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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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Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. They are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. These general purpose regions are critical for structuring and implementing ecosystem management strategies across federal agencies, state agencies, and nongovernment organizations that are responsible for different types of resources within the same geographical areas. The approach used to compile this map is based on the premise that ecological regions can be identified through the analysis of patterns of biotic and abiotic phenomena, including...
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These heatmaps show a top 3 stressor or service, as ranked by participants, and the concentration of participants who reported as working in each municipality or county who also voted for that stressor or service across the landscape. This map shows the percentage of participants from each county and municipality who ranked Increased Drought as a top 3 ecosystem stressor in the Montane Ecosystem Functionality category in their region. Symbology represents the percentage of participants with 0% = dark green, 0.0001 % - 24.99% = light green, 25% - 49.99% = yellow, 50% - 74.99% = orange, 75% - 100% = red. All counties and municipalities identified by participants as areas where they work were given a tally for each...
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These heatmaps show a top 3 stressor or service, as ranked by participants, and the concentration of participants who reported as working in each municipality or county who also voted for that stressor or service across the landscape.
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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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This dataset contains data pertaining to chaparral vegetation dieback based on the difference or change in the Normalized Difference Vegetation Index (NDVI) prior to and 6 years into an extensive drought before the 2017 Thomas and 2018 Woolsey Fires in southern California. The difference in mean NDVI is provided for 9322 study plots as are values for a number of physical and climatological variables and burn severity following the two fires. These data support the following publication: Keeley, J.E., Brennan-Kane, T.J., and Syphard, A.D., 2022. The effects of prolonged drought on vegetation dieback and megafires in southern California chaparral. Ecosphere, 13(8), e4203. https://doi.org/10.1002/ecs2.4203.
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These shapefiles represent the spatial distribution of mean annual groundwater recharge, in inches, for Kauaʻi, Oʻahu, Molokaʻi, Maui, and the Island of Hawaiʻi for a set of water-budget scenarios that characterize unique combinations of drought and land-cover conditions. Two water-budget scenarios were developed to quantify the effects of severe drought and future climate conditions on groundwater recharge for each island as follows: (1) rainfall conditions representative of the driest conditions during 1920–2012 and 2020 land cover, and (2) rainfall conditions representative of the driest conditions during a future dry-climate condition and 2020 land cover. Each drought condition was combined with two hypothetical...
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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...
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This data release includes data-processing scripts, data products, and associated metadata for a remote-sensing based approach to characterize vegetation conditions within a dry, mixed conifer forest study area in southern Oregon in 2001 (a single year drought without any widespread insect mortality) and 2009 (during a multi-year drought that coincided with a severe outbreak of mountain pine beetle; MPB). This analysis involved several steps. First, time-series climate data were compiled and plotted to identify drought periods. Similarly, time-series data representing insect outbreaks were compiled and plotted to identify trends in insect mortality. The study area was classified into forest canopy types using existing...
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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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This data set maps sagebrush mortality in Utah delineated by Utah Division of Wildlife Resources personnel during the summer of 2003.
map background search result map search result map Sagebrush Mortality in Utah - 2003 Southwest Energy Development and Drought 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 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 Analysis of remotely-sensed vegetation conditions during droughts and a mountain pine beetle outbreak, Gearhart Mountain Wilderness, Oregon Grasslands - Ecosystem Functionality Stressors - Increased Drought Riparian - Ecosystem Functionality Stressors - Increased Drought Montane - Ecosystem Functionality Stressors - Increased Drought The Effect of Prolonged Drought on Chaparral Dieback within the Perimeters of the Thomas and Woolsey Fires in Southern California, USA Mean annual groundwater recharge rates for Kauaʻi, Oʻahu, Molokaʻi, Maui, and the Island of Hawaiʻi, for a set of drought and land-cover conditions Analysis of remotely-sensed vegetation conditions during droughts and a mountain pine beetle outbreak, Gearhart Mountain Wilderness, Oregon Drought stress changing the Takhini landscape Response of plant community structure and primary productivity to experimental drought and flooding in an Alaskan fen The Effect of Prolonged Drought on Chaparral Dieback within the Perimeters of the Thomas and Woolsey Fires in Southern California, USA 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 Mean annual groundwater recharge rates for Kauaʻi, Oʻahu, Molokaʻi, Maui, and the Island of Hawaiʻi, for a set of drought and land-cover conditions Sagebrush Mortality in Utah - 2003 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 Southwest Energy Development and Drought Riparian - Ecosystem Functionality Stressors - Increased Drought Montane - Ecosystem Functionality Stressors - Increased Drought Grasslands - Ecosystem Functionality Stressors - Increased Drought 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