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Physical Sciences and Mathematics Commons™
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- Keyword
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- Climate (3)
- Drought (3)
- Remote sensing (3)
- Agriculture (2)
- Cyanobacteria (2)
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- MODIS (2)
- Phytoplankton (2)
- Sandhills (2)
- Abundance estimation (1)
- Adaptation (1)
- Africa (1)
- Alaska (1)
- Algae (1)
- Aluminum sulfate (1)
- Beef (1)
- Biological monitoring (1)
- Bos gaurus (1)
- Botswana (1)
- Camera trapping (1)
- Chlorophyll-a (1)
- Colorimetric (1)
- Conservation (1)
- Cosmic-ray neutron probe; soil moisture; calibration parameters; remote sensing; maize; soybean (1)
- Crop gross primary production (1)
- Crop rotation (1)
- Dendrochronology (1)
- Drought index (1)
- Ecology (1)
- Emissions (1)
- Endangered species (1)
Articles 1 - 20 of 20
Full-Text Articles in Physical Sciences and Mathematics
Demographic Consequences Of Off-River Nesting For Piping Plover (Charadrius Melodus) And Interior Least Tern (Sternula Antillarum Athalassos) In The Lower Platte River System, Nebraska, Elsa M. Forsberg
School of Natural Resources: Dissertations, Theses, and Student Research
Piping plovers (Charadrius melodus; hereafter, plovers) and interior least terns (Sternula antillarum athalassos; hereafter, terns) are two avian species that nest along the Lower Platte River system (LPRS) in Nebraska. In the LPRS, river sandbars provide natural nesting habitat, but off-river sites provide substantial nesting habitat especially when sandbar habitat is scarce. Although presumed to be important for the persistence of plovers and terns, off-river habitat is not self-sustaining and predicted to decline. Understanding the vital rates of plovers and terns in the LPRS will inform the role of off- river sites in the future conservation …
The Last Drought Frontier: Building A Drought Index For The State Of Alaska, Olivia Campbell
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 …
Coupling Dendrochronology And Remote Sensing Techniques To Assess The Biophysical Traits Of Juniperus Virginiana And Pinus Ponderosa Within Grassland Communities In The Semi-Arid Grasslands Of The Nebraska Sandhills, Reece Allen
School of Natural Resources: Dissertations, Theses, and Student Research
Woody species encroachment is occurring within the sandhills region in Nebraska, primarily driven by Juniperus virginiana and Pinus ponderosa, altering ecosystems and the services they provide. Effective, low cost, and cross-scale monitoring of woody species growth and performance is necessary for integrated grassland and forest management in the face of climate variability and change. In this study, we sought to establish a relationship between remote sensing-derived vegetation indices (VIs) and dendrochronological (raw and standardized tree ring width) measurements to assess the performance of encroaching woody J. virginiana and P. ponderosa located within the Nebraska National Forest in the sandhills. …
Comprehensive And Agricultural Greenhouse Gas Emissions Inventories For Nebraska And The Midwest As Baselines For Climate Change Mitigation, Eric R. Holley
Comprehensive And Agricultural Greenhouse Gas Emissions Inventories For Nebraska And The Midwest As Baselines For Climate Change Mitigation, Eric R. Holley
School of Natural Resources: Dissertations, Theses, and Student Research
Climate change is the paramount challenge of today for a sustainable future. Mitigation of greenhouse gas (GHG) emissions is necessary to reduce the associated risks and impacts on society. Using the EPA’s SIT and literature review, comprehensive GHG-emissions inventories were developed for the state of Nebraska over 25 years (1990-2015) and agricultural GHG emissions inventories were developed for the Midwest U.S for one year (2016). Nebraska’s net emissions increased from 56.2 million metric tons of carbon dioxide equivalent (MMtCO2e) in 1990 to 87.4 MMtCO2e in 2016. Agriculture was found to be the sector with the most …
Investigation Of Grace-Derived Information On Forest Drought Stress Across The Contiguous Us, Beichen Zhang
Investigation Of Grace-Derived Information On Forest Drought Stress Across The Contiguous Us, Beichen Zhang
School of Natural Resources: Dissertations, Theses, and Student Research
This research derives z-score monthly groundwater storage (GWS) anomalies and z-score monthly root zone soil moisture (RZSM) anomalies from products of Gravity Recovery and Climate Experiment Data Assimilation (GRACE-DA). Z-score monthly GWS and RZSM anomalies are compared to two drought indicators: Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) to investigate the usefulness of GRACE-DA information to detect drought conditions at tree-ring sites. This study also compares z-score monthly GWS and RZSM anomalies with the Tree Ring Standardized Growth Index (TRSGI) that is resampled by bootstrapping to investigate the capability of monitoring forest drought stress. Finally, this research uses …
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 …
The Cosmic-Ray Neutron Probe Method For Estimating Field Scale Soil Water Content: Advances And Applications, William A. Avery
The Cosmic-Ray Neutron Probe Method For Estimating Field Scale Soil Water Content: Advances And Applications, William A. Avery
School of Natural Resources: Dissertations, Theses, and Student Research
The need for accurate, real-time, reliable, and multi-scale soil water content (SWC) monitoring is critical for a multitude of scientific disciplines trying to understand and predict the earth’s terrestrial energy, water, and nutrient cycles. One promising technique to help meet this demand is fixed and roving cosmic-ray neutron probes (CRNP). However, the relationship between observed low-energy neutrons and SWC is affected by local soil and vegetation calibration parameters. This effect may be accounted for by a calibrated equation based on local soil type and the amount of standing biomass. However, determining the calibration parameters for this equation is labor and …
Gaur (Bos Gaurus) Abundance, Distribution, And Habitat Use Patterns In Kuiburi National Park, Southwestern Thailand, Supatcharee Tanasarnpaiboon
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
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 …
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 …
Occupancy Analysis And Density Estimation Of Kori Bustards (Ardeotis Kori) And Helmeted Guineafowl (Numida Meleagris) For Use In Landscape Conservation Planning In The Northern Tuli Game Reserve, Botswana, Kathryn R. Mccollum
School of Natural Resources: Dissertations, Theses, and Student Research
For understudied species, more informed conservation planning and decision-making on both the local and landscape levels may be attained through the use of occupancy and abundance estimations. Here, we focus on two iconic bird species in eastern Botswana, kori bustards (Ardeotis kori) and helmeted guineafowl (Numida meleagris). The overall goal of this project was to better understand the hierarchy of factors that influence occupancy (ψ) and density of kori bustard and helmeted guineafowl populations within the Northern Tuli Game Reserve and how these factors may interact to affect landscape conservation and usage. We performed distance sampling …
Effects Of Wind Turbine Noise On Male Greater Prairie-Chicken Vocalizations And Chorus, Cara E. Whalen
Effects Of Wind Turbine Noise On Male Greater Prairie-Chicken Vocalizations And Chorus, Cara E. Whalen
School of Natural Resources: Dissertations, Theses, and Student Research
Wind energy facilities are constructed without full knowledge of their effects on birds, and the noise generated by wind turbines is a particular concern. I investigated the effects of wind turbine noise on male Greater Prairie-Chicken (Tympanuchus cupido pinnatus) vocalizations and chorus near Ainsworth, NE, USA in 2013 and 2014. I studied 14 leks located in the area surrounding a 36-turbine wind energy facility. I used two main approaches in this study. First, I recorded Greater Prairie-Chicken boom, cackle, whine, and whoop vocalizations at each of the study leks and measured the duration, sound pressure level, peak frequency, …
Analyzing The Relationship Of Soil Moisture And Biophysical Variables In Wet And Dry Seasons At A Rainfed And Irrigated Field In Eastern Nebraska, Eric Hunt
School of Natural Resources: Dissertations, Theses, and Student Research
Agriculture production, particularly of maize and soybeans, is a major component of Nebraska’s economy and identity. However, agricultural production in Nebraska faces increasing challenges. One of the challenges is the potential for excessive groundwater depletion due to increased demand for food and fuel from irrigated Nebraska crops and increasing risks of water stress due to climate change. Therefore, it is has become essential for a deeper understanding of the soil-plant-atmosphere continuum to help producers make more informed management decisions. One of the most important variables is soil moisture. Soil moisture is an integral part of the hydrologic cycle and an …
Combating Eutrophication: An Ecosystem Scale Analysis Of Aluminum Sulfate (Alum) Effectiveness Among Lakes, With Comparison To Alum And Biomanipulation Dual Treatment, Christa M. Webber
Combating Eutrophication: An Ecosystem Scale Analysis Of Aluminum Sulfate (Alum) Effectiveness Among Lakes, With Comparison To Alum And Biomanipulation Dual Treatment, Christa M. Webber
School of Natural Resources: Dissertations, Theses, and Student Research
Eutrophic conditions in lakes and reservoirs in agricultural regions often drive summer blooms of toxic cyanobacteria. Aluminum sulfate (alum) applications are commonly used to control cyanobacteria blooms and restore water quality in eutrophic lakes. However, studies of alum treatments often lack true replication, comparison to reference lakes, or comparison to other restoration techniques, such as an alum and biomanipulation combined or “dual” treatments. Without these comparisons, the variation of treatment response between replicate lakes and restoration techniques remains uncertain. Therefore, I sought to assess how water quality is affected by multiple restoration techniques among geographically proximate (1.4 km2) …
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 …
Interactions Of Zooplankton And Phytoplankton With Cyanobacteria, Rebecca Alexander
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 …
Chlorophyll-Based Approach For Remote Estimation Of Crop Gross Primary Production: From In Situ Measurements To Satellite Imagery, Yi Peng
School of Natural Resources: Dissertations, Theses, and Student Research
The synoptic and accurate quantification of crop gross primary production (GPP) is essential for studying carbon budgets in croplands and monitoring crop status. The objective of this dissertation is to develop a quantitative technique to estimate crop GPP using remotely sensed data collected from close range to satellite altitudes. In this study, a model based on a recently developed paradigm, which relates crop GPP to a product of total crop chlorophyll content and incident radiation affecting vegetation photosynthesis, was justified for the remote estimation of GPP in crops. The model was tested with ground-observed incoming photosynthetically active radiation (PARin …
Ecological Impacts Of Stream Bank Stabilization In A Great Plains River, Christopher M. Pracheil
Ecological Impacts Of Stream Bank Stabilization In A Great Plains River, Christopher M. Pracheil
School of Natural Resources: Dissertations, Theses, and Student Research
Reduced ecological complexity, decreased water quality, and accelerated stream bank erosion are common disturbances in rivers with agriculturally dominated watersheds. Massive bank failures, increased sediment loads, and decreased riverine habitat are current problems in the agriculturally dominated Cedar River of central Nebraska. In an effort to slow erosion and prevent further ecological degradation, 20 reach scale stream bank stabilization projects were installed on the Cedar River from 2001 to 2004. The objective of this study was to determine the impact of the Cedar River stream bank stabilization projects on the ecological conditions within the Cedar River. Stream bank erosion, suspended …
Influence Of Canopy Cover, Nutrients, And Season On Stoichiometric Variation Of Epilithon In Neotropical Streams., Tyler J. Kohler
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 …
Satellite-Based Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters, Wesley Moses
Satellite-Based Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters, Wesley Moses
School of Natural Resources: Dissertations, Theses, and Student Research
Inland, coastal, and estuarine waters, which are often turbid and biologically productive, play a crucial role in maintaining global bio-diversity and are of immense value to aquatic life as well as human-beings. Concentration of chlorophyll-a (chl-a) is a key indicator of the trophic status of these waters, which should be regularly monitored to ensure that their ecological balance is not disturbed. Remote sensing is a powerful tool for this.
Due to the optical complexity of turbid productive waters, standard algorithms that use blue and green reflectances are unreliable for estimating chl-a concentration. Algorithms based on red and near-infrared (NIR) reflectances …