Physical Sciences and Mathematics Commons^™

Discovering Native Bees, Alison P. Stevens

School of Natural Resources: Faculty Publications

No abstract provided.

Chapter 18- Chick Survival Of Greater Prairie-Chickens, Adam C. Schole, Ty W. Matthews, Larkin A. Powell, Jeffrey J. Lusk, J. Scott Taylor

School of Natural Resources: Faculty Publications

Chick survival during the first three weeks of life is a critical stage in the demography of Greater Prairie-Chickens (Tympanuchus cupido), but little information is available. Biologists often estimate brood success using periodic flushes of radio-marked females, but it is impossible to determine mortality factors if chicks are not radio-marked. We used sutures to attach 0.5-g transmitters to 1- to 2-day-old chicks in Johnson County, Nebraska, during 2008. Our objectives were to (1) assess causes of mortality of 0- to 21-day-old chicks, (2) estimate daily survival probability for 0- to 21-day-old chicks, and (3) evaluate the effect of applying …

Intense Natural Selection On Morphology Of Cliff Swallows (Petrochelidon Pyrrhonota) A Decade Later: Did The Population Move Between Adaptive Peaks? Sélection Naturelle Intensive Sur La Morphologie De Petrochelidon Pyrrhonota Une Décennie Plus Tard: La Population S’Est-Elle Déplacée Entre Deux Pics Adaptatifs?, Mary Bomberger Brown, Charles R. Brown

School of Natural Resources: Faculty Publications

Unusual climatic events often lead to intense natural selection on organisms. Whether episodic selection events result in permanent microevolutionary changes or are reversed by opposing selection pressures at a later time is rarely known, because most studies do not last long enough to witness rare events and document their aftermath. In 1996, unusually cold and wet weather in southwestern Nebraska led to the deaths of thousands of Cliff Swallows (Petrochelidon pyrrhonota) over a 6-day period. Survivors were skeletally larger, with shorter wings and tails, and had less asymmetry in wing length than those that died. We determined trajectories of morphological …

Long-Term Rice-Based Cropping System Effects On Near-Surface Soil Compaction, J. M. Motschenbacher, K. R. Brye, M. M. Anders

School of Natural Resources: Faculty Publications

No abstract provided.

Estimates Of Duck Breeding Populations In The Nebraska Sandhills Using Double Observer Methodology, Mark P. Vrtiska, Larkin A. Powell

School of Natural Resources: Faculty Publications

The Nebraska Sandhills are an important area for breeding ducks in the Great Plains, but reliable estimates of breeding populations are unavailable. Double-observer methodology was used to estimate abundance of breeding duck populations in the Nebraska Sandhills. Aerial transect surveys were conducted using methodology similar to the cooperative Waterfowl Breeding Population and Habitat Survey conducted by the U.S. Fish and Wildlife Service and Canadian Wildlife Service. Observations by two front-seat observers and one rear-seat observer were used to account for incomplete detectability. Transect-specific population size and detection probabilities were estimated using program SURVIV; estimates were species-specific by type of social …

Land Use/Land Cover Changes And Climate: Modeling Analysis And Observational Evidence, Roger A. Pielke Sr., Andy Pitman, Dev Niyogi, Rezaul Mahmood, Clive Mcalpine, Faisal Hossain, Kees Klein Goldewijk, Udaysankar S. Nair, Richard Betts, Souleymane Fall, Markus Reichstein, Pavel Kabat, Nathalie De Noblet

School of Natural Resources: Faculty Publications

This article summarizes the changes in landscape structure because of human land management over the last several centuries, and using observed and modeled data, documents how these changes have altered biogeophysical and biogeochemical surface fluxes on the local, mesoscale, and regional scales. Remaining research issues are presented including whether these landscape changes alter large-scale atmospheric circulation patterns far from where the land use and land cover changes occur. We conclude that existing climate assessments have not yet adequately factored in this climate forcing. For those regions that have undergone intensive human landscape change, or would undergo intensive change in the …

Sensitivity Of Planetary Boundary Layer Atmosphere To Historical And Future Changes Of Land Use/Land Cover, Vegetation Fraction, And Soil Moisture In Western Kentucky, Usa, Rezaul Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.

Impacts Of Irrigation On Dry Season Precipitation In India, Rezaul Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.

Heat Flux Measurements And Modeling Of Malodorous Compounds Above An Anaerobic Swine Lagoon, Rezaul Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.

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 …