Life Sciences Commons^™

The Utility Of Environmental Dna And Species Distribution Models In Assessing The Habitat Requirements Of Twelve Fish Species In Alaskan North Slope Rivers, James B. Eddings

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Subsistence fishing is a vital component of Alaska’s North Slope borough economy and culture that is being threatened by human disturbance. These threats mean the fish must be protected, but the size of the region makes conservation planning difficult. Fortunately, advances in species distribution models (SDMs), environmental DNA (eDNA), and remote sensing technologies provide potential to better understand species’ needs and guide management. The objectives of my study were to: (1) map the current habitat suitability for twelve fish species, occurring in Alaska’s North Slope, (2) determine if SDMs based on eDNA data performed similarly to, or improved, models based …

Forage Inventory And Modeling In Uintah And Ouray Reservation Rangelands, Scott N. Zimmer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Uintah and Ouray Reservation in northeastern Utah has not been widely studied, and access to non-tribal members is highly restricted. We sampled vegetation to summarize condition in 300,000 acres of unsurveyed Reservation lands in 2017-2018, combining these data with data collected by the Bureau of Indian Affairs from 2010-2015 to complete an initial rangeland vegetation inventory of the Reservation. This survey was designed to inform management of the area by determining cattle stocking rates and overall ecological condition across the Reservation. Both the density of forage available to cattle and appropriate cattle stocking rates vary greatly throughout management units …

Modeling The Ecological Consequences Of Visitor Behavior In Off-Trail Areas Of Dispersed Recreation Use, Ashley L. D'Antonio

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Parks and protected areas are often created to protect important social, ecological, or cultural resources from impairment. In the United States, a large majority of these parks and protected areas are also public land where recreational activities such as hiking or scenic driving are allowed. Managers of many parks and protected areas must therefore try to protect resources while also allowing for recreation use that may put these resources at risk for damage. The field of recreation ecology is interested in understanding how recreation use in parks and protected areas can sometimes cause ecological impacts to vegetation, soil, wildlife, water, …

Modeling Usa Stream Temperatures For Stream Biodiversity And Climate Change Assessments, Ryan A. Hill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Stream temperature in one of the most biologically important aspects of water quality, but we lack temperature information for the vast majority of streams within the USA. Stream temperature can be influenced by several types of landscape and waterway alteration including upstream urbanization, agriculture, and reservoir releases. Stream temperatures are also expected to be affected by climate change over the next
century. We need to know how stream temperatures vary naturally, how they are influenced by human activity, and how they will respond to climate changes to effectively manage stream ecosystems. I used data from several thousand streams within the …

15n Tracer And Modeling Analyses Of Nutrient Transport Through Lakes In A Subalpine Watershed, David M. Epstein

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Lakes have historically been overlooked as important nutrient processors within their watersheds. In general ecologists have focused on streams as zones of uptake and transformation, while viewing lakes as simple nutrient traps. However, recent research has highlighted the large influence that lakes may have on water chemistry within their watersheds. Within the field of limnology, researchers have traditionally focused on the pelagic zone for in-lake production. Further research in shallow lakes has highlighted the role benthic production within the littoral zone plays in the lake ecosystem. The greater influence of lakes is highlighted when comparing watersheds containing lakes with watersheds …

Gregarious Behavior In Large Mammals: Modeling, Methodology, And Application, Thomas L. Morton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Gregarious behavior of ungulates was considered in four ways. The first concern was W. D. Hamilton's hypothesis that a simple movement rule could reduce predation risk and encourage grouping behavior. Simulations showed little effect of this nearest-neighbor rule on predation risk. Similar, more complicated rules reduced predation risk by up to two thirds.

The second focus was on the accuracy of ground observers in diagramming individual animal locations in small herds of elk. A remotely controlled airplane was used to photograph the herds from above. A substantial distance discrepancy was found between "true" and "observed" animal locations. This discrepancy increased …

The Modeling And Measurement Of Respiratory Carbon Use And Net Carbon Gain Of Two Agropyron Bunchgrasses, Halldor Thorgeirsson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The rate of photosynthetic carbon fixation and of root and shoot respiratory carbon use was measured in the laboratory and in the field (shoots only) for Agropyron desertorum (Fisch. ex Link) Schult. and Agropyron spicatum (Pursh) Scribn. and Smith. The rate of respiratory carbon use of the root system declined within hours of the shading or defoliation of the shoot system, resulting in as much as 60% reduction in specific rate of root respiration. The mean whole-plant growth efficiency (the ratio of whole-plant net carbon gain to gross photosynthetic carbon fixation) in full irradiance in the laboratory was 0.53 and …

A New Approach To Forest Site Quality Modeling, David L. Verbyla

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Multiple regression and discriminant analysis procedures are commonly used to develop forest site quality models. 'When they contain many independent variables relative to sample size, these models may be subject to predicton bias. Fit statistics such as R² in regression and classification tables in discriminant analysis show the apparent model accuracy but this may be a biased estimate of the model's actual accuracy. Sample splitting methods such as cross-validation and the bootstrap can be used to get an unbiased actual accuracy estimate.

A discriminant procedure called classification tree analysis uses cross-validation to build the classifier with the greatest estimated …