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Abstract. To determine the influence of fire and thermokarst in a boreal landscape, we investigated peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate ~600 years of vegetation succession with a transition from a terrestrial forest to a sedge-dominated wetland over 100 years ago, and to a Sphagnum-dominated peatland in approximately 1970. The shift from sedge to Sphagnum, and a decrease in the detrended tree-ring width index of black spruce trees adjacent to the collapse coincided with an increase in the growing...
Growing season CH4 fluxes were monitored over a two year period following the start of ecosystem-scale manipulations of water table position and surface soil temperatures in a moderate rich fen in interior Alaska. The largest CH4 fluxes occurred in plots that received both flooding (raised water table position) and soil warming, while the lowest fluxes occurred in unwarmed plots in the lowered water table treatment. A combination of treatment and soil hydroclimate variables explained more than 70% of the variation in ln-transformed CH4 fluxes, with mean daily water table position representing the strongest predictor. We used quantitative PCR of the -subunit of mcr operon to explore the influence of soil climate...
To determine the influence of fire and thermokarst in a boreal landscape, we investigated peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate approximately 600 years of vegetation succession with a transition from a terrestrial forest to a sedge-dominated wetland over 100 years ago, and to a Sphagnum-dominated peatland in approximately 1970. The shift from sedge to Sphagnum, and a decrease in the detrended tree-ring width index of black spruce trees adjacent to the collapse coincided with an increase in the growing...
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Growing season CH4 fluxes were monitored over a two year period following the start of ecosystem-scale manipulations of water table position and surface soil temperatures in a moderate rich fen in interior Alaska. The largest CH4 fluxes occurred in plots that received both flooding (raised water table position) and soil warming, while the lowest fluxes occurred in unwarmed plots in the lowered water table treatment. A combination of treatment and soil hydroclimate variables explained more than 70% of the variation in ln-transformed CH4 fluxes, with mean daily water table position representing the strongest predictor. We used quantitative PCR of the -subunit of mcr operon to explore the influence of soil climate...


map background search result map search result map Land cover disturbances and feedbacks to the climate system in Canada and Alaska Changes in vegetation in northern Alaska under scenarios of climate change, 2003-2100: implications for climate feedbacks Short-term response of methane fluxes and methanogen activity to water table and soil warming manipulations in an Alaskan peatland Exploring the sensitivity of soil carbon dynamics to climate change, fire disturbance and permafrost thaw in a black spruce ecosystem Short-term response of methane fluxes and methanogen activity to water table and soil warming manipulations in an Alaskan peatland Exploring the sensitivity of soil carbon dynamics to climate change, fire disturbance and permafrost thaw in a black spruce ecosystem Changes in vegetation in northern Alaska under scenarios of climate change, 2003-2100: implications for climate feedbacks Land cover disturbances and feedbacks to the climate system in Canada and Alaska