Physical Sciences and Mathematics Commons^™

First Record Of Pseudorabies In Feral Swine In Nebraska, Sam Wilson, Alan R. Doster, Justin D. Hoffman, Scott E. Hygnstrom

School of Natural Resources: Faculty Publications

In 2007, two new populations of feral swine were discovered in Nance and Valley counties, Nebraska, USA. Necropsies and serologic testing was done on two individuals from the Nance County herd. Results indicated that a lactating sow had positive antibodies for pseudorabies virus (PRV). Investigations conducted by Nebraska Game and Parks Commission Law Enforcement division confirmed that the infected individual was transported illegally to Nebraska, USA, from Texas, USA. All domestic swine herds located within an 8 km radius of the infected individual tested negative for antibodies to PRV. Our results provide a clear example of how diseases can spread …

A Modified Advection-Aridity Model Of Evapotranspiration, Jozsef Szilagyi, Michael T. Hobbins, Janos Jozsa

School of Natural Resources: Faculty Publications

No abstract provided.

Analytical Solution Of The Coupled 2-D Turbulent Heat And Vapor Transport Equations And The Complementary Relationship Of Evaporation, Jozsef Szilagyi, Janos Jozsa

School of Natural Resources: Faculty Publications

No abstract provided.

Estimating Spatially Distributed Monthly Evapotranspiration Rates By Linear Transformations Of Modis Daytime Land Surface Temperature Data, J. Szilagyi, J. Jozsa

School of Natural Resources: Faculty Publications

No abstract provided.

Nutrient Uptake And Mineralization During Leaf Decay In Streams – A Model Simulation, J. R. Webster, J. D. Newbold, Steven A. Thomas, P. J. Mulholland

School of Natural Resources: Faculty Publications

We developed a stoichiometrically explicit computer model to examine how heterotrophic uptake of nutrients and microbial mineralization occurring during the decay of leaves in streams may be important in modifying nutrient concentrations. The simulations showed that microbial uptake can substantially decrease stream nutrient concentrations during the initial phases of decomposition, while mineralization may produce increases in concentrations during later stages of decomposition. The simulations also showed that initial nutrient content of the leaves can affect the stream nutrient concentration dynamics and determine whether nitrogen or phosphorus is the limiting nutrient. Finally, the simulations suggest a net retention (uptake > mineralization) of …

Characterizing The Seasonal Dynamics Of Plant Community Photosynthesis Across A Range Of Vegetation Types, Lianhong Gu, Wilfred M. Post, Dennis D. Baldocchi, T. Andrew Black, Andrew E. Suyker, Shashi Verma, Timo Vesala, Steve C. Wofsy

School of Natural Resources: Faculty Publications

The seasonal cycle of plant community photosynthesis is one of the most important biotic oscillations to mankind. This study built upon previous efforts to develop a comprehensive framework to studying this cycle systematically with eddy covariance flux measurements. We proposed a new function to represent the cycle and generalized a set of phenological indices to quantify its dynamic characteristics. We suggest that the seasonal variation of plant community photosynthesis generally consists of five distinctive phases in sequence each of which results from the interaction between the inherent biological and ecological processes and the progression of climatic conditions and reflects the …

Spring Home Ranges Of White Bass In Irrigation Reservoirs Of The Republican River Basin, Nebraska, D. R. Martin, Larkin A. Powell, Kevin L. Pope

School of Natural Resources: Faculty Publications

Fishery biologists have documented small home ranges, relative to available habitat, for many littoral freshwater fishes. Home ranges for pelagic species, such as white bass Morone chrysops, are generally not well described, yet are thought to be large. We studied white bass movement using acoustic telemetry in two irrigation reservoirs of the Republican River basin in south-western Nebraska. Acoustic transmitters were implanted in fall of the previous year and tracking occurred a minimum of once per week throughout spring (mid-March to May) 2007 and 2008. Linear home ranges were calculated from observed locations of individual fish. Twelve of the …

Latitudinal Patterns Of Magnitude And Interannual Variability In Net Ecosystem Exchange Regulated By Biological And Environmental Variables, Wenping Yuan, Yiqi Luo, Andrew D. Richardson, Ram Oren, Sebastiaan Luyssaert, Ivan A. Janssens, Reinhart Ceulemans, Xuhui Zhou, Thomas Grünwald, Marc Aubinet, Christian Berhofer, Dennis D. Baldocci, Jiquan Chen, Allison L. Dunn, Jared L. Deforest, Danilo Dragoni, Allen H. Goldstein, Eddy Moors, J. William William Munger, Russell K. Monson, Andrew E. Suyker, Gregory Starr, Russell L. Scott, John Tenhunen, Shashi Verma, Timo Vesala, Steven C. Wofsy

School of Natural Resources: Faculty Publications

Over the last two and half decades, strong evidence showed that the terrestrial ecosystems are acting as a net sink for atmospheric carbon. However the spatial and temporal patterns of variation in the sink are not well known. In this study, we examined latitudinal patterns of interannual variability (IAV) in net ecosystem exchange (NEE) of CO₂ based on 163 site-years of eddy covariance data, from 39 northern-hemisphere research sites located at latitudes ranging from ~29°N to ~ 64°N. We computed the standard deviation of annual NEE integrals at individual sites to represent absolute interannual variability (AIAV), and the corresponding …

Seasonal Changes In Depth Of Water Uptake For Encroaching Trees Juniperus Virginiana And Pinus Ponderosa And Two Dominant C4 Grasses In A Semiarid Grassland, Kathleen D. Eggemeyer, Tala Awada, F. Edwin Harvey, David A. Wedin, Xinhua Zhou, C. William Zanner

School of Natural Resources: Faculty Publications

We used the natural abundance of stable isotopic ratios of hydrogen and oxygen in soil (0.05–3 m depth), plant xylem and precipitation to determine the seasonal changes in sources of soil water uptake by two native encroaching woody species (Pinus ponderosa P. & C. Lawson, Juniperus virginiana L.), and two C₄ grasses (Schizachyrium scoparium (Michx.) Nash, Panicum virgatum L.), in the semiarid Sandhills grasslands of Nebraska. Grass species extracted most of their water from the upper soil profile (0.05–0.5 m). Soil water uptake from below 0.5 m depth increased under drought, but appeared to be minimal in …

Landscape Structure Control On Soil Co2 Efflux Variability In Complex Terrain: Scaling From Point Observations To Watershed Scale Fluxes, Diego Andrés Riveros-Iregui, Brian L. Mcglynn

School of Natural Resources: Faculty Publications

We investigated the spatial and temporal variability of soil CO₂ efflux across 62 sites of a 393-ha complex watershed of the northern Rocky Mountains. Growing season (83 day) cumulative soil CO₂ efflux varied from ~300 to ~2000 g CO₂ m^—2, depending upon landscape position, with a median of 879.8 g CO₂ m^—2. Our findings revealed that highest soil CO₂ efflux rates were observed in areas with persistently high soil moisture (riparian meadows), whereas lower soil CO₂ efflux rates were observed on forested uplands (98% of watershed area). Furthermore, upslope accumulated …

Differential Soil Respiration Responses To Changing Hydrologic Regimes, Vincent J. Pacific, Brian L. Mcglynn, Diego Andrés Riveros-Iregui, Howard E. Epstein, Daniel J. Welsch

School of Natural Resources: Faculty Publications

Soil respiration is tightly coupled to the hydrologic cycle (i.e., snowmelt and precipitation timing and magnitude). We examined riparian and hillslope soil respiration across a wet (2005) and a dry (2006) growing season in a subalpine catchment. When comparing the riparian zones, cumulative CO₂ efflux was 33% higher, and peak efflux occurred 17 days earlier during the dry growing season. In contrast, cumulative efflux in the hillslopes was 8% lower, and peak efflux occurred 10 days earlier during the drier growing season. Our results demonstrate that soil respiration was more sensitive to drier growing season conditions in wet (riparian) …

Integrating Remote Sensing And Geographic Information Systems, James W. Merchant, Sunil Narumalani

School of Natural Resources: Faculty Publications

Remote sensing and geographic information systems (GIS) comprise the two major components of geographic information science (GISci), an overarching field of endeavor that also encompasses global positioning systems (GPS) technology, geodesy and traditional cartography (Goodchild 1992, Estes and Star 1993, Hepner et al. 2005). Although remote sensing and GIS developed quasi-independently, the synergism between them has become increasingly apparent (Aronoff 2005). Today, GIS software almost always includes tools for display and analysis of images, and image processing software commonly contains options for analyzing ‘ancillary’ geospatial data (Faust 1998). The significant progress made in ‘integration’ of remote sensing and GIS has …

Remote Sensing Of Cropland Agriculture, M. Duane Nellis, Kevin P. Price, Donald Rundquist

School of Natural Resources: Faculty Publications

Remote sensing has long been used in monitoring and analyzing agricultural activities. Well prior to the first coining of the term ‘remote sensing’ in 1958 by Eveyln Pruitt of the U.S. Office of Naval Research (Estes and Jensen 1998), scientists were using aerial photography to complete soil and crop surveys associated with agricultural areas in the United States and other parts of the world (Goodman 1959). Most of such work in the 1930s involved general crop inventories by the U.S. Department of Agriculture and soil survey mapping as part of the work of the then U.S. Soil Conservation Service. With …

Non-Destructive Estimation Of Anthocyanins And Chlorophylls In Anthocyanic Leaves, Anatoly A. Gitelson, Olga B. Chivkunova, Mark N. Merzlyak

School of Natural Resources: Faculty Publications

The anthocyanin and chlorophyll contents in leaves provide valuable information about the physiological status of plants. Thus, there is a need for accurate, efficient, and practical methodologies to estimate these biochemical parameters of vegetation. In this study, we tested the performance and accuracy of several nondestructive, reflectance-based techniques for estimating anthocyanin and chlorophyll contents in leaves of four unrelated species, European hazel ( Corylus avellana ), Siberian dogwood ( Cornus alba = Swida alba ), Norway maple ( Acer platanoides ), and Virginia creeper ( Parthenocissus quinquefolia ), with widely variable pigment content and composition. An anthocyanin reflectance index, which …

Non-Destructive Detection Of Water Stress And Estimation Of Relative Water Content In Maize, Art I. Zygielbaum, Anatoly A. Gitelson, Timothy J. Arkebauer, Donald C. Rundquist

School of Natural Resources: Faculty Publications

Non-destructive estimation of leaf water content provides vital information about vegetation productivity. We report here on controlled seven day experiments using greenhouse-grown maize. Fifty plants were randomly assigned to two equal groups: water stressed and well watered. Spectroscopic, relative water content (RWC), and chlorophyll concentration measurements were made daily. Because water molecules absorb radiation in near- and middle-infrared, most efforts to sense water deficit remotely utilize infrared wavelengths. In these experiments, we identified a strong, systematic, and repeatable relationship between photosynthetically active radiation (PAR, 400-700 nm) albedo and leaf RWC. We show that visible spectrum reflectance provides a means to …

Nondestructive Estimation Of Anthocyanin Content In Grapevine Leaves, Mark R. Steele, Anatoly A. Gitelson, Donald C. Rundquist, Mark N. Merzlyak

School of Natural Resources: Faculty Publications

The anthocyanin (Anth) content in leaves provides valuable information about the physiological status of plants. Thus, there is a need for accurate, efficient, practical methodologies to estimate this biochemical parameter. Reflectance measurement is a means of quickly and nondestructively assessing leaf Anth content in situ. The objective of this study was to test the overall performance and accuracy of nondestructive techniques for estimating Anth content in grapevine leaves. Relationships were established between Anth content and four vegetation indices: NIR (near-infrared)/green, red/green, anthocyanin reflectance index (ARI, based on reflectances in bands within the green and the red-edge regions), and a modified …

A Bio-Optical Algorithm For The Remote Estimation Of The Chlorophyll-A Concentration In Case 2 Waters, Anatoly A. Gitelson, Daniela Gurlin, Wesley Moses, Tadd Barrow

School of Natural Resources: Faculty Publications

The objective of this work was to test the performance of a recently developed three-band model and its special case, a two-band model, for the remote estimation of the chlorophyll-a (chl-a) concentration in turbid productive case 2 waters. We specifically focused on (a) determining the ability of the models to estimate chl-a < 20 mg m⁻³, typical for coastal and estuarine waters, and (b) assessing the potential of MODIS and MERIS to estimate chl-a concentrations in turbid productive waters, using red and near-infrared (NIR) bands. Reflectance spectra and water samples were collected in 89 stations over lakes in …

Estimation Of Chlorophyll-A Concentration In Case Ii Waters Using Modis And Meris Data—Successes And Challenges, Wesley J. Moses, Anatoly A. Gitelson, V. Povazhnyy

School of Natural Resources: Faculty Publications

We present and discuss here the results of our work using MODIS (moderate resolution imaging spectroradiometer) and MERIS (medium resolution imaging spectrometer) satellite data to estimate the concentration of chlorophyll-a (chl-a) in reservoirs of the Dnieper River and the Sea of Azov, which are typical case II waters, i.e., turbid and productive. Our objective was to test the potential of satellite remote sensing as a tool for near-real-time monitoring of chl-a distribution in these water bodies. We tested the performance of a recently developed three-band model, and its special case, a two-band model, which use the …

Variability Of Anaerobic Animal Waste Lagoon Delta15N Source Signatures, Sadayappan Mariappan, Mary Exner Spalding, Glen E. Martin, Roy F. Spalding

School of Natural Resources: Faculty Publications

High ammonium-N concentrations derived from animal wastes stored and partially treated in earthen anaerobic lagoons at confined feeding facilities can seep to groundwater. δ¹⁵N-NH₄⁺ values from +2.0 to +59.1‰ in 13 lagoons complicate identification of lagoon seepage as well as land-applied lagoon effluent in ground and surface waters. The spectrum of δ¹⁵N values requires site-specific isotope characterization of the potential source. Feed and fresh manure and urine δ¹⁵N values indicate that most N isotopic fractionation occurs after excretion. Lagoon management clearly affects enrichment. δ¹⁵N-total Kjeldahl N (TKN) and δ^{15 …}

Long-Term Agricultural Land-Use Trends In Nebraska, 1866–2007, Tim L. Hiller, Larkin A. Powell, Tim D. Mccoy, Jeffrey J. Lusk

School of Natural Resources: Faculty Publications

Although landscape changes from anthropogenic causes occur at much faster rates than those from natural processes (e.g., geological, vegetation succession), human perception of such changes is often subjective, inaccurate, or nonexistent. Given the large-scale land-use changes that have occurred throughout the Great Plains, the potential impacts of land-use changes on ecological systems, and the insight gained from knowledge of land-use trends (e.g., to compare to wildlife population trends), we synthesized information related to land-use trends in Nebraska during 1866–2007. We discussed and interpreted known and potential causes of short- and long-term land-use trends based on agricultural and weather data; farm …

Spring Home Ranges Of White Bass In Irrigation Reservoirs Of The Republican River Basin, Nebraska, D. R. Martin, Larkin A. Powell, K. L. Pope

School of Natural Resources: Faculty Publications

Fishery biologists have documented small home ranges, relative to available habitat, for many littoral freshwater fishes. Home ranges for pelagic species, such as white bass Morone chrysops, are generally not well described, yet are thought to be large. We studied white bass movement using acoustic telemetry in two irrigation reservoirs of the Republican River basin in south-western Nebraska. Acoustic transmitters were implanted in fall of the previous year and tracking occurred a minimum of once per week throughout spring (mid-March to May) 2007 and 2008. Linear home ranges were calculated from observed locations of individual fish. Twelve of the …

Ecological Divergence Of Two Sympatric Lineages Of Buggy Creek Virus, An Arbovirus Associated With Birds, Charles R. Brown, Abinash Padhi, Amy T. Moore, Mary Bomberger Brown, Jerome E. Foster, Martin Pfeffer, Valerie A. O'Brien, Nicholas Komar

School of Natural Resources: Faculty Publications

Most arthropod-borne viruses (arboviruses) show distinct serological subtypes or evolutionary lineages, with the evolution of different strains often assumed to reflect differences in ecological selection pressures. Buggy Creek virus (BCRV) is an unusual RNA virus (Togaviridae, Alphavirus) that is associated primarily with a cimicid swallow bug (Oeciacus vicarius) as its vector and the Cliff Swallow (Petrochelidon pyrrhonota) and the introduced House Sparrow (Passer domesticus) as its amplifying hosts. There are two sympatric lineages of BCRV (lineages A and B) that differ from each other by .6% at the nucleotide level. Analysis of 385 …

2009 Interior Least Tern And Piping Plover Monitoring, Research, Management, And Outreach Report For The Lower Platte River, Nebraska, Mary Bomberger Brown, Joel G. Jorgensen

School of Natural Resources: Faculty Publications

This document reports on our monitoring, research, management, and outreach activities during the past 12 months (2009). We prepared it to inform our partners, cooperating agencies, funding sources, and other interested parties of our activities and to provide a preliminary summary of our results.

The Tern and Plover Conservation Partnership (TPCP), based at the University of Nebraska–School of Natural Resources, and the Nongame Bird Program (NBP), based at the Nebraska Game and Parks Commission (NGPC) work cooperatively on Interior Least Tern and Piping Plover monitoring, research, management, and education-outreach activities. While the proximate focus of our work is the Lower …

Incorporation Of Crop Phenology In Simple Biosphere Model (Sibcrop) To Improve Land-Atmosphere Carbon Exchanges From Croplands, Erandathie Lokupitiya, S. Denning, K. Paustian, I. Baker, K. Schaefer, Shashi B. Verma, T. Meyers, C. J. Bernacchi, Andrew E. Suyker, M. L. Fischer

School of Natural Resources: Faculty Publications

Croplands are man-made ecosystems that have high net primary productivity during the growing season of crops, thus impacting carbon and other exchanges with the atmosphere. These exchanges play a major role in nutrient cycling and climate change related issues. An accurate representation of crop phenology and physiology is important in land-atmosphere carbon models being used to predict these exchanges. To better estimate time-varying exchanges of carbon, water, and energy of croplands using the Simple Biosphere (SiB) model, we developed crop-specific phenology models and coupled them to SiB. The coupled SiBphenology model (SiBcrop) replaces remotely-sensed NDVI information, on which SiB originally …

Corrigendum To “Incorporation Of Crop Phenology In Simple Biosphere Model (Sibcrop) To Improve Land-Atmosphere Carbon Exchanges From Croplands” Published In Biogeosciences, 6, 969–986, 2009, Erandathie Lokupitiya, S. Denning, K. Paustian, I. Baker, K. Schaefer, Shashi B. Verma, T. Meyers, C. J. Bernacchi, Andrew E. Suyker, M. L. Fischer

School of Natural Resources: Faculty Publications

In the above mentioned manuscript a mistake in Fig. 11 occured. The corrected version of the figure is as follows.

A Century Of Climate Change For Fairbanks, Alaska, Gerd Wendler, Martha Shulski

School of Natural Resources: Faculty Publications

Climatological observations are available for Fairbanks, Interior Alaska, for up to 100 years. This is a unique data set for Alaska, insofar as it is of relatively high quality and without major breaks. Applying the best linear fit, we conclude that the mean annual temperature rose from -3.6°C to -2.2°C over the century, an increase of 1.4°C (compared to 0.8°C worldwide). This comparison clearly demonstrates the well-known amplification or temperature change for the polar regions. The observed temperature increase is neither uniform over the time period nor uniform throughout the course of a year. The winter, spring, and summer seasons …

Lithobates Catesbeianus (American Bullfrog) Predation On Cliff Swallows, Mary Bomberger Brown, Charles R. Brown

School of Natural Resources: Faculty Publications

During a 25-year study of Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, we observed Lithobates catesbeianus prey on, or attempt to prey on, Cliff Swallows. As we were mist-netting Cliff Swallows at a 10-nest colony on 7 July 1998, a L. catesbeianus attempted to eat a Cliff Swallow that was caught in the net.

Lichen Recovery Following Heavy Grazing By Reindeer Delayed By Climate Warming, David R. Klein, Martha Shulski

School of Natural Resources: Faculty Publications

Introduced reindeer, Rangifer tarandus, over exploited lichen-rich plant communities on St. Matthew Island in the Bering Sea. A die-off of the reindeer followed, exacerbated by extreme weather in 1964, resulting in extirpation of the reindeer. A similar pattern of removal of lichens as major components of plant communities has occurred following introductions of reindeer to other islands at high latitudes. By 1985, two decades following die-off of the reindeer, total lichen biomass was only 6% of that in similar plant communities on adjacent Hall Island, not reached by the reindeer. By 2005, 41 y after the reindeer die-off, lichen …

Probabilistic Movement Model With Emigration Simulates Movements Of Deer In Nebraska, 1990–2006, Charles J. Frost, Scott E. Hygnstrom, Andrew J. Tyre, Kent M. Eskridge, David M. Baasch, Justin R. Boner, Gregory M. Clements, Jason M. Gilsdorf, Travis C. Kinsell, Kurt C. Vercauteren

School of Natural Resources: Faculty Publications

Movements of deer can affect population dynamics, spatial redistribution, and transmission and spread of diseases. Our goal was to model the movement of deer in Nebraska in an attempt to predict the potential for spread of chronic wasting disease (CWD) into eastern Nebraska. We collared and radio-tracked >600 white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) in Nebraska during 1990–2006.We observed large displacements (>10 km) for both species and sexes of deer, including migrations up to 100 km and dispersals up to 50 km. Average distance traveled between successive daily locations was 166m for …

Scaling Up Of Co2 Fluxes From Leaf To Canopy In Maize-Based Agroecosystems, Timothy J. Arkebauer, Elizabeth A. Walter-Shea, Mark A. Mesarch, Andrew E. Suyker, Shashi Verma

School of Natural Resources: Faculty Publications

Carbon dioxide fluxes are being measured in three maize-based agroecosystems in eastern Nebraska in an effort to better understand the potential for these systems to sequester carbon in the soil. Landscape-level fluxes of carbon, water and energy were measured using tower eddy covariance systems. In order to better understand the landscape-level results, measurements at smaller scales, using techniques promoted by John Norman, were made and scaled up to the landscape-level. Single leaf gas exchange properties (CO₂ assimilation rate and stomatal conductance) and optical properties, direct and diffuse radiation incident on the canopy, and photosynthetically active radiation (PAR) reflected and …