Skip to main content
Advanced Search

Filters: Contacts: University of Alaska Fairbanks (X)

365 results (66ms)   

Filters
Date Range
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
In order to evaluate the impact of natural organic matter (NOM) on drinking water, the hydrology of the Caribou-Poker Creeks Research Watershed (CPCRW) was considered. The CPCRW provided an excellent opportunity to investigate contaminant transport as it relates to hydrology in a well studied, discontinuous permafrost environment. The seasonal variation of organic chemistry of three different water sources (i.e. ground water, artesian spring and stream) was studied during the course of the year 2001. This thesis comprises three chapters, each of which seeks to gain a better understanding of the contaminant transport pathways in a boreal watershed, Caribou Poker Creeks Research Watershed. The hypothesis of Chapter...
Symbioses between plants and nitrogen (N) fixing bacteria are ecologically and economically important interactions with complex evolution and ecology. Theoretical and experimental studies suggest that host specificity and environmental variation are important determinants of both evolutionary and ecological patterns in such interactions, but detailed descriptions of these parameters in natural habitats are lacking for most N-fixing systems. The aim of this set of studies was to provide such information for the symbiosis between alder ( Alnus spp.) plants and Frankia bacteria in interior Alaska. Major objectives were to determine whether: 1) different Alnus species (A. tenuifolia and A. viridis ) associate with different...
Categories: Publication; Types: Citation; Tags: M1-Flora
thumbnail
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...
thumbnail
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...
thumbnail
Summary: "Total Hg (THg) and methylmercury (MeHg) were examined in muscle and liver samples of salmon species (Chinook: Oncorhynchus tshawytscha; Chum: O. keta; Sockeye: O. nerka; Coho: O. kisutch) and freshwater fish species (Pike: Esox lucius; Grayling: Thymallus arcticus; Whitefish: Caregonus nelsoni) collected in 1999 and 2000 from the Western Alaska rivers (Yukon, Kuskokwim, Nushagak and Kvichak). The THg in salmon muscles has a mean value of 62 ng/g (ww). In Pike muscles, THg has a mean value of 879 ng/g. The mean concentrations of THg in Grayling and Whitefish muscle are 153 ng/g and 32 ng/g respectively. In salmon muscle and liver the MeHg levels constitute 77% and 62% of the THg levels, respectively. In...
This study describes the community, population, and growth dynamics of Alnus tenuifolia (thinleaf alder) and implications for nutrient cycling on the Tanana River floodplains. Through symbiotic N-fixation inputs, alder contributed to soil N accumulation with time. N-fixation itself was likely limited by soil P. Soil N was positively related to alder stem density in early successional stands. Community structure varied along a temporal gradient of changing environmental characteristics, but variations in successional patterns were found. Landscape scale alder recruitment varied temporally and was apparently linked to interactions between geofluvial processes, seed production and dispersal, and herbivory. A widespread...
The objective of this dissertation was to estimate the magnitude and mechanisms of lake area change in Alaskan National Wildlife Refuges. An efficient and objective approach to classifying lake area from Landsat imagery was developed, tested, and used to estimate lake area trends at multiple spatial and temporal scales for ∼23,000 lakes in ten study areas. Seven study areas had long-term declines in lake area and five study areas had recent declines. The mean rate of change across study areas was -1.07% per year for the long-term records and -0.80% per year for the recent records. The presence of net declines in lake area suggests that, while there was substantial among-lake heterogeneity in trends at scales of...
A spruce bark beetle (Dendroctonus rufipennis) epidemic in the Copper Basin of Alaska beginning in the late 1980's has infested over 200,000 ha of white spruce forests in the region. The impact of spruce beetle-induced habitat changes on the northern red-backed vole (Clethrionomys rutilus) was investigated using mark/recapture techniques for 2 field seasons. Vole abundance and recruitment was significantly greater on low versus heavily infested sites but a large vole survival response was lacking. Vole food resources and protective vegetative cover did not vary substantially in areas with different levels of spruce mortality. Male movement distances were influenced by sex ratio, and females appeared to respond to...
Categories: Publication; Types: Citation; Tags: M1-Mammals
Because of the key role played by fire in structuring boreal forest ecosystems, interactions between vegetation and fire regime may be an important and dynamic control of forest response to climate change. This research uses a series of field observations and experiments in boreal forests to examine the nature of several potential fire and vegetation interactions, and how such interactions may influence forest response to climate change. Long-term observations of post-fire succession provide information on the timing of tree establishment and the effects of early establishment on subsequent successional trajectories. The role of competitive interactions in driving patterns of early establishment was tested with...
We isolated luminous bacteria from drying chum salmon, Oncorhynchus keta, reported by Alaska native fishermen to be 'glowing in the dark.' The salmon were harvested for subsistence use from the Yukon River, Alaska. We identified our luminous bacterial isolates as Photobacterium phosphoreum based on nutritional versatility, and 16S rDNA and luxA gene sequences. P. phosphoreum has previously only been isolated from the marine environment. We tested whether our strains, isolated from fish harvested in freshwater, represent cold-adapted, freshwater-tolerant strains of P. phosphoreum. We also analyzed lux operon composition and organization, and examined the 5' promoter region of the lux operon for shared genes and regulatory...
Categories: Publication; Types: Citation; Tags: B5-Chum Salmon, M1-Fish
The North America boreal forest extends across more than 10° of latitude from central Labrador to interior Alaska. Periods of major climate fluctuations, including glacial and interglacial cycles, drove major migrations in the Quaternary history of the boreal forest. Beringia, the unglaciated region between the Lena and Mackenzie rivers, is recognized as an important refugium for arctic plants during the last ice age, but its role for boreal trees remains controversial. The paleobotanical record indicates Populus balsamifera (balsam poplar) survived within Beringia during the last glacial. My research employed an interdisciplinary approach, combining techniques in the fields of ecology, evolution and population...
Chemical and isotopic analyses of pore water from permafrost cores taken from the dry lake bed of ancient Lake Atna in the Copper River Basin and from an upland loess deposit northeast of Fairbanks, Alaska reveal information about the local past environments not available by other means. Thawed core samples from both sites were analyzed for δ 18 O and δD values using an isotope ratio mass spectrometer. Water content was determined as well, and subsamples of the cores were analyzed for nitrogen and carbon content. Water extracts of the core samples were analyzed for cations (Ca, Mg, K and Fe), as well as pH, electrical conductivity, and bicarbonate. Magnetic susceptibility was determined on samples from the Fairbanks...
The boreal forest covers 12 million kM2 of the northern hemisphere and contains roughly 40% of the world's reactive soil carbon. The Northern high latitudes have experienced significant warming over the past century and there is a pressing need to characterize the response of the disturbance regime in the boreal forest to climatic change. The interior Alaskan boreal forest contains approximately 60 million burnable hectares and, relative to the other disturbance mechanisms that exist in Alaska, fire dominates at the landscape-scale. In order to assess the impact of forecast climate change on the structure and function of the Alaskan boreal forest, the interactions among climate, fire and vegetation need to be quantified....
thumbnail
Summary: "Aspects of migration, fattening, and molt in trans-continental passerine migrants were examined during spring and autumn migration in Fairbanks, Alaska (64050' N, 147050' W). From 1992-1998, 25,718 birds of 18 species were banded. Based on median dates of spring and autumn passage, species-level estimates of the duration of breeding range occupation ranged from 48 to 129 days. Adults departed significantly later than immatures in 11 of the 18 species examined and significantly earlier than immatures in only one species, the Alder Flycatcher. Adults had significantly higher fat scores than immatures in most species, but these differences were attributable to the influence of ambient temperatures, length...
We isolated luminous bacteria from drying chum salmon, Oncorhynchus keta, reported by Alaska native fishermen to be 'glowing in the dark.' The salmon were harvested for subsistence use from the Yukon River, Alaska. We identified our luminous bacterial isolates as Photobacterium phosphoreum based on nutritional versatility, and 16S rDNA and luxA gene sequences. P. phosphoreum has previously only been isolated from the marine environment. We tested whether our strains, isolated from fish harvested in freshwater, represent cold-adapted, freshwater-tolerant strains of P. phosphoreum. We also analyzed lux operon composition and organization, and examined the 5' promoter region of the lux operon for shared genes and regulatory...
Categories: Publication; Types: Citation; Tags: B5-Chum Salmon, M1-Fish
Data limitation is a common property of many fisheries. Some Pacific salmon populations are a typical example of this situation because the monitoring of numerous tributaries within an area becomes logistically intractable. Fishery management often responds to this scenario with qualitative stock assessments in the form of harvest projections. In some cases, fishery data, although limited, exists in a variety of sources and may be integrated to develop quantitative population estimates. The first objective of this investigation is to generate a modeling process that combines multiple data sources to estimate abundance and escapement estimates for data-limited salmon populations. Second, we consider the reliability...
Categories: Publication; Types: Citation; Tags: B5-Chum Salmon, M1-Fish
Because of the key role played by fire in structuring boreal forest ecosystems, interactions between vegetation and fire regime may be an important and dynamic control of forest response to climate change. This research uses a series of field observations and experiments in boreal forests to examine the nature of several potential fire and vegetation interactions, and how such interactions may influence forest response to climate change. Long-term observations of post-fire succession provide information on the timing of tree establishment and the effects of early establishment on subsequent successional trajectories. The role of competitive interactions in driving patterns of early establishment was tested with...
map background search result map search result map Temporal patterns of migration, molt, and fat storage among high-latitude passerine migrants Assessment of total mercury and methyl mercury in selected subsistence fish in Western Alaska Quantifying the effects of fuels reduction treatments on fire behavior and post-fire vegetation dynamics - Final Report to the Joint Fire Science Program.  Soil environment characteristics inventory and long-term monitoring in the Rock Creek Watershed, Denali National Park and Preserve, Alaska Export of carbon, nitrogen and major solutes from a boreal forest watershed: The influence of fire and permafrost Human Impact on Fire Regime in 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.  Temporal patterns of migration, molt, and fat storage among high-latitude passerine migrants Export of carbon, nitrogen and major solutes from a boreal forest watershed: The influence of fire and permafrost Soil environment characteristics inventory and long-term monitoring in the Rock Creek Watershed, Denali National Park and Preserve, Alaska Human Impact on Fire Regime in Interior Alaska Assessment of total mercury and methyl mercury in selected subsistence fish in Western Alaska