Physical Sciences and Mathematics Commons^™

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 …

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 …

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 …

Impacts Of Land Use/Land Cover Change On Climate And Future Research Priorities, Rezaul Mahmood, Roger A. Pielke Sr., Kenneth G. Hubbard, Dev Niyogi, Gordon Bonan, Peter Lawrence, Richard Mcnider, Clive Mcalpine, Andres Etter, Samuel Gameda, Budong Qian, Andrew Carleton, Adriana Beltran-Przekurat, Thomas Chase, Arturo I. Quintanar, Jimmy O. Adegoke, Sajith Vezhapparambu, Glen Connor, Salvi Asefi, Elif Sertel, David R. Legates, Yuling Wu, Robert Hale, Oliver W. Frauenfeld, Anthony Watts, Marshall Shepherd, Chandana Mitra, Valentine G. Anantharaj, Souleymane Fall, Robert Lund, Anna Treviño, Peter D. Blanken, Jinyang Du, Hsin-I Chang, Ronnie Leeper, Udaysankar S. Nair, Scott Dobler, Ravinesh Deo, Jozef Syktus

School of Natural Resources: Faculty Publications

Human activities have modified the environment for thousands of years. Significant population increase, migration, and accelerated socioeconomic activities have intensified these environmental changes over the last several centuries. The climate impacts of these changes have been found in local, regional, and global trends in modern atmospheric temperature records and other relevant climatic indicators.

An important human influence on atmospheric temperature trends is extensive land use/land cover change (LULCC) and its climate forcing. Studies using both modeled and observed data have documented these impacts (e.g., Chase et al. 2000; Kalnay and Cai 2003; Cai and Kalnay 2004; Trenberth 2004; Vose et …

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 …

Improving Farmers’ Perception And Use Of Climate Predictions In Farming Decisions: A Transition Model, Lisa M. Pytlikzillig, Qi Hu, Kenneth G. Hubbard, Gary D. Lynne, Roger H. Bruning

School of Natural Resources: Faculty Publications

Despite tremendous efforts to improve weather and climate predictions and to inform farmers about the use of such weather products, farmers’ attitudes toward forecast use remain poor and farmer use of forecasts has not increased. This paper describes features of a new conceptual model for facilitating farmers’ use of weather products and offers preliminary evidence for its effectiveness based on a test-of-concept prototype. The prototype system provides farmers with contextualized information, the opportunity to use that information in relevant farming contexts, and collaborative interaction with other users. In addition, scaffolding and feedback are incorporated in the model to enhance learning …

Satellite Estimation Of Chlorophyll-A Concentration Using The Red And Nir Bands Of Meris—The Azov Sea Case Study, Wesley J. Moses, Anatoly A. Gitelson, Sergey Berdnikov, Vasiliy Povazhnyy

School of Natural Resources: Faculty Publications

We present here the results of calibrating and validating a three-band model and, its special case, a two-band model, which use MEdium Resolution Imaging Spectrometer (MERIS) reflectances in the red and near-infrared spectral regions for estimating chlorophyll-a (chl-a) concentration in inland, estuarine, and coastal turbid productive waters. During four data collection campaigns in 2008 and one campaign in 2009 in the Taganrog Bay and the Azov Sea, Russia, water samples were collected, and concentrations of chl-a and total suspended solids were measured in the laboratory. The data collected in 2008 were used for model calibration, and the …

Corrections To “Satellite Estimation Of Chlorophyll-A Concentration Using The Red And Nir Bands Of Meris—The Azov Sea Case Study”, Wesley J. Moses, Anatoly A. Gitelson, Sergey Berdnikov, Vasiliy Povazhnyy

School of Natural Resources: Faculty Publications

We correct here some errors that appear in our paper: W.J. Moses, A.A. Gitelson, S. Berdnikov, and V. Povazhnyy, “Satellite estimation of chlorophyll-a concentration using the red and NIR bands of MERIS—The Azov Sea case study,” IEEE Geoscience and Remote Sensing Letters, volume 6, number 4, pp. 845–849, October 2009.

Estimation Of Chlorophyll-A Concentration In Case Ii Waters Using Modis And Meris Data—Successes And Challenges, Wesley Moses, Anatoly Gitelson, Sergey Berdnikov, Vasiliy Povazhnyi

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 reflectance at red and …

Retrieval Of Foliar Information About Plant Pigment Systems From High Resolution Spectroscopy, Susan L. Ustin, Anatoly A. Gitelson, Stéphane Jacquemoud, Michael Schaepman, Gregory P. Asner, John A. Gamon, Pablo Zarco-Tejada

School of Natural Resources: Faculty Publications

Life on Earth depends on photosynthesis. Photosynthetic systems evolved early in Earth history and have been stable for 2.5 billion years, providing prima facie evidence for the significance of pigments in plant functions. Photosynthetic pigments fill multiple roles from increasing the range of energy captured for photosynthesis to protective functions. Given the importance of pigments to leaf functioning, greater effort is needed to determine whether individual pigments can be identified and quantified in vivo using high fidelity spectroscopy. We review recent advances in detecting plant pigments at the leaf level and discuss successes and reasons why challenges remain for robust …

Photosynthetic Performance Of Invasive Pinus Ponderosa And Juniperus Virginiana Seedlings Under Gradual Soil Water Depletion, Saadia Bihmidine, N. M. Bryan, K. R. Payne, M. R. Parde, Jane A. Okalebo, Sharon E. Cooperstein, Tala Awada

School of Natural Resources: Faculty Publications

Changes in climate, land management and fire regime have contributed to woody species expansion into grasslands and savannas worldwide. In the USA, Pinus ponderosa P. & C. Lawson and Juniperus virginiana L. are expanding into semiarid grasslands of Nebraska and other regions of the Great Plains. We examined P. ponderosa and J. virginiana seedling response to soil water content, one of the most important limiting factors in semiarid grasslands, to provide insight into their success in the region. Photosynthesis, stomatal conductance, maximum photochemical efficiency of PSII, maximum carboxylation velocity, maximum rate of electron transport, stomatal limitation to photosynthesis, water potential, …

Wilderness Serendipity: Planning And Assessing Learning During An Experiential Field Course, Larkin A. Powell, Andrew J. Tyre, Scott E. Hygnstrom, David A. Wedin, P. R. Hanson, Mark S. Kuzila, James B. Swinehart

School of Natural Resources: Faculty Publications

Experiential learning opportunities promote skill in problem-solving and critical thinking, but they require unique assessment methods because traditional approaches are difficult to implement in the field. We have conducted a study tour course involving a canoe trip in a wilderness area in northern Minnesota since 2004. Here, we describe how we developed our course's learning experiences, ensured the learning experiences materialized, and assessed the student learning objectives. Proper planning can result in valuable, spontaneous learning experiences. We used a student journal, field-based quiz, and participation grade to effectively assess the breadth of student learning that was inherent in our course. …

Quality Control Of Soil Water Data In Applied Climate, Jinshing You, Kenneth Hubbard, Rezaul Mamood, Venkataramana Sridhar, Dennis Todey

School of Natural Resources: Faculty Publications

Abstract: Soil moisture is a key state variable from both climate and hydrologic cycle assessment perspectives. Recently, automated measurements of soil moisture with sensors deployed at sites in a real-time monitoring network have provided valuable new data to monitor the soil water resource. However, to assure the quality of the data, quality control QC tools are needed. Earlier studies left little literature on the QC of soil water data as measurements were generally not part of a network that routinely collected measurements. This paper presents a systematic QC analysis and methodology to evaluate the performance of candidate QC techniques using …

Tree Canopy Effect On Grass And Grass/Legume Mixtures In Eastern Nebraska, Michael El. L. Perry, Walter H. Schacht, Gregory A. Ruark, James R. Brandle

School of Natural Resources: Faculty Publications

A study to determine the feasibility of producing forage for grazing livestock under trees was conducted as a step toward evaluating the potential for silvopasture systems in the northern and central Great Plains. The effects of overstory leaf area index (LAI), percentage understory light transmittance (LT), and soil moisture (SM) on yield and crude protein (CP) of big bluestem [Andropogon gerardii Vitman; (BB)], smooth bromegrass [ Bromus inermis Leyss.; (SB)], and mixtures with birdsfoot trefoil [ Lotus corniculatus L.; (BFT)] were examined. The study was conducted in both Scotch pine (Pinus sylvestris L.) and green ash (Fraxinus …

Avian Foraging Patterns In Crop Field Edges Adjacent To Woody Habitat, Heidi L. Puckett, James R. Brandle, Ron J. Johnson, Erin E. Blankenship

School of Natural Resources: Faculty Publications

As natural predators of pest insects, woodland birds provide biological pest suppression in crop fields adjacent to woody edges. Although many birds using these habitats forage widely, earlier studies have found that most foraging activity occurs within 50 m of the woody edge. The goals of this study were to determine the primary area of use, or functional edge, for birds foraging in crop fields adjacent to woody edges, and to evaluate their foraging distance patterns. During the summers of 2005 and 2006, avian foraging behavior was observed at 12 research sites in east central Nebraska that contained either a …

Phylogeography Of The Rufous-Naped Wren (Campylorhynchus Rufinucha): Speciation And Hybridization In Mesoamerica, Hernan Vazquez-Miranda, Adolfo G. Navarro-Siguenza, Kevin E. Omland

School of Natural Resources: Faculty Publications

The Rufous-naped Wren (Campylorhynchus rufinucha) is a sedentary, morphologically variable species distributed in the dry forests of Mesoamerica. It ranges from Colima, Mexico, south to Costa Rica along the Pacific slope, with a disjunct population in central Veracruz. Populations of two forms on the Pacific slope intergrade in Chiapas, Mexico, apparently as a result of secondary contact. We sequenced a mitochondrial DNA (mtDNA) gene to explore phylogeographic patterns and hybridization. We found three divergent lineages, two geographically spanning the Isthmus of Tehuantepec and a disjunct Veracruz population. Analyses of molecular variation and statistics are consistent with genetically distinct …

A Comparison Between Above-Water Surface And Subsurface Spectral Reflectances Collected Over Inland Waters, Asif M. Bhatti, Donald Rundquist, John Schalles, Luis Ramirez, Seigo Nasu

School of Natural Resources: Faculty Publications

The objective of the research was to undertake a quantitative comparison of spectral-reflectance measurements made slightly above the surface of water bodies with the measurements made slightly below the surface. The study is focused on three rivers; two in Georgia, USA and one in Japan. As expected, the differences in reflectance are not constant and vary with the wavelength. The contribution of surface-reflection effects to the surface reflectance measured slightly above the water is both pronounced and highly variable, but although they do alter the magnitude of the upwelling signal, they do not change the general shape of the spectral …

Evapotranspiration Of Irrigated And Rainfed Maize–Soybean Cropping Systems, Andrew E. Suyker, Shashi Verma

School of Natural Resources: Faculty Publications

We have been making year-round measurements of mass and energy exchange in three cropping systems: (a) irrigated continuous maize, (b) irrigated maize–soybean rotation, and (c) rainfed maize–soybean rotation in eastern Nebraska since 2001. In this paper, we present results on evapotranspiration (ET) of these crops for the first 5 years of our study. Growing season ET in the irrigated and rainfed maize averaged 548 and 482 mm, respectively. In irrigated and rainfed soybean, the average growing season ET was 452 and 431 mm, respectively. On average, the maize ET was higher than the soybean ET by 18% for irrigated crops …

Development Of A Healthy Farm Index To Assess Ecological, Economic, And Social Function On Organic And Sustainable Farms In Nebraska's Four Agroecoregions., James R. Brandle

School of Natural Resources: Faculty Publications

No abstract provided.

An Evaporation Estimation Method Based On The Coupled 2-D Turbulent Heat And Vapor Transport Equations, Jozsef Szilagyi, Janos Jozsa

School of Natural Resources: Faculty Publications

The analytical solution of the coupled turbulent diffusion equations of heat and vapor transport across a moisture discontinuity under near-neutral atmospheric conditions and constant energy available at the evaporating surface yields a simple equation (i.e., the wet-surface equation [WSE]) that relates the change in surface temperature to the change in the land surface moisture content as the environment dries. With the help of percent possible sunshine, air temperature, and humidity measurements at selected weather stations as well as land surface temperature values from MODIS data, monthly, warm-season evaporation rates were estimated for five rectangular regions across the contiguous U.S. employing …

Complementary Relationship Of Evaporation And The Mean Annual Water-Energy Balance, Jozsef Szilagyi, Janos Jozsa

School of Natural Resources: Faculty Publications

By combining the complementary relationship of evaporation with the coupled long-term water-energy balance of Porporato et al. (2004) in a Budyko-type framework, one can, from atmospheric measurements alone, derive important ecosystem characteristics, such as the mean effective relative soil moisture and the maximum soil water storage, as well as predict changes in the rooting depth of vegetation as a response to climate variations.

Comment On ‘‘Power Law Catchment-Scale Recessions Arising From Heterogeneous Linear Small-Scale Dynamics’’ By C. J. Harman, M. Sivapalan, And P. Kumar, Jozsef Szilagyi

School of Natural Resources: Faculty Publications

It is demonstrated that a near-linear subsurface runoff response from a short and relatively steep slope segment and a nonlinear response at the watershed scale may primarily arise from geometry rather than from an assumed linear nature of the subsurface runoff response from the hillslope, as Harman et al. [2009] employed for the Panola Mountain Research (PMR) catchment in Georgia. The authors caution in their paper that hydraulic theory (exemplified by the study of Brutsaert and Nieber [1977]) cannot generally account for the heterogeneity in the watershed scale and therefore should be used with certain reservation when employing it for …

Movements, Distribution, And Abundance Of Great Argus Pheasants (Argusianus Argus) In A Sumatran Rainforest, Nurul L. Winarni, Timothy G. O'Brien, John P. Carroll, Margaret F. Kinnaird

School of Natural Resources: Faculty Publications

We used radiotelemetry, habitat sampling, camera trapping, and line-transect surveys to explore movement patterns, distribution, and abundance of Great Argus Pheasants (Argusianus argus) in Sumatra, Indonesia. We radiotracked six adult and one subadult males. Territories averaged 14.5 ± 8.5 ha, and home-range size did not vary by month or by relative abundance of selected plant foods. Daily travel distance (849 ± 211 m) varied significantly between months but did not reflect changes in plant foods. Territories were used almost exclusively by resident males. Males preferentially used undisturbed forest (habitat I). Vegetation structure at male display sites and random points indicated …

A Phylogenetic Supertree Of The Fowls (Galloanserae, Aves), Soo Hyumg Eo, Olaf R.P. Bininda-Emonds, John P. Carroll

School of Natural Resources: Faculty Publications

The fowls (Anseriformes and Galliformes) comprise one of the major lineages of birds and occupy almost all biogeographical regions of the world. The group contains the most economically important of all bird species, each with a long history of domestication, and is an ideal model for studying ecological and evolutionary patterns. Yet, despite the relatively large amount of systematic attention fowls have attracted because of their socio-economic and biological importance, the species-level relationships within this clade remain controversial. Here we used the supertree method matrix representation with parsimony to generate a robust estimate of species-level relationships of fowls. The supertree …

Modeling Lakes And Reservoirs In The Climate System, M. D. Mackay, P. J. Neale, C. D. Arp, L. N. De Senerpont Domis, X. Fang, G. Gal, K. D. Johnk, G. Kirillin, J. D. Lenters, E. Litchman, S. Macintyre, P. Marsh, J. Melack, W. M. Mooij, F. Peeters, A. Quesada, S. G. Schladow, M. Schmid, C. Spence, S. L. Stokes

School of Natural Resources: Faculty Publications

Modeling studies examining the effect of lakes on regional and global climate, as well as studies on the influence of climate variability and change on aquatic ecosystems, are surveyed. Fully coupled atmosphere–land surface–lake climate models that could be used for both of these types of study simultaneously do not presently exist, though there are many applications that would benefit from such models. It is argued here that current understanding of physical and biogeochemical processes in freshwater systems is sufficient to begin to construct such models, and a path forward is proposed. The largest impediment to fully representing lakes in the …