Physical Sciences and Mathematics 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 …

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 …

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 …

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 …

Recreational Angler Site Choice And Behavior Within Midwestern Reservoirs, Brian S. Harmon

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

Anglers are the dominant predator in most inland fisheries. Although anglers make decisions across multiple scales, most research targets larger spatial and temporal scales of angler behavior, and thus little is known regarding angler behavior within a fishing trip. Outcomes of within-trip behavior affect larger spatial and temporal scales and are thus important to the management of recreational fisheries. Bank angler site choice was recorded at four reservoirs in the Salt Valley system across the open-water season of 2016. Previous research indicated that angler distribution did not match the distribution of fish, so another approach was taken. Counts of anglers …

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 …

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 …

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 …

Heterogeneity Of Avian Breeding Habitat On Grazing Lands Of The Northern Great Plains, Maggi S. Sliwinski

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

Native rangelands in the Great Plains are largely privately owned and used for beef production. Vegetation heterogeneity is important for maintaining biodiversity, but private land may be more homogenous than desired. My research had two components: 1) to examine whether a variety of grazing strategies created vegetation heterogeneity in a large, intact rangeland, and 2) to understand beef producers’ attitudes about vegetation heterogeneity.

First, I sampled vegetation structure, composition, and bird abundance at multiple plots on eleven management units in Cherry County, Nebraska. Units were managed with commonly used grazing strategies (e.g., short-duration grazing and season-long continuous grazing). I examined …

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 …

Influences Of Catch-And-Release Angling On Fish Avoidance Behavior, Alexis D. Fedele

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

Newly opened recreational fisheries provide the opportunity to explore direct social impacts on controlled (i.e., managed), naïve (i.e., previously unexploited by anglers) population of fish. Herein, we examine the direct influence of angling on wild fish populations, and aim to identify the behavioral outcomes in fish resulting from angling through laboratory experiments. Using two naïve fish populations from newly opened reservoirs in Nebraska, we assessed the short-term (30 d) response of fish populations to recreational angling. At one reservoir, we noted declining catch rates in catch-and-release regulated fish but not in harvested-regulated fish. We hypothesized that catch-and-released fish were given …

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 …