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This dissertation includes three discrete projects addressing various aspects of the neuroendocrine control of song in the Dark-eyed Junco (Junco hyemalis), a migratory songbird. Specifically, the roles of testosterone, photoperiodic condition [length of daylight], opioids, and age were investigated with respect to song production and neural plasticity in the regions of the brain that control song (vocal control regions, VCRs). I found that, in males photoperiodic condition and testosterone interact to regulate seasonal VCR volume plasticity, whereas testosterone alone controls song production. The opioid system is probably not involved in VCR plasticity or song production, but is indicated to play a role in song...
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Increasing levels of resource development and population growth along Alaska's relatively pristine coastline require responsible environmental stewardship that is based on scientifically defensible monitoring and assessment. This thesis develops a methodology to assess the spatial distribution of coastal sediment trace metals and estimate their natural condition along Alaska's coastline. Marine sediments provide a better integrated long-term signal for naturally occurring and anthropogenic chemicals than repeated water measurements. The first of three manuscripts reports on marine sediment trace metal concentrations from a probabilistic sampling survey of Alaska's Southcentral coastal region. Results are described...
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The Mead Site, located in the Tanana River Valley in Interior Alaska, is a deeply buried archaeology site with multiple occupations and excellent preservation. The site provides a rare opportunity to study the human/climate relationship in prehistory. Magnetic susceptibility, micromorphology, geochemical and spatial analysis were utilized to (I) determine the amount of post-depositional disturbance at the site, (2) see if there are detectable buried surfaces that indicate cultural occupation in the upper sratigraphic layers and, (3) investigate the paleosols at the site and determine if the occupations at the site correlate with ameliorating climate. The results show that the upper three cultural zones are heavily...
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Complete nucleotide sequences of the mitochondrial cytochrome b , tRNAproline and tRNA threonine genes of the eight extant species of ursids, as well as 166 brown bears (Ursus arctos L.) from 10 geographic regions of Alaska and elsewhere, are used to generate hypotheses about phylogenetic relationships among ursids and phylogeographic relationships among brown bears. Additional data were obtained from mitochondrial DNA control region from over 200 brown bears among 14 populations in Alaska, to assess structuring among brown bears. Phylogenetic analyses indicate the giant panda ( Ailuropoda melanoleuca ) and spectacled bear (Tremarctos ornata ) represent basal extant taxa. Ursines, including the sun bear (Helarctos...
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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...
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An up-to-date permafrost distribution map is critical for making engineering decisions during the planning and design of any engineering project in Interior Alaska. I used a combination of empirical-statistical and remote sensing techniques to generate a high-resolution spatially continuous near-surface (< 1.6 m) permafrost map by exploiting the correlative relationships between permafrost and biophysical terrain parameters. A Binary Logistic Regression (BLR) model was used to establish the relationship between vegetation type, aspect-slope and permafrost presence. The logistic coefficients for each variable class obtained from the BLR model were supplied to respective variable classes mapped from remotely sensed...
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Chinook salmon Oncorhynchus tshawytscha recruitment in the Yukon and Kuskokwim (Y-K) region of western Alaska is important for subsistence and commercial harvest. Recruitment of Chinook salmon in this region has been unpredictable in recent years, and managers and subsistence harvesters are searching for answers. Chinook salmon require freshwater growth to smolt, and larger smolts are thought to have higher marine survival. In this study, I tested for correlations between freshwater growth and recruitment using measurements from scale digitizations. All analyses were conducted at the tributary scale, with one tributary representing each river system. Linear regressions were used to check for correlations between...
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Northway, Alaska is a small, mostly Athabascan community with a large Formerly Used Defense Site, located near the Alaska Highway in Eastern Interior Alaska. Despite remediation in the 1990s, local residents are concerned about the contamination of wild foods. This Community Based Participatory Research project comprised two studies: the Northway Wild Food Study, to investigate contaminant levels in locally prioritized traditional foods; and the Northway Health Study, to investigate locally suspected links between historic pollution sources and health problems. The project identifies multiple pathways of exposure that were more significant in the past, including a clear water creek, whitefish, a pipeline corridor,...
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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...
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"Stratospheric ozone is of crucial importance for life on Earth. This thin layer protects us from the ultraviolet solar radiation and also works as a greenhouse gas that helps maintain our climate. Large changes in thickness and vertical distribution of the ozone abundance may have detrimental effects on life on Earth. But even small changes could have considerable impact on UV irradiance, bio-production and cancer rates. During the last decade record low spring time vertical column amounts of stratospheric ozone have been observed over Northern Europe. However, this decrease is not as severe as the depletion observed over Antarctica and at mid-latitudes in the Southern Hemisphere. The discovery of the spring time...
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Summary: "The global distribution of persistent organic pollutants has initiated considerable effort towards understanding long range atmospheric transport and partitioning of these potentially damaging compounds. Apparent latitude dependent concentration gradients of organic pollutants in otherwise pristine environments has given rise to a global fractionation model, coined the cold finger effect. According to the cold finger theory, semi-volatile persistent organic pollutant will show a preference for partitioning from the atmosphere to the ground and vegetation at northern latitudes. Here we present a study of hexachlorobenzene in spruce needle samples across Alaska, which offers a large range of climates, from...
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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....
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The lack of research on the common goldeneye (Bucephala clangula) in Interior Alaska prompted this study. My objectives were to estimate duckling survival relative to several explanatory variables and to characterize incubation behaviors in a subset of females nesting in the Chena River State Recreation Area. My estimates of duckling survival were higher than previously reported for this species: 0.65 (95% CI 0.49 to 0.82) and 0.68 (95% CI 0.58 to 0.79) for 2002 and 2003 respectively. Seasonally, duckling survival increased linearly throughout 2002, remained nearly constant in 2003, and was negatively related to daily precipitation in both years. Nest attendance patterns and incubation behaviors were not related...
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I examined social and ecological influences on moose (Alces alces gigas ) in Alaska, USA, with respect to hunting success, antler size, and population genetic structure. Catch per unit effort (CPUE) is frequently used to assess hunter success; thus I hypothesized that landscape characteristics and moose density would affect success. Using hunter harvest tickets returned to the Alaska Department of Fish and Game, I modeled CPUE with Weibull regression. I determined success is significantly predicted by hunt location, mode of transportation, hunting regulations, use of commercial services (i.e., guides), year, road density, hunter-to-moose ratio, moose density, and hunter residency status. Antler size is an important...
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A rapidly changing climate and human disturbance patterns have accelerated the spread of invasive plants species in Alaska. Non-native plant invasions can disrupt pollinator services to native plants and have the potential to impact the pollination and fruit set in berry species important for subsistence harvest. My dissertation aims to address the dual need for greater understanding of the impacts of invasive plants on pollination of berry species in boreal ecosystems and the need for research on education strategies that best prepare Alaskans to respond to the issue. I integrate an ecological field experiment, a citizen science program where data is used to validate phenology models derived from heraium data,...
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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...
map background search result map search result map Neuroendocrine control of song in the dark-eyed junco (Junco hyemalis) The Northway Wild Food and Health Project: Confronting the legacy of toxic waste along the Alcan New 3-d video methods reveal novel territorial drift-feeding behaviors that help explain environmental correlates of Chena River chinook salmon productivity Experimental and theoretical investigation of stratospheric ozone depletion in the northern hemisphere caused by heterogeneous chemistry Micromorphology, site spatial variation and patterning, and climate change at the Mead Site (XBD-071): A multi-component archaeological site in Interior Alaska Development and application of a methodology to estimate regional natural conditions for trace metals in marine sediments of southcentral Alaska's coastal region Invasive plants and pollination of Alaskan berry species: integrating ecology and education The treeline ecotone in interior Alaska: from theory to planning and the ecology in between Ecological and social influences on population dynamics and genetics of moose in Alaska Utilizing multi-source abundance estimation and climate variability to forecast Pacific salmon populations Freshwater growth and recruitment of Yukon and Kuskokwim River Chinook salmon: A retrospective growth analysis Duckling survival and incubation behaviors in common goldeneyes in Interior Alaska Carbon sequestration in Alaska's boreal forest: Planning for resilience in a changing landscape Fire and successional trajectories in boreal forest: Implications for response to a changing climate Distribution of hexachlorobenzene concentrations in spruce needle samples across Alaska Permafrost distribution mapping and temperature modeling along the Alaska Highway corridor, Interior Alaska New 3-d video methods reveal novel territorial drift-feeding behaviors that help explain environmental correlates of Chena River chinook salmon productivity Duckling survival and incubation behaviors in common goldeneyes in Interior Alaska Neuroendocrine control of song in the dark-eyed junco (Junco hyemalis) Experimental and theoretical investigation of stratospheric ozone depletion in the northern hemisphere caused by heterogeneous chemistry Invasive plants and pollination of Alaskan berry species: integrating ecology and education The Northway Wild Food and Health Project: Confronting the legacy of toxic waste along the Alcan Permafrost distribution mapping and temperature modeling along the Alaska Highway corridor, Interior Alaska Micromorphology, site spatial variation and patterning, and climate change at the Mead Site (XBD-071): A multi-component archaeological site in Interior Alaska Development and application of a methodology to estimate regional natural conditions for trace metals in marine sediments of southcentral Alaska's coastal region The treeline ecotone in interior Alaska: from theory to planning and the ecology in between Fire and successional trajectories in boreal forest: Implications for response to a changing climate Carbon sequestration in Alaska's boreal forest: Planning for resilience in a changing landscape Distribution of hexachlorobenzene concentrations in spruce needle samples across Alaska Ecological and social influences on population dynamics and genetics of moose in Alaska Freshwater growth and recruitment of Yukon and Kuskokwim River Chinook salmon: A retrospective growth analysis Utilizing multi-source abundance estimation and climate variability to forecast Pacific salmon populations