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Detailed observations of stream, soil, and groundwater chemistry were used to determine the role of fire, permafrost and snowmelt processes on the fluxes of carbon, nitrogen and major solutes from interior Alaskan catchments. We examined an experimentally burned watershed and two reference watersheds that differ in permafrost coverage (high, 53%; medium-burn, 18%; and low, 4%) during the FROSTFIRE prescribed burn in July 1999. The fire elevated stream nitrate concentrations for a short period during the first post-fire storm, but nitrate declined thereafter, suggesting that less severe fires that leave an intact riparian zone may have only a short-term effect on stream chemistry. Nevertheless, we found fundamental...
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Concerns about wildland fuel levels and a growing wildland-urban interface (WUI) have pushed wildland fire risk mitigation strategies to the forefront of fire management activities. Mechanical (e.g., shearblading) and manual (e.g., thinning) fuel treatments have become the preferred strategy of many fire managers and agencies. This Joint Fire Science Program funded project seeks to document and quantify mechanical and manual fuel treatment effects on fire behavior. Alaska's Federal and State fire management agencies have identified this 'data gap' as their most important fire science research need and priority. The Nenana Ridge Ruffed Grouse Project Area is 6,000 acres of typical interior Alaska boreal forest located...
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The likely direction of change in soil organic carbon (SOC) in the boreal forest biome, which harbors roughly 22% of the global soil carbon pool, is of marked concern because climate warming is projected to be greatest in high latitudes and temperature is the cardinal determinant of soil C mineralization. Moreover, the majority of boreal forest SOC is harbored in surficial organic horizons which are the most susceptible to consumption in wildfire. This research focuses on mechanisms of soil C accumulation in recently burned (2004) and unburned (61850-1950) black spruce (Picea mariana [Mill.] BSP) forests along gradients in stand productivity and soil temperature. The primary research questions in these three chapters...
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We examined direct and indirect impacts of millennial-scale climate change on fire regimes in the south-central Brooks Range, Alaska, USA, using four lake sediment records and existing paleoclimate interpretations. New techniques were introduced to identify charcoal peaks semi-objectively and to detect statistical differences between fire regimes. Peaks in charcoal accumulation rates provided estimates of fire return intervals (FRIs), which were compared among vegetation zones identified by fossil pollen and stomata. Climatic warming between ca. 15?000?9000 yr BP (calendar years before Common Era CE] 1950) coincided with shifts in vegetation from herb tundra to shrub tundra to deciduous woodlands, all novel species...
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A 1000-yr record of forest fire activity has been developed using three annually dated ice cores from Eclipse Icefield, Yukon, Canada. Forest fire signals were identified as NH4+ residuals above a robust spline and corroborated by an empirical orthhogonal function (EOF) analysis that identified a chemical association in the NH4+ , C2 O42- and K+ records similar to that observed in forest fire plumes. These statistical techniques yielded similar records of forest fire activity, although the EOF analysis provides more conservative identification of forest fire signals. Comparison of forest fire signals in the Eclipse ice cores with the record of annual area burned in Alaska and the Yukon demonstrates that 80% of high...
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Boreal forests contain significant quantities of soil carbon that may be oxidized to CO2 given future increases in climate warming and wildfire behavior. At the ecosystem scale, decomposition and heterotrophic respiration are strongly controlled by temperature and moisture, but we questioned whether changes in microbial biomass, activity, or community structure induced by fire might also affect these processes. We particularly wanted to understand whether postfire reductions in microbial biomass could affect rates of decomposition. Additionally, we compared the short-term effects of wildfire to the long-term effects of climate warming and permafrost decline. We compared soil microbial communities between control...
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Climate change has the potential to affect the boreal forest of Canada. Forest fires are a crucial component of the boreal ecosystem and climate change may substantially alter the fire regime. Statistical relations between climate and forest fire were obtained by regression for three fire subdistricts (Old Crow, Mayo and Watson Lake) of Yukon Territory. The relations were derived from fire and climate records, available, in general, since 1960. Summer temperature was found to be positively correlated to forest fire occurrence, area burned, the Fire Weather Index and Seasonal Severity Rating. In most cases, summer precipitation and relative humidity were negatively correlated with these variables. Climate change...
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Permafrost soils are large reservoirs of potentially labile carbon (C). Understanding the dynamics of C release from these soils requires us to account for the impact of wildfires, which are increasing in frequency as the climate changes. Boreal wildfires contribute to global emission of greenhouse gases (GHG[mdash]CO2, CH4 and N2O) and indirectly result in the thawing of near-surface permafrost. In this study, we aimed to define the impact of fire on soil microbial communities and metabolic potential for GHG fluxes in samples collected up to 1[thinsp]m depth from an upland black spruce forest near Nome Creek, Alaska. We measured geochemistry, GHG fluxes, potential soil enzyme activities and microbial community...
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In the boreal forest of North America, as in any fire-prone biome, three environmental factors must coincide for a wildfire to occur: an ignition source, flammable vegetation, and weather that is conducive to fire. Despite recent advances, the relative importance of these factors remains the subject of some debate. The aim of this study was to develop models that identify the environmental controls on spatial patterns in area burned for the period 1980-2005 at several spatial scales in the Canadian boreal forest. Boosted regression tree models were built to relate high-resolution data for area burned to an array of explanatory variables describing ignitions, vegetation, and long-term patterns in fire-conducive weather...


map background search result map search result map Forest floor moisture content and fire danger indices in Alaska Effects of Experimental Water Table and Temperature Manipulations on Ecosystem CO2 Fluxes in an Alaskan Rich Fen Fire severity mediates climate‐driven shifts in understorey community composition of black spruce stands of interior Alaska Quantifying the effects of fuels reduction treatments on fire behavior and post-fire vegetation dynamics - Final Report to the Joint Fire Science Program.  Moose Survey Teslin Burn Area Early-Winter 2013 Climate change and forest fires in Yukon Territory Interactive effects of wildfire and permafrost on microbial communities and soil processes in an Alaskan black spruce forest Bark-beetle-attacked trees produced more charcoal than unattacked trees during a forest fire on the Kenai Peninsula, Southern Alaska A Burning Interest in Boreal Forests: Researchers in Alaska Link Fires with Climate Change Scale-dependent controls on the area burned in the boreal forest of Canada, 1980-2005 Human Impacts on the Fire Regime of Interior Alaska: Interactions among Fuels, Ignition Sources, and Fire Suppression Fire history of white and Lutz spruce forests on the Kenai Peninsula, Alaska, over the last two millennia as determined from soil charcoal A 1000-yr record of forest fire activity from Eclipse Icefield, Yukon, Canada Export of carbon, nitrogen and major solutes from a boreal forest watershed: The influence of fire and permafrost Resistance of microbial and soil properties to warming treatment seven years after boreal fire Mechanisms of soil carbon stabilization in black spruce forests of interior Alaska: Soil temperature, soil water, and wildfire Vegetation mediated the impacts of postglacial climate change on fire regimes in the south-central Brooks Range, Alaska Recent changes in the fire regime across the North American boreal region—Spatial and temporal patterns of burning across Canada and Alaska Impact of fire on active layer and permafrost microbial communities and metagenomes in an upland Alaskan boreal forest Planning for resilience: modeling change in human-fire interactions in the Alaskan boreal forest Quantifying the effects of fuels reduction treatments on fire behavior and post-fire vegetation dynamics - Final Report to the Joint Fire Science Program.  Effects of Experimental Water Table and Temperature Manipulations on Ecosystem CO2 Fluxes in an Alaskan Rich Fen Impact of fire on active layer and permafrost microbial communities and metagenomes in an upland Alaskan boreal forest Interactive effects of wildfire and permafrost on microbial communities and soil processes in an Alaskan black spruce forest Moose Survey Teslin Burn Area Early-Winter 2013 Resistance of microbial and soil properties to warming treatment seven years after boreal fire Export of carbon, nitrogen and major solutes from a boreal forest watershed: The influence of fire and permafrost A 1000-yr record of forest fire activity from Eclipse Icefield, Yukon, Canada Bark-beetle-attacked trees produced more charcoal than unattacked trees during a forest fire on the Kenai Peninsula, Southern Alaska Fire history of white and Lutz spruce forests on the Kenai Peninsula, Alaska, over the last two millennia as determined from soil charcoal Vegetation mediated the impacts of postglacial climate change on fire regimes in the south-central Brooks Range, Alaska Forest floor moisture content and fire danger indices in Alaska Fire severity mediates climate‐driven shifts in understorey community composition of black spruce stands of interior Alaska Climate change and forest fires in Yukon Territory Human Impacts on the Fire Regime of Interior Alaska: Interactions among Fuels, Ignition Sources, and Fire Suppression Mechanisms of soil carbon stabilization in black spruce forests of interior Alaska: Soil temperature, soil water, and wildfire Planning for resilience: modeling change in human-fire interactions in the Alaskan boreal forest A Burning Interest in Boreal Forests: Researchers in Alaska Link Fires with Climate Change Recent changes in the fire regime across the North American boreal region—Spatial and temporal patterns of burning across Canada and Alaska Scale-dependent controls on the area burned in the boreal forest of Canada, 1980-2005