Ecology and Evolutionary Biology Commons^™

Using Tree-Ring Growth And Stable Isotopes To Explore Ponderosa Pine Ecophysiological Responses To Climate Variability And The 2012-2015 California Drought, Rachel M. Keen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Climate warming in recent decades has resulted in more frequent and severe drought events in the western United States. These changes are projected to continue, making it exceedingly important to understand how forests respond to severe drought stress, and how we can manage these forests to reduce mortality during future events. The 2012-2015 California drought is a recent example of a severe, multi-year drought that was coupled with an epidemic-scale outbreak of western pine beetle, killing nearly 90% of ponderosa pines in the central and southern Sierra Nevadas. In the first portion of this study, we compared pairs of surviving …

Ecosystem Functioning Of Great Salt Lake Wetlands, Maya Cassidy Pendleton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Great Salt Lake (GSL) wetlands account for ~75% of all Utah wetlands and provide not only critical habitat for millions of migratory birds, but also provide valuable ecosystem functions and services as well as economic benefits to Utahns. However, these wetlands are facing an aggressive invader, Phragmites australis, that has spreading across the GSL wetlands and replacing native wetland habitats. Wetland managers have spent countless resources and time trying to control the spread of P. australis and restore GSL wetlands. However, we do not fully understand how these wetlands functions and services are being altered with this habitat …

The Vulnerability Of Littoral Structures Under Multiyear Drought Conditions, Jenna M. Keeton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Climate change is associated with altered environmental conditions and shifting mosaics of suitable habitats for organisms. Climate change in the form of drought can shift important lake shoreline habitats downslope, altering the lakes chemistry and habitat availability. Additionally, negative biological consequences can occur after a loss of submerged habitat along shorelines, hereafter littoral habitat. The objective of this study is to evaluate whether littoral habitat is lost (cobble, coarse woody habitat (fallen trees; CWH), and aquatic vegetation) under drought conditions across the United States. I used the National Lakes Assessment physical habitat data collected in summer 2012, when 75% of …

The Spatial Ecology Of Predator-Prey Interactions: A Case Study Of Yellowstone Elk, Wolves, And Cougars, Michel T. Kohl

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The loss of large apex predators, and their subsequent reintroduction, has been identified as a substantial driver on the structure and function of ecological communities through behavioral mediated trophic cascades (BMTCs). The reintroduction of wolves (Canis lupus) to Yellowstone National Park (YNP) has served as foundational case study of BMTCs. In our system, it has been suggested that wolves have established a ‘landscape of fear’ in which the primary prey, elk (Cervus elaphus), now avoid risky places, which ultimately led to the recovery of the vegetation community. Although this case is frequently cited as a well-understood …

Impacts Of Cattle Grazing As A Tool To Control Phragmites Australis In Wetlands On Nitrogen, Phosphorus, And Carbon, Brittany L. Duncan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Phragmites australis is a plant that is causing problems in wetlands by outcompeting native plants that provide food and shelter for millions of migratory birds. Currently, managers try to control Phragmites australis by spraying herbicide, burning, and mowing, but these methods are costly, time consuming, and have low levels of success. Adding grazing as a tool to control Phragmites australis provides a cheap and low labor alternative. However, there are many concerns regarding if grazing will cause nutrient loading in our wetlands that will decrease water quality and alter beneficial functions of wetlands.

To better understand the effects of grazing …

Fire - Herbivory Interactions In An East African Savanna: Effects On Acacia Drepanolobium Trees, Eric M. Lamalfa

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Globally, changes in plant community structure have occurred in ecosystems where humans have altered natural disturbance regimes. Many plants have adaptive life histories and morphological traits that have coevolved with fire and herbivory, which allows them to thrive despite repeated tissue losses. Therefore, altering the type, frequency, or severity of disturbance affects individual plant growth and competition among species. When these changes benefit or disadvantage different plant functional groups (i.e., grasses, shrubs, trees) it alters ecosystem structure and function. Understanding and predicting these vegetation changes, is critical for conservation and management of biodiversity, wildlife habitat, livestock forage, and water.

Savannas …

Monitoring Desert Ungulates Via Fecal Dna-Based Capture Recapture, Stephen S. Pfeiler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Estimates of population abundance and survival are critical for effective wildlife management. Obtaining estimates of these kind using traditional wildlife monitoring techniques (i.e. ground and aerial surveys) has proven to be difficult, especially for species that are wide ranging and exist in small, patchily distributed populations.

My objective was to implement fecal DNA-based capture-recapture surveys to estimate abundance and survival of two different ungulate populations that inhabit the deserts of southeastern California. I also compared fecal DNA-based capture-recapture techniques to traditional methods by evaluating the costs and precision associated with both methods. Using artificial water sources as focal sampling sites, …

The Nesting Ecology Of Woodpeckers In The Eastern Cascades And Their Interactions With Nest Competitors And Predators, Samuel D. Cowell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Woodpeckers create nesting cavities for other birds and animals in forests. This creates dynamic interactions between both woodpeckers and these other animals. Using video cameras, we documented direct behavioral interactions between nesting woodpeckers and other animals in the Eastern Washington Cascades during the 2015 and 2016 breeding seasons. Additionally, we offered 937 students in a General Biology laboratory course to participate in this original research opportunity and described and the impact the experience had on the participants as well as the researchers.

In 2015, Western Blubebirds took over two active Black-backed Woodpecker nests by physically attacking the woodpeckers. In 2016, …

Efficacy Of Translocation As A Management Tool For Urban Mule Deer In Utah, Channing R. Howard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An increase in urbanization in the United States has led to an increase in human-wildlife interactions with deer (Odocoileus spp.) which have been able to adapt and thrive in these urban environments. In Utah, urbanization has occurred along the Wasatch Front which was once traditional mule deer (Odocoileus hemionus) winter range habitat. This urban expansion coupled with an increasing use of these urban areas by mule deer, have led to increasing conflicts with deer. Overabundant urban deer have led to increased concerns over safety from deer-vehicle collisions, and damage to personal property including gardens and landscaping. …

Interactions Between Fire Severity And Forest Biota In The Central Sierra Nevada: Formation And Impact Of Small-Scale Fire Refugia And The Effect Of Fire On Forest Structure Predictive Of Fisher (Pekania Pennanti) Den Habitat, Erika M. Blomdahl

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Fire is a natural and essential component of forests in western North America. Fire maintains biodiversity through the creation of different habitat types, and regular fire rotations reduce the accumulation of woody fuels and thick understory plant densities that give rise to catastrophic fire. The practice of fire exclusion has altered western forests and increased the risk of widespread change under rising temperatures projected for the 21^st century. To manage for the reintroduction of fire it is critical that we understand the interactions between fire and forest biota in recently fire-suppressed forests.

In Chapter 2, I studied the formation …

Landscape Planning For Climate Change Resilience In The Southern Rockies, Jeffrey D. Haight

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The unique species, ecosystems and landscapes of the Western United States are experiencing unprecedented pressures from climate change, creating new challenges for conservation. As temperatures rise and patterns of precipitation shift, plant and wildlife species have been shifting their ranges to new areas in search of more suitable climates, building groupings of species that are historically unfamiliar. These climate -driven migrations place an additional burden on species that are already threatened from habitat loss and other human-related activities. The impacts of climate change are of particular concern in landscapes that have long been conserved and managed based on the ecological …

The Abiotic And Biotic Controls Of Arctic Lake Food Webs: A Multifaceted Approach To Quantifying Trophic Structure And Function, Stephen L. Klobucar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Arctic is warming faster than any other region of the globe. To conserve and manage many thousands of lakes across arctic landscapes, scientists need to understand historic and present conditions within these lakes to predict how the lakes, and the organisms that inhabit them, may respond to a changing climate. The goal of my research was to improve our understanding of what physical, chemical, and biological factors contribute to: 1) how lake food webs are assembled; and, 2) how these food webs may change in the future. First, I used long-term observations and lab experiments to determine how fish …

Sociodemographic And Climatic Factors Shaping The Development Of Drought Policies In Major U.S. Cities, Riana S. Gayle

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In most parts of the world, drought is an inevitable and natural occurrence. However, as the climate continues to warm, and populations grow and expand, the negative impacts of this extreme weather event are predicted to become more pronounced. This leads many communities and stakeholders to question what is being done to prepare society for widespread drought? The following research determines different social and atmospheric characteristics that affect a city’s likelihood of having a drought policy in place.To do this, a thorough search was conducted at the city level to determine where drought policies are currently located in theU.S. The …

Plant Evolutionary Response To Climate Change: Detecting Adaptation Across Experimental And Natural Precipitation Gradients, Jacqueline J. Peña

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Global climate change is a real-time problem that presents threats to many species. Climate change can alter ecosystems and may lead to species extinction. Species can respond to climate change by moving to a better environment or adapting. Therefore, it is necessary to rely on several approaches and perspectives to anticipate ecological impacts of climate change. A common strategy uses models to understand how populations respond to different climate scenarios. Ecological models have helped us understand population persistence, but they often ignore how populations adapt to environmental stress. Adaptive evolution has been ignored because it was assumed that evolution was …

Organic Matter Sources, Composition, And Quality In Rivers And Experimental Streams, Julia E. Kelso

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Organic matter (OM) is often considered the “currency” for ecosystem processes, such as respiration and primary production. OM in aquatic ecosystems is derived from multiple sources, and is a complex mixture of thousands of different chemical constituents. Therefore, it is difficult to identify all the sources of OM that enter and exit aquatic ecosystems. As humans develop undisturbed land, the rate at which terrestrial OM (e.g. soil and plants) and associated nutrients (e.g. nitrogen) enters rivers has increased. Increased nutrients may lead to increased primary production from aquatic plants and algae, potentially causing eutrophication and harmful algal blooms. …

Assessing The Ecological Implications Of The Altered Flow And Sediment Regimes Of The Rio Grande Along The West Texas-Mexico Border, Demitra E. Blythe

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Large, exotic (those whose headwaters are in distant places) rivers are some of the most unique and diverse ecosystems on earth. Because they often flow through a multitude of biomes and climates, their waters are a vital resource not only for the organisms that inhabit these rivers, but for human societies as well. Thus, large rivers, like the Rio Grande, that flow through arid and agricultural regions are highly regulated and diverted. Regulation and dewatering upset a river’s natural flow regime (e.g., magnitude, duration, timing of large flood events), subsequently impacting the river’s ability to transport its sediment supply, and …

An Evaluation Of Bull Trout Movement Dynamics In The Walla Walla River, Courtney Newlon

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Bull trout are a fish species listed as threatened under the Endangered Species Act. Historically, they ranged from Northern California at the southernmost extent, into Canada at the northern most extent, and east into Nevada and Montana. Bull trout are highly migratory and require large, unfragmented habitats to persist and are thus highly susceptible to human induced land-use practices. The goal of my thesis was to obtain a better understanding of bull trout movement patterns in the Walla Walla River, Washington using complimentary techniques; Passive Integrated Transponder (PIT) technology and otolith microchemistry. PIT tags can be injected into a fish …

Geospatial Modeling Of Land Cover Change In The Chocó-Darien Global Ecoregion Of South America: Assessing Proximate Causes And Underlying Drivers Of Deforestation And Reforestation, José Camilo Fagua

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Chocó-Darien Global Ecoregion (CGE) in South America is one of 25 global biodiversity hotspots prioritized for conservation. I performed the first land-use and land-cover (LULC) change analysis for the entire CGE in this dissertation. There were three main objectives: 1) Select the best available imagery to build annual land-use and land-cover maps from 2001 to 2015 across the CGE. 2) Model LULC across the CGE to assess forest change trends from 2002 to 2015 and identify the effect of proximate causes of deforestation and reforestation. 3) Estimate the effects of underlying drivers on deforestation and reforestation across the CGE …

The Macroinvertebrate And Fish Communities Of In-Stream Beaver Ponds In Northeastern Utah, Susan Washko

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Beavers were virtually extirpated from North America during the fur trade, but populations have since recovered. Dams built by recolonizing beaver alter stream habitat by forming deep, slow ponds within the streams. Such changes to the habitat is likely to have consequences for organisms such as macroinvertebrates and fish. The objective of this study was to identify the differences in the macroinvertebrate and trout community in beaver ponds and lotic (e.g. flowing reaches of a stream) reaches in tributaries to the Logan River in northeastern Utah. The macroinvertebrate community of beaver ponds had fewer species, fewer numbers, and lower biomass …

Influence Of Environmental Variables On Survival Rates Of Pronghorn (Antilocapra Americana) Neonates Across Idaho, Brett R. Panting

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study was completed to better understand pronghorn antelope (Antilocapra americana) populations found throughout Idaho. Antelope were studied in three separate and distinct study areas. The Big Desert, Camas Prairie, and Little Lost and Pahsimeroi valleys were all selected as study sites. Idaho Department of Fish and Game (IDFG) is concerned with current pronghorn populations found throughout Idaho. Pronghorn are a valued big game species found in Idaho. Increasing pronghorn populations in Idaho is a focus of IDFG.

We captured and VHF-collared pronghorn fawns found in our three study areas. Fawns were monitored daily with telemetry equipment for …

Understanding Plant Secondary Metabolites; Above And Below Ground, Andrea K. Clemensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Plants naturally produce primary and secondary metabolites. Primary metabolites are directly involved with plant growth and metabolic function. Plant secondary metabolites (PSM) were once thought of as metabolic waste products, and more recently viewed as toxins to herbivores. However, ongoing research shows that PSM are beneficial to herbivores at low doses, and PSM aid plants by attracting pollinators, recovering from injury, protecting from ultraviolet radiation, increasing drought tolerance, and aid in defense against pathogens, diseases, and herbivores. Plant secondary metabolites also influence soil nutrient cycling, and can increase the sustainability of agroecosystems. Endophyte-infected tall fescue (Festuca arundinacea Schreb.), which …

Impacts Of Phragmites Australis Management On Wetland Plant Community Recovery, Seedbank Composition, And The Physical Environment In The Chesapeake Bay, Eric L. G. Hazelton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Biological invasions have adverse economic, cultural, and ecological effects worldwide. Among the most impactful in North America is the invasion of Phragmites australis (Phragmites), a large-scale clonal grass that rapidly colonizes wetlands. Phragmites crowds out native plants and alters habitat for native fauna. In doing so, Phragmites also alters human access to water resources and has adverse economic effects, including decreasing property value, inhibiting recreational use, and limiting populations of game species.

The efforts described in this dissertation are a component of a large, multidisciplinary effort to better understand the anthropogenic stressors to Chesapeake Bay, Maryland, at the …

Relationships Among Invasive Coqui Frogs, The Small Indian Mongoose And Rat Species In Hawaii, Shane A. Hill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Non-native species are increasing globally, and with this increase, it is likely that there will be new, unique relationships found among non-natives as well as additional impacts on native species. Rats and mongooses have been introduced to islands throughout the world where they impact native species, including birds, reptiles, and amphibians. The coqui frog was introduced to Hawaii in the 1980’s, where there were already abundant rat and mongoose populations. Previous research suggests that the high densities of coqui frogs may provide enough of a new food source for mongooses and rats that their populations would grow larger than they …

Using Anthropogenic Risks To Inform Salmonid Conservation At The Landscape Scale, Andrew W. Witt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The expansion and industrialization of humanity has caused many unforeseen consequences to the natural world. Due to the importance of freshwater for people, rivers have been particularly altered to meet human needs, often at the expense of the natural world. Supplying water for farms, industries, and cities has reshaped the natural state of rivers by altering river paths, chemistry, and species compositions. These changes have harmed many species that prospered before widespread human alterations, including the native trout and salmon of western North America. As human populations continue to grow, new threats will surface for rivers, and the trout and …

Integrated Management Of Billbugs (Coleoptera: Dryophthoridae) In Intermountain West Turfgrass, Madeleine M. Dupuy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Billbugs are a serious pest of turfgrass in the Intermountain West. Billbug larvae severely discolor and eventually kill turfgrass by feeding in stems, on roots, and on crowns of the plant. Billbugs are typically managed with preventive, calendar-based applications of insecticides. Most of our knowledge on the biology and management of billbugs comes from research in the eastern U.S, and little is known about billbug biology and best management practices in the Intermountain West. First, I examined the seasonal activity of billbug life stages in Intermountain West turfgrass and developed a predictive degree-day model to better time management strategies against …

Patterns Of Threatened Vertebrates Based On Trophic Level, Diet, And Biogeography, Shaley A. Valentine

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Humans have indirectly and directly contributed to the extinction of over 500 species within the past 500 years, a rate far higher than we have seen in the past. The high extinction rate and the fact that 18% of vertebrates may become extinct within the next century have pushed Earth into a biodiversity crisis. Understanding what makes species more at risk of extinction is needed to protect Earth’s biodiversity.

Generally, it is expected that predators have greater extinction risk than omnivores and herbivores because predators are larger in body size, depend on other animal species for food, need large home …

Biological Condition And Stressors Of Blm Wadeable Streams In Northeastern California And Northwestern Nevada, Nicole Cappuccio

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Taxpayer dollars can be used more efficiently by land management agencies to monitor streams if agency-wide monitoring protocols are adopted. To address this issue, the Bureau of Land Management (BLM) developed the National Aquatic Monitoring Framework (NAMF) to implement standardized assessments of stream condition and trend in the Western United States. As one of the first applications of the NAMF I sought to develop and apply an analytical framework to determine the biological condition of streams, extent of instream stressors and their impact on biological condition, and anthropogenic sources of stressors in Northeast California and Northwest Nevada over three years …

The Effects Of Enhanced Flows On Community Structure And Ecosystem Functioning In A Montane Utah River System, Joshua A. Epperly

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Due to growing human demands for freshwater within the last century, manmade flow alterations are now a common characteristic of rivers worldwide. Alterations to the volume and timing of flows in rivers are known to negatively impact aquatic biodiversity, biological productivity and ecosystem functions such as nutrient cycling. While previous research has focused on the effects of flow reductions and spates, there is a lack of knowledge on how high flows across longer timespans (i.e. ‘enhanced flows’) impact the structure of river communities and the integrity of ecosystem functions.

The Utah Reclamation, Mitigation and Conservation Commission has expressed interest in …

Invasive Phragmites Australis Management In Great Salt Lake Wetlands: Context Dependency And Scale Effects On Vegetation And Seed Banks, Christine B. Rohal

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Invasive plants can outcompete native plants, replacing diverse plant communities with monocultures, which can negatively impact the whole ecosystem. One invasive plant, Phragmites australis, has invaded wetlands across North America. In Utah’s Great Salt Lake, it has greatly reduced the area of native plants that are important habitat for migratory birds. Here we describe experiments that assess multiple treatments for Phragmites removal and evaluate the return of native plants after Phragmites management. The treatments were applied to Phragmites patches at two scales (small 1/4-acre plots and large 3-acre plots) and across multiple sites to evaluate how patch size and …

Effects Of Livestock Grazing Management Practices On Greater Sage-Grouse Nest And Female Survival, Seth J. Dettenmaier

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The decline in greater sage-grouse (Centrocercus urophasianus; sage-grouse) populations across western North America has been primarily attributed to loss and fragmentation of their sagebrush (Artemisia spp.) habitats. This habitat loss is largely the result of increased human activities, with grazing by domestic livestock as the most predominant land use across the sagebrush ecosystem in North America. The goal of my research was to increase our understanding of the effects of livestock on sage-grouse populations. I reviewed the peer-reviewed literature for all published studies that reported potential effects of grazing on grouse species worldwide. I found that there …