Physical Sciences and Mathematics Commons^™

Comparison Of Instream Methods For Measuring Hydraulic Conductivity In Sandy Streambeds, Matthew K. Landon, David L. Rus, F. Edwin Harvey

School of Natural Resources: Faculty Publications

Streambed hydraulic conductivity (K) values were determined at seven stream transects in the Platte River Basin in Nebraska using different instream measurement techniques. Values were compared to determine the most appropriate technique(s) for use in sandy streambeds. Values of K determined from field falling- and constant-head permeameter tests analyzed using the Darcy equation decreased as permeameter diameter increased. Seepage meters coupled with hydraulic gradient measurements failed to yield K values in 40% of the trials. Consequently, Darcy permeameter and seepage meter tests were not preferred approaches. In the upper 0.25 m of the streambed, field falling- and constant-head permeameter tests …

Reflectance Spectral Features And Detection Of Superficial Scald–Induced Browning In Storing Apple Fruit, Olga B. Chivkunova, Alexei E. Solovchenko, S. G. Sokolova, Mark N. Merzlyak, I. V. Reshetnikova, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

Reflectance (R) spectra of Antonovka apples in the visible and near infrared ranges of the spectrum were studied during fruit storage. Specific spectral features of reflectance of healthy ripening fruits and those arising as a result of superficial scald development and browning induced artificially by n–hexane treatment were revealed and compared. Both superficial scald and n–hexane treatment brought about a strong decrease of reflectance, especially, in the green near 550 nm. During natural fruit ripening in the absence of superficial scald development, a high correlation was found between reflectances at 550 and 700 nm. In contrast, as a …

Do Species And Functional Groups Differ In Acquisition And Use Of C, N And Water Under Varying Atmospheric Co2 And N Availability Regimes? A Field Test With 16 Grassland Species, Peter B. Reich, David Tilman, Joseph Craine, David Ellsworth, Mark G. Tjoelker, Johannes M. H. Knops, David A. Wedin, Shahid Naeem, Dan Bahauddin, Jenny Goth, Wendy Bengtson, Tali D. Lee

School of Natural Resources: Faculty Publications

Summary:

• To evaluate whether functional groups have a similar response to global change, the responses to CO₂ concentration and N availability of grassland species from several functional groups are reported here.
• Sixteen perennial grassland species from four trait-based functional groups (C₃ grasses, C₄ grasses, non-leguminous forbs, legumes) were grown in field mono-cultures under ambient or elevated (560 μmol mol^-1) CO₂using free-air CO₂enrichment (FACE), in low N (unamended field soil) or high N (field soil + 4 g N m^-2 years^-1) treatments.
• There were no CO …

Gap Filling Strategies For Long Term Energy Flux Data Sets, Eva Falge, Dennis D. Baldocchi, Richard Olson, Peter Anthoni, Marc Aubinet, Christian Bernhofer, George Burba, Reinhart Ceulemans, Robert Clement, Han Dolman, Andre Granier, Patrick Gross, Thomas Grunwald, David Hollinger, Niels-Otto Jensen, Gabriel Katul, Petri Keronen, Andrew Kowalski, Chun Ta Lai, Beverly E. Law, Tilden Meyers, John Moncrieff, Eddy Moors, J. William Munger, Kim Pilegaard, Ullar Rannik, Corinna Rebmann, Andrew E. Suyker, John Tenhunen, Kevin Tu, Shashi Verma, Timo Vesala, Kell Wilson, Steve Wofsy

School of Natural Resources: Faculty Publications

At present a network of over 100 field sites are measuring carbon dioxide, water vapor and sensible heat fluxes between the biosphere and atmosphere, on a nearly continuous basis. Gaps in the long term measurements of evaporation and sensible heat flux must be filled before these data can be used for hydrological and meteorological applications. We adapted methods of gap filling for NEE (net ecosystem exchange of carbon) to energy fluxes and applied them to data sets available from the EUROFLUX and AmeriFlux eddy covariance databases. The average data coverage for the sites selected was 69% and 75% for latent …

Gap Filling Strategies For Defensible Annual Sums Of Net Ecosystem Exchange, Eva Falge, Dennis D. Baldocchi, Richard Olson, Peter Anthoni, Marc Aubinet, Christian Bernhofer, George Burba, Reinhart Ceulemans, Robert Clement, Han Dolman, Andre Grainer, Thomas Grunwald, David Hollinger, Niels-Otto Jensen, Gabriel Katul, Petri Keronen, Andrew Kowalski, Chun Ta Lai, Beverly E. Law, Tilden Meyers, Jon Moncrieff, Eddy Moors, J. William Munger, Kim Pilegaard, Ullar Rannik, Corinna Rebmann, Andrew E. Suyker, John Tenhunen, Kevin Tu, Shashi Verma, Timo Vesala, Kell Wilson, Steve Wofsy

School of Natural Resources: Faculty Publications

Heightened awareness of global change issues within both science and political communities has increased interest in using the global network of eddy covariance flux towers to more fully understand the impacts of natural and anthropogenic phenomena on the global carbon balance. Comparisons of net ecosystem exchange (F_NEE) responses are being made among biome types, phenology patterns, and stress conditions. The comparisons are usually performed on annual sums of F_NEE; however, the average data coverage during a year is only 65%. Therefore, robust and consistent gap filling methods are required.

We review several methods of gap …

Fluxnet: A New Tool To Study The Temporal And Spatial Variability Of Ecosystem-Scale Carbon Dioxide, Water Vapor, And Energy Flux Densities, Dennis Baldocchi, Eva Falge, Lianhong Gu, Richard Olson, David Hollinger, Steve Running, Peter Anthoni, Ch. Bernhofer, Kenneth Davis, Robert Evans, Jose Fuente, Allen Goldstein, Gabriel Katul, Beverly Law, Xuhui Lee, Yadvinder Malhi, Tilden Meyers, William Munge, Walt Oechel, K.T. Paw U, Kim Pilegaard, H.P. Schmid, Riccardo Valentini, Shashi Verma, Timo Vesala, Kell Wilson, Steve Wofsy

School of Natural Resources: Faculty Publications

FLUXNET is a global network of micrometeorological flux measurement sites that measure the exchanges of carbon dioxide, water vapor, and energy between the biosphere and atmosphere. At present over 140 sites are operating on a long-term and continuous basis. Vegetation under study includes temperate conifer and broadleaved (deciduous and evergreen) forests, tropical and boreal forests, crops, grasslands, chaparral, wetlands, and tundra. Sites exist on five continents and their latitudinal distribution ranges from 70°N to 30°S.

FLUXNET has several primary functions. First, it provides infrastructure for compiling, archiving, and distributing carbon, water, and energy flux measurement, and meteorological, plant, and soil …

Test Of An Extended Mathematical Approach To Calculate Maize Leaf Area Index And Leaf Angle Distribution, Elizabeth A. Walter-Shea, Mark A. Mesarch

School of Natural Resources: Faculty Publications

No abstract provided.

Evaluation Of An Algorithm For Predicting Albedo In Heliotropic Crops, Elizabeth A. Walter-Shea, A. Weiss

School of Natural Resources: Faculty Publications

No abstract provided.

Value Of Incorporating Satellite-Derived Land Cover Data In Mm5/Place For Simulating Surface Temperatures, Todd M. Crawford, David J. Stensrud, Franz Mora, James W. Merchant, Peter J. Wetzel

School of Natural Resources: Faculty Publications

The Parameterization for Land–Atmosphere–Cloud Exchange (PLACE) module is used within the Fifth- Generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) to determine the importance of individual land surface parameters in simulating surface temperatures. Sensitivity tests indicate that soil moisture and the coverage and thickness of green vegetation [as manifested by the values of fractional green vegetation coverage (fVEG) and leaf area index (LAI)] have a large effect on the magnitudes of surface sensible heat fluxes. The combined influence of LAI and fVEG is larger than the influence of soil moisture on the partitioning of the surface energy …

Some Perspectives On Recent In Situ Air Temperature Observations: Modeling The Microclimate Inside The Radiation Shields*, X. Lin, Kenneth Hubbard, Elizabeth A. Walter-Shea, James Brandle, G.E. Meyer

School of Natural Resources: Faculty Publications

Air temperature measurement has inherent biases associated with the particular radiation shield and sensor deployed. The replacement of the Cotton Region Shelter (CRS) with the Maximum–Minimum Temperature System (MMTS) and the introduction of Automated Surface Observing System (ASOS) air temperature observing systems during the NWS modernization introduced bias shifts in federal networks that required quantification. In rapidly developing nonfederal networks, the Gill shield temperature systems are widely used. All of these systems house an air temperature sensor in a radiation shield to prevent radiation loading on the sensors; a side effect is that the air temperature entering a shield is …

Impacts Of Predation On Northern Bobwhite And Scaled Quail, Dale Rollins, John P. Carroll

School of Natural Resources: Faculty Publications

Northern bobwhite (Colinus virginianus) and scaled quail (Callipepla squamata) populations have declined throughout most of their distribution, and these declines have become more dramatic in recent years. In this review, we examine the role of predation in quail management. Predation is the major source of nest loss and of mortality for young and adult quail. Mean nest success across studies reviewed was 28%. Estimates of annual survival rates have varied from 5 to 26% for radiotelemetry studies and from 15 to 30% based on age-ratio studies. Breeding season survival estimates ranged from 13 to 51% in telemetry …

Bollgard Cotton: An Assessment Of Global Economic, Environmental, And Social Benefits, Julie M. Edge, John H. Benedict, John P. Carroll, H. Keith Reding

School of Natural Resources: Faculty Publications

Insect-protected crops like Bollgard (Monsanto Company, St. Louis) Bacillus thuringiensis (Bt) cotton are bringing cotton growers new alternatives to broad-spectrum insecticide use in integrated pest management. After five years (1996-2000) of commercial use, a number of benefits of Bt cotton technology to growers, the environment, and society at large have been reported; however, the benefits of the technology have not been examined to date from a holistic point of view. Accordingly, the objectives of this paper were to examine the potential economic, environmental, and social benefits of Bt cotton compared with broad-spectrum insecticide use, as reported in current literature, …

Field-Scale Remediation Of A Metolachlor-Contaminated Spill Site Using Zerovalent Iron, Steven Comfort, Patrick J. Shea, Thomas A. Machacek, H. Gaber, B.-T. Oh

School of Natural Resources: Faculty Publications

Pesticide spills are common occurrences at agricultural cooperatives and farmsteads. When inadvertent spills occur, chemicals normally beneficial can become point sources of ground and surface water contamination. We report results from a field trial where approximately 765 m³ of soil from a metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] spill site was treated with zerovalent iron (Fe⁰). Preliminary laboratory experiments confirmed metolachlor dechlorination by Fe⁰ in aqueous solution and that this process could be accelerated by adding appropriate proportions of Al₂(SO₄)₃ or acetic acid (CH₃COOH). The field project was …

Monthly Fractional Green Vegetation Cover Associated With Land Cover Classes Of The Conterminous Usa, Kevin P. Gallo, Dan Tarpley, Ken Mitchell, Ivan Csiszar, Timothy Owen, Brad Reed

School of Natural Resources: Faculty Publications

The land cover classes developed under the coordination of the International Geosphere-Biosphere Programme Data and Information System (IGBP-DIS) have been analyzed for a study area that includes the Conterminous United States and portions of Mexico and Canada

Escherichia Coli O157:H7 In Free-Ranging Deer In Nebraska, David G. Renter, Jan M. Sargeant, Scott E. Hygnstrom, Jeff D. Hoffmann, Jerry R. Gillespie

School of Natural Resources: Faculty Publications

In order to determine the prevalence and distribution of the human pathogen, Escherichia coli O157:H7, in free-ranging deer, hunters were asked to collect and submit fecal samples from deer harvested during a regular firearm season (14–22 November 1998). Prior to the season, 47% of the hunters with permits in the southeastern Nebraska (USA) study area indicated a willingness to participate in the study. Approximately 25% of successful hunters in the area submitted deer fecal samples. Escherichia coli O157:H7 was cultured from four (0.25%) of 1,608 total samples submitted. All of the fecal samples that were properly identified (1,426) and all …

Non-Destructive And Remote Sensing Techniques For Estimation Of Vegetation Status, Anatoly A. Gitelson, M. N. Merzlyak, Y. Zur, R. Stark, U. Gritz

School of Natural Resources: Faculty Publications

The goal of this work is to develop non-destructive techniques that can conveniently, rapidly and accurately assess crop physiological status and objectively evaluate plant responses to environmental factors, both natural and anthropogenic. High spectral resolution reflectance and absorption spectra of different and unrelated plant species were analyzed to determine spectral variability and information content in the visible and near-infrared spectrum at leaf and canopy levels. Techniques were developed to quantitatively retrieve chlorophyll, carotenoid and anthocyanin content from reflectance in a wide range of pigment content and composition.

Techniques for vegetation fraction retrieval those based on channels in visible range of …

Remote Estimation Of Vegetation Fraction In Corn Canopies, D. Rundquist, Anatoly A. Gitelson, D. Derry, J. Ramirez, R. Stark, Galina P. Keydan

School of Natural Resources: Faculty Publications

The aim of the paper was to test two new techniques that make use of channels in the visible range of the spectrum only to estimate vegetation fraction in corn canopies. High spectral resolution radiometers were employed to measure spectral reflectance, and the information content of spectra was investigated. Radiances in spectral channels of MODIS and MERIS were used to calculate Visible Atmospherically Resistant Indices, VARI_green=(R_green- R_red)/(R_green+R_red-R_blue) and VARI₇₀₀=(R₇₀₀-1.7*R_red+0.7*R_blue)/(R₇₀₀+2.3*R_red-1.3*R_blue). The indices allowed for estimation …

Estimating Abundance Of Galliformes: Tools And Application, Michael J. Conroy, John P. Carroll

School of Natural Resources: Faculty Publications

A large number of techniques are available for assessing populations of vertebrates. However, application of many of those techniques to Galliformes is hampered by a variety of constraints. These problems are often magnified by poor understanding of the biology of many species of concern, and an absence of valid estimates of abundance and demographic parameters. Researchers interested in developing estimates of Galliformes populations must address a number of key issues before collecting field data, to avoid biases in the resulting population estimates. General guidance exists for the identification of appropriate population estimation techniques, and a dichotomous key has been developed …

Geochemical Evolution Of Ground Water In The Great Plains (Dakota) Aquifer Of Nebraska: Implications For The Management Of A Regional Aquifer System, David C. Gosselin, F. Edwin Harvey, Carol D. Frost

School of Natural Resources: Faculty Publications

The Great Plains (Dakota) aquifer system is one of the most extensive in North America, extending from the Arctic Circle to New Mexico, and underlies approximately 94% of Nebraska. In Nebraska, we do not have the physical ground water monitoring data at the scale that is necessary to manage ground water flow systems. However, first-order management strategies for this regional aquifer can be developed by understanding the geochemical evolution of the ground water. Using major-ion water chemistry data from 203 wells in 19 counties in eastern Nebraska, reconnaissance δ¹⁸O, δD, and δ⁸⁷Sr data, and two geochemical …