Ecology and Evolutionary Biology Commons^™

Individual And Population Responses To Hydrologic Variability In A Headwater Stream Salamander, Madaline Cochrane

Graduate Student Theses, Dissertations, & Professional Papers

Understanding how organisms respond to environmental variability is a central goal in ecology – a goal made even more pressing by the herculean challenge global climate change presents to all organisms. Climate change is increasing the frequency and intensity of floods and droughts, which will likely have disproportionate effects on freshwater organisms. Many stream-associated species have multi-stage life histories. However, we lack an empirical understanding of life history and movement responses of these organisms to hydrologic disturbances, and how these responses may influence demographic rates. In my dissertation, I used a combination of growth, developmental, movement, and demographic data to …

Predicting Mountain Lion Resource Selection And Abundance In North America, William Connor O'Malley

Graduate Student Theses, Dissertations, & Professional Papers

The relationship between habitat quality and density is well documented in lower trophic levels but to what extent it can be extended to higher trophic levels is unknown. I tested the relationship between habitat quality, home-range size and density using a wide-ranging, well-studied, top carnivore, the mountain lion (Puma concolor). First, I created a second-order resource selection function (RSF) for mountain lions in their current North American range using GPS collar data from 476 individuals in 20 study sites and remotely-sensed landscape data. I used the RSF and home range estimates derived from collared animals to quantify mountain …

How Aquatic Insects Mitigate Temperature-Oxygen Challenges Via Behavioral, Morphological, And Physiological Plasticity, Jackson H. Birrell

Graduate Student Theses, Dissertations, & Professional Papers

How do organisms respond to environmental challenges and to environmental change? These questions occupy a central place in ecology and answering them will help us to understand why species live where they do, how organisms are affected by human activities, and, ultimately, how to choose among alternative conservation strategies. These questions are difficult, however, for two reasons. First, environmental challenges often involve multiple, interacting stressors. Second, individual responses can be modified by behavioral, morphological, and physiological plasticity. My dissertation investigates how interactions between temperature and oxygen influence the performance and survival of aquatic insects and how plasticity allows individuals to …

Evaluating The Relative Influence Of Soil Water Potential, Soil Moisture, And Vapor Pressure Deficit On Semi-Arid Vegetation Dynamics, Kayla R. Jamerson

Graduate Student Theses, Dissertations, & Professional Papers

Knowledge of vegetation’s response to soil water availability and atmospheric demand is critical to understanding the impact of climate change on semi-arid ecosystems. However, limited field-based research has been conducted to assess the relative importance of these drivers and previous research has simplified the assessment of soil water availability by relying on soil volumetric water content (VWC) as a primary control on plant growth, which, as opposed to soil water potential (Ψsoil), does not account for the effects of soil texture on plant available water. To address these gaps, we compared remotely sensed indicators of vegetation response to field based …

Invasive Earthworms In The Crown Of The Continent System And Implications For Land Management, Meghan Elizabeth Scott

Graduate Student Theses, Dissertations, & Professional Papers

The United States contains invasive earthworms originating from Europe and Asia; the majority are European lumbricids. Direct introduction occurs primarily through human activity and, once established, earthworm populations are difficult to address. When exotic earthworms engage in bioturbation, they negatively alter subterranean food webs and nutrient cycling by disrupting soil layering systems. The most prominent form of physical alteration is the change and removal of the topmost organic layer. This disruption is associated with altered nitrogen and carbon cycling, as well as altered forest floor plant communities.

The Crown of the Continent ecosystem is located in southwestern Alberta, southeastern British …

Nitrogen Dynamics And Transport Along Flowpaths In A Rural Wetland-Stream Complex, Colton Kyro

Graduate Student Theses, Dissertations, & Professional Papers

Human activities have doubled the rate of nitrogen inputs onto the landscape resulting in elevated nitrogen concentrations in our streams. Anthropogenically applied nitrogen is largely transported to stream networks via groundwater movement. Groundwater discharge occurs in distinct points along a stream but whose influences can often persist far beyond that area due to insufficient biogeochemical removal of imported nitrogen potentially causing alterations in community structure and precipitating large algae blooms. To understand the factors governing nitrogen abundance in a historical polluted stream, I used a mass-balance approach to quantify groundwater-surface water interaction and the magnitude of groundwater nitrogen input and …

Monitoring The Wetland Landscape: White-Faced Ibis (Plegadis Chihi) Breeding Habitat As A Model Assemblage, Shea P. Coons

Graduate Student Theses, Dissertations, & Professional Papers

Wetlands structure landscape biodiversity by providing critical habitat to numerous fish and wildlife species. However, climate change, growing human populations, and shifting land use practices strain limited water supplies that sustain wetlands in the semi-arid western US. Conserving a wetland network with prominent value to wildlife is paramount to ensure future security of habitat and ecosystem processes. Here, I use white-faced ibis (Plegadis chihi; hereafter ‘ibis’) breeding colonies as a model system to identify and monitor a landscape-scale wetland network across the semi-arid western US. Ibis serve an important role in marking ecologically important wetland networks because they require a …

Concentration And Composition Of Nanoparticles And Colloidal Particles In A Mine-Waste Contaminated River, Kaitlin Rose Perkins

Graduate Student Theses, Dissertations, & Professional Papers

Metals and metalloids (metal(loid)s) in aquatic ecosystems are often described through measures of their concentrations in whole and filtered waters. The filtered fraction is operationally defined as “dissolved,” and assumed to be primarily composed of free metal(loid) ions or of ions bound by low molecular weight organic matter. This definition ignores that the dissolved fraction also likely contains colloidal particles (1 to 1000 nm) that can pass through commonly used filters. This colloidal fraction can also be preferentially removed from the water column by algae and other aquatic organisms compared to free metal(loid) ions and organic bound metal(loid)s. Though they …

Management And Conservation Of Westslope Cutthroat Trout In An Impacted, Connected River System, Troy Weant Smith

Graduate Student Theses, Dissertations, & Professional Papers

Westslope cutthroat trout Oncorhynchus clarkii lewisi (WCT) is a native species of high conservation value that historically exhibited partially migratory behavior throughout its range. Long-term persistence of WCT is threatened by human habitat modification, fragmentation, introduction of non-native species, and hybridization. As a result of these changes, remnant populations in Montana have shifted toward resident populations in headwater systems and away from migratory populations in larger connected river networks. This is compounded by the historic introduction of rainbow trout O. mykiss (RBT) that hybridize with WCT, especially in larger river habitats. Rock Creek in western Montana, USA was historically managed …

Decoupled Diel Solutes: Linking Primary Production And Nitrate Uptake In A Montane Stream, Kimberly Bray

Graduate Student Theses, Dissertations, & Professional Papers

Tight coupling of surface water diel dissolved oxygen (DO) and nitrate-N (NO₃-N) signals reflects stoichiometric demand of carbon and nitrogen in stream ecosystems. However, DO and NO₃-N can become decoupled due to alternative drivers of diel solutes, resulting in conflicting estimates of stoichiometric and modeled NO₃-N uptake. In this study, I measured benthic biomass, hydrology, and dissolved solutes in a montane stream located in western MT over a growing season (June-October 2019). Daily stream metabolism and NO₃-N uptake were modeled using a single-station open-channel approach. Timing and amplitude of key diel signals …

Protecting Biodiversity On National Forests: The Evolution And Implementation Of Forest Planning Regulations, Anna Wearn

Graduate Student Theses, Dissertations, & Professional Papers

In 2012, the U.S. Forest Service (USFS) promulgated new forest planning regulations that significantly altered national forest management. One of the most controversial and important advancements was the inclusion of what were meant to be stronger biodiversity protections. An analysis of USFS’s rationale in revising the biodiversity regulations provides insights into how to interpret the substantively and procedurally new ecosystem and species protections. Examining this regulatory history reveals three key changes to the manner in which national forests are required to manage and monitor biodiversity: 1) a greater reliance on science to inform planning, 2) a new emphasis on ecological …

Food Web Effects Of Lake Trout (Salvelinus Namaycush) Invasion In Northwestern Montana, Charles Wainright

Graduate Student Theses, Dissertations, & Professional Papers

Around the turn of the 20th century, lake trout (Salvelinus namaycush) were widely introduced in several lakes and reservoirs outside their native range in western North America. Since then, lake trout have become problematic in many lakes where they were introduced, causing significant declines in popular sport fishes and native species, most notably federally protected bull trout (Salvelinus confluentus). Despite evidence that invasive fish can cause cascading trophic effects in aquatic communities, the impacts of lake trout introduction / invasion on aquatic food webs remain poorly understood. Moreover, native fish restoration programs tend to focus on suppression …

Selection Of Forage And Avoidance Of Predation Risk By Partially Migratory Mule Deer, Collin Jeffrey Peterson

Graduate Student Theses, Dissertations, & Professional Papers

Migration by ungulates has traditionally been thought of as a strategy that increases access to forage quality or reduces exposure to risk of predation, but the benefits of migration may be waning globally. In partially migratory populations, the persistence of both migrant and resident strategies is an intriguing ecological phenomenon, because migrants and residents often face contrasting fitness consequences. Partial migration is common in mule deer (Odocoileus hemionus), a species that has experienced widespread declines across the western United States during recent decades. Mule deer seldom switch between migratory strategies throughout their lifetime, which may make them less resilient to …

Influence Of Livestock And Electrified Fences On Livestock Depredation And Habitat Selection By Grizzly Bears In The Mission Valley, Montana, Kari Lynn Eneas

Graduate Student Theses, Dissertations, & Professional Papers

Balancing protection between livestock and carnivores has been a long-standing challenge in conservation. When encounters between carnivores and livestock or humans result in conflict or livestock depredation, the safety of both wildlife and humans are at risk. Reducing livestock depredation by grizzly bears (Ursus arctos horribilis) will be important as populations continue to recover and expand beyond public lands in the Northern Continental Divide Ecosystem. We used GPS locations from 8 female grizzly bears spanning 5 years in the Mission Valley, Montana, to evaluate the effect of livestock on habitat selection of grizzly bears. The Mission Valley is located on …

Population And Breeding Ecology Of Sagebrush Steppe Songbirds, Kayla Ann Ruth

Graduate Student Theses, Dissertations, & Professional Papers

Sagebrush steppe is one of the most threatened ecosystems in North America. Domestic livestock grazing is the dominant land use of sagebrush steppe across the west. Rest-rotation grazing systems can be a conservation management tool, most recently, by the Natural Resource Conservation Service - Sage Grouse Initiative (SGI). The goal of SGI is to encourage private landowners to use a livestock grazing regime that maintains or improves habitat for greater sage-grouse (Centrocercus urophasianus), as well as improve rangeland productivity. Songbirds are biological indicators that can assess the health of sagebrush steppe. Avian adult density estimates are often used …

Tiger Monitoring In Bhutan Using Non-Invasive Genetic Tools, Tashi Dhendup

Graduate Student Theses, Dissertations, & Professional Papers

Large carnivores are one of the most threatened group of animals in the world. They suffer from prey depletion, persecution by humans, and habitat loss and fragmentation which are extensively driven by anthropogenic activities. One such species is the tiger Panthera tigris. Tigers are found in thirteen countries in Asia and are protected across the range; however, tiger numbers have declined as an after effect of habitat loss, prey depletion and poaching. Human-induced changes have reduced the tiger's historical range to about 7% in which a little more than 3900 tigers are found. Most of these individuals currently exist …

Colloidal And Truly Dissolved Metal(Loid)S In Wastewater Lagoons And Their Removal With Floating Treatment Wetlands, Lauren Sullivan

Graduate Student Theses, Dissertations, & Professional Papers

Climate change is predicted to cause continuing declines in late-season streamflow, thus increasing the relative contribution of wastewater effluent to surface water flows. Wastewater effluent represents a critical point source of metal and metalloid contamination to aquatic ecosystems and wastewater lagoons are the most common wastewater treatment system in the rural United States. Although the fraction of total wastewater metals and metalloids in "dissolved" forms (defined here asnm) likely drives the potential for negative effects on receiving waters, this broad operational definition lumps truly dissolved solutes (nm) with small colloids and nanomaterials (1-450 nm; hereafter colloids). This size distinction may …

Bottom-Up And Top-Down Controls On Food Webs In Headwater Streams, Miriam O. Bayer

Graduate Student Theses, Dissertations, & Professional Papers

Headwater streams account for 70% of stream channel length in the USA and are important as hotspots of nutrient uptake and native biodiversity. Biofilm, the mixed auto- and heterotrophic microbial community covering stream substrates, is where the majority of nutrient processing occurs, and forms the base of stream food webs, particularly in heavily shaded, oligotrophic streams. Both bottom-up (e.g., nutrients, light) and top-down (i.e., consumption) processes are known to affect periphyton, the autotrophic component of biofilm, but little is known about what controls the biofilm community as a whole. Top-down effects are common in streams, where fish are often the …

Avian Community Responses To Bison Grazing In North American Intermountain Grasslands, Danielle A. Fagre

Graduate Student Theses, Dissertations, & Professional Papers

Grassland and shrubland songbird species are a guild of conservation concern in North America. Many of these species have experienced severe population declines, due to habitat loss and land use change. This makes the conservation and management of remaining habitat of crucial importance for this guild. Grazing by large herbivores is an ecosystem process in grassland systems, and in North America, one of the major historic grazers was the Plains bison (Bison bison). Bison are considered ecosystem engineers, because they modify habitat to be more or less suitable for other species, such as grassland and shrubland songbirds. Bison …

Understanding Patterns And Drivers Of Alaskan Fire-Regime Variability Across Spatial And Temporal Scales, Tyler J. Hoecker

Graduate Student Theses, Dissertations, & Professional Papers

Boreal forest and tundra ecosystems are globally important because the mobilization of large carbon stocks, and changes in energy balance could act as positive feedbacks to ongoing climate warming. In Alaska, wildfire is a key driver of ecosystem structure and function, and therefore fire strongly determines the feedbacks between high-latitude ecosystems and the larger Earth system. The paleoecological record from Alaska reveals the sensitivity of fire regimes to climatic and vegetation change over centennial to millennial time scales, highlighting increased burning with warming and/or increased landscape flammability associated with large-scale vegetation changes. This thesis focuses on two studies aimed at …

Coupling Biophysical Complexity And Forest Metabolism In A Floodplain Landscape, Peter Davis

Graduate Student Theses, Dissertations, & Professional Papers

Floodplains are biophysically complex systems that are considered among the most productive and biodiverse ecosystems on Earth. Until recently, quantitative assessment of the relationship between complexity and terrestrial production has been constrained by technological limitation. To address how floodplain biophysical complexity and ecosystem function are related, I employed remote sensing, GIS, and spatial analyses to quantify and couple metrics of complexity and terrestrial production, as well as explore the relationship among complexity, vegetation structural diversity, and terrestrial primary productivity. The study site is a 6.75-km by 1.75-km portion of the Bitterroot River floodplain near Carlton, MT upon which 551 sample …

Assessing Stream Channel Restoration: The Phased Recovery Framework, Jacob M. Dyste

Graduate Student Theses, Dissertations, & Professional Papers

Channel reconfiguration projects command a large portion of stream restoration resources, while long-term monitoring and research is severely underfunded and rarely implemented. This has led to a limited knowledge base about ecological response and efficacy. Although channel reconfiguration projects are being implemented to restore biological function to lotic systems, the document responses are highly variable and little evidence has shown these projects are reaching their target goals. I predicted the inconsistent response to these projects is the result of disturbance-induced successional processes and catchment-scale water quality impairment. To address how these endogenous and exogenous factors influence stream response to channel …

Response Of Amphibian And Invertebrate Communities To Wetland Mitigation In The Greater Yellowstone Ecosystem, Leah K. Swartz

Graduate Student Theses, Dissertations, & Professional Papers

Wetlands play a critical role in supporting freshwater biodiversity and ecosystem services, but human activities have resulted in large-scale loss and degradation of these habitats across the globe. To offset the decline of wetland area, mitigation wetlands are now frequently constructed, but their ability to replace the functions of natural habitats, including providing habitat for native fauna, remains uncertain. A recent highway reconstruction project in northwestern Wyoming caused impacts to and the destruction of multiple natural wetlands. To mitigate this loss, new wetlands were constructed along the highway corridor. To evaluate the performance of these created wetlands relative to reference …

Baseline Study Of Recovering Headwater Streams In The Sapphire Mountains, Western Montana, Morgan Vinyard

Graduate Student Theses, Dissertations, & Professional Papers

Many riparian areas in the western United States have been degraded by grazing and logging. In the year 2000, the Montana Department of Environmental Quality (DEQ) re-initiated an effort to identify and characterize reference streams, or least impacted streams in each region of the state. In Montana’s Bitterroot Valley, most streams have been impacted by grazing, irrigation, and timber production. The Montana DEQ has not been able to identify reference streams in the Sapphire Mountains on the east side of this valley. MPG Ranch, located on the west-facing slopes of the Sapphire Mountains and purchased in 2009 by a conservation-minded …

Spatio-Temporal Analysis Of Ungulate Browsing On Willow (Salix Spp.) Communities Within The Northern Range Of Yellowstone, Donald L. Belile Jr.

Graduate Student Theses, Dissertations, & Professional Papers

Variation in ungulate browsing intensity on willow (Salix spp.) communities across Yellowstone’s northern range has been attributed to various biophysical factors including climate, topography, and predators. These studies were conducted without a long-term browsing dataset; they lacked a spatially extensive sampling design, and did not include dynamic snow characteristics known to affect ungulate mobility, habitat selection, and foraging strategies. We therefore focused on snow, an extreme landscape level disturbance that places nutritional stress on ungulates during the winter when most browsing on shrubs occurs. We applied a non-destructive sampling method by consecutively recording whether stem leaders were browsed between …

Synthesis Of Satellite Microwave Observations For Monitoring Global Land-Atmosphere Co2 Exchange, Lucas Alan Jones

Graduate Student Theses, Dissertations, & Professional Papers

This dissertation describes the estimation, error quantification, and incorporation of land surface information from microwave satellite remote sensing for modeling global ecosystem land-atmosphere net CO₂ exchange. Retrieval algorithms were developed for estimating soil moisture, surface water, surface temperature, and vegetation phenology from microwave imagery timeseries. Soil moisture retrievals were merged with model-based soil moisture estimates and incorporated into a light-use efficiency model for vegetation productivity coupled to a soil decomposition model. Results, including state and uncertainty estimates, were evaluated with a global eddy covariance flux tower network and other independent global model- and remote-sensing based products.

Cows And Plows: Science-Based Conservation For Grassland Songbirds In Agricultural Landscapes, Marisa K. Lipsey

Graduate Student Theses, Dissertations, & Professional Papers

Temperate grasslands are among earth’s most imperiled ecosystems. In North America, steep declines of endemic songbird populations indicate that grassland loss and degradation may be approaching critical levels. Grasslands are agricultural landscapes largely (~85%) under private ownership with little formal protection status. Remaining bird populations depend on grazing lands that have not been converted to cropland. We combine regional data from a hotspot for grassland bird diversity (northeast Montana, USA; 26,500-km2) with continental data spanning the northern Great Plains (1,000,000-km2) to evaluate how land use and management influence bird distribution and abundance. Regionally, habitat used by seven grassland specialists spanned …

Use Of Airborne Digital Imagery To Examine Floodplain Complexity At Varying Discharges, Katelyn P. Driscoll

Graduate Student Theses, Dissertations, & Professional Papers

Floodplains are composed of aquatic and terrestrial habitats that are frequently reshaped by hydrologic processes operating at various spatial and temporal scales. I hypothesized that floodplain habitat complexity is maximized at intermediate discharges because small changes in flow result in substantial aquatic habitat changes and extreme discharges are associated with a decreased habitat heterogeneity. Between April and September 2014, I collected ultra-high resolution digital multispectral imagery of the Clark Fork River, Montana taken on 6 dates between early spring and fall. Following image mosaicking into a single image, unsupervised classification of the spectral reflectance was used to identify and quantify …

Abundance, Density, And Opinions About Columbian Black-Tailed Deer, Whidbey Island, Washington, Robert P. Wingard

Graduate Student Theses, Dissertations, & Professional Papers

Obtaining reliable knowledge is the first step towards properly managing wildlife species. Columbian black-tailed deer (Odocoileus hemionus columbianus) on Whidbey Island, Washington have not been the subject of study, and little is known about the population, or the opinion of resident’s of Whidbey Island towards the deer population. However, wildlife managers suggest deer on the island may be overabundant or over social carrying capacity. Given the lack of empirical knowledge about the deer population or human opinions towards deer on Whidbey Island, I designed research to determine the abundance and density of Columbian black-tailed deer on Whidbey Island, …

Decadal Scale Responses Of Soil And Ecosystem Processes To Forest Restoration In Rocky Mountain Conifer Forests, Peter Ganzlin

Graduate Student Theses, Dissertations, & Professional Papers

Decades of fire suppression have left much of the forest in the intermountain western United States exceedingly dense, and forest restoration techniques – including thinning and prescribed fire – are increasingly being used in an attempt to mitigate the potentially disastrous effects of severe wildfire, to enhance tree growth and regeneration, and to stimulate soil nutrient cycling. While many of the short-term effects of forest restoration have been established, the long-term effects on soil biogeochemical and ecosystem processes are largely unknown. In this thesis I present two manuscripts documenting and synthesizing these long-term impacts. The first chapter focuses on the …