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The fundamental niche of a species is rarely if ever realized because the presence of other species restricts it to a narrower range of ecological conditions. The effects of this narrower range of conditions define how resources are partitioned. Resource partitioning has been inferred but not demonstrated previously for sympatric ursids. We estimated assimilated diet in relation to body condition (body fat and lean and total body mass) and reproduction for sympatric brown bears (Ursus arctos) and American black bears (U. americanus) in south-central Alaska, 1998?2000. Based on isotopic analysis of blood and keratin in claws, salmon (Oncorhynchus spp.) predominated in brown bear diets (>53% annually) whereas black...
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We examined the effects of fire disturbance on permafrost degradation and thaw settlement across a series of wildfires (from ~1930 to 2010) in the forested areas of collapse-scar bog complexes in the Tanana Flats lowland of interior Alaska. Field measurements were combined with numerical modeling of soil thermal dynamics to assess the roles of fire severity and climate history in postfire permafrost dynamics. Field-based calculations of potential thaw settlement following the loss of remaining ice-rich permafrost averaged 0.6 m. This subsidence would cause the surface elevations of forests to drop on average 0.1 m below the surface water level of adjacent collapse-scar features. Up to 0.5 m of thaw settlement was...
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Black spruce (Picea mariana) forests represent the dominant vegetation type throughout the North American and Siberian taiga and are generally considered to be pristine, N-limiting environments. The aim of this study was to investigate the fundamental underlying mechanisms which control N availability in these soils with particular reference to the dynamics of dissolved organic nitrogen (DON). Our results showed that in these highly organic and low pH soils, soluble N is dominated by organic forms with correspondingly low concentrations of ammonium and nitrate. Amino acids, which are known to be directly taken up by plants growing in these soils, were calculated to constitute 10–20% of the total DON pool. The microbial...
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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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We investigated wildfire-related effects on a slow ecological variable, i.e., forage production, and fast social-ecological variables, i.e., seasonal harvest rates, hunter access, and forage offtake, in a moose–hunter system in interior Alaska. In a 1994 burn, average forage production increased slightly (5%) between 2007 and 2013; however, the proportional removal across all sites declined significantly (10%). This suggests that moose are not utilizing the burn as much as they have in the past and that, as the burn has aged, the apparent habitat quality has declined. Areas with a greater proportion of accessible burned area supported both high numbers of hunters and harvested moose. Our results suggest that evaluating...
map background search result map search result map Establishment and growth of white spruce on a boreal forest floodplain: interactions between microclimate and mammalian herbivory Effects of fire severity on plant nutrient uptake reinforce alternate pathways of succession in boreal forests Integrating local knowledge and science: economic consequences of driftwood harvest in a changing climate Interactive effects of wildfire and climate on permafrost degradation in Alaskan lowland forests Effects of variable fire severity on forage production and foraging behavior of moose in winter Edaphic and microclimatic controls over permafrost response to fire in interior Alaska Movements, activity patterns, and habitat use of snowshoe hares ( Lepus americanus) in interior Alaska Plant physiological responses to hydrologically mediated changes in nitrogen supply on a boreal forest floodplain: a mechanism explaining the discrepancy in nitrogen demand and supply Contribution of winter processes to soil nitrogen flux in taiga forest ecosystems Nitrogen retention in the hyporheic zone of a glacial river in interior Alaska Applications of resilience theory in management of a moose–hunter system in Alaska What factors determine cyclic amplitude in the snowshoe hare (Lepus americanus) cycle? Soil amino acid turnover dominates the nitrogen flux in permafrost-dominated taiga forest soils Understanding the effects of wildfire severity on moose habitat characteristics and use in Interior, Alaska Resilience of Athabascan subsistence systems to interior Alaska’s changing climate Plant toxins and trophic cascades alter fire regime and succession on a boreal forest landscape Interactive controls of herbivory and fluvial dynamics on landscape vegetation patterns on the Tanana River floodplain, interior Alaska INTERSPECIFIC RESOURCE PARTITIONING IN SYMPATRIC URSIDS Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing Establishment and growth of white spruce on a boreal forest floodplain: interactions between microclimate and mammalian herbivory Contribution of winter processes to soil nitrogen flux in taiga forest ecosystems Nitrogen retention in the hyporheic zone of a glacial river in interior Alaska Movements, activity patterns, and habitat use of snowshoe hares ( Lepus americanus) in interior Alaska Effects of variable fire severity on forage production and foraging behavior of moose in winter Effects of fire severity on plant nutrient uptake reinforce alternate pathways of succession in boreal forests Understanding the effects of wildfire severity on moose habitat characteristics and use in Interior, Alaska Interactive effects of wildfire and climate on permafrost degradation in Alaskan lowland forests Soil amino acid turnover dominates the nitrogen flux in permafrost-dominated taiga forest soils Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing Edaphic and microclimatic controls over permafrost response to fire in interior Alaska Plant physiological responses to hydrologically mediated changes in nitrogen supply on a boreal forest floodplain: a mechanism explaining the discrepancy in nitrogen demand and supply Plant toxins and trophic cascades alter fire regime and succession on a boreal forest landscape Interactive controls of herbivory and fluvial dynamics on landscape vegetation patterns on the Tanana River floodplain, interior Alaska INTERSPECIFIC RESOURCE PARTITIONING IN SYMPATRIC URSIDS Applications of resilience theory in management of a moose–hunter system in Alaska Resilience of Athabascan subsistence systems to interior Alaska’s changing climate Integrating local knowledge and science: economic consequences of driftwood harvest in a changing climate What factors determine cyclic amplitude in the snowshoe hare (Lepus americanus) cycle?