Natural Resources and Conservation Commons^™

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 …

The Influence Of Training On Guides And Their Environmentally Responsible Behaviors And Transformational Leadership Abilities, Nancy Qwynne Lackey

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

The ecotourism and interpretive fields were established, in part, to protect natural environments. This goal is achieved by implementing environmentally responsible practices and by providing transformative experiences for visitors. Previous research suggests that ecotour and interpretive guides play a vital role in implementing environmentally responsible behaviors (ERBs) and creating transformative visitor experiences. Other researchers have found that guide training yields many benefits for guides and their abilities, but few have explored the influence of training on guides in detail. The purpose of this research was to explore the influence of established training programs on guides and their ERBs and transformational …

Gaur (Bos Gaurus) Abundance, Distribution, And Habitat Use Patterns In Kuiburi National Park, Southwestern Thailand, Supatcharee Tanasarnpaiboon

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

Population status of gaur (Bos gaurus), a wild cattle, in most habitats where they are present, is still unknown. As the use of camera traps in wildlife studies are widespread, I developed photographic individual identification procedures and utilized encounter histories of gaur individuals from camera trap data to estimate gaur abundance and density using the spatially explicit capture-recapture analysis. The study was conducted at Kuiburi National Park, southwestern Thailand, comprised of dry evergreen forest, moist evergreen forest, and man-modified secondary forest during November 2013- January 2015. I conducted 71 direct observations in a savannah-like habitat area to observe …

Improved Microplate Fluorometric Soil Enzyme Assay For Β-Glucosidase Detection, Emily C. Hoehn

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

Soil microbes produce extracellular enzymes responsible for degrading complex organic compounds to release energy and nutrients. Measurement of soil enzymes can be considered an indicator of soil health and microbial community composition because of its sensitivity to agricultural and management practices. Fluorescence enzyme assays tend to be more sensitive than spectrophotometric (ie. colorimetric) assays and a 96-well plate has the potential capacity for high-throughput use. Development of a newly modified enzyme assay using fluorometric (4-methylumbelliferone), automated pipetting system and sonication, as well as a reduction in replicates allows for a higher sample throughput rate suitable for service laboratory use. The …

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 …

Introducing Green Manures In An Organic Soybean–Winter Wheat–Corn Rotation: Effects On Crop Yields, Soil Nitrate, And Weeds, Katja Koehler-Cole

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

In organic soybean– winter wheat – corn rotations, animal manure is a common choice to maintain high yields, but leguminous crops grown as green manures after wheat harvest and incorporated into the soil before corn planting, can be an alternative when animal manure is not accessible. Forage legumes with high dry matter (DM) production and high biological N fixation have been shown to meet corn N demand. However, in Eastern Nebraska, lack of precipitation can reduce green manure growth and N fixation, leading to an insufficient N supply for corn, but corn growth can also be impacted by green manure …

Plant Diversity Affects Performance Of Invasive Thistles In Restored Nebraska Grasslands, Katilyn J. Price

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

Invasive plant species threaten native grasslands, affecting nutrient cycling, biodiversity, wildlife habitat, and usable land for production. Consequently, preventing establishment of invasive species is critical before removal becomes difficult and expensive. The purpose of this study was to examine the effects of grassland plant diversity on musk thistle (Carduus nutans) and Canada thistle (Cirsium arvense) establishment and determine which environmental factors (light penetration, soil moisture, plant diversity, and soil nitrogen) account for resistance to invasions. In a field experiment at The Nature Conservancy’s Wood River site (Nebraska), the two invasive thistle species were planted into replicated …

Shorebird Migratory Stopover Responses To Local And Regional Change: Habitat Decisions In A Vanishing Landscape, Caitlyn Gillespie

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

Understanding the consequences of anthropogenic change for migratory species is challenging because although they have evolved to cope with environmental uncertainty, migrants still rely on predictable relationships within and among habitats to make informed decisions. Calidris shorebirds rely on ephemeral wetlands during northward migration through mid-continental North America, where favorable habitat conditions are annually and regionally unpredictable and increasingly altered by land-use change. During spring 2013 and 2014, we assessed Calidris habitat use in the Rainwater Basin (RWB) and the Prairie Pothole Region (PPR) at both local and landscape scales. Although anthropogenic change has altered the wetland landscape in both …

Green Roof Energy Balances For Native Grasses And Sedum, Chris Schwarz

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

Green roofs offer a possible solution to reduce urban heat island effects caused by urbanization. Conventional green roofs use sedum for plant cover but growing evidence suggests native species offer better results for harsher environments. However, more information is needed to understand the potential of native species for green roof use in terms of survivability and cooling potential. This study was conducted from July 2013 through October 2013 to quantify the energy balance components for native grasses and sedum on a Midwestern green roof. The semi-intensive green roof located on the Larson Building parking garage in Lincoln, NE was used …

Evaluation Of Evaporative Drivers And Hydrologic Influences Using Energy And Water Budget Techniques At A Shallow Saline Lake In The Western Sandhills Of Nebraska, Usa, Colin Peake

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

The western Sandhills of Nebraska contain many shallow lakes and wetlands that interact strongly with groundwater and the overlying atmosphere. The region is semi-arid, and most of the lakes are saline, supporting a wide range of ecosystems. Water levels and salt concentrations are highly sensitive to variations in precipitation, evaporation, and groundwater fluxes, making the Sandhills an excellent laboratory for examining the effects of climate on the water balance of interdunal lakes. In this study, we investigate the atmospheric controls on evaporation rates, as well as the water balance of Alkali Lake, one of the more saline lakes in the …

Quantifying And Modeling Stream–Aquifer Interactions In The Elkhorn River Basin, Nebraska, Can Liu

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

This study combined statistical analyses, field investigations and numerical groundwater flow modeling to quantify the connectivity between the Elkhorn River and its adjacent aquifers in Nebraska. The Mann-Kendall trend tests were conducted to detect increasing or decreasing tendencies on the time series data of streamflow, which were collected from eighteen gauging stations in the Elkhorn River and its tributaries. Decreasing trends were not found in the annual streamflow data.

Field investigation of streambed hydraulic properties was performed in the Elkhorn River near Winslow and Norfolk. Vertical hydraulic conductivities (K_v) of the shallow streambed sediments were obtained by …

Spatial And Temporal Participation In Recreational Fishing, Dustin R. Martin

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

Buffering inland fisheries against large-scale changes in ecosystem function, climate regimes, and societal valuations of natural resources requires progressive management approaches that incorporate fish and angler dynamics at large spatial and temporal scales. Current paradigms of inland fishery management generally utilize waterbody-specific, fish-centric frameworks designed to regulate fish populations directly, and anglers indirectly, through fish stock enhancement and harvest regulation. In reality, anglers are the most manageable component of a fishery but management of anglers requires explicit consideration of their behavior (e.g., spatial and temporal patterns of participant use), which, unlike fish populations, operates at a scale larger than a …

Determining Scaphirhynchus Sturgeon Population Demographics And Dynamics: Implications For Range-Wide Management, Recovery, And Conservation, Martin J. Hamel

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

Sturgeons (Acipenseridae) have experienced world-wide declines as a result of anthropogenic effects such as over-harvest, habitat degradation, altered flow regimes, and pollution. Nearly all European and Asian sturgeon species have experienced population declines and have subsequently been classified as either threatened or endangered. North American sturgeons have experienced a similar plight in that all eight native sturgeon species are listed as endangered, threatened, or of special concern. Direct linkages between North American sturgeon declines and anthropogenic effects are difficult to assess due to scale considerations, fluctuating environmental conditions, difficulty in capture, and the interaction of all these effects. To recover, …

Decomposition And Nutrient Release Of Different Cover Crops In Organic Farm Systems, Jianru Shi

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

Cover crops act as green manure adding organic matter to agricultural-soils. For legume green manures to be an effective nitrogen (N) source for organic farming systems, their N release must be in synchrony with crop N demand. The objectives of this study were 1) determine the decomposition rates of three common cover crops (white clover, (Trifolium repens,L ) red clover (Trifolium pratense L.) and soybean (Glycine max L) in order to determine when most N was released and its synchrony with subsequent corn crop uptake; 2) we focused on the effect of cover crops on soil …

New Tools For Quantitative Decision Analysis In Applied Ecology And Conservation, Adam W. Schapaugh

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

Scientists have generated a massive body of theory aimed at predicting and managing the impacts of anthropogenic activities on populations, species, and ecosystems. Transforming this research into knowledge that informs complex decision-making problems remains a major challenge in environmental management and conservation. My dissertation research aims to address this issue through the development and application of mathematical and statistical models. I integrate tools, concepts, and techniques from ecology, applied mathematics, computer science, and statistics to build structured decision-making frameworks for spatial prioritization, resource allocation, and optimal scheduling. I also tackle several of the technical challenges limiting the utility of such …

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 …

Interactions Of Zooplankton And Phytoplankton With Cyanobacteria, Rebecca 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 …

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 …

Role Of The Leguminous Shrub Amorpha Canescens (Leadplant) In The Nebraska Sandhills Grasslands: Water Relations And Patterns Of Water Uptake, Adam Yarina

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

This study investigated the ecophysiological role of Amorpha canescens, a leguminous shrub native to the Nebraska Sandhills. Although A. canescens is an important ecological player in the Sandhills, its impacts on the surrounding plant community are poorly understood. To remedy this, two sites were selected for study at the Gudmundsen Sandhills Laboratory near Whitman, Nebraska – one with A. canescens (G-L) and one without A. canescens (G-NL). Both sites contained five representative herbaceous species: two C₃ grasses (Hesperostipa comata and Koeleria macrantha), two C₄ grasses (Andropogon hallii and Calamovilfa longifolia), and one forb …

Interactions Among Evaporation, Ice Cover, And Water Temperature On Lake Superior: Decadal, Interannual, And Seasonal Variability, Katherine Van Cleave

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

Lake Superior, the largest freshwater lake in the world by surface area, has enormous impacts on the regional weather and climate. The lake also comprises over half of the total water volume in the Great Lakes system and is an important resource for commercial shipping, water supplies, hydropower, recreation, and aquatic ecosystems. Water temperature and evaporation on Lake Superior have been found to be increasing in recent decades, while ice cover has been decreasing at a very rapid pace. A careful analysis of the long-term trends, however, shows that these changes have not been linear through time. Rather, a step-change …

River Otter (Lontra Canadensis) Home Range, Habitat Use, Overnight Movement, And Survival In The Platte River Of Nebraska, Samuel P. Wilson

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

River otters (Lontra canadensis) are native to Nebraska but were extirpated by the early 1900s. The Nebraska Game and Parks Commission (NGPC) reintroduced river otters during 1986­–1991 to restore the species in the state but little is known regarding the habitat needs and status of this high profile threatened species. To provide information for management I conducted research to determine home range, habitat use, overnight movement distance, and annual survival of river otters in the central Platte River of Nebraska.

I trapped, implanted telemetry transmitters, and tracked 18 river otters during 2006–2009. I obtained 996 locations and constructed …

Channel Catfish Population Dynamics, Abundance Estimates, And Short-Term Trends In The Platte River, Nebraska, Aaron J. Blank

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

Fishing for channel catfish (Ictalurus punctatus) is popular in Nebraska and channel catfish are the most sought after fish species in the Platte River. Anglers on the Platte River are also harvest oriented. Little is known about the effects anglers have on channel catfish population dynamics in the lower Platte River. The goal of this study was to determine if there were effects of angling on channel catfish at two high use fishing areas in the lower Platte River. My first objective was to evaluate differences in relative abundance, size structure, condition, age structure, growth, and mortality between …

Modeling Field-Scale Vulnerability To Pesticide Runoff, Atefeh Hosseini

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

Identifying areas vulnerable to off-site agrichemical movement and surface and ground water contamination through conventional data collection is labor-intensive, costly and time-consuming. To promote efficient pesticide use and protect water resources, a process-based index model was previously developed to estimate landscape vulnerability to pesticide runoff and leaching at a watershed or regional scale using Soil Survey Geographic (SSURGO) data. Because mitigation of contamination requires implementation of best management practices, the model was adapted to the field scale. The field-scale model was developed based on a Digital Elevation Model (DEM) with 5 ´ 5 m resolution for a research site in …

A Climatological Analysis Of The Warm-Season Wind Regimes Of The Beaufort/Chukchi Seas Coasts, William J. Baule

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

Climate records for wind speed, wind direction, and temperature are analyzed for the period from 1979-2009 for the Beaufort/Chukchi Seas region of the Arctic. Wind records have historically been subject to far fewer analyses than other meteorological variables, such as temperature or precipitation. This is particularly true for data sparse regions. Data were collected for a large area in the Beaufort/Chukchi Seas region, which includes portions of Russia, the United States, and Canada. Data from 250 stations were collected from a variety of networks throughout the region and uniformly quality controlled. Eight long-term stations were identified for data completeness and …

Agricultural Landuse Change Impacts On Bioenergy Production, Avifauna, And Water Use In Nebraska's Rainwater Basin, Daniel R. Uden

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

Agriculture is an economically important form of landuse in the North American Great Plains. Since 19^th Century European settlement, conversion of grasslands to rowcrops has increased food and bioenergy production, but has decreased wildlife habitat. Future agricultural landuse changes may be driven by alternative energy demands and regional climatic changes. Landuse change and its drivers could affect bioenergy production, wildlife populations and natural resources, and considering the potential impacts of impending changes in advance could assist with preparations for an uncertain future.

This study addressed how the conversion of marginally productive agricultural lands in the Rainwater Basin region of …

Characterization Of The Stream–Aquifer Hydrologic Connection In The Elkhorn River Basin, Zhaowei Wang

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

In this study, the hydrologic relationship between the Elkhorn River and the surrounding aquifer at eight study sites were studied. The calculated hydraulic gradient showed that the adjacent aquifer recharges the Elkhorn River all year. Reversed gradient was only found at Atkinson site during pumping seasons from 2008 to 2010. Geoprobe log data and in-situ permeameter test data were combined to calculate the equivalent hydraulic conductivity (K) and unit-length streambed conductance (C) at eight sites, where the greatest values were found at Neligh and the lowest values found at Hadar. Accordingly, the result of cross correlation analysis on the lag …

The Impact Of Place Attachment On Land Succession Of Nebraska Agriculturists, Shari Kunert

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

Many Nebraska agriculturists rely on small family farms for their livelihood. The farm is their source of income and may be an important inheritance for their family when they retire or die. Land succession planning is a process to allow landowners to pass farmland on to the next generation without incurring a potentially debilitating tax liability for the heirs. The purpose of this study is to determine the influence of place attachment on land succession planning of Nebraska agriculturists. This comparative research, mixed methods in nature, involves Nebraska agriculturists who have a land succession plan and Nebraska agriculturists who do …