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Climate change has increased the area affected by forest fires each year in boreal North America. Increases in burned area and fire frequency are expected to stimulate boreal carbon losses. However, the impact of wildfires on carbon emissions is also affected by the severity of burning. How climate change influences the severity of biomass burning has proved difficult to assess. Here, we examined the depth of ground-layer combustion in 178 sites dominated by black spruce in Alaska, using data collected from 31 fire events between 1983 and 2005. We show that the depth of burning increased as the fire season progressed when the annual area burned was small. However, deep burning occurred throughout the fire season...
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* In most high-latitude wetlands, carbon accumulation as peat represents a balance between plant net primary productivity and heterotrophic decomposition. We hypothesized that this assessment of ecosystem metabolism is incomplete as it does not include information on energy inputs from microalgae, which form complex biofilms with heterotrophic micro-organisms on the peat surface. * To investigate the potential for algae (and associated exudates) to support heterotrophic metabolism under ambient and elevated nutrient levels, we conducted a factorial enrichment of nutrients (nitrogen and phosphorus) and carbon (glucose) in mesocosms with and without the presence of algae (using light-transparent and dark treatments,...
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Fire is an important control on the carbon (C) balance of the boreal forest region. Here, we present findings from two complementary studies that examine how fire modifies soil organic matter properties, and how these modifications influence rates of decomposition and C exchange in black spruce (Picea mariana) ecosystems of interior Alaska. First, we used laboratory incubations to explore soil temperature, moisture, and vegetation effects on CO2 and DOC production rates in burned and unburned soils from three study regions in interior Alaska. Second, at one of the study regions used in the incubation experiments, we conducted intensive field measurements of net ecosystem exchange (NEE) and ecosystem respiration...
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Permafrost thaw can alter the soil environment through changes in soil moisture, frequently resulting in soil saturation, a shift to anaerobic decomposition, and changes in the plant community. These changes, along with thawing of previously frozen organic material, can alter the form and magnitude of greenhouse gas production from permafrost ecosystems. We synthesized existing methane (CH4) and carbon dioxide (CO2) production measurements from anaerobic incubations of boreal and tundra soils from the geographic permafrost region to evaluate large-scale controls of anaerobic CO2 and CH4 production and compare the relative importance of landscape-level factors (e.g., vegetation type and landscape position), soil...
map background search result map search result map Recent changes in the fire regime across the North American boreal region-Spatial and temporal patterns of burning across Canada and Alaska (DOI 10.1029/2006GL025677) Controls on ecosystem and root respiration across a permafrost and wetland gradient in interior Alaska Algae alleviate carbon limitation of heterotrophic bacteria in a boreal peatland Seasonal ice and hydrologic controls on dissolved organic carbon and nitrogen concentrations in a boreal-rich fen The importance of nutrient co-limitation in regulating algal community composition, productivity and algal-derived DOC in an oligotrophic marsh in interior Alaska A dynamic organic soil biogeochemical model for simulating the effects of wildfire on soil environmental conditions and carbon dynamics of black spruce forests Spatial and temporal variability of algal community dynamics and productivity in floodplain wetlands along the Tanana River, Alaska Evaluation of the composite burn index for assessing fire severity in Alaskan black spruce forests Evaluating the potential of Landsat TM/ETM+ imagery for assessing fire severity in Alaskan black spruce forests Algal community response to experimental and interannual variation in hydrology in an Alaskan boreal fen Interactive Effects of Fire, Soil Climate, and Moss on CO2 Fluxes in Black Spruce Ecosystems of Interior Alaska The role of mosses in ecosystem succession and function in Alaska's boreal forest The response of soil organic carbon of a rich fen peatland in interior Alaska to projected climate change Sphagnum mosses limit total carbon consumption during fire in Alaskan black spruce forests Recent changes in the fire regime across the North American boreal region—Spatial and temporal patterns of burning across Canada and Alaska A pan-Arctic synthesis of CH4 and CO2 production from anoxic soil incubations Recovery of Carbon Pools a Decade Following Wildfire in Black Spruce Forests of Interior Alaska: Effects of Soil Texture and Landscape Position Controls on ecosystem and root respiration across a permafrost and wetland gradient in interior Alaska Algae alleviate carbon limitation of heterotrophic bacteria in a boreal peatland The importance of nutrient co-limitation in regulating algal community composition, productivity and algal-derived DOC in an oligotrophic marsh in interior Alaska The role of mosses in ecosystem succession and function in Alaska's boreal forest Seasonal ice and hydrologic controls on dissolved organic carbon and nitrogen concentrations in a boreal-rich fen Sphagnum mosses limit total carbon consumption during fire in Alaskan black spruce forests A dynamic organic soil biogeochemical model for simulating the effects of wildfire on soil environmental conditions and carbon dynamics of black spruce forests The response of soil organic carbon of a rich fen peatland in interior Alaska to projected climate change Spatial and temporal variability of algal community dynamics and productivity in floodplain wetlands along the Tanana River, Alaska Algal community response to experimental and interannual variation in hydrology in an Alaskan boreal fen Interactive Effects of Fire, Soil Climate, and Moss on CO2 Fluxes in Black Spruce Ecosystems of Interior Alaska Recovery of Carbon Pools a Decade Following Wildfire in Black Spruce Forests of Interior Alaska: Effects of Soil Texture and Landscape Position Evaluation of the composite burn index for assessing fire severity in Alaskan black spruce forests A pan-Arctic synthesis of CH4 and CO2 production from anoxic soil incubations Evaluating the potential of Landsat TM/ETM+ imagery for assessing fire severity in Alaskan black spruce forests Recent changes in the fire regime across the North American boreal region-Spatial and temporal patterns of burning across Canada and Alaska (DOI 10.1029/2006GL025677) Recent changes in the fire regime across the North American boreal region—Spatial and temporal patterns of burning across Canada and Alaska