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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.
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: P2-Changes in Plant and Animal Species Due to Climate Change
Categories: Data,
Publication;
Types: Citation,
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OGC WMS Layer,
Shapefile;
Tags: Relationship Understanding 2b-Effects of Fire on Ecosystems
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...
Categories: Data,
Publication;
Types: Citation,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: BIRDS,
CLIMATE CHANGE IMPACT ASSESSMENT MODELS,
Charadrius montanus,
Charadrius montanus,
Climate Change,
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...
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Monitoring 1-Changes in Plant and Animal Distribution: Ecosystems
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...
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...
Categories: Data,
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Tags: Monitoring 1-Changes in Plant and Animal Distribution: Flora
Categories: Data,
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Types: Citation,
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Tags: R1-Vulnerability Forest Species and Communities to Climate Change
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
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Tags: P2-Changes in Plant and Animal Species Due to Climate Change
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...
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Monitoring 1-Changes in Plant and Animal Distribution: Flora
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Monitoring 1-Changes in Plant and Animal Distribution: Ecosystems
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...
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile
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...
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Relationship Understanding 2b-Effects of Fire on Ecosystems
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,...
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Monitoring 1-Changes in Plant and Animal Distribution: Ecosystems
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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Types: Citation,
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OGC WMS Layer,
OGC WMS Service;
Tags: Conservation NGOs,
Conservation NGOs,
Conservation planning,
Conservation planning,
Federal resource managers,
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...
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Types: Citation,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: 2012,
AZ-01,
AZ-02,
AZ-03,
AZ-04,
Wildfires are a common experience in Alaska where, on average, 3,775 km^sup 2^ burn annually. More than 90% of the area consumed occurs in Interior Alaska, where the summers are relatively warm and dry, and the vegetation consists predominantly of spruce, birch, and cottonwood. Summers with above normal temperatures generate an increased amount of convection, resulting in more thunderstorm development and an amplified number of lightning strikes. The resulting dry conditions facilitate the spread of wildfires started by the lightning. Working with a 55-year dataset of wildfires for Alaska, an increase in the annual area burned was observed. Due to climate change, the last three decades have shown to be warmer than...
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Relationship Understanding 2b-Effects of Fire on Ecosystems
Global vegetation models predict that boreal forests are particularly sensitive to a biome shift during the 21st century. This shift would manifest itself first at the biome?s margins, with evergreen forest expanding into current tundra while being replaced by grasslands or temperate forest at the biome?s southern edge. We evaluated changes in forest productivity since 1982 across boreal Alaska by linking satellite estimates of primary productivity and a large tree-ring data set. Trends in both records show consistent growth increases at the boreal?tundra ecotones that contrast with drought-induced productivity declines throughout interior Alaska. These patterns support the hypothesized effects of an initiating...
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: R1-Vulnerability Forest Species and Communities to Climate Change
Algae are important to many of the processes that characterize wetland ecosystems. Despite their importance, we know relatively little about the factors that regulate algal communities in wetlands. This is particularly true for northern boreal regions where wetlands are abundant and are considered to be extremely vulnerable to disturbances associated with climate change. My dissertation research investigates how nutrients, grazing, light, and hydrology regulate algal primary production and taxonomic structure in high latitude wetlands. I documented spatial and temporal variability in algal structure and function in six northern boreal wetlands in interior Alaska to determine the contribution of algal primary production...
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Tags: A1-Best management practices,
Monitoring 1-Changes in Plant and Animal Distribution: Ecosystems,
P2-Changes in Plant and Animal Species Due to Climate Change,
landscape scale conservation
Vegetation and land-cover changes are not always directional but follow complex trajectories over space and time, driven by changing anthropogenic and abiotic conditions. We present a multi-observational approach to land-change analysis that addresses the complex geographic and temporal variability of vegetation changes related to climate and land use. Using land-ownership data as a proxy for land-use practices, multitemporal land-cover maps, and repeat photography dating to the late 19th century, we examine changing spatial and temporal distributions of two vegetation types with high conservation value in the southwestern United States: grasslands and riparian vegetation. In contrast to many reported vegetation...
Categories: Publication;
Types: Citation,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Arizona,
climate,
grassland,
land cover,
management,
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