Physical Sciences and Mathematics Commons^™

Remote Estimation Of Gross Primary Production In Maize, Yi Peng, Anatoly A. Gitelson, Galina Keydan, Donald C. Rundquist, Bryan Leavitt, Shashi B. Verma, Andrew E. Suyker

School of Natural Resources: Faculty Publications

There is a growing interest in the estimation of gross primary productivity (GPP) in crops due to its importance in regional and global studies of carbon balance. We have found that crop GPP was closely related to its total chlorophyll content, and thus chlorophyll can be used as a proxy of GPP in crops. In this study, we tested the performance of various vegetation indices for estimating GPP. The indices were derived from spectral data collected remotely but at close-range over a period of eight years, from 2001 through 2008. The results show that chlorophyll indices, based on near infrared …

Structured Decision-Making And Rapid Prototyping To Plan A Management Response To An Invasive Species, Sean M. Blomquist, Trisha D. Johnson, David R. Smith, Geoff P. Call, Brant N. Miller, W. Mark Thurman, Jamie E. Mcfadden, Mary J. Parkin, G. Scott Boomer

School of Natural Resources: Faculty Publications

We developed components of a decision structure that could be used in an adaptive management framework for responding to invasion of hemlock woolly adelgid Adeleges tsugae on the Cumberland Plateau of northern Tennessee. Hemlock woolly adelgid, an invasive forest pest, was first detected in this area in 2007. We used a structured decision-making process to identify and refine the management problem, objectives, and alternative management actions, and to assess consequences and tradeoffs among selected management alternatives. We identified four fundamental objectives: 1) conserve the aquatic and terrestrial riparian conservation targets, 2) protect and preserve hemlock, 3) develop and maintain adequate …

Using Advancements In Cable-Trapping To Overcome Barriers To Furbearer Management In The United States, Stephen Vantassel, Tim L. Hiller, Kelly D. J. Powell, Scott E. Hygnstrom

School of Natural Resources: Faculty Publications

Harvest of furbearers through trapping has been challenged by anti-trapping organizations for centuries, with organizational goals often including prohibition of all forms of trapping. Challenges to trapping may also include dissention among state wildlife agencies, pro-hunting organizations, and pro-trapping organizations. Despite recent efforts by anti-trapping organizations and occasional dissention among consumptive-use groups, national trends in snaring regulations included less restrictive regulations through time. This positive trend may offer opportunities for state wildlife agencies and pro-trapping organizations to enhance the public image of trapping, increase recruitment of trappers, and reverse the increasing trend of wildlife damage and associated costs. We offer …

Winter Ecology Of Buggy Creek Virus (Togaviridae, Alphavirus) In The Central Great Plains, Charles R. Brown, Stephanie A. Strickler, Amy T. Moore, Sarah A. Knutie, Abinash Padhi, Mary Bomberger Brown, Ginger R. Young, Valerie A. O'Brien, Jerome E. Foster, Nicholas Komar

School of Natural Resources: Faculty Publications

A largely unanswered question in the study of arboviruses is the extent to which virus can overwinter in adult vectors during the cold winter months and resume the transmission cycle in summer. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an unusual arbovirus that is vectored primarily by the swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) and amplified by the ectoparasitic bug’s main avian hosts, the migratory cliff swallow (Petrochelidon pyrrhonota) and resident house sparrow (Passer domesticus). Bugs are sedentary and overwinter in the swallows’ mud nests. We evaluated the prevalence of BCRV and extent of …

A Model‐Data Intercomparison Of Co2 Exchange Across North America: Results From The North American Carbon Program Site Synthesis, Christopher R. Schwalm, Christopher A. Williams, Kevin Schaefer, Ryan S. Anderson, M. Altaf Arain, Ian Baker, Alan Barr, T. Andrew Black, Guangsheng Chen, Jing Ming Chen, Philippe Ciais, Kenneth J. Davis, Ankur R. Desai, Michael Dietze, Danilo Dragoni, Marc L. Fischer, Lawrence B. Flanagan, Robert Grant, Lianhong Gu, David Hollinger, R. Cesar Izaurralde, Chris Kucharik, Peter Lafleur, Beverly E. Law, Longhui Li, Zhengpeng Li, Shuguang Liu, Erandathie Lokupitiya, Yiqi Luo, Siyan Ma, Hank Margolis, Roser Matamala, Harry Mccaughey, Russell K. Monson, Walter C. Oechel, Changhui Peng, Benjamin Poulter, David T. Price, Dan M. Riciutto, William Riley, Alok Kumar Sahoo, Michael Sprintsin, Jianfeng Sun, Hanqin Tian, Christian Tonitto, Hans Verbeeck, Shashi B. Verma

School of Natural Resources: Faculty Publications

Our current understanding of terrestrial carbon processes is represented in various models used to integrate and scale measurements of CO₂ exchange from remote sensing and other spatiotemporal data. Yet assessments are rarely conducted to determine how well models simulate carbon processes across vegetation types and environmental conditions. Using standardized data from the North American Carbon Program we compare observed and simulated monthly CO₂ exchange from 44 eddy covariance flux towers in North America and 22 terrestrial biosphere models. The analysis period spans ~220 site‐years, 10 biomes, and includes two large‐scale drought events, providing a natural experiment to evaluate …

Translocation To A Fragmented Landscape: Survival, Movement, And Site Fidelity Of Northern Bobwhites, Theron M. Terhune, D. Clay Sisson, William E. Palmer, Brant C. Faircloth, H. Lee Stribling, John P. Carroll

School of Natural Resources: Faculty Publications

Habitat fragmentation, degradation, and loss have taxed early-successional species including the Northern Bobwhite (Colinus virginianus) and numerous grassland obligate birds. Translocation is often applied to counteract the consequences of habitat fragmentation through the creation, reestablishment, or augmentation of wild populations for the purposes of conservation, biodiversity maintenance. However, the implementation of these techniques is often conducted without valid experimental designs and therefore lacks robust, empirical data needed to evaluate and advance the knowledge and application of translocation. Despite the increasing amount of habitat management applied to patches among fragmented landscapes, a paucity of source populations often limits natural …

Upwelling Couples Chemical And Biological Dynamics Across The Littoral And Pelagic Zones Of Lake Tanganyika, East Africa, Jessica R. Corman, P. B. Mcintyre, B. Kuboja, W. Mbemba, D. Fink, C. W. Wheeler, C. Gans, E. Michel, A. S. Flecker

School of Natural Resources: Faculty Publications

We studied the effects of upwelling on nutrient and phytoplankton dynamics in the pelagic and littoral zones of Lake Tanganyika near Kigoma, Tanzania. During the dry season of 2004, a rise in the thermocline and sudden drop in surface water temperatures indicated a substantial upwelling event. Increases in concentrations of nitrate, soluble reactive phosphorus, and silica in the surface waters occurred simultaneously after the temperature drop. Within days, chlorophyll a concentrations increased and remained elevated, while inorganic nutrient concentrations returned to preupwelling levels and organic nutrient concentrations peaked. We observed parallel temporal patterns of water temperature, nutrient concentrations, and phytoplankton …

Recursive Streamflow Forecasting: A State-Space Approach, Jozsef Szilagyi, Andras Szollosi-Nagy

School of Natural Resources: Faculty Publications

No abstract provided.

Testing The Intergenerational Differences In Mental Boundaries, John E. Barbuto Jr., Stephanie Bryant, Lisa Pennisi

School of Natural Resources: Faculty Publications

No abstract provided.

Locus Of Control, Sources Of Motivation, And Mental Boundaries As Antecedents Of Leader-Member Exchange Quality, John E. Barbuto Jr., Dayna Finch Weltmer, Lisa A. Pennisi

School of Natural Resources: Faculty Publications

No abstract provided.

Diurnal Fluctuations In Shallow Groundwater Levels And In Streamflow Rates And Their Interpretation: A Review, Zoltan Gribovszki, Jozsef Szilagyi, Peter Kalicz

School of Natural Resources: Faculty Publications

No abstract provided.

Complementary-Relationship-Based Evapotranspiration Mapping (Cremap) Technique For Hungary, Jozsef Szilagyi, Akos Kovacs

School of Natural Resources: Faculty Publications

No abstract provided.

Introduction To The Basic Drivers Of Climate, Alison P. Stevens

School of Natural Resources: Faculty Publications

Climates on Earth vary from the warm, wet tropics to the cold, dry Arctic and Antarctic. What drives this variation?

Every day, we note the weather: temperature, rain, cloud cover, wind and humidity. Climate is the long-term prevailing weather in an area and is largely determined by temperature and precipitation. The climate in a desert is hot and dry. The climate in the tropics is warm and wet. The climate of a particular area is the largest determinant to the life found there. Climate is a key focus in ecology. Variations in climate include daily and seasonal cycles. Climatic variation …

Albedo Estimates For Land Surface Models And Support For A New Paradigm Based On Foliage Nitrogen Concentration, David Y. Hollinger, S. V. Ollinger, A. D. Richardson, T. P. Meyers, D. B. Dail, M. E. Martin, N. A. Scott, T. J. Arkebauer, D. D. Baldocchi, K. L. Clark, P. S. Curtis, K. J. Davis, A. R. Desai, D. Dragoni, M. L. Goulden, L. Gu, G. G. Katul, S. G. Pallardy, K. T. Pawu, H. P. Schmid, P. C. Stoy, Andrew E. Suyker, Shashi Verma

School of Natural Resources: Faculty Publications

Vegetation albedo is a critical component of the Earth’s climate system, yet efforts to evaluate and improve albedo parameterizations in climate models have lagged relative to other aspects of model development. Here, we calculated growing season albedos for deciduous and evergreen forests, crops, and grasslands based on over 40 site-years of data from the AmeriFlux network and compared them with estimates presently used in the land surface formulations of a variety of climate models. Generally, the albedo estimates used in land surface models agreed well with this data compilation. However, a variety of models using fixed seasonal estimates of albedo …

A Black Hills-Madison Aquifer Origin For Dakota Aquifer Groundwater In Northeastern Nebraska, Randy Stotler, F. Edwin Harvey, David C. Gosselin

School of Natural Resources: Faculty Publications

Previous studies of the Dakota Aquifer in South Dakota attributed elevated groundwater sulfate concentrations to Madison Aquifer recharge in the Black Hills with subsequent chemical evolution prior to upward migra¬tion into the Dakota Aquifer. This study examines the plausibility of a Madison Aquifer origin for groundwater in northeastern Nebraska. Dakota Aquifer water samples were collected for major ion chemistry and isotopic analysis (¹⁸O, ²H, ³H, ¹⁴C, ¹³C, ³⁴S, ¹⁸O-SO₄, ⁸⁷Sr, ³⁷Cl). Results show that groundwater beneath the eastern, un¬confined portion of the study area is distinctly different from …

Measuring Economic Impacts Of Drought: A Review And Discussion, Ya Ding, Michael J. Hayes, Melissa Widhalm

School of Natural Resources: Faculty Publications

A comprehensive assessment of drought economic impacts provides critical information to rational decisions supporting drought mitigation policies and programs. The objective of this paper is to increase the understanding of the full scope of drought economic impacts and the associated quantitative assessment methodologies. To accomplish this, the paper reviews the literature of drought economic impact studies in both agricultural and non-agricultural sectors, summarizes the methods and data employed, compares the various results, and investigates the problems and limitations of previous studies. The paper concludes with a discussion of the challenges and directions of future improvement on drought economic impact assessment.

Modeling Whole-Tree Carbon Assimilation Rate Using Observed Transpiration Rates And Needle Sugar Carbon Isotope Ratios, Jia Hu, David J. P. Moore, Diego Andrés Riveros-Iregui, Sean P. Burns, Russell K. Monson

School of Natural Resources: Faculty Publications

• Understanding controls over plant–atmosphere CO₂ exchange is important for quantifying carbon budgets across a range of spatial and temporal scales. In this study, we used a simple approach to estimate whole-tree CO₂ assimilation rate (A_Tree) in a subalpine forest ecosystem.
• We analysed the carbon isotope ratio (δ¹³C) of extracted needle sugars and combined it with the daytime leaf-to-air vapor pressure deficit to estimate tree water-use efficiency (WUE). The estimated WUE was then combined with observations of tree transpiration rate (E) using sap flow techniques to estimate A_Tree. …

Algorithms For Remote Estimation Of Chlorophyll-Α In Coastal And Inland Waters Using Red And Near Infrared Bands, Alexander A. Gilerson, Anatoly A. Gitelson, Jing Zhou, Daniela Gurlin, Wesley Moses, Ioannis Ioannou, Samir A. Ahmed

School of Natural Resources: Faculty Publications

Remote sensing algorithms that use red and NIR bands for the estimation of chlorophyll-α concentration [Chl] can be more effective in inland and coastal waters than algorithms that use blue and green bands. We tested such two-band and three-band red-NIR algorithms using comprehensive synthetic data sets of reflectance spectra and inherent optical properties related to various water parameters and a very consistent in situ data set from several lakes in Nebraska, USA. The two-band algorithms tested with MERIS bands were R_rs(708)/R_rs(665) and R_rs(753)/Rrs(665). The three-band algorithm with MERIS bands was in the form R3 …

Non-Destructive Estimation Pigment Content Ripening Quality And Damage In Apple Fruit With Spectral Reflectance In The Visible Range, Alexei E. Solovchenko, Olga B. Chivkunova, Anatoly A. Gitelson, Mark N. Merzlyak

School of Natural Resources: Faculty Publications

Modern non-destructive optical-reflectance-based techniques for estimation of pigment (chlorophyll, carotenoid, anthocyanin, and flavonol) contents, the rate of on- and off-tree ripening as well as for detection of common physiological disorders, such as sunscald, superficial scald, and water core, and other damages to apple fruit are an emphasis on the methods developed by the authors. The basic spectral features of fruit reflectance in the visible and near infra-red are briefly considered together with their implications for the development of algorithms for non-destructive pigment content assessment. The use of reflectance spectroscopy for estimating chlorophyll and carotenoid content as well as carotenoid/chlorophyll ratio …

Algorithms For Remote Estimation Of Chlorophyll-A In Coastal And Inland Waters Using Red And Near Infrared Bands, Alexander A. Gilerson, Anatoly A. Gitelson, Jing Zhou, Daniela Gurlin, Wesley Moses, Ioannis Ioannou, Samir A. Ahmed

School of Natural Resources: Faculty Publications

Remote sensing algorithms that use red and NIR bands for the estimation of chlorophyll-a concentration [Chl] can be more effective in inland and coastal waters than algorithms that use blue and green bands. We tested such two-band and three-band red-NIR algorithms using comprehensive synthetic data sets of reflectance spectra and inherent optical properties related to various water parameters and a very consistent in situ data set from several lakes in Nebraska, USA. The two-band algorithms tested with MERIS bands were R_rs(708)/R_rs(665) and R_rs(753)/R_rs(665). The three-band algorithm with MERIS bands was in the …

Long-Term Response Of Groundwater Nitrate Concentrations To Management Regulations In Nebraska’S Central Platte Valley, Mary Exner Spalding, Hugo Perea-Estrada, Roy F. Spalding

School of Natural Resources: Faculty Publications

The impact of 16 years (1988–2003) of management practices on high groundwater nitrate concentrations in Nebraska’s central Platte River valley was assessed in a 58,812-ha (145,215-ac) groundwater quality management area intensively cropped to irrigated corn (Zea mays L.). Crop production and groundwater nitrate data were obtained from ~23,800 producer reports. The terrace, comprising ~56% of the study area, is much more intensively cropped to irrigated corn than the bottomland. From 1987 to 2003, average groundwater nitrate concentrations in the primary aquifer beneath the bottomland remained static at ~8 mg N/l. During the same period, average groundwater nitrate concentrations in the …

Finding The Smoothest Path To Success: Model Complexity And The Consideration Of Nonlinear Patterns In Nest-Survival Data, Max Post Van Der Burg, Larkin A. Powell, Andrew J. Tyre

School of Natural Resources: Faculty Publications

Quantifying patterns of nest survival is a first step toward understanding why birds decide when and where to breed. Most studies of nest survival have relied on generalized linear models (GLM) to explore these patterns. However, GLMs require assumptions about the models’ structure that might preclude finding nonlinear patterns in survival data. Generalized additive models (GAM) provide a flexible alternative to GLMs for estimating linear and nonlinear patterns in data. Here we present a comparison of GLMs and GAMs for explaining variation in nest-survival data. We used two different model-selection criteria, the Bayes (BIC) and Akaike (AIC) information criteria, to …

Assessment Of Hatchery-Reared Pallid Sturgeon Survival In The Lower Missouri River, Kirk D. Steffensen, Larkin A. Powell, Jeff D. Koch

School of Natural Resources: Faculty Publications

The population of pallid sturgeon Scaphirhynchus albus in the lower Missouri River between Gavins Point Dam (river kilometer [rkm] 1,305.2) and the confluence with the Mississippi River (rkm 0.0) remains imperiled, little to no natural recruitment occurring. Artificial propagation and subsequent population augmentation (i.e., stocking) may be the only viable option for maintaining pallid sturgeon populations in the lower Missouri River in the near term. Because relatively little is known about the ability of hatchery-reared pallid sturgeon to survive, the objective of this study was to quantify survival estimates for hatchery-reared pallid sturgeon stocked into the lower Missouri River. We …

A Continuous Measure Of Gross Primary Production For The Conterminous United States Derived From Modis And Ameriflux Data, Jingfeng Xiao, Qianlai Zhuang, Beverly E. Law, Jiquan Chen, Dennis D. Baldocchi, David R. Cook, Ram Oren, Andrew D. Richardson, Sonia Wharton, Siyan Ma, Timothy A. Martin, Shashi Verma, Andrew E. Suyker, Russell L. Scott, Russell K. Monson, Marcy Litvak, David Y. Hollinger, Ge Sun, Kenneth J. Davis, Paul Bolstad, Sean Burns, Peter S. Curtis, Bert G. Drake, Matthias Falk, Marc L. Fischer, David R. Foster, Lianhong Gu, Julian L. Hadley, Gabriel G. Katul, Roser Matamala, Steve Mcnulty, Tilden P. Meyers, J. William Munger, Asko Noormets, Walter Oechel, Kyaw Tha Paw U, Hans Peter Schmid, Gregory Starr, Margaret S. Torn, Steven C. Wofsy

School of Natural Resources: Faculty Publications

The quantification of carbon fluxes between the terrestrial biosphere and the atmosphere is of scientific importance and also relevant to climate-policy making. Eddy covariance flux towers provide continuous measurements of ecosystem-level exchange of carbon dioxide spanning diurnal, synoptic, seasonal, and interannual time scales. However, these measurements only represent the fluxes at the scale of the tower footprint. Here we used remotely sensed data from the Moderate Resolution Imaging Spectroradiometer (MODIS) to upscale gross primary productivity (GPP) data from eddy covariance flux towers to the continental scale. We first combined GPP and MODIS data for 42 AmeriFlux towers encompassing a wide …

Toward Regional Climate Services The Role Of Noaa’S Regional Climate Centers, Arthur T. Degaetano, Timothy J. Brown, Steven D. Hilberg, Kelly Redmond, Kevin Robbins, Peter Robinson, Martha Shulski, Marjorie Mcguirk

School of Natural Resources: Faculty Publications

A comprehensive national climate services strategy requires the infrastructure, operational services, and applied research activities that have characterized the Regional Climate Center Program since its inception.

Diagnosis Of Extended Cold-Season Temperature Anomalies In Alaska, Martha Shulski, John Walsh, Eric Stevens, Richard Thoman

School of Natural Resources: Faculty Publications

During the early winter of 2002 and late winter of 2007, the Alaskan sector of the North Pacific Ocean region experienced record-breaking temperature anomalies. The duration of these episodes was unusually long, with each lasting more than 1 month: 55 days for the warm anomaly of October–December 2002 and 37 days for the cold anomaly of February–March 2007. Temperature departures over each respective period were the largest for the continental climate of interior Alaska (>10°C) and the smallest for the maritime regions of Alaska (

Finding The Smoothest Path To Success: Model Complexity And The Consideration Of Nonlinear Patterns In Nest-Survival Data Encontrando El Camino Mas Facil Hacia El Exito: Complejidad De Los Modelos Y Consideraci6n De Patrones No Lineales En Datos De Supervivencia De Nidos, Max Post Van Der Burg, Larkin A. Powell, Andrew J. Tyre

School of Natural Resources: Faculty Publications

Quantifying patterns of nest survival is a first step toward understanding why birds decide when and where to breed. Most studies of nest survival have relied on generalized linear models (GLM) to explore these patterns. However, GLMs require assumptions about the models' structure that might preclude finding nonlinear patterns in survival data. Generalized additive models (GAM) provide a flexible alternative to GLMs for estimating linear and nonlinear patterns in data. Here we present a comparison of GLMs and GAMs for explaining variation in nest-survival data. We used two different model-selection criteria, the Bayes (BIC) and Akaike (AIC) information criteria, to …

2010 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 (2010). 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 outreach activities. While the focus of our work is the Lower Platte, …

Coupling Of Carbon Dioxide And Water Vapor Exchanges Of Irrigated And Rainfed Maize–Soybean Cropping Systems And Water Productivity, Andrew E. Suyker, Shashi B. Verma

School of Natural Resources: Faculty Publications

Continuous measurements of CO₂ and water vapor exchanges made in three cropping systems (irrigated continuous maize, irrigated maize–soybean rotation, and rainfed maize–soybean rotation) in eastern Nebraska, USA during 6 years are discussed. Close coupling between seasonal distributions of gross primary production (GPP) and evapotranspiration (ET) were observed in each growing season. Mean growing season totals of GPP in irrigated maize and soybean were 1738 ± 114 and 996 ± 69 g C m⁻², respectively (±standard deviation). Corresponding mean values of growing season ET totals were 545 ± 27 and 454 ± 23 mm, respectively. Irrigation affected GPP …

Resource Selection By Elk In An Agro-Forested Landscape Of Northwestern Nebraska, David M. Baasch, Justin W. Fischer, Scott E. Hygnstrom, Kurt C. Vercauteren, Andrew J. Tyre, Joshua J. Millspaugh, James W. Merchant, Jerry D. Volesky

School of Natural Resources: Faculty Publications

In recent years, elk have begun recolonizing areas east of the Rocky Mountains that are largely agroforested ecosystems composed of privately owned land where management of elk is an increasing concern due to crop and forage depredation and interspecific disease transmission. We used a Geographic Information System, elk use locations (n = 5013), random locations (n = 25,065), discrete-choice models, and information-theoretic methods to test hypotheses about elk resource selection in an agro-forested landscape located in the Pine Ridge region of northwestern Nebraska, USA. Our objectives were to determine landscape characteristics selected by female elk and identify publicly owned land …