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Causes and consequences of late Holocene fluctuations of Kluane Lake in Yukon Territory have been reconstructed from several sediment cores. In the last 5000 years the level of Kluane Lake has varied from $27 m below its present level to 12 m above, primarily due to changes in inputs of water from Slims and Duke rivers. Discharge form the Slims River catchment into Kluane Lake is associated with glacial advances. During periods when neither Duke nor Slims rivers flowed into Kluane Lake, the level of the lake fell and stable thermal stratification developed with anoxic conditions in the hypolimnion. Climate related changes in catchment permafrost affected nutrient mineralization and the quality of runoff. Recent...
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Discontinuous permafrost in the North American boreal forest is strongly influenced by the effects of ecological succession on the accumulation of surface organic matter, making permafrost vulnerable to degradation resulting from fire disturbance. To assess factors affecting permafrost degradation after wildfire, we compared vegetation composition and soil properties between recently burned and unburned sites across three soil landscapes (rocky uplands, silty uplands, and sandy lowlands) situated within the Yukon Flats and Yukon-Tanana Uplands in interior Alaska. Mean annual air temperatures at our study sites from 2011 to 2012 were relatively cold (-5.5 degrees C) and favorable to permafrost formation. Burning...
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INTRODUCTION This report briefly describes and presents geochemical and biogeochemical data for a cooperative study in the Fortymile Mining District, east central Alaska. This study is being funded by the U.S. Geological Survey (USGS) Mineral Resources Program through Fiscal Year 2001. Cooperative funds are being provided from various State of Alaska sources through the Alaska Department of Natural Resources. Results for the first field season completed in June 1997 are presented in Crock and others (1999). The study's second field season was completed in June 1998 and the results of the sample analyses for this phase of the study are presented here. Primary objectives of this study are: * Determine the regional...
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Due to the recent warming trend, the arctic regions have experienced significant land cover and hydrology changes which include extended shrub coverage, shrinking water bodies and melting permafrost. All these changes have and will certainly continue to affect the carbon cycles of those regions which have the largest soil organic carbon pools in the world. Of these large soil organic carbon pools, we selected the portion of the Yukon River Basin in the state of Alaska to investigate the dynamic in land cover changes and methane (CH 4 ) emission from 1980s onwards. We also developed a dissolved organic carbon (DOC) transport model to analyze the DOC trends for a watershed in the Yukon River Basin. We used the newly-released...
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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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The Alaska Highway crosses numerous terrain units underlined by warm and ice-rich discontinuous permafrost highly susceptible to thermal degradation. For years, this infrastructure, which is essential to transportation in northwestern Canada and Alaska, has been showing signs of road damage induced by permafrost degradation. In 2008, Yukon Highways and Public Works, and its international collaborators, implemented a road experimental site near Beaver Creek (Yukon) to test mitigation techniques aiming to control permafrost degradation. Permafrost investigations were done accordingly to a geosystem approach based on the hypothesis that permafrost has a distinctive sensitivity to climate and terrain conditions at a...
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In arctic tundra and boreal forest ecosystems vegetation structural and functional influences on the surface energy balance can strongly influence permafrost soil temperatures. As such, vegetation changes will likely play an important role in permafrost soil carbon dynamics and associated climate feedbacks. Processes that lead to changes in vegetation, such as wildfire or ecosystem responses to rising temperatures, are of critical importance to understanding the impacts of arctic and boreal ecosystems on future climate. Yet these processes vary within and between ecosystems and this variability has not been systematically characterized across the arctic-boreal region. Here we quantify the distribution of vegetation...
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Introduction Improving vehicle trafficability planning is a major defense mission, and we believe that this research has made significant improvements towards this end. We are striving to develop new space-borne Synthetic Aperture Radar (SAR) techniques to measure temporal changes in soil moisture, soil freeze/thaw state, and snowmelt, utilizing both amplitude and phase signal information. Such knowledge is of great use to a variety of end-users. Military planners need to predict the bearing strength of the underlying soil and thus the number and weight of vehicles able to travel across it. Global climate modelers need to know the surface greenhouse gas and latent heat flux. The common variables in these applications...
Intensification of permafrost thaw has increased the frequency and magnitude of large permafrost slope disturbances (mega slumps) in glaciogenic terrain of northwestern Canada. Individual thermokarst disturbances up to 40 ha in area have made large volumes of previously frozen, highly weatherable fine-grained sediments available for leaching and transport to adjacent streams, significantly increasing sediment and solute loads in these systems. To test the effects of this climate-sensitive disturbance regime on the ecology of Arctic streams, we explored the relationship between physical and chemical variables and benthic macroinvertebrate communities in disturbed and undisturbed stream reaches in the Peel Plateau...
The Geological Survey of Canada (GSC), in collaboration with other government partners, has been developing and maintaining a network of active-layer and permafrost thermal monitoring sites which contribute to the Canadian Permafrost Monitoring Network and the Global Terrestrial Network for Permafrost. Recent results from the thermal monitoring sites maintained by the GSC and other federal government agencies are presented. These results indicate that the response of permafrost temperature to recent climate change and variability varies across the Canadian permafrost region. Warming of shallow permafrost temperatures of between 0.3 and 0.6°C per decade has occurred since the mid- to late 1980s in the central and...
Stratigraphic, sedimentologic, geomorphic and geophysical investigations were made of a 1000 km reach of the unglaciated middle Yukon River between central Yukon and Alaska. The purpose is to examine the record of a large northern latitude river's response to climate change over the last 3 million years. Permafrost first appears in the Yukon basin, and its first known occurrence in North America, in the form of ice-wedge casts in the Klondike area at 3.2 Ma. The first Cordilleran glaciation of Yukon follows prior to 2.6 Ma showing a strong synchroneity with North Pacific ocean core records. This extensive glaciation is associated with diversion of a south-flowing paleo-Yukon River northwest into central Alaska....
map background search result map search result map Regional Geochemical Results from the Analyses of Rock, Water, Soil, Stream Sediment, and Vegetation Samples -- Fortymile River Watershed, East-Central Alaska, 1998 Sampling Edaphic and microclimatic controls over permafrost response to fire in interior Alaska Permafrost thaw affects boreal deciduous plant transpiration through increased soil water, deeper thaw, and warmer soils Dissolved organic carbon fluxes in a discontinuous permafrost subarctic alpine catchment Equivalent Elevation: A New Method to Incorporate Variable Surface Lapse Rates into Mountain Permafrost Modelling The importance of nutrient co-limitation in regulating algal community composition, productivity and algal-derived DOC in an oligotrophic marsh in interior Alaska Paleolimnology of Kluane Lake Permafrost conditions near shorelines of oriented lakes in Old Crow Flats, Yukon Territory    A geosystems approach to permafrost investigations for engineering applications, an example from a road stabilization experiment, Beaver Creek, Yukon, Canada Determining the Utility of Synthetic Aperture Radar (SAR) in Estimating Surface Soil Moisture Conditions for Trafficability Analyses; Phase III Progress Report Carbon and water dynamics in the Alaska Yukon River Basin: Analysis using process-based biogeochemistry models and satellite data Impact of fire on active layer and permafrost microbial communities and metagenomes in an upland Alaskan boreal forest Regional Geochemical Results from the Analyses of Rock, Water, Soil, Stream Sediment, and Vegetation Samples -- Fortymile River Watershed, East-Central Alaska, 1998 Sampling The importance of nutrient co-limitation in regulating algal community composition, productivity and algal-derived DOC in an oligotrophic marsh in interior Alaska Impact of fire on active layer and permafrost microbial communities and metagenomes in an upland Alaskan boreal forest A geosystems approach to permafrost investigations for engineering applications, an example from a road stabilization experiment, Beaver Creek, Yukon, Canada Permafrost conditions near shorelines of oriented lakes in Old Crow Flats, Yukon Territory    Paleolimnology of Kluane Lake Dissolved organic carbon fluxes in a discontinuous permafrost subarctic alpine catchment Permafrost thaw affects boreal deciduous plant transpiration through increased soil water, deeper thaw, and warmer soils Determining the Utility of Synthetic Aperture Radar (SAR) in Estimating Surface Soil Moisture Conditions for Trafficability Analyses; Phase III Progress Report Edaphic and microclimatic controls over permafrost response to fire in interior Alaska Equivalent Elevation: A New Method to Incorporate Variable Surface Lapse Rates into Mountain Permafrost Modelling Carbon and water dynamics in the Alaska Yukon River Basin: Analysis using process-based biogeochemistry models and satellite data