Other Environmental Sciences Commons^™

Improving The Accuracy Of Cosmic-Ray Neutron Probe Estimate Of Soil Water Content Using Multiple Detectors And Remote Sensing Estimates Of Vegetation, Xiaochen Dong

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

The recently developed Cosmic-ray Neutron Probe (CRNP) for estimating soil water content (SWC) fills a critical measurement gap between point scale methods and large scale measurements collected from remote sensing. CRNP works by measuring the change in low-energy neutron intensity over time. However, the accuracy of CRNP to measure SWC is well known to be affected by other hydrogen sources (e.g. soil organic content, atmospheric water vapor, vegetation and surface water). This study focuses on the influence of rapidly growing vegetation in agricultural fields on the accuracy of the CRNP method. Here we use data from three long-term CRNP study …

Assessing Relationships Between Angling Effort And Larval Trematodes In Small Bluegill, Alexis Park

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

I wanted to determine if catch-and-release angling increased larval trematodes in small (50-160 mm) bluegill (Lepomis macrochirus). I used angling effort as a proxy for amount of catch-and-release angling. I assumed bluegill assessed, due to their size and age, experienced catch-and-release events. I assessed larval trematode intensity, black spot (Crassiphiala bulboglossa), and white grub (Posthodiplostomum minimum centrarchi), in 750 bluegill. The first objective was to quantify the association between angling effort and reservoir area. Angling effort and reservoir area were positively correlated. The second objective was to determine if angling effort, reservoir area, bluegill …

Mapping The Ecology Of Information: Hierarchical Habitat Selection By Nebraska Pheasant Hunters, Lyndsie Wszola

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

Hunting regulations are assumed to moderate the effects of hunting consistently across a game population. A growing body of evidence suggests that hunter effort varies temporally and spatially, and that variation in effort at multiple spatial scales can affect game populations in unexpected ways. We set out to determine the causes of variation in hunting effort among ring-necked pheasant (Phasianus colchicus) hunters at four spatial scales: among regions within the state of Nebraska, among sites within a given region, among access points at a given site, and among habitat patches within a site. At each scale, pheasant hunters used direct …

Understanding Cigarette Butt Littering Behavior On Public Beaches: A Case Study Of Jekyll Island, Georgia, Maranda R. Miller

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

The world’s natural environment is degrading, and human behavior is a leading cause. Therefore, in order to address environmental problems it is important to understand the factors driving environmentally degrading behaviors and subsequently design behavioral interventions to alter undesirable behaviors.

One environmental issue of particular concern is toxins leeching from trash. Specifically, cigarette butts are of concern due to their prevalence in the environment. Cigarette butt discarding behavior is affected by personal attributes, but data regarding which personal attributes and how these affect discarding behavior is lacking. This thesis seeks to understand cigarette butt disposal on public beaches by exploring …

Soil Ecosystem Service Tradeoffs And Social–Ecological Resilience In The North Central Great Plains, Hannah E. Birge

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

Humans seek to improve their wellbeing by altering ecological processes to maximize the output of specific ecosystem services, which often leave the system vulnerable to unintended and undesirable side effects. Ecosystem services emerge from complex interactions among ecological structures and processes occurring at multiple scales. The degree to which an ecosystem maintains a predictable range of structures and processes in the face of disturbance can be described as its resilience. The 1930s Dust Bowl of the North American Great Plains is an example of a system reconfiguration and loss of resilience that was ultimately driven by human optimization for a …

Trophic Dynamics Of Flathead Catfish In The Missouri River Bordering Nebraska, Dylan R. Turner

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

Understanding the trophic dynamics of large, riverine ecosystems is complex and requires knowledge from several inputs and outputs of the ecosystem. Most riverine ecosystems have been altered in some way whether through damming, channelizing, or diverting water. The Missouri River is not immune to these anthropogenic alterations. The river has dams throughout its middle portion and is channelized from Sioux City, Iowa to its confluence with the Mississippi River. Flathead Catfish pylodictus olivarius are one of the most ecologically harmful introduced species but little research has looked at the influence native populations of Flathead Catfish have on native prey populations …

Fish And Macroinvertebrate Response To Restored Off Channel Habitats On The Lower Platte River, Nebraska, Caleb Uerling

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

Anthropogenic alterations to large rivers ranging from impoundments to levees have caused many rivers to no longer access the floodplain. The ecological integrity of floodplain rivers depends on the interaction between main-channel and floodplain habitats. Fish communities inhabiting floodplain habitats are often dictated by the type of habitat and conditions within that habitat. As restoration projects are undertaken it is imperative that managers understand how fish and macroinvertebrates respond to these events. We collected fish, macroinvertebrates, and habitat parameters on two restored floodplain habitats on the lower Platte River, Nebraska to answer questions about aquatic community response to floodplain restoration …

Integration Of Hydrogeophysical Datasets For Improved Water Resource Management In Irrigated Systems, Catherine E. Finkenbiner

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

Water scarcity is predicted to be the major limitation to increasing agronomic outputs to meet future food and fiber demands. With the agricultural sector accounting for 80 – 90% of all consumptive water use and an average water use efficiency (WUE) of less than 45%, major advances must be made in irrigation water management. Precision agriculture, specifically variable-rate irrigation (VRI) and variable-speed irrigation (VSI) systems, offers the technologies to address and manage for infield variability and incorporate that into management decisions. The major limitation to implementing this technology often lies in the management of spatial datasets and the development of …

Problematizing Socio-Scientific Issues: An Approach To Understanding Student Decision-Making Using Construal Level Theory, Ashley M. Peterson

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

Socio-scientific issues (SSIs) are challenges at the intersection of science and everyday life that require use of scientific knowledge, argumentation skills, personal values, and morals to articulate science-informed decisions. While addressing SSIs, the ways in which individuals define a problem will influence the solution or decision reached. The problem definition can differ along many dimensions, including content and construal level. A construal is a mental construction of the past and future, other places and people, and unlikely events. Construal Level Theory (CLT) suggests pro-environmental intentions are associated with abstract situations. I explore the application of CLT to teaching and learning …

Plant Diversity Influences The Structure And Function Of A Restored Prairie And Its Responses To Added Disturbances, Rebecca Bevans

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

As global warming, human conversion of natural landscapes to agricultural uses, and widespread biodiversity losses continue to alter the ecosystems we depend on, an understanding of the relationship between ecosystem structure, composition, and function is needed to maintain valuable ecosystem states and their associated functions. Research testing the limits of an ecosystem’s ability to maintain essential structure and functioning under disturbance conditions can aid in this goal.

In this study, I measured the relationship between plant diversity, community structure and functional traits, and their responses to added disturbances. I added disturbances representing those either caused or intensified by human activity …

Assessing Responses Of Betula Papyrifera (Paper Birch) To Climate Variability In A Remnant Population Along The Niobrara River In Nebraska Through Dendroecological And Remote Sensing Techniques, Evan Bumann

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

Remnant populations of the boreal species Betula papyrifera, found along north-facing canyons and river banks of the Niobrara River Valley in north-central Nebraska, represent one of the southernmost distributions of the species in North America. Although, the species has persisted in the Great Plains after the Wisconsin Glaciation due to the local topography and microclimatic conditions, canopy dieback has been reported in recent years, which is believed to be attributed to temperature change. Therefore, the goals of this research are to: 1) use dendroecological techniques, or the study of tree rings to assess the responses B. papyrifera to intra- and …

Exploration Of Student Biodiversity Knowledge And Decision-Making For A Wildlife Conservation Socioscientific Issue, Ashley R. Alred

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

Global biodiversity, a foundation for ecosystem function, is diminishing at a rate unprecedented in the last 50 years. Biodiversity loss and ecosystem services deterioration is linked to increased food insecurity, reduced water quality and availability, decreased energy security, higher economic losses and human suffering (Millennium Ecosystem Assessment, 2005). Consequently, educators should invest in supporting students in their development of ecological understanding and formal decision-making skills so they are equipped with meaningful tools they can use as scientifically literate citizens. To contribute to that mission, this study seeks to explore student 1) comprehension and explanation of biodiversity concepts and 2) decision-making …

College And University Sustainability Officers’ Experiences With Green Office Programs: A Qualitative Investigation, Logan Lamb

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

The number of sustainability programs in higher education continues to increase. Green office programs have become a cornerstone of sustainability programming on college and university campuses across the country. This exploratory qualitative study involves college and university sustainability officers and investigates their experiences changing behaviors through green office programs. The goal of this study was to provide insight into green office programs. Two side-by-side studies were conducted to provide a detailed analysis of green office programs at both small and large institutions of higher education. Eleven major themes emerged from the study. Six themes emerged from the qualitative analysis of …

River Otter (Lontra Canadensis) Distribution And Habitat Suitability In Nebraska, Nathan R. Bieber

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

River otters (Lontra Canadensis) were extirpated in Nebraska by the early 1900’s, but in 1986, the Nebraska Game and Parks Commission (NGPC) began reintroduction efforts. Following reintroductions, the otter was listed as a tier-1 at-risk species in Nebraska. With increasing otter populations, NGPC is evaluating a de-listing plan. In order to inform de-listing efforts, I surveyed Nebraska’s rivers documenting otter sign and used modeling techniques to estimate otter distribution and habitat suitability.

Otter sign surveys were conducted on the navigable rivers of Nebraska. Occupancy modeling techniques were used to examine patterns in otter detections. The best model incorporated distance …

Interpreting Temperature- And Precipitation-Related Scientific Information For The Agricultural Community In The U.S. Corn Belt, Shuwei Dai

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

Climate change has been widely recognized in the U.S. Corn Belt, but what does it really mean to the agricultural community? In an era of explosive information, isolating useful climate change data and interpreting these data in usable ways is critical to the success of the broad corn production industry. In this study, three key questions are answered: (1) How have temperature and precipitation changed in the Midwest since 1980? (2) What is the best method to estimate thermal time for corn when temperature data are limited to a daily timescale? and (3) What are the historical effects of temperature …

Applications Of Time-Lapse Imagery For Monitoring And Illustrating Ecological Dynamics In A Water-Stressed System, Emma Brinley Buckley

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

Understanding and perceiving the natural world is a key part of management, policy, conservation, and inevitably for our future. Increased demand on natural resources has heightened the importance of documenting ecosystem changes, and knowledge-sharing to foster awareness. The advancement of digital technologies has improved the efficiency of passive monitoring, connectivity among systems, and expanded the potential for innovative and communicative approaches. From technological progression, time-lapse imagery has emerged a valuable tool to capture and depict natural systems. I sought to enhance our understanding of a water-stressed system by analyzing imagery, in addition to integrating images with data visualization to illustrate …

Resilience And Heterogeneity Following Fire In The Nebraska Sandhills, Jack R. Arterburn

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

The Nebraska Sandhills grassland is an expansive, semi-arid ecosystem characterized by vegetation-stabilized rolling sand dunes. The Sandhills grassland is managed for livestock production by seeking to minimizing disturbances, such as fire, that increase bare ground. The increase in bare ground following fire has contributed to the fear of fire leading to the emergence of a mobile sand dune state. We tracked vegetation response following a growing season wildfire that occurred during extreme drought conditions. In wildfire and drought conditions are when one would expect resilience to be overcome leading to a lack of vegetation recovery and a transition to a …

Adaptation To Climate Change Via Insurance And Financial Incentives, Eric R. Holley

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

Catastrophic climatic events have accounted for 72% of global insurance claims and totaled ~$1 trillion from 1980 to 2012. Costs are driven by socio-economic developments and an increased frequency and severity of climatic disasters in which climate change may have been a contributing factor. Climate change is projected to become a more prominent driver of these changes in the decades ahead. Government policies to reduce systemic risk have been the predominant approach for multi-level mitigation and adaptation to climate change. The analysis presented here shows how forceful and effective market-based approaches for adaptation and mitigation to climate change already operate …

Optimizing The Safety Margins Governing A Deterministic Design Process While Considering The Effects Of A Future Test And Redesign On Epistemic Model Uncertainty, Nathaniel B. Price

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

At the initial design stage, engineers often rely on low-fidelity models that have high uncertainty. Model uncertainty is reducible and is classified as epistemic uncertainty; uncertainty due to variability is irreducible and classified as aleatory uncertainty. In a deterministic safety-margin-based design approach, uncertainty is implicitly compensated for by using fixed conservative values in place of aleatory variables and ensuring the design satisfies a safety-margin with respect to design constraints. After an initial design is selected, testing (e.g. physical experiment or high-fidelity simulation) is performed to reduce epistemic uncertainty and ensure the design achieves the targeted levels of safety. Testing is …

Three-Dimensional Wind Speed And Flux Measurements Over A Rain-Fed Soybean Field Using Orthogonal And Non-Orthogonal Sonic Anemometer Designs, Taylor Thomas

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

The eddy covariance method for estimating fluxes of trace gases, energy and momentum in the constant flux layer above a plant canopy fundamentally relies on accurate measurements of the vertical wind speed. This wind speed is typically measured using a three-dimensional ultrasonic anemometer. Previous studies comparing anemometers with orthogonal transducer sets to those with non-orthogonal transducer sets suggest differences in measured 3D wind speed components, particularly for a vertical component. These differences, attributed to additional flow distortion caused by the non-orthogonal transducer arrangement and support structure, directly affect fluxes of trace gases, energy and momentum. A field experiment was conducted …

Decision Support Tools To Address Climate Change: Climate Model–Land Surface Models, Zea Mays L. (Corn) Phenology And Evapotranspiration–Yield Sensitivity Models For Nebraska, Usa, Jane A. Okalebo

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

Nebraska's climate is highly variable and is expected to change in the future with anthropogenic global warming (AGW), resulting in warmer spring and summer temperatures coupled with more erratic rainfall events. This has strong implications for agriculture in the region, yet it is not clear that current modeling and decision-support tools are adequate to address these looming changes and provide planning, mitigation and adaptation strategies. To address climate change and its implications to agriculture in Nebraska, a set of robust decision support tools are very crucial. This study herein are divided into three chapters, with each chapter addressing a specific …

Assessment Of Tillage Practices Using Landsat-Tm 5 In Nebraska., Sonisa Sharma

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

Tillage management practices are an important component to crop production and to federal and state conservation efforts and crop subsidy programs. Crop residue created by conservation tillage reduces soil erosion and reduce evaporation from exposed soil. Agro-hydrological models require information on tillage practices to estimate their impacts on soil-water-holding capacity, total evapotranspiration, carbon sequestration, water runoff and water and wind erosion for agricultural lands. Classification of tillage practices using remote sensing offers promise for the rapid collection of tillage information on individual fields over large areas. Using satellite imagery proves to be challenging due to the similarity in spectral signatures …

Interactions Of Zoo Plankton And Phytoplankton With Cyanobacteria, Rebecca J. Alexander

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

Cyanobacteria are a major concern in Nebraska reservoirs and are capable of producing toxins that can cause skin irritations and gastrointestinal problems, as well as affect the nervous system. It is important to determine the mechanisms that can cause cyanobacteria blooms due to the effect they can have on human health. The interaction of zooplankton and other phytoplankton groups with cyanobacteria is important because there is a biological component in surface waters that should be taken into consideration along with the physical and chemical parameters that have been noted to promote cyanobacteria. For example, zooplankton have the ability to alter …

The Use Of Tree Rings To Study The Impacts Of Stream Flow And Climate Variability On Native And Invasive Woody Species Along A Semi-Arid Riparian Ecosystem In The Great Plains, Usa, Kristen M. Skolaut

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

Forested riparian areas of the Northern Great Plains have historically been dominated by the native Populus deltoides L. vegetation type. Changes in climate, stream flow, groundwater, and management practices in the past few decades have promoted the expansion of the upland native woody species Juniperus virginiana L. and the invasion of the non-native Elaeagnus angustifolia L. into these riparian ecosystems. This study aims at using dendrochronology, or the study of tree rings, to assess the impacts of intra- and inter- annual climatic variability and stream flow over the past decades, on the annual tree ring growth, oxygen and carbon isotopic …

Impacts Of Climate Change On The Surface Water Balance Of The Central United States, 1984–2007, Bo Dong

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

The climate system and the hydrologic cycle are strongly connected with each other. Understanding the interactions between these two systems is important, since variations in climate can trigger extensive changes in the hydrologic cycle, with significant impacts on agriculture, ecosystems, and society. Observations over the central U.S. in recent decades show numerous changes in climatic variables. This includes decreases in cloud cover and wind speed, increases in air temperature, and seasonal shifts in precipitation rate and rain/snow fraction. To assess the impacts of these variations in climate on the regional water cycle, a terrestrial ecosystem/land surface hydrologic model (Agro-IBIS) is …

The Textural Discontinuity Hypothesis And Its Relation To Nomadism, Migration, Decline, And Competition, Aaron L. Alai

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

The causes of nomadism, migration, and decline in vertebrates are debated issues in the ecological sciences. Literature suggests nomadism may arise in species that specialize in granivory, nectivory, or the utilization of rodent outbreaks. Migration is thought to arise as a result of the exploitation of certain scarce or variable food resources. Species decline is hypothesized to be the result of many different factors as well; large species, island species and specialists may be more prone to decline.

A fresh perspective regarding the causes for species nomadism, migration, and decline is being investigated utilizing the ideas within the Textural Discontinuity …

Influence Of Canopy Cover, Nutrients, And Season On Stoichiometric Variation Of Epilithon In Neotropical Streams., Tyler J. Kohler

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

Light and nutrient availability are strong factors determining the nutrient composition of epilithon in temperate stream ecosystems. However, little work has been performed regarding this association in tropical streams. In our study, we investigated 1) how gradients of canopy cover and nutrients and 2) wet/dry seasonality influence epilithon standing stocks and nutrient quality. We surveyed 18 stream locations within six watersheds that varied in nutrient and light conditions during both the wet and dry seasons on the island of Trinidad to test these questions. Additionally, we sampled four stream reaches bimonthly for three years, thinning the canopy of two of …

Hydrochemistry Of Wetlands Along The Platte River Near Ashland, Nebraska, Carrie L. Wiese

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

No abstract provided.

Impacts Of Human Physical Disturbance Of Benthic Communities In Tributaries Of The Niobrara National Scenic River, Kimberly D. Laing

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

No abstract provided.

Preferences For Rural Amenities In Lancaster County, K. Koehler-Cole

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

No abstract provided.