Life Sciences Commons^™

Extreme, Positive Geomorphic Change In A Historically Degraded Desert River: Implications For Imperiled Fishes, Tansy T. Remiszewski

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rivers comprise some of the most unique and biodiverse ecosystems on the planet with their waters supporting both human societies as well as the organisms that make these rivers their home. Large rivers like the Colorado are often highly regulated and diverted in order to support human residence in arid regions like the desert Southwest, and these water diversions often have dramatic, negative impacts on the natural flow regime of the river. These impacts leave large reaches of the river dry, reduce the river’s capacity to transport sediment, cause channel and habitat homogenization, and significantly reduce the amount of suitable …

Dietary Shifts Related To Water Availability And The Demographic Response To Changing Prey Abundance Of Carnivores In The West Desert, Utah, Ashley E. Hodge

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The decrease in number and range of North American large carnivores, has often all owed smaller carnivores ( < 15 kg) to fill the role of the top predator. This has favored some carnivores such as coyotes (Canis latrans), who have expanded their distribution. Other small carnivores such as kit foxes (Vulpes macrotis) have experienced a range shrinkage and their population status throughout the United States is a concern. Historically, western U.S. natural resource management agencies installed artificial water sources to assist desert wildlife, but some researchers believe the access to water allowed more coyotes to live in Utah’s West Desert. In the late-1980s, research proposed that without free drinking water, coyotes would have to triple …

Direct And Indirect Effects Of Climate Change On Plant Populations And Communities In Sagebrush Steppe, Andrew R. Kleinhesselink

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rapid climate change presents humanity with a number of big problems. Foremost among these is the sad fact that the climate we will pass on to our children will likely be nothing like the climate that we inherited from our parents. Ecologists have collected solid evidence that climate change has already begun to affect the living things around us and the ecosystems humans depend on. Unfortunately, predicting the future effects of climate change on life on earth is not easy. We focused on three research goals as part of an effort to improve our ability to predict how plants and …

Behavioral Response Of Desert Bighorn Sheep To Human Harassment: A Comparison Of Disturbed And Undisturbed Populations, Michael M. King

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Desert bighorn sheep (Ovis canadensis nelsoni) response to human disturbance was evaluated in southeastern Utah from 1981-1983. Bighorn response was compared between the Red Canyon area, an area with relatively high levels of human disturbance, and the White Canyon area, an area with relatively low levels of human disturbance. Bighorn were deliberately harassed by vehicles and hikers and immediate response and distance fled were recorded. When bighorn remained in the presence of the harassing stimuli, actual time spent in and proportion of animals engaged in various behaviors were recorded to determine group wariness and activity budgets under harassed …

Comparison Of Microbial Activity In Desert Soils Of The Western United States, Patricia Ann Trujillo Y Fulgham

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Soils from four regional deserts, Great Basin, Sonoran, Chihuahuan, and Mojave, were collected at times throughout the year which would best exhibit microbial response to moisture or vegetation. The soils were analyzed for several chemical and physical properties. Biological and biochemical characteristics, namely respiration, dehydrogenase activity, adenosine triphosphate concentration, proteolytic activity, nitrification potential, and microbial numbers, were measured.

The soils exhibited fluctuations in microbial activity as measured by respiration, dehydrogenase activity, adenosine triphosphate concentration, proteolytic activity, and nitrification potential during different moisture seasons.

Increase in soil moisture as modified by precipitation did not cause a significant difference in respiration or …

The Nitrogen Budget Of Two Salt Desert Shrub Plant Communities Of Western Utah, Richard S. Bjerregaard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The nitrogen budgets of Eurotia lanata (Pursh.) Moq. and Atriplex confertifolia (Torr. and Frem.) S. Wats salt desert shrub plant communities were investigated. In each, a complete biomass and organic nitrogen inventory was made. In addition, investigations of the nitrogen fixation potential of soil surface microflora and inorganic soil nitrogen relationships were carried out.

Greater total biomass and organic nitrogen was found in the above-ground portions, annual shoot productivity, and litter of the Atriplex community. However, the Atriplex community was exceeded by the Eurotia community in root biomass. Roots accounted for 74 and 87 percent of the plant biomass and …