhabda carinulata. The beetle has spread throughout virtually the entire upper Colorado River Basin, established major populations at Lake Mead in 2012, and is now poised to expand into the lower Colorado River Basin concordant with documented evolutionary change in beetle developmental response that may enable survival in southern regions. Superimposed on this direct plant/herbivore relationship...
Categories: Data, Publication; Types: Citation, Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: 2012, AZ-01, AZ-02, AZ-03, AZ-04, All tags...


map background search result map search result map Drought and Cooler Temperatures Are Associated with Higher Nest Survival in Mountain Plovers Precipitation-driven decrease in wildfires in British Columbia Stable carbon isotope analysis reveals widespread drought stress in boreal black spruce forests Impacts of drought on forest growth and regeneration following fire in southwestern Yukon, Canada Drought-induced stomatal closure probably cannot explain divergent white spruce growth in the Brooks Range, Alaska Carbon isotope discrimination in tree ring alpha-cellulose indicates that drought stress cannot explain white spruce growth declines in the eastern Brooks Range, Alaska Relationship between fire, climate oscillations, and drought in British Columbia, Canada, 1920–2000 Remote sensing of interannual boreal forest NDVI in relation to climatic conditions in interior Alaska Response of plant community structure and primary productivity to experimental drought and flooding in an Alaskan fen Longitudinal variation of radial growth at Alaska's northern treeline; recent changes and possible scenarios for the 21st century Spatial variation of trends in wildfire and summer drought in British Columbia, Canada, 1920-2000 The sensitivity of carbon fluxes to spring warming and summer drought depends on plant functional type in boreal forest ecosystems [electronic resource] Reduced growth of Alaskan white spruce in the twentieth century from temperature-induced drought stress Drought stress changing the Takhini landscape Publication: Demographic consequences of climate change and land cover help explain a history of extirpations and range contraction in a declining snake species Final Report and Publication: From Genotype to River Basin: The combined impacts of climate change on bio-control on a dominant riparian invasive tree/shrub Climate Change Implications for Tropical Islands: Interpolating and Interpreting Statistically Downscaled GCM Projections for Management and Planning Drought stress changing the Takhini landscape Response of plant community structure and primary productivity to experimental drought and flooding in an Alaskan fen Climate Change Implications for Tropical Islands: Interpolating and Interpreting Statistically Downscaled GCM Projections for Management and Planning Impacts of drought on forest growth and regeneration following fire in southwestern Yukon, Canada Reduced growth of Alaskan white spruce in the twentieth century from temperature-induced drought stress Final Report and Publication: From Genotype to River Basin: The combined impacts of climate change on bio-control on a dominant riparian invasive tree/shrub Stable carbon isotope analysis reveals widespread drought stress in boreal black spruce forests Drought-induced stomatal closure probably cannot explain divergent white spruce growth in the Brooks Range, Alaska Carbon isotope discrimination in tree ring alpha-cellulose indicates that drought stress cannot explain white spruce growth declines in the eastern Brooks Range, Alaska Longitudinal variation of radial growth at Alaska's northern treeline; recent changes and possible scenarios for the 21st century Drought and Cooler Temperatures Are Associated with Higher Nest Survival in Mountain Plovers Remote sensing of interannual boreal forest NDVI in relation to climatic conditions in interior Alaska The sensitivity of carbon fluxes to spring warming and summer drought depends on plant functional type in boreal forest ecosystems [electronic resource] Precipitation-driven decrease in wildfires in British Columbia Relationship between fire, climate oscillations, and drought in British Columbia, Canada, 1920–2000 Spatial variation of trends in wildfire and summer drought in British Columbia, Canada, 1920-2000 Publication: Demographic consequences of climate change and land cover help explain a history of extirpations and range contraction in a declining snake species