Physical Sciences and Mathematics Commons^™

Assistance With Wildlife Damage Problems In Nebraska, Scott E. Hygnstrom, John M. Hobbs, James G. Bruner, James Weverka, Dallas R. Virchow, Dennis M. Ferraro

Papers in Natural Resources

Nebraskans who experience damage and nuisance problems with wildlife can get assistance from several public and private organizations. This NebFact describes the most direct route to the solution of your problem. A reference guide (Table I) lists who to contact for information, materials, permits, and hands-on assistance. Wildlife play an important role in our environment. In addition, we gain many recreational, economic, and aesthetic benefits from them. Unfortunately, the activities of wildlife occasionally conflict with human interests in personal property, agricultural production, and health and safety. The most common wildlife damage and nuisance problems in Nebraska are caused by bats, …

Planning For Robust Reserve Networks Using Uncertainty Analysis, Atte Moilanen, Michael C. Runge, Jane Elith, Andrew Tyre, Yohay Carmel, Eric Fegraus, Brendan A. Wintle, Mark Burgman, Yakov Ben-Haim

Papers in Natural Resources

Planning land-use for biodiversity conservation frequently involves computer-assisted reserve selection algorithms. Typically such algorithms operate on matrices of species presence–absence in sites, or on species-specific distributions ofmodel predicted probabilities of occurrence in grid cells. There are practically always errors in input data—erroneous species presence–absence data, structural and parametric uncertainty in predictive habitat models, and lack of correspondence between temporal presence and long-run persistence. Despite these uncertainties, typical reserve selection methods proceed as if there is no uncertainty in the data or models. Having two conservation options of apparently equal biological value, one would prefer the option whose value is relatively …

Price Elasticity Reconsidered: Panel Estimation Of An Agricultural Water Demand Function, Karina Schoengold, David L. Sunding, Georgina Moreno

Papers in Natural Resources

Using panel data from a period of water rate reform, this paper estimates the price elasticity of irrigation water demand. Price elasticity is decomposed into the direct effect of water management and the indirect effect of water price on choice of output and irrigation technology. The model is estimated using an instrumental variables strategy to account for the endogeneity of technology and output choices in the water demand equation. Estimation results indicate that the price elasticity of agricultural water demand is -0.79, which is greater than that found in previous studies.

Ecophysiology Of Two Native Invasive Woody Species And Two Dominant Warm-Season Grasses In The Semiarid Grasslands Of The Nebraska Sandhills, Kathleen D. Eggemeyer, Tala Awada, David A. Wedin, F. Edwin Harvey, Xinhua Zhou

Papers in Natural Resources

Populations of Pinus ponderosa and Juniperus virginiana are expanding into semiarid Sandhills grasslands in Nebraska. To evaluate the physiological basis of their success, we measured the seasonal course of leaf gas exchange, plant water status, and carbon isotope discrimination in these two native trees and two native C₄ grasses (Schizachyrium scoparium and Panicum virgatum). Compared to the trees, grasses had higher net photosynthetic rates (A_net) and water use efficiency (WUE) and more negative predawn and midday water potentials (Ψ) in June and July. While leaf Ψ and rates of leaf gas exchange declined for all …

Climate Variability Has A Stabilizing Effect On The Coexistence Of Prairie Grasses, Peter B. Adler, Janneke Hille Ris Lambers, Phaedon C. Kyriakidis, Qingfeng Guan, Jonathan M. Levine

Papers in Natural Resources

How expected increases in climate variability will affect species diversity depends on the role of such variability in regulating the coexistence of competing species. Despite theory linking temporal environmental fluctuations with the maintenance of diversity, the importance of climate variability for stabilizing coexistence remains unknown because of a lack of appropriate long-term observations. Here, we analyze three decades of demographic data from a Kansas prairie to demonstrate that interannual climate variability promotes the coexistence of three common grass species. Specifically, we show that (i) the dynamics of the three species satisfy all requirements of ‘‘storage effect’’ theory based on recruitment …

Planning For Robust Reserve Networks Using Uncertainty Analysis, Atte Moilanen, Michael Runge, Jane Elith, Andrew J. Tyre, Yohay Carmel, Eric Fegraus, Brendan A. Wintle, Mark A. Burgman, Yakov Ben-Haim

Papers in Natural Resources

Planning land-use for biodiversity conservation frequently involves computer-assisted reserve selection algorithms. Typically such algorithms operate on matrices of species presence–absence in sites, or on species-specific distributions of model predicted probabilities of occurrence in grid cells. There are practically always errors in input data—erroneous species presence–absence data, structural and parametric uncertainty in predictive habitat models, and lack of correspondence between temporal presence and long-run persistence. Despite these uncertainties, typical reserve selection methods proceed as if there is no uncertainty in the data or models. Having two conservation options of apparently equal biological value, one would prefer the option whose value is …

Monitoring Sustainability In Tropical Forests: How Changes In Canopy Spatial Pattern Can Indicate Forest Stands For Biodiversity Surveys, Naikoa Aguilar, Geoffrey Henobry

Papers in Natural Resources

Sustainable management of tropical forests has been identified as one of the main objectives for global conservation and management of carbon stocks. Toward this goal, managers need tools to determine whether current management practices are sustainable. Several international initiatives have been undertaken for the development of criteria and indicators to aid managers in moving toward sustainable practices. Despite these efforts, the question of how to apply and assess indicators remains to be answered from an operational, field-based perspective. Field surveys are expensive and time-consuming when management areas are large and in the face of logistical constraints. Thus, there is a …

An Experimental Approach To Modeling The Strength Of Canine Teeth, Patricia W. Freeman, Cliff A. Lemen

Papers in Natural Resources

The strength of canine teeth in several carnivores is found through direct fracture experiments. The average forces required to break the canines of adult animals are coyote 1170 N, red fox 533 N, bobcat 737 N and raccoon 512 N. Stresses created in teeth at the breaking load are predicted by finite-element analysis and beam theory. The ultimate tensile stress sustainable in these teeth is 338 MPa in adult animals. The large pulp cavity in the canines of young animals significantly weakens the bases of their teeth (by about 25%), but as the animal ages the pulp cavity decreases and …

Effect Of Bio-Optical Parameter Variability And Uncertainties In Reflectance Measurements On The Remote Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters: Modeling Results, Giorgio Dall'olmo, Anatoly A. Gitelson

Papers in Natural Resources

Most algorithms for retrieving chlorophyll-a concentration (Chla) from reflectance spectra assume that bio-optical parameters such as the phytoplankton specific absorption coefficient (a_φ*) or the chlorophyll-a fluorescence quantum yield (η) are constant. Yet there exist experimental data showing large ranges of variability for these quantities. The main objective of this study was to analyze the sensitivity of two Chla algorithms to variations in bio-optical parameters and to uncertainties in reflectance measurements. These algorithms are specifically designed for turbid productive waters and are based on red and near-infrared reflectances. By means of simulated data, it is shown …

Patterns In Body Mass Distributions: Sifting Among Alternative Hypotheses, Craig R. Allen, A. S. Garmestani, T. D. Havlicek, P. A. Marquet, G. D. Peterson, C. Restrepo, C. A. Stow, B. E. Weeks

Papers in Natural Resources

Understanding how animals interact with their environment is critical for evaluating, mitigating and coping with anthropogenic alteration of Earth’s biosphere. Researchers have attempted to understand some aspects of these interactions by examining patterns in animal body mass distributions. Energetic, phylogenetic, biogeographical, textural discontinuity and community interaction hypotheses have been advanced to explain observed patterns. Energetic and textural discontinuity hypotheses focus upon the allometry of resource use. The community interaction hypothesis contends that biotic interactions within assemblages of species are of primary importance. Biogeographical and phylogenetic hypotheses focus on the role of constraints on the organization of communities. This paper examines …

Technical Documentation For The Approximate Point Locations And Year Of Collection For Over 50,000 Specimens In The University Of Michigan Herbarium's Michigan Flora Database, Rachel A. Simpson

Papers in Natural Resources

This is the technical documentation for a set of mapped points representing the approximate locations at which over 50,000 plant specimens were collected in Michigan. The specimens are a subset of those documented in the University of Michigan Herbarium's Michigan Flora Database, compiled by E.G. Voss.

A Multi-Site Analysis Of Random Error In Tower-Based Measurements Of Carbon And Energy Fluxes, Andrew D. Richardson, David Y. Hollinger, George C. Burba, Kenneth J. Davis, Lawrence B. Flanagan, Gabriel G. Katul, J. William Munger, Daniel M. Ricciuto, Paul C. Stoy, Andrew E. Suyker, Shashi Verma, Steven C. Wofsy

Papers in Natural Resources

Measured surface-atmosphere fluxes of energy (sensible heat, H, and latent heat, LE) and CO₂ (FCO₂) represent the ‘‘true’’ flux plus or minus potential random and systematic measurement errors. Here, we use data from seven sites in the AmeriFlux network, including five forested sites (two of which include “tall tower” instrumentation), one grassland site, and one agricultural site, to conduct a cross-site analysis of random flux error. Quantification of this uncertainty is a prerequisite to model-data synthesis (data assimilation) and for defining confidence intervals on annual sums of net ecosystem exchange or making statistically valid comparisons between …

Three-Band Model For Noninvasive Estimation Of Chlorophyll Carotenoids And Anthocyanin Contents In Higher Plant Leaves, Anatoly A. Gitelson, Galina P. Keydan, Mark N. Merzlyak

Papers in Natural Resources

Leaf pigment content and composition provide important information about plant physiological status. Reflectance measurements offer a rapid, nondestructive technique to estimate pigment content. This paper describes a recently developed three-band conceptual model capable of remotely estimating total of chlorophylls, carotenoids and anthocyanins contents in leaves from many tree and crop species. We tuned the spectral regions used in the model in accord with pigment of interest and the optical characteristics of the leaves studied, and showed that the developed technique allowed accurate estimation of total chlorophylls, carotenoids and anthocyanins, explaining more than 91%, 70% and 93% of pigment variation, respectively. …

Severe Convective Wind Environments, Evan L. Kuchera, Matthew D. Parker

Papers in Natural Resources

Nontornadic thunderstorm winds from long-lived, widespread convective windstorms can have a tremendous impact on human lives and property. To examine environments that support damaging wind producing convection, sounding parameters from Rapid Update Cycle model analyses (at 3-hourly intervals) from 2003 were compared with 7055 reports of damaging winds and 377 081 occurrences of lightning. Ground- relative wind velocity was the most effective at discriminating between damaging and nondamaging wind convective environments. Steep surface-based lapse rates (a traditional damaging wind parameter) gener- ally did not discriminate between damaging and nondamaging wind convective environments. Other pa- rameters, such as convective available potential …

A Hybrid, Markov Chain-Based Model For Daily Streamflow Generation At Multiple Catchment Sites, Jozsef Szilagyi, Gabor Balint, Andras Csik

Papers in Natural Resources

No abstract provided.

A Convective Line With Leading Stratiform Precipitation From Bamex, Brandom Storm, Matthew D. Parker, David P. Jorgensen

Papers in Natural Resources

On 31 May 2003, a front-fed convective line with leading stratiform precipitation (FFLS) was observed during the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX). The high-resolution BAMEX measurements provided one of the first opportunities to thoroughly observe the characteristics of an FFLS system. The 31 May system had an overturning updraft during its early stages, and produced leading stratiform precipitation. As the system matured, a jump updraft developed and the system began to produce trailing stratiform precipitation. It appears that this transition was facilitated by a local decrease in the low-level line-perpendicular vertical wind shear over time, as well …

Trend Identification In Twentieth-Century U.S. Snowfall: The Challenges, Kenneth E. Kunkel, Michael A. Palecki, Kenneth G. Hubbard, David A. Robinson, Kelly T. Redmond, David R. Easterling

Papers in Natural Resources

There is an increasing interest in examining long-term trends in measures of snow climatology. An examination of the U.S. daily snowfall records for 1900–2004 revealed numerous apparent inconsistencies. For example, long-term snowfall trends among neighboring lake-effect stations differ greatly from insignificant to +100% century -1.

Internal inconsistencies in the snow records, such as a lack of upward trends in maximum seasonal snow depth at stations with large upward trends in snowfall, point to inhomogeneities. Nationwide, the frequency of daily observations with a 10:1 snowfall-to-liquid-equivalent ratio declined from 30% in the 1930s to a current value of around 10%, a change …

Ecophysiology Of Two Native Invasive Woody Species And Two Dominant Warm-Season Grasses In The Semiarid Grasslands Of The Nebraska Sandhills, Kathleen D. Eggemeyer, Tala Awada, David A. Wedin, F. Edwin Harvey, Xinhua Zhou

Papers in Natural Resources

Populations of Pinus ponderosa and Juniperus virginiana are expanding into semiarid Sandhills grasslands in Nebraska. To evaluate the physiological basis of their success, we measured the seasonal course of leaf gas exchange, plant water status, and carbon isotope discrimination in these two native trees and two native C₄ grasses (Schizachyrium scoparium and Panicum virgatum). Compared to the trees, grasses had higher net photosynthetic rates (A_net) and water use efficiency (WUE) and more negative predawn and midday water potentials (Ψ) in June and July. While leaf Ψ and rates of leaf gas exchange declined for all …

Absorption Properties Of Dissolved And Particulate Matter In Turbid Productive Inland Lakes, Giorgio Dall'olmo, Anatoly A. Gitelson

Papers in Natural Resources

The objective of this study is to extend the knowledge on the absorption properties of turbid productive lakes by describing the spectral characteristics of a_CDOM, a_nap and a_φ spectra measured in an agriculturally dominated region of North America (Nebraska, USA).

Methodology And Results Of Calculating Central California Surface Temperature Trends: Evidence Of Human-Induced Climate Change?, John R. Christy, William B. Norris, Kelly Redmond, Kevin P. Gallo

Papers in Natural Resources

A procedure is described to construct time series of regional surface temperatures and is then applied to interior central California stations to test the hypothesis that century-scale trend differences between irrigated and non-irrigated regions may be identified. The procedure requires documentation of every point in time at which a discontinuity in a station record may have occurred through (a) the examination of metadata forms (e.g., station moves) and (b) simple statistical tests. From this “homogeneous segments” of temperature records for each station are defined. Biases are determined for each segment relative to all others through a method employing mathematical graph …

Effects Of Aphid (Homoptera) Abundance And Surrounding Vegetation On The Encounter Rate Of Coccinellidae (Coleoptera), Chrysopidae (Neuroptera) And Nabidae (Hemiptera) In Alfalfa., James R. Brandle

Papers in Natural Resources

No abstract provided.

Ownership Structure, Corporate Governance And Top Management Fraud In Listed Companies: An Empirical Analysis Based On Chinese Cases, H. Zhou, J. Li, T. Liu

Papers in Natural Resources

No abstract provided.

Assessing Stream-Aquifer Interactions Through Inverse Modeling Of Flow Routing, Jozsef Szilagyi, Marc B. Parlange, Gabor Balint

Papers in Natural Resources

No abstract provided.

Discussion Of "Estimation Of The Water Balance Using Observed Soil Water In The Nebraska Sandhills" By V. Sridhar And K.G. Hubbard, Jozsef Szilagyi

Papers in Natural Resources

No abstract provided.

Simulation Of The Superimposition Of Floods In The Upper Tisza Region, In "Transboundary Floods: Reducing Risks Through Flood Management", Jozsef Szilagyi, Gabor Balint, Andras Csik, Balazs Gauzer, Margit Horoszne Gulyas

Papers in Natural Resources

No abstract provided.

Comment On "Using Numerical Modelling To Evaluate The Capillary Fringe Groundwater Ridging Hypothesis Of Streamflow Generation" By H. L. Cloke, M. G. Anderson, J. J. Mcdonnell, And J. P. Renaud, Jozsef Szilagyi

Papers in Natural Resources

No abstract provided.

Prevalence And Serovars Of Salmonella In The Feces Of Free-Ranging White-Tailed Deer (Odocoileus Virginianus) In Nebraska, David G. Renter, David P. Gnad, Jan M. Sargeant, Scott E. Hygnstrom

Papers in Natural Resources

To determine the prevalence and serovars of Salmonella in free-ranging deer, we cultured feces from white-tailed deer (Odocoileus virginianus) harvested by hunters during a regular firearm season in southeastern Nebraska (USA). We recovered Salmonella from 5 (1%; 95% confidence interval: 0.37– 2.20%) of 500 samples and identified four different Salmonella enterica serovars [Litchfield (1), Dessau (1), Infantis (2), and Enteritidis (1)]. Although the prevalence of Salmonella in free-ranging deer appears to be low, the serovars recovered are known to be pathogenic to humans and animals.

Relationship Between Gross Primary Production And Chlorophyll Content In Crops: Implications For The Synoptic Monitoring Of Vegetation Productivity, Anatoly A. Gitelson, Andrés Viña, Shashi Verma, Donald C. Rundquist, Timothy J. Arkebauer, Galina P. Keydan, Bryan Leavitt, Veronica Ciganda, George G. Burba, Andrew E. Suyker

Papers in Natural Resources

Accurate estimation of spatially distributed CO2 fluxes is of great importance for regional and global studies of carbon balance. We applied a recently developed technique for remote estimation of crop chlorophyll content to assess gross primary production (GPP). The technique is based on reflectance in two spectral channels: the near-infrared and either the green or the red-edge. We have found that in irrigated and rainfed crops (maize and soybean), midday GPP is closely related to total crop chlorophyll content. The technique provided accurate estimations of midday GPP in both crops under rainfed and irrigated conditions with root mean square error …

The Geoprofile Metadata, Exposure Of Instruments, And Measurement Bias In Climatic Record Revisited, Rezaul Mahmood

Papers in Natural Resources

No abstract provided.

Impacts Of Irrigation On 20th Century Temperature In The Northern Great Plains, Rezaul Mahmood

Papers in Natural Resources

No abstract provided.