Physical Sciences and Mathematics Commons^™

Population Demography Of A Glacial-Relict Stream Fish Mediated Via Anthropogenic Alteration, Joseph M. Spooner

School of Natural Resources: Dissertations, Theses, and Student Research

Northern Pearl Dace Margariscus nachtriebi are a small-bodied glacial-relict fish species of greatest conservation need (SGCN) found throughout Canada and the northern United Sates. Their distribution within the Nebraska Sandhills Ecoregion is isolated from the northern core distribution of the species following the last glaciation period approximately 18,000 years ago. Headwater streams within the Nebraska Sandhills Ecoregion are predominately groundwater fed and provide the cool water temperatures needed to support Northern Pearl Dace and other glacial-relict SGCN. Headwater streams within the Nebraska Sandhills Ecoregion have been geomorphically altered through anthropogenic processes such as channelization whereby habitat homogenization has occurred. Evidence …

Habitat Heterogeneity In Nebraska Streams And Distribution Prediction For Tier-1 Cyprinids Using Multi-Scale Modeling Of Fluvial And Landscape Features, Connor P. Hart

School of Natural Resources: Dissertations, Theses, and Student Research

Multiscale environmental processes determine in-stream habitat conditions which drive species distributions. Habitat constitutes the physical template upon which ecological processes occur and species conduct life stage activities. Habitat heterogeneity promotes biodiversity of aquatic systems. Stream classification informs freshwater conservation by providing a useful framework to account for habitat heterogeneity, often based on landscape regions of similar environmental processes. A greater understanding of landscape-based classification frameworks as means to classify stream systems may improve understanding of drivers of biodiversity. Using Nebraska as a case study, on a statewide scale, objectives were 1) to characterize habitat availability for several at-risk fish species, …

Connecting The Nebraska Water Quality Index To The Aquatic Microbial Community Of The North Platte River Basin, Nebraska, Paula R. Guastello

School of Natural Resources: Dissertations, Theses, and Student Research

The Nebraska Water Quality Index, under development by the Nebraska Department of Environment and Energy, summarizes in a single value eight environmental parameters that have been monitored in Nebraska for nearly 20 years. Water quality parameters including those used in the Nebraska Water Quality Index have been shown in previous studies to impact bacterial growth. As such, this index has the potential to correlate with the freshwater microbial community. Here, I relate the Nebraska Water Quality Index to microbial community composition and structure using 16S rRNA gene amplicon sequence data collected from the North Platte River Basin, Nebraska. This index …

Understanding The Factors Affecting Nebraskan Farmers’ And Landowners' Decision To Adopt Precision Agricultural Technologies And Programs, Corrin C. Winter

School of Natural Resources: Dissertations, Theses, and Student Research

Advisors: Andrew Little, Christopher Chizinski

To gain insights into the challenges faced by Nebraska farmers and landowners when adopting precision agriculture technologies, I analyzed data collected from a 2022 survey involving 7,503 participants, consisting of producers and farmland owners from across the state of Nebraska. The primary objective was to provide valuable insights for agencies seeking to improve their precision agriculture and conservation outreach efforts for the benefit of conservation and Nebraskan farmers and landowners. This study aimed to understand key factors influencing adoption behaviors by evaluating the constraints to precision agriculture adoption, assessing the impact of producer and landowner …

Pronghorn Survival And Resource Selection In Western Nebraska's Agriculturally Dominated Landscape, Katie Piecora

School of Natural Resources: Dissertations, Theses, and Student Research

Nebraska’s pronghorn population has been stable over the last decade, yet their presence on the landscape remains a contentious subject amongst private landowners. Conversion of grassland for crop production and increased anthropogenic activity has drastically altered pronghorn behavior throughout their current range, however basic ecology and resource use by pronghorn in Nebraska remains poorly understood. Establishing baseline population metrics and seasonal patterns of resource use for this population at the eastern periphery of the species range is critical to guide management actions. We deployed GPS collars on 110 adult pronghorn to quantify survival, mortality risk, and seasonal resource selection in …

Mentoring Experiences Of Undergraduate Students And Faculty Members In Science, Technology, Engineering, And Mathematics, Pamela Martínez Oquendo

School of Natural Resources: Dissertations, Theses, and Student Research

I present a comprehensive view of mentoring experiences of undergraduate students and faculty members in science, technology, engineering, and mathematics (STEM). In CHAPTER 1, I describe a brief outline of this dissertation. In CHAPTER 2, I present an interpretative phenomenological analysis of the lived experiences of former STEM undergraduate mentors of the Nebraska STEM For You (NE STEM 4U) afterschool mentoring program. In CHAPTER 3, I describe how the ramifications of faculty mentorship influence the science pipeline using a qualitative synthesis. In CHAPTER 4, I describe how the STEM faculty-student mentoring engagement involves a strong psychological support component using a …

The Last Drought Frontier: Building A Drought Index For The State Of Alaska, Olivia Campbell

School of Natural Resources: Dissertations, Theses, and Student Research

Drought is characterized by periods of below average precipitation. There are five major types of drought recognized in the literature: meteorological, hydrological, agricultural, socioeconomic, and ecological. A relatively new concept in the drought literature is “snow drought.” A key part of the definition of drought is that it is not always accompanied by extreme heat. This means drought can occur even in cold climates, cold seasons, and higher latitudes and altitudes, like Alaska. Drought is a natural part of climate variability, but Alaska’s climate is changing faster than any other state in the United States. Alaska is no stranger to …

Sturgeon Chub Distributional Patterns And Habitat Use And Benthic Fish Assemblage Structure In Missouri River Tributaries Of South Dakota, Mitchell R. Magruder

School of Natural Resources: Dissertations, Theses, and Student Research

Native species of the Missouri River drainage inhabiting benthic habitats dominate state and federal lists of species at risk. Sicklefin Chub Macrhybopsis meeki and Sturgeon Chub Macrhybopsis gelida are two native Missouri River benthic minnows that are currently under review for federal listing under the Endangered Species Act (ESA) due to extensive population declines and local extirpations within their native range. Substantial alterations to the Missouri River threaten Macrhybopsis spp. and other benthic fishes; however, large, less impacted tributaries in South Dakota may act as refugia for native species. The extent of Sicklefin Chub and Sturgeon Chub populations is largely …

The North Platte River Valley: The Intersectionality Between Water Quality And People, Anni Poetzl

School of Natural Resources: Dissertations, Theses, and Student Research

The North Platte River (NPR) Valley of western Nebraska is a semi-arid watershed with row crop production, livestock production, and urban land use activity and has a population of diverse stakeholders. These land use activities contribute to the enrichment of surface waters, such as streams, which can affect human and ecosystem health, as well as economic development and recreational activities. The project objectives are to: (1) quantify the movement of dissolved inorganic nutrients from the land within the NPR Valley to the NPR via tributaries and canals, (2) identify spatiotemporal variability of nutrient limitation of periphyton growth within the NPR, …

Understanding Conservation Specialists’ Role In The Adoption Of Precision Agriculture In Nebraska, Morgan L. Register

School of Natural Resources: Dissertations, Theses, and Student Research

There is a complex issue by the need for strategic development of agricultural lands to ensure we can feed a growing world, while simultaneously reducing impacts on our natural resources such as water pollution from runoff, soil degradation, and habitat fragmentation. To address these growing concerns, researchers are looking for ways to optimize both agricultural production and natural resource conservation. Precision conservation was developed to ensure sustainable ecosystems for future generations. Our research evaluates conservation specialists’ ability to clearly articulate how precision conservation can help agricultural producers feed a growing world while simultaneously reducing impacts on our natural resources, I …

Analysis Of Soil Change Across Nebraska, Trinity Baker

School of Natural Resources: Dissertations, Theses, and Student Research

The world’s population is growing and an increasing populace requires more resources. These requirements place increasing pressure on the environment and the soil. Soils serve many important functions throughout the world. These functions range from offering a media for food production, providing a sink for organic carbon, nutrient cycling, and improving water quality. It is important to focus on the human impact on soils and their change over time.

For my research I examined how soils across Nebraska have changed over a time period of roughly 65 years. I sampled and analyzed 39 pedons from four Major Land Resource Areas …

Irrigation’S Impact On A Precipitation Event During Grainex In Nebraska, Usa, Daniel Whitesel

School of Natural Resources: Dissertations, Theses, and Student Research

Numerous precipitation events were observed during the Great Plains Irrigation Experiment (GRAINEX). However, the precipitation event that was observed the morning of 23 July 2018 is the focus of this thesis. Six experiments were conducted which involved increasing or decreasing soil moisture by 5% increments over the irrigated cropland. An additional experiment, which changed the irrigated land use to grassland, showed precipitation increases. It was found that regardless of strength of irrigation, average precipitation decreased. Average precipitation decreased by up to 72% when irrigation increased compared to the control simulation and decreased by up to 85% when irrigation decreased compared …

Right Side Up: Payment For Ecosystem Services On Privately Owned Grasslands In Nebraska, Kyle Martens

School of Natural Resources: Dissertations, Theses, and Student Research

Grasslands are an important ecological and economic resource in the United States. As part of a natural system, these landscapes can provide income for ranching operations and employment in rural communities; habitat for grassland plants, animals, and migratory species; and offer other services not always readily observed such as improved soil health, clean water, and carbon sequestration. Despite the overarching benefits, the conversion of grasslands to other uses remains widespread throughout much of the remaining Great Plains ecosystem.

Shifting from livestock ranching to another land use often reflects a tipping point. This occurs when the alternative land use is perceived …

Soil Morphology And Carbon Stocks Of Deflation Basin Wetlands In Eastern Nebraska, Usa, Aubrey Grace Kemper

School of Natural Resources: Dissertations, Theses, and Student Research

Wetlands contribute important ecosystem services such as water filtration and storage, wildlife habitat, and carbon sequestration. The objective of this study is to compare the soil morphology and the carbon and nitrogen stocks between the upland, basin edge, and basin floor in playa wetlands of eastern Nebraska. This work was conducted in three deflation basin wetlands in the Todd Valley, a loess-mantled, former course of the Platte River, in eastern Nebraska. Soil morphological descriptions were evaluated to two meters’ depth using cores collected along three transects from the upland to the basin floor in three basins, carbon and nitrogen stocks …

Groundwater Education: An Investigation Of Students' Use Of A Groundwater Modeling Tool, Holly White

School of Natural Resources: Dissertations, Theses, and Student Research

Groundwater is a critical resource for life on Earth. However, our groundwater resources are at risk due to human activities, making this a topic of importance within K-12 and undergraduate environmental education. Yet, students hold alternative conceptions and may have limited awareness about groundwater systems. One way to support students’ learning is by incorporating computer-based modeling tools into classrooms. Here, we explore the use a groundwater modeling tool, the Hydrogeology Challenge (HGC), among two age groups of students: seventh grade students and undergraduate students. In the seventh-grade population, we investigated how students relate or map model components to their real-world …

Bioaccumulation And Partitioning Of Heavy Metals In Cicindelidia Haemorrhagica In Yellowstone National Park, Monica Gotschall

School of Natural Resources: Dissertations, Theses, and Student Research

The tiger beetle Cicindelidia haemorrhagica (Coleoptera: Cicindelidae) are widely distributed in Yellowstone National Park (YNP) and exclusively living on thermal areas. Heavy metals including arsenic, copper, lead, and selenium are present in these thermal springs, presenting an unique environment for C. haemorrhagica. Therefore, from 2018 – 2020 I sampled adult C. haemorrhagica from YNP and adult C. haemorrhagica from a known population in a salt flat in Idaho not associated with a hot spring and measured heavy metal concentrations. All populations of C. haemorrhagica bioaccumulated heavy metals. Cuticular waxes showed small concentrations of metals indicating that those metals are …

Occurrence And Potential Transformation Pathways Of Nitrogen Species In The Intermediate Vadose Zone, Jordan Shields

School of Natural Resources: Dissertations, Theses, and Student Research

Nebraska is a large agricultural producing state with a heavy reliance on groundwater resources and nitrogen fertilizer application to maintain output. Poor management, such as excessive fertilizer application, improper timing, and over irrigation can lead to contamination of groundwater. Nitrate is the leading groundwater contaminant in Nebraska and chronic consumption at medium to high concentrations leads to adverse health effects. Nitrate, a highly soluble anion, is present in the root zone in numerous forms and undergoes biogeochemical transformations before being leached through the profile. In order to predict the timing and quantity of nitrate contamination in groundwater, researchers study the …

A Conceptual Model Evaluation Framework For Adaptive Governance And Adaptive Management In Large-Scale Restoration Programs, Chadwin Smith

School of Natural Resources: Dissertations, Theses, and Student Research

Adaptive management (AM) has become a kind of plastic phrase applied as a formulaic panacea for most major species recovery and ecosystem restoration efforts now underway across the United States. AM emerged as an application of the scientific method to resource management, closely tying management to science learning through experimental actions. The phrase “learning by doing” best captures the premise behind developing an experimental management approach that could be applied on the larger scale of a river system or ecosystem. In nearly five decades of application, however, examples of successful AM implementation at large scales are few and conflict remains …

Impacts Of Irrigated Agriculture On The Near Surface And Planetary Boundary Layer Atmosphere: Results From The Great Plains Irrigation Experiment (Grainex), Emilee Lachenmeier

School of Natural Resources: Dissertations, Theses, and Student Research

Modification of natural prairie grasslands into irrigated and rainfed agriculture in the Great Plains produced significant impacts on regional weather and climate including temperatures, precipitation, energy fluxes, and the planetary boundary layer (PBL) atmosphere. The Great Plains Irrigation Experiment (GRAINEX) during the 2018 growing season collected data over irrigated and non-irrigated crop fields to further understand these impacts. The data were collected during two intensive observation periods (IOPs) in early June (IOP 1: 30 May – 13 June of 2018) and late July (IOP 2: 16 July – 30 July of 2018). The data analyzed include latent (LE) and sensible …

Use Of Citizen Science In Monitoring Groundwater Quality: A Case Study From Nebraska, Christopher Olson

School of Natural Resources: Dissertations, Theses, and Student Research

Citizen science has a key role in modernizing effective communication between professional scientists and the general public. However, citizen science differs to that of professional science due to equipment and experience and is a topic argued against citizen science. However, technology in water quality testing has developed in simplicity and affordability to a point where high school students, with hands-on training, can collect groundwater samples and test for quality themselves. Nebraska groundwater quality is a critical part of the state and can utilize high school students as citizen scientists for their communities. High school students from rural communities across Nebraska …

Nitrate Dynamics And Source Within Nested Watersheds Of An Agricultural Stream, Nebraska, Usa, Galen Richards

School of Natural Resources: Dissertations, Theses, and Student Research

Nitrate concentrations have been increasing throughout the globe, primarily due to heightened agricultural activity. Nitrate concentrations in Bazile Creek, located in Northeastern Nebraska, have been steadily rising since the early 2000s. Groundwater nitrate concentrations within the Bazile Creek watershed are high (> 10 mg/L nitrate-N), and there is strong connectivity between groundwater and surface water systems. This study aimed to better understand temporal nitrate concentration variability within the watershed through sampling tributaries and the main channel during baseflow conditions. Nitrate source was also investigated though the use of dual δ¹⁵N and δ¹⁸O nitrate isotopes, with samples …

Using Return Intervals And Nutrient Spiraling To Examine The 2019 Nebraska Flood, Alexa Davis

School of Natural Resources: Dissertations, Theses, and Student Research

In March of 2019, flooding levels in many parts of Nebraska was the worst that streams and rivers had in decades, and in some locations, on record. Theses historic floods present an optimal case study to examine how current technological resources can be used to enhance our understanding of floods and how these floods impact in situ stream ecosystem processes like nitrogen and phosphorus cycling. Currently, there are only a few resources available to quantify the extent of floods; for my thesis, I will focus on satellite imagery and in situ water level gages. Unfortunately, due to technical issues with …

Geoscience Education Research: Trends And Applications In Undergraduate Courses, Diane Lally

School of Natural Resources: Dissertations, Theses, and Student Research

Water resources are progressively under pressure from anthropogenic uses. Students need to learn about water systems as they are the future decision-makers and problem solvers who will be faced with unknown challenges in the future. The overarching goals of this dissertation were: 1) to identify ways in which geoscience instructors are incorporating systems thinking and science modeling in their teaching along with the accompanying methods for improving systems thinking and modeling implementation and 2) explore how the implementation of science modeling and systems thinking increase student evaluation of models and the understanding of hydrologic content. Data for these studies came …

Charismatic Predators In Modern Africa: Spotted Hyena (Crocuta Crocuta) And Human Coexistence In The Northern Tuli Game Reserve, Botswana, Jazmin Castillo

School of Natural Resources: Dissertations, Theses, and Student Research

Increasing human populations has led researchers to investigate the impacts of high human population density and its impact on carnivore populations. Spotted hyenas (Crocuta crocuta) hold a unique place in African ecosystems due to being a very successful top predator with an adaptable diet whereas other top predators, like the African lion, are rapidly decreasing in abundance. We investigated past and current spotted hyena abundance within the Northern Tuli Game Reserve to better aid in wildlife management. Spotted hyenas showed no significant difference in the change in population abundance throughout the different years of the study (2008-2016). Spotted …

The Effects Of Temperature On Evacuation Rates And Absorption Efficiency Of Flathead Catfish, Zach Horstman

School of Natural Resources: Dissertations, Theses, and Student Research

Knowledge of fish gastric evacuation rates are a necessary component for both field and laboratory studies when trying to understand feeding rates, modeling energy budgets, and understanding trophic dynamics of aquatic ecosystems. Many freshwater fish encounter a broad range of environmental temperatures across life history stages, but the mechanistic link between temperature and physiological processes often remains poorly understood. We designed three recirculating aquatic systems capable of rearing Flathead Catfish Plyodictis olivaris in order to quantify gastric evacuation rates and gross energy absorption at three temperatures (17º C, 22º C and 25º C). We examined the relationship between temperature and …

In Hot Water: Influence Of Multiple Stressors On Thermal Tolerance Of Fathead Minnows Pimephales Promelas, Alexander Engel

School of Natural Resources: Dissertations, Theses, and Student Research

Freshwater aquatic systems around the globe are often subjected to physical, biological, and chemical alterations to support societal needs. The Great Plains contains one of the largest agricultural industries in North America, but its productivity has ecological repercussions for adjacent freshwater ecosystems. Specifically, the dependency on surface water irrigation and application of chemical treatments has altered the thermal and chemical composition of freshwater ecosystems throughout the region. Stressors such as elevated temperatures, altered flow regimes, increased contaminant loads affect the physiology and behavior of fishes and can lead to long-term population effects. We examined thermal tolerance of Fathead minnows Pimephales …

Impact Of Streambank Stabilization On Sediment Deposition And Erosion In Central Nebraska Streams, Matthew Russell

School of Natural Resources: Dissertations, Theses, and Student Research

Stabilization projects are increasingly used to mitigate the effects of anthropogenic streambank erosion, yet the effectiveness of these practices has been insufficiently monitored and assessed to date. Sound monitoring practices promote engineered effectiveness, in addition to allowing adjustments in implementation and maintenance to improve practices over time. However, current methods to quickly and efficiently quantify deposition and erosion within a stream continue to be costly and inefficient. Therefore, the objectives of this project were to 1) Measure streambank migration of three reaches at Cedar River in Nebraska, from 1993 to 2006 (pre-stabilization) and from 2006 to 2018 (post-stabilization) using aerial …

Exploring How Graduates Of The Nebraska Water Leaders Academy Influence Community Capitals: Two Case Studies, Dakota Staggs

School of Natural Resources: Dissertations, Theses, and Student Research

Natural resources are foundational to any community and so leadership regarding those resources is a key factor to consider in order to understand communities. The vitality and strength of a community, however, is not solely dependent upon the natural resources available to it but depends on the collection of assets and individuals within it. This study sought to understand how individual leaders, graduates of the Nebraska Water Leaders Academy, influence each of the seven community capitals outlined by Flora, Flora, and Gasteyer (2016), and how their individual civic capacity, as defined by Sun and Anderson (2012), contribute to community capacity. …

Improving Aquifer Characterization Through Integration Of Airborne Electromagnetics (Aem) And Well Hydrographs, Jacqueline Polashek

School of Natural Resources: Dissertations, Theses, and Student Research

The objective of this study is to evaluate methods of hydrostratigraphic modeling using geophysics and well hydrographs at the eastern edge of the High Plains aquifer (HPA) in Platte and Colfax counties within Nebraska, USA. The HPA is very heterogeneous in the study area, being hosted by architecturally complex glacial sediments and having many irregular hydraulic boundaries. Further, the HPA exhibits local variations between unconfined and confined conditions. Pumping in such bounded aquifers can be unsustainable because of cost increases and lost agricultural productivity. Moreover, the large drawdowns typical of confined aquifers can contribute to well interference during heavy pumping. …

Nitrate Removal And Placement Of Floating Treatment Wetlands In The Midwest, Mary G. Keilhauer

School of Natural Resources: Dissertations, Theses, and Student Research

The Midwestern United States is vulnerable to eutrophic conditions from high nutrient concentrations. Recommendations for nonpoint source pollution management include runoff treatment (i.e., filter strips, riparian buffers) and in-situ lake treatment practices (i.e., aluminum sulfate (alum) treatments, aeration, up/downdraft pumping, floating treatment wetlands). Floating treatment wetlands (FTWs) are an innovative wetland design for nutrient removal from nonpoint sources and provide a unique in-situ treatment. Best management practice studies have commonly focused on adjacent to water practices, which have resulted in a gap for guidance for in-situ treatment placement and design. Therefore, the objectives of this project were to (1) Quantify …