Physical Sciences and Mathematics Commons^™

Data-Driven Diagnostics Of Terrestrial Carbon Dynamics Over North America, Jingfeng Xiao, Scott V. Ollinger, Steve Frolking, George Hurtt, David Y. Hollinger, Kenneth J. Davis, Yude Pan, Xiaoyang Zhang, Feng Deng, Jiquan Chen, Dennis D. Baldocchi, Beverly E. Law, M. Altaf Arain, Ankur R. Desai, Andrew D. Richardson, Ge Sun, Brian Amiro, Hank Margolis, Lianhong Gu, Russell L. Scott, Peter D. Blanken, Andrew E. Suyker

School of Natural Resources: Faculty Publications

The exchange of carbon dioxide is a key measure of ecosystem metabolism and a critical intersection between the terrestrial biosphere and the Earth’s climate. Despite the general agreement that the terrestrial ecosystems in North America provide a sizeable carbon sink, the size and distribution of the sink remain uncertain. We use a data-driven approach to upscale eddy covariance flux observations from towers to the continental scale by integrating flux observations, meteorology, stand age,aboveground biomass, and a proxy for canopy nitrogen concentrations from AmeriFlux and Fluxnet-Canada Research Network as well as a variety of satellite data streams from the MODIS sensors. …

Estimation Of Crop Gross Primary Production (Gpp): FaparChl Versus Mod15a2 Fpar, Qingyuan Zhang, Yen-Ben Cheng, A. I. Lyapustin, Yujie Wang, Feng Gao, Andrew E. Suyker, Shashi B. Verma, Elizabeth M. Middleton

School of Natural Resources: Faculty Publications

Photosynthesis (PSN) is a pigment level process in which antenna pigments (predominately chlorophylls) in chloroplasts absorb photosynthetically active radiation (PAR) for the photochemical process. PAR absorbed by foliar non-photosynthetic components is not used for PSN. The fraction of PAR absorbed (fAPAR) by a canopy/vegetation (i.e., fAPAR_canopy) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) images, referred to as MOD15A2 FPAR, has been used to compute absorbed PAR (APAR) for PSN (APAR_PSN) which is utilized to produce the standard MODIS gross primary production (GPP) product, referred to as MOD17A2 GPP. In this study, the fraction of PAR …

Variation In Age Composition Among Colony Sizes In Cliff Swallows, Charles R. Brown, Erin A. Roche, Mary Bomberger Brown

School of Natural Resources: Faculty Publications

Variation in group size is characteristic of most social species. The extent to which individuals sort among group sizes based on age may yield insight into why groups vary in size and the age-specific costs and benefits of different social environments. We investigated the age composition of Cliff Swallow (Petrochelidon pyrrhonota) colonies of different sizes over 18 yr at a long-term study site in western Nebraska, USA. Using years elapsed since banding as a relative measure of age for over 194,000 birds, we found that the proportion of age-class-1 swallows (birds banded as nestlings or juveniles or adults in the …

On The Role Of Budget Sufficiency, Cost Efficiency, And Uncertainty In Species Management, Max Post Van Der Burg, Bartholomew B. Bly, Tammy Vercauteren, James B. Grand, Andrew J. Tyre

School of Natural Resources: Faculty Publications

Many conservation planning frameworks rely on the assumption that one should prioritize locations for management actions based on the highest predicted conservation value (i.e., abundance, occupancy). This strategy may underperform relative to the expected outcome if one is working with a limited budget or the predicted responses are uncertain. Yet, cost and tolerance to uncertainty rarely become part of species management plans. We used field data and predictive models to simulate a decision problem involving western burrowing owls (Athene cunicularia hypugaea) using prairie dog colonies (Cynomys ludovicianus) in western Nebraska. We considered 2 species management strategies: …

You Are Not Always What We Think You Eat: Selective Assimilation Across Multiple Whole-Stream Isotopic Tracer Studies, W. K. Dodds, S. M. Collins, S. K. Hamilton, J. L. Tank, S. Johnson, J. R. Webster, K. S. Simon, M. R. Whiles, H. M. Rantala, W. H. Mcdowell, S. D. Peterson, T. Riis, C. L. Crenshaw, S. A. Thomas, P. B. Kristensen, B. M. Cheever, A. S. Flecker, N. A. Griffiths, T. Crowl, E. J. Rosi-Marshall, R. El-Sabaawi, E. Marti

School of Natural Resources: Faculty Publications

Analyses of 21 ¹⁵N stable isotope tracer experiments, designed to examine food web dynamics in streams around the world, indicated that the isotopic composition of food resources assimilated by primary consumers (mostly invertebrates) poorly reflected the presumed food sources. Modeling indicated that consumers assimilated only 33–50% of the N available in sampled food sources such as decomposing leaves, epilithon, and fine particulate detritus over feeding periods of weeks or more. Thus, common methods of sampling food sources consumed by animals in streams do not sufficiently reflect the pool of N they assimilate. Isotope tracer studies, combined with modeling and …

Estimation Of Crop Gross Primary Production (Gpp): I. Impact Of Modisobservation Footprint And Impact Of Vegetation Brdf Characteristics, Qingyuan Zhang, Yen-Ben Cheng, Alexei I. Lyapustin, Yujie Wang, Xiangming Xiao, Andrew E. Suyker, Shashi Verma, Bin Tan, Elizabeth M. Middleton

School of Natural Resources: Faculty Publications

Accurate estimation of gross primary production (GPP) is essential for carbon cycle and climate change studies. Three AmeriFlux crop sites of maize and soybean were selected for this study. Two of the sites were irrigated and the other one was rainfed. The normalized difference vegetation index (NDVI), the enhanced vegetation index (EVI), the green band chlorophyll index (CI_green), and the green band wide dynamic range vegetation index (WDRVI_green) were computed from the moderate resolution imaging spectroradiometer (MODIS) surface reflectance data. We examined the impacts of the MODIS observation footprint and the vegetation bidirectional reflectance distribution function …

2014 Interior Least Tern And Piping Plover Monitoring, Research, Management, And Outreach Report For The Lower Platte River, Nebraska, Mary Bomberger Brown, Joel G. Jorgensen, Lauren R. Dinan

School of Natural Resources: Faculty Publications

This document reports on our monitoring, research, management, and outreach activities during the past 12 months (2013–2014). 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 lower Platte River and its major tributaries provide important nesting and migratory stopover habitat for two bird species of special conservation concern: the state and federally endangered Interior Least Tern (Sternula antillarum athalassos) and threatened Piping Plover (Charadrius melodus). The Tern and Plover Conservation Partnership (TPCP), based at the University of …

Spatial Accuracy Of Climate Networks: A Case Study In Nebraska, Andrea J. Coop, Kenneth Hubbard, Martha Shulski, Jinsheng You, David B. Marx

School of Natural Resources: Faculty Publications

Climate data are increasingly scrutinized for accuracy because of the need for reliable input for climaterelated decision making and assessments of climate change. Over the last 30 years, vast improvements to U.S. instrumentation, data collection, and station siting have created more accurate data. This study explores the spatial accuracy of daily maximum and minimum air temperature data in Nebraska networks, including the U.S. Historical Climatology Network (HCN), the Automated Weather Data Network (AWDN), and the more recent U.S. Climate Reference Network (CRN). The spatial structure of temperature variations at the earth’s surface is compared for timeframes 2005–09 for CRN and …

Iron Clad Wetlands: Soil Iron-Sulfur Buffering Determines Coastal Wetland Response To Salt Water Incursion, Valerie Anne Schoepfer, Emily S. Bernhardt, Amy J. Burgin

School of Natural Resources: Faculty Publications

Coastal freshwater wetland chemistry is rapidly changing due to increased frequency of salt water incursion, a consequence of global change. Seasonal salt water incursion introduces sulfate, which microbially reduces to sulfide. Sulfide binds with reduced iron, producing iron sulfide (FeS), recognizable in wetland soils by its characteristic black color. The objective of this study is to document iron and sulfate reduction rates, as well as product formation (acid volatile sulfide (AVS) and chromium reducible sulfide (CRS)) in a coastal freshwater wetland undergoing seasonal salt water incursion. Understanding iron and sulfur cycling, as well as their reduction products, allows us to …

Annual Patterns And Budget Of Co2 Flux In An Arctic Tussock Tundra Ecosystem, Walter C. Oechel, Cheryl A. Laskowski, George Burba, Beniamino Gioli, Aram A. M. Kalhori

School of Natural Resources: Faculty Publications

The functioning of Arctic ecosystems is not only critically affected by climate change, but it also has the potential for major positive feedback on climate. There is, however, relatively little information on the role, patterns, and vulnerabilities of CO₂ fluxes during the nonsummer seasons in Arctic ecosystems. Presented here is a year-round study of CO₂ fluxes in an Alaskan Arctic tussock tundra ecosystem, and key environmental controls on these fluxes. Important controls on fluxes vary by season. This paper also presents a new empirical quantification of seasons in the Arctic based on net radiation. The fluxes were computed …

Coupled Heat And Vapor Transport: The Thermostat Effect Of A Freely Evaporating Land Surface, Jozsef Szilagyi, Aaron Schepers

School of Natural Resources: Faculty Publications

Analytical solutions of the 2-D heat and vapor transport equations for a surface moisture jump are often based on a constant streamwise temperature (T_ws) assumption over the wet vegetated surface. By analyzing 90 thermal infrared images taken over center-pivot irrigated areas in Nebraska, it has been demonstrated for the first time that such an assumption is realistic. Average temperature difference between the perimeter and core of the irrigated full or half circles stayed between -0.11 and 0.09°C (standard deviation of 0.25–0.41°C). It was further demonstrated that wet-bulb temperatures (a proxy of T_ws) remain near constant during …

Land Cover Changes And Their Biogeophysical Effects On Climate, Rezaul Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.

Analysis And Mapping Of Climate Change Risk And Vulnerability In Central Rift Valley Of Ethiopia, L. Gizachew, A. Shiferaw

School of Natural Resources: Faculty Publications

No abstract provided.

Land Cover Changes And Their Biogeophysical Effects On Climate, Rezaul Mahmood, Roger A. Pielke Sr., Kenneth Hubbard, Dev Niyogi, Paul Dirmeyer, Clive Mcalpine, Andrew Carleton, Robert Hale, Samuel Gameda, Adriana Beltran-Przekurat, Bruce Baker, Richard Mcnider, David R. Legates, Marshall Shepherd, Jinyang Du, Peter D. Blanken, Oliver W. Frauenfeld, U. S. Nair, Souleymane Fall

School of Natural Resources: Faculty Publications

Land cover changes (LCCs) play an important role in the climate system. Research over recent decades highlights the impacts of these changes on atmospheric temperature, humidity, cloud cover, circulation, and precipitation. These impacts range from the local- and regional-scale to sub-continental and global-scale. It has been found that the impacts of regional-scale LCC in one area may also be manifested in other parts of the world as a climatic teleconnection. In light of these findings, this article provides an overview and synthesis of some of the most notable types of LCC and their impacts on climate. These LCC types include …

Taphonomic Considerations Of A Whipworm Infection In A Mummy From The Dominican Church Of The Holy Spirit, Vilnius, Lithuania, Johnica J. Morrow, Annie S. Larsen, Dario Piombino-Mascali, Rimantas Jankauskas, Justina Kozakaitė, Adauto Araújo, Karl J. Reinhard

School of Natural Resources: Faculty Publications

In the present study, the abdominal contents of 10 mummies from beneath the Dominican Church of the Holy Spirit in Vilnius, Lithuania, were examined for the presence of helminth parasites using standard archaeoparasitological techniques. Of the mummies examined, only one individual presented with evidence of parasitism. This individual was infected with both Trichuris trichiura and Ascaris lumbricoides (5,222 parasite eggs/gram). The conditions of many of the T. trichiura eggs suggest that a fortuitously embedded female whipworm decomposed within the individual’s gut to release the eggs, as opposed to the eggs actually being passed by the adult helminth. This study highlights …

Assessing Satellite-Based Start-Of-Season Trends In The U.S High Plains, Rezaul Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.

Drainage Structure Datasets And Effects On Lidar-Derived Surface Flow Modeling, Ruopu Li, Zhenghong Tang, Xu Li, Jessie Winter

School of Natural Resources: Faculty Publications

With extraordinary resolution and accuracy, Light Detection and Ranging (LiDAR)-derived digital elevation models (DEMs) have been increasingly used for watershed analyses and modeling by hydrologists, planners and engineers. Such high-accuracy DEMs have demonstrated their effectiveness in delineating watershed and drainage patterns at fine scales in low-relief terrains. However, these high-resolution datasets are usually only available as topographic DEMs rather than hydrologic DEMs, presenting greater land roughness that can affect natural flow accumulation. Specifically, locations of drainage structures such as road culverts and bridges were simulated as barriers to the passage of drainage. This paper proposed a geospatial method for producing …

Elucidating The Population Dynamics Of Japanese Knotweed Using Integral Projection Models, Joseph T. Dauer, Eelke Jongejans

School of Natural Resources: Faculty Publications

Plant demographic studies coupled with population modeling are crucial components of invasive plant management because they inform managers when in a plant’s life cycle it is most susceptible to control efforts. Providing land managers with appropriate data can be especially challenging when there is limited data on potentially important transitions that occur belowground. For 2 years, we monitored 4 clonal Japanese knotweed (Polygonum cuspidatum) infestations for emergence, survival, shoot height until leaf senescence, dry shoot biomass after senescence, and rhizome connections for 424 shoots. We developed an integral projection model using both final autumn shoot height and shoot …

Behavioral Niche Partitioning In A Sympatric Tiger Beetle Assemblage And Implications For The Endangered Salt Creek Tiger Beetle, Tierney R. Brosius, Leon G. Higley

School of Natural Resources: Faculty Publications

How behavioral patterns are related to niche partitioning is an important question in understanding how closely related species within ecological communities function. Behavioral niche partitioning associated with thermoregulation is well documented in tiger beetles as a group. Co-occurring species of salt flat tiger beetles have adapted many thermoregulatory behaviors to cope with this harsh ecosystem. On first examination these beetles appear to occur in overlapping microhabitats and therefore compete for resources. To determine if behavioral niche partitioning is allowing multiple species to occur within the same harsh salt flat ecosystem we observed Cicindela nevadica lincolniana, Cicindela circumpicta, Cicindela fulgida, and …

Inconsistent Outcomes Of Heterogeneity-Based Management Underscore Importance Of Matching Evaluation To Conservation Objectives, Devan Allen Mcgranahan, David M. Engle, Samuel D. Fuhlendorf, Stephen L. Winter, James R. Miller, Diane M. Debinski

School of Natural Resources: Faculty Publications

Conservation policy often incentivizes managers of human-impacted areas to create landscape heterogeneity to maximize biodiversity. In rangeland, patchy disturbance regimes create landscape heterogeneity (patch contrast), but outcomes of heterogeneity-based management are rarely tested for a universal response. We analyzed four habitat variables—vegetation structure, plant functional group composition, litter cover, and bare ground—from five experimental rangelands in Oklahoma and Iowa, USA. We tested for response consistency to heterogeneity-based management across and within locations. We calculated effect sizes for each variable to compare patch contrast on pastures managed for heterogeneity (patch burn-grazing) and pastures managed for homogeneity (grazing with homogeneous fire regimes). …

Individual And Population Level Resource Selection Patterns Of Mountain Lions Preying On Mule Deer Along An Urban-Wildland Gradient, John F. Benson, Jeff A. Sikich, Seth P. D. Riley

School of Natural Resources: Faculty Publications

Understanding population and individual-level behavioral responses of large carnivores to human disturbance is important for conserving top predators in fragmented landscapes. However, previous research has not investigated resource selection at predation sites of mountain lions in highly urbanized areas. We quantified selection of natural and anthropogenic landscape features by mountain lions at sites where they consumed their primary prey, mule deer (Odocoileus hemionus), in and adjacent to urban, suburban, and rural areas in greater Los Angeles. We documented intersexual and individual-level variation in the environmental conditions present at mule deer feeding sites relative to their availability across home …

A Protected Area Influences Genotype-Specific Survival And The Structure Of A Canis Hybrid Zone, John F. Benson, Brent R. Patterson, Peter J. Mahoney

School of Natural Resources: Faculty Publications

It is widely recognized that protected areas can strongly influence ecological systems and that hybridization is an important conservation issue. However, previous studies have not explicitly considered the influence of protected areas on hybridization dynamics. Eastern wolves are a species of special concern and their distribution is largely restricted to a protected population in Algonquin Provincial Park (APP), Ontario, Canada, where they are the numerically dominant canid. We studied intrinsic and extrinsic factors influencing survival and cause-specific mortality of hybrid and parental canids in the three-species hybrid zone between eastern wolves, eastern coyotes, and gray wolves in and adjacent to …

Reviewing Models Of Land Availability And Dynamics For Biofuel Crops In The United States And The European Union, Ruopu Li, Nicola Di Virgilio, Qingfeng Guan, Song Feng, Goetz M. Richter

School of Natural Resources: Faculty Publications

The biofuel-related land use in the USA and the EU has significantly expanded during the last decade; models have been used to estimate land availability and demand in these regions. This paper provides an overview of different land-use modeling practices applicable to first- and second-generation biofuels. We review the importance of different land categories for biofuels, modeling approaches (top-down/bottom-up) and their integration, data availability for calibration and validation, model scale, and uncertainty. Possible future changes of biofuel land use and research gaps and limitations are synthesized. Key issues are the lack of data for independent validation and the need for …

Seasonal Fires, Bison Grazing, And The Tallgrass Prairie Forb Arnoglossum Plantagineum Raf., Stephen L. Winter, Karen R. Hickman, Carla L. Goad, Samuel D. Fuhlendorf, Mark S. Gregory

School of Natural Resources: Faculty Publications

Fire and grazing can interact to affect the structure and composition of vegetation communities in a manner that may differ from the effects of fire or grazing that occurs in isolation of the other. In order to better understand the effects of a fire-grazing interaction at the level of an individual plant species, we studied the response of a perennial tallgrass prairie forb, Arnoglossum plantagineum Raf., to the interaction of spring and summer fires with grazing by bison (Bison bison L.). During one field season (2006), we collected data in areas that had been treated with summer fires while …

Transforming The Teaching Of Geoscience And Sustainability, David Gosselin, Cathy Manduca, Timothy J. Bralower, David Mogk

School of Natural Resources: Faculty Publications

The geosciences have an important role to play in addressing whether humans can live sustainably on Earth. From water to energy, from climate change to natural hazards, geoscience is central to solving a wide range of problems.

Two projects funded by the National Science Foundation (NSF) support faculty in incorporating aspects of sustainability in their teaching: the Interdisciplinary Teaching of Geoscience for a Sustainable Future ( InTeGrate) Center in the Geosciences and the On the Cutting Edge Faculty Development Program in the Geosciences. The former is funded by NSF’s Science Technology, Engineering, and Mathematics (STEM) Faculty Development Program, and the …

Source And Magnitude Of Error In An Inexpensive Image-Based Water Level Measurement System, Troy E. Gilmore, François Birgand, Kenneth W. Chapman

School of Natural Resources: Faculty Publications

Recent technological advances have opened the possibility to use webcams and images as part of the environmental monitoring arsenal. The potential sources and magnitude of uncertainties inherent to an image-based water level measurement system are evaluated in an experimental design in the laboratory. Sources of error investigated include image resolution, lighting effects, perspective, lens distortion and water meniscus. Image resolution and meniscus were found to weigh the most in the overall uncertainty of this system. Image distortion, although largely taken into account by the software developed, may also significantly add to uncertainty. Results suggest that ‘‘flat’’ images with little distortion …

Fluctuating Viability Selection On Morphology Of Cliff Swallows Is Driven By Climate, Charles R. Brown, Mary Bomberger Brown, Erin A. Roche

School of Natural Resources: Faculty Publications

The extent to which fluctuating selection can maintain evolutionary stasis in most populations remains an unresolved question in evolutionary biology. Climate has been hypothesized to drive reversals in the direction of selection among different time periods and may also be responsible for intense episodic selection caused by rare weather events. We measured viability selection associated with morphological traits in cliff swallows (Petrochelidon pyrrhonota) in western Nebraska, USA, over a 14-year period following a rare climatic event. We used mark-recapture to estimate the annual apparent survival of over 26 000 individuals whose wing, tail, tarsus, and bill had been …

Phylogeography Of The California Gnatcatcher (Polioptila Californica) Using Multilocus Dna Sequences And Ecological Niche Modeling: Implications For Conservation, Robert M. Zink, Jeffrey G. Groth, Hernan Vázquez-Miranda

School of Natural Resources: Faculty Publications

An important step in conservation is to identify whether threatened populations are evolutionarily discrete and significant to the species. A prior mitochondrial DNA (mtDNA) phylogeographic study of the California Gnatcatcher (Polioptila californica) revealed no geographic structure and, thus, did not support the subspecies validity of the threatened coastal California Gnatcatcher (P. c. californica). The U.S. Fish and Wildlife Service concluded that mtDNA data alone were insufficient to test subspecies taxonomy. We sequenced eight nuclear loci to search for historically discrete groupings that might have been missed by the mtDNA study (which we confirmed with new ND2 …

Quantifying Free-Roaming Domestic Cat Predation Using Animal-Borne Video Cameras, Kerrie Anne T. Loyd, Sonia M. Hernandez, John Carroll, Kyler J. Abernathy, Greg J. Marshall

School of Natural Resources: Faculty Publications

Domestic cats (Felis catus) are efficient and abundant non-native predators. Predation by domestic cats remains a topic of considerable social and scientific debate and warrants attention using improved methods. Predation is likely a function of cat behavior, opportunity to hunt, and local habitat. Previous predation studies relied on homeowner reports of wildlife captures from prey returns to the household and other indirect means. We investigated hunting of wildlife by owned, free-roaming cats in a suburban area of the southeastern USA. Specific research goals included: (1) quantifying the frequency of cat interactions with native wildlife, (2) identifying common prey …

Recapture Heterogeneity In Cliff Swallows: Increased Exposure To Mist Nets Leads To Net Avoidance, Erin A. Roche, Charles R. Brown, Mary Bomberger Brown, Kristen M. Lear

School of Natural Resources: Faculty Publications

Ecologists often use mark-recapture to estimate demographic variables such as abundance, growth rate, or survival for samples of wild animal populations. A common assumption underlying mark-recapture is that all animals have an equal probability of detection, and failure to meet or correct for this assumption–as when certain members of the population are either easier or more difficult to capture than other animals–can lead to biased and inaccurate demographic estimates. We built within-year and among-years Cormack-Jolly-Seber recaptures-only models to identify causes of capture heterogeneity for a population of colonially nesting cliff swallows (Petrochelidon pyrrhonota) caught using mist-netting as a …