Results :: Search Electronic Theses and Dissertations (ETDs)

Biodiversity Potential in the Pacific and Inland Northwest: The Relative Importance of Forest Structure and Available Energy in Driving Species Diversity: Author: Verschuyl, Jacob Pieter; Date: 2007-05-15; Program: Ecology and Environmental Sciences; Abstract: Currently, the most common strategy of forest biodiversity managers in the Pacific and Inland Northwest (PINW) is to maintain structural complexity within forest stands and create the full range of seral stages across the landscape. Recent advances in ecological theory reveal that biodiversity at regional to continental scales is strongly influenced by available energy (i.e. factors influencing vegetative growth such as precipitation, temperature, radiation, soil fertility). We hypothesized bird species richness (BSR) exhibits a positive or unimodal relationship with energy across landscapes a...; Download File | View full details

Bird response to landscape pattern and disturbance across productivity gradients in forests on the Pacific Northwest: Author: McWethy, David Burch; Date: 2007-08-15; Program: Ecology and Environmental Sciences; Abstract: Managing forest lands for biodiversity is a common goal in the public and private forests of the Pacific Northwest and is typically achieved through harvests that result in an array of vegetation structural conditions that provide suitable habitat for a number of species. The assumption is made that the causative factors of biodiversity do not vary geographically and that silviculture, as a management tool, can be applied similarly across different biophysical locales. The primary aim of this research is to better understand how species respond to both local and landscape-scale forest structur...; Download File | View full details

Risk effects in elk (Cervus elaphus): behavioral and nutritional responses to wolves and Environmental conditions: Author: Christianson, David Alan; Date: 2008-05-15; Program: Ecology and Environmental Sciences; Abstract: Until recently, predators have been though to regulate prey primarily through direct predation, in ecosystems where top down effects have been shown to be important. However, experiments and recent empirical observations show that the costs of antipredator responses in individuals that successfully avoid predation can exert equal or larger driving forces on population dynamics than the numerical effect of direct predation. Such a mechanism has not been explored in a large terrestrial vertebrate. I explored the antipredator responses of elk (Cervus elaphus) to wolves (Canis lupus) in the Upper ...; Download File | View full details

Microbial interactions with arsenite, hydrogen and sulfide in an acid-sulfate-chloride geothermal spring: Author: D'Imperio, Seth; Date: 2008-05-15; Program: Ecology and Environmental Sciences; Abstract: The work presented in this thesis investigated the importance of hydrogen, sulfide and arsenite in microbial community structure and function within a model Acid-Sulfate-Chloride (ASC) spring in Yellowstone National Park. Previous studies in this spring found that microbial arsenite [As(III)] oxidation is absent in regions of the spring outflow channel where H2S exceeds ~5 μM. Ex situ assays with microbial mat samples demonstrated immediate As(III) oxidation activity when H2S was absent or in low concentrations, suggesting the presence of functional As(III) oxidase enzymes in reg...; Download File | View full details

Invasiveness of Yellow Toadflax (Linaria Vulgaris) resulting from disturbance and Environmental conditions: Author: Lehnhoff, Erik Adam; Date: 2008-05-15; Program: Ecology and Environmental Sciences; Abstract: Invasive plant species are considered to be one of the greatest threats to ecosystems and biological diversity throughout the world, and are thus often aggressively managed. The degree of plant invasiveness, however, varies both with environment and with type of landscape disturbance. This research was designed to understand how the factors of environment and disturbance affect the invasiveness of Linaria vulgaris (yellow toadflax) in southwest Montana and to quantify the varying degrees of invasiveness resulting from each factor. Data were obtained through four separate projects. The effects ...; Download File | View full details

The impacts of a stem boring weevil, Mecinus janthinus, on dalmation toadflax, Linaria dalmatica: Author: Schat, Marjolein; Date: 2008-12-15; Program: Ecology and Environmental Sciences; Abstract: Classical biological control of weeds is generally considered an effective, safe, and cost effective tool for controlling widespread weeds in natural areas. However, only 60% of releases have become established and, of those, only 50% have led to control. Therefore, understanding the impacts of agents on target weeds across spatial scales, at different insect densities, and over time can give biological control practitioners the knowledge necessary to improve establishment and success rates. My studies characterized the impacts the biological control agent, Mecinus janthinus, on the rangeland ...; Download File | View full details

Mapping changes in Yellowstone's geothermal areas: Author: Savage, Shannon Lea; Date: 2009-08-15; Program: Ecology and Environmental Sciences; Abstract: Yellowstone National Park (YNP) contains the world's largest concentration of geothermal features, and is legally mandated to protect and monitor these natural features. Remote sensing is a component of the current geothermal monitoring plan. Landsat satellite data have a substantial historical archive and will be collected into the future, making it the only available thermal imagery for historical analysis and long-term monitoring of geothermal areas in the entirety of YNP. Landsat imagery from Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) sensors was explored as a tool for m...; Download File | View full details