Physical Sciences and Mathematics Commons^™

Denitrification By Sulfur-Oxidizing Bacteria In A Eutrophic Lake, Amy J. Burgin, Stephen K. Hamilton, Stuart E. Jones, Jay T. Lennon

School of Natural Resources: Faculty Publications

Understanding the mechanistic controls of microbial denitrification is of central importance to both environmental microbiology and ecosystem ecology. Loss of nitrate (NO₃ ⁻) is often attributed to carbon-driven (heterotrophic) denitrification. However, denitrification can also be coupled to sulfur (S) oxidation by chemolithoautotrophic bacteria. In the present study, we used an in situ stable isotope (¹⁵NO₃ ⁻) tracer addition in combination with molecular approaches to understand the contribution of sulfur-oxidizing bacteria to the reduction of NO3 ⁻ in a eutrophic lake. Samples were incubated across a total dissolved sulfide (H₂S) gradient (2 to …

Impacts Of An Invasive Snail (Tarebia Granifera) On Nutrient Cycling In Tropical Streams: The Role Of Riparian Deforestation In Trinidad, West Indies, Jennifer M. Moslemi, Sunny B. Snider, Keeley Macneill, James F. Gilliam, Alexander S. Flecker

School of Natural Resources: Faculty Publications

Non-native species and habitat degradation are two major catalysts of environmental change and often occur simultaneously. In freshwater systems, degradation of adjacent terrestrial vegetation may facilitate introduced species by altering resource availability. Here we examine how the presence of intact riparian cover influences the impact of an invasive herbivorous snail, Tarebia granifera, on nitrogen (N) cycling in aquatic systems on the island of Trinidad. We quantified snail biomass, growth, and N excretion in locations where riparian vegetation was present or removed to determine how snail demographics and excretion were related to the condition of the riparian zone. In three …

Remote Estimation Of Crop Gross Primary Production With Landsat Data, Anatoly Gitelson, Yi Peng, Jeffrey G. Masek, Donald Rundquist, Shashi Verma, Andrew E. Suyker, John M. Baker, Tilden Meyers

School of Natural Resources: Faculty Publications

An accurate and synoptic quantification of gross primary production (GPP) in crops is essential for studies of carbon budgets at regional and global scales. In this study, we tested a model, relating crop GPP to a product of total canopy chlorophyll (Chl) content and potential incident photosynthetically active radiation (PAR_potential). The approach is based on remotely sensed data; specifically, vegetation indices (VI) that are proxies for total Chl content and PARpotential, which is incident PAR under a condition of minimal atmospheric aerosol loading. Using VI retrieved from surface reflectance Landsat data, we found that the model is capable …

Complex Terrain Leads To Bidirectional Responses Of Soil Respiration To Inter-Annual Water Availability, Diego Andrés Riveros-Iregui, Brian L. Mcglynn, Ryan E. Emanuel, Howard E. Epstein

School of Natural Resources: Faculty Publications

Research on the terrestrial C balance focuses largely on measuring and predicting responses of ecosystem-scale production and respiration to changing temperatures and hydrologic regimes. However, landscape morphology can modify the availability of resources from year to year by imposing physical gradients that redistribute soil water and other biophysical variables within ecosystems. This article demonstrates that the well-established biophysical relationship between soil respiration and soil moisture interacts with topographic structure to create bidirectional (i.e., opposite) responses of soil respiration to inter-annual soil water availability within the landscape. Based on soil respiration measurements taken at a subalpine forest in central Montana, we …

The General Ensemble Biogeochemical Modeling System (Gems) And Its Applications To Agricultural Systems In The United States, Shuguang Liu, Zhengxi Tan, Mingshi Chen, Jinxun Liu, Anne Wein, Zhengpeng Li, Shengli Huang, Jennifer Oeding, Claudia Young, Shashi Verma, Andrew Suyker, Stephen Faulkner, Gregory W. Mccarty

School of Natural Resources: Faculty Publications

The General Ensemble Biogeochemical Modeling System (GEMS) (Liu, 2009; Liu et al., 2004c) was developed to integrate well-established ecosystem biogeochemical models with various spatial databases for the simulations of biogeochemical cycles over large areas. Figure 18.1 shows the overall structure of the GEMS. Some of the key components are described below.

General Ensemble Biogeochemical

Modeling System (GEMS) 310

Multiple Underlying Biogeochemical Models 310

Monte Carlo Simulations 311

Model Inputs: Management Practices and Others 311

Model Outputs 311

Data Assimilation 311

Simulation of Agricultural Practices: EDCM as an Example 312

Net Primary Production (NPP) and Improvements in Crop Genetics and Agronomics …

Interior Least Tern Powerline Collision On The Lower Platte River, Lauren R. Dinan, Joel G. Jorgensen, Mary Bomberger Brown

School of Natural Resources: Faculty Publications

Collisions with electrical powerlines are a well-known documented cause of avian mortality (Avian Power Line Interaction Committee [APLIC] 1994, Savereno et al. 1996). Mortality caused by collisions with powerlines can be an important concern for many bird species, but is a serious conservation problem for threatened and endangered species because any mortality can have biological and legal ramifications (Janss 2000). Loss of individuals, particularly breeding adults, from an already small population may impede a species’ recovery by reducing reproduction and recruitment into the breeding population. The death of an individual from a threatened or endangered species as a result of …

Fish Assemblage Shifts And Population Dynamics Of Smallmouth Bass (Micropterus Dolomieu) In The Beaver Archipelago, Northern Lake Michigan: A Comparison Between Historical And Recent Time Periods Amidst Ecosystem Changes., Mark A. Kaemingk, Tracy L. Galarowicz, John A. Clevenger, David F. Clapp, Herbert L. Lenon

School of Natural Resources: Faculty Publications

The ecological and economic importance of Great Lakes nearshore areas and the paucity of information on nearshore Lake Michigan fish assemblages prompted us to document changes that occurred from a historical time period (1969–1972, 1975, 1977, and 1984) to a recent period (2005–2008) in a nearshore northern Lake Michigan (Beaver Archipelago) fish assemblage, with an emphasis on smallmouth bass Micropterus dolomieu. From historical to recent periods, the Beaver Archipelago fish assemblage shifted from predominantly brown bullheads Ameiurus nebulosus to predominantly smallmouth bass. Relative abundance of brown bullheads and white suckers Catostomus commersonii declined from historical to recent time periods, as …

Priority Effects Among Young-Of-The-Year Fish: Reduced Growth Of Bluegill Sunfish (Lepomis Macrochirus) Caused By Yellow Perch (Perca Flavescens)?, Mark A. Kaemingk, Jeffrey C. Jolley, David W. Willis, Steven R. Chipps

School of Natural Resources: Faculty Publications

1. When available, Daphnia spp. are often preferred by age-0 yellow perch and bluegill sunfish because of energetic profitability. We hypothesised that predation by age-0 yellow perch could lead to a midsummer decline (MSD) of Daphnia spp. and that priority effects may favour yellow perch because they hatch before bluegill, allowing them to capitalise on Daphnia spp. prior to bluegill emergence.

2. Data were collected from 2004 to 2010 in Pelican Lake, Nebraska, U.S.A. The lake experienced a prolonged MSD in all but 1 year (2005), generally occurring within the first 2 weeks of June except in 2008 and 2010 …

Phosphorus In Phoenix: A Budget And Spatial Representation Of Phosphorus In An Urban Ecosystem, Genevieve S. Metson, Rebecca L. Hale, David M. Iwaniec, Elizabeth M. Cook, Jessica R. Corman, Christopher S. Galletti, Daniel L. Childers

School of Natural Resources: Faculty Publications

As urban environments dominate the landscape, we need to examine how limiting nutrients such as phosphorus (P) cycle in these novel ecosystems. Sustainable management of P resources is necessary to ensure global food security and to minimize freshwater pollution. We used a spatially explicit budget to quantify the pools and fluxes of P in the Greater Phoenix Area in Arizona, USA, using the boundaries of the Central Arizona– Phoenix Long-Term Ecological Research site. Inputs were dominated by direct imports of food and fertilizer for local agriculture, while most outputs were small, including water, crops, and material destined for recycling. Internally, …

Monitoring Live Fuel Moisture Using Soil Moisture And Remote Sensing Proxies, Yi Qi, Philip E. Dennison, Jessica Spencer, David Riano

School of Natural Resources: Faculty Publications

Live fuel moisture (LFM) is an important fuel property controlling fuel ignition and fire propagation. LFM varies seasonally, and is controlled by precipitation, soil moisture, evapotranspiration, and plant physiology. LFM is typically sampled manually in the field, which leads to sparse measurements in space and time. Use of LFM proxies could reduce the need for field sampling while potentially improving spatial and temporal sampling density. This study compares soil moisture and remote sensing data to field-sampled LFM for Gambel oak (Quercus gambelii Nutt) and big sagebrush (Artemisia tridentata Nutt) in northern Utah. Bivariate linear regression models were constructed …

Bats In And Around Structures, Dennis M. Ferraro, Lisa Pennisi, Scott E. Hygnstrom, Stephen M. Vantassel

School of Natural Resources: Faculty Publications

No abstract provided.

The Collaborative Forest Landscape Restoration Program: A History And Overview Of The First Projects, Courtney A. Schultz, Theresa Jedd

School of Natural Resources: Faculty Publications

No abstract provided.

Predation, Herbivory, And Parasitism, Alison N.P. Stevens

School of Natural Resources: Faculty Publications

No abstract provided.

Planet Protectors, A.P. Stevens

School of Natural Resources: Faculty Publications

No abstract provided.

Dynamics Of Predation, Alison N.P. Stevens

School of Natural Resources: Faculty Publications

No abstract provided.

Factors Affecting Global Climate, Alison N.P. Stevens

School of Natural Resources: Faculty Publications

No abstract provided.

Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters Using Airborne Hyperspectral Data, Wesley J. Moses, Anatoly Gitelson, Richard L. Perk, Daniela Gurlin, Donald C. Rundquist, Bryan C. Leavitt, Tadd M. Barrow, Paul Brakhage

School of Natural Resources: Faculty Publications

Algorithms based on red and near infra-red (NIR) reflectances measured using field spectrometers have been previously shown to yield accurate estimates of chlorophylla concentration in turbid productive waters, irrespective of variations in the bio-optical characteristics of water. The objective of this study was to investigate the performance of NIR-red models when applied to multi-temporal airborne reflectance data acquired by the hyperspectral sensor, Airborne Imaging Spectrometer for Applications (AISA), with non-uniform atmospheric effects across the dates of data acquisition. The results demonstrated the capability of the NIR-red models to capture the spatial distribution of chlorophyll-a in surface waters without the need …

Application Of Day And Night Digital Photographs For Estimating Maize Biophysical Characteristics, Toshihiro Sakamoto, Anatoly Gitelson, Brian D. Wardlow, Timothy J. Arkebauer, Shashi Verma, Andrew E. Suyker, Michio Shibayama

School of Natural Resources: Faculty Publications

In this study, an inexpensive camera-observation system called the Crop Phenology Recording System (CPRS), which consists of a standard digital color camera (RGB cam) and a modified near-infrared (NIR) digital camera (NIR cam), was applied to estimate green leaf area index (LAI), total LAI, green leaf biomass and total dry biomass of stalks and leaves of maize. The CPRS was installed for the 2009 growing season over a rainfed maize field at the University of Nebraska-Lincoln Agricultural Research and Development Center near Mead, NE, USA. The vegetation indices called Visible Atmospherically Resistant Index (VARI) and two green–red–blue (2g–r–b) were calculated …

Groundwater Beneath A Phase Iii Management Area In The Central Platte Natural Resources District, Nebraska: National Institute Of Food And Agriculture–Conservation Effects Assessment Project, Donald W. Meals, Roy F. Spalding, Mary Exner Spalding, Richard B. Ferguson, Mark L. Mcfarland, Deanna L. Osmond, Jean Spooner

School of Natural Resources: Faculty Publications

The goal of the Nebraska National Institute of Food and Agriculture–Conservation Effects Assessment Project (NIFA–CEAP), Phase III, Central Platte Natural Resources District Project, Effectiveness of Irrigated Crop Management Practices in Reducing Groundwater Nitrate Concentrations, was to evaluate the effectiveness of documented farm management practices in lowering groundwater nitrate concentrations in a predominantly irrigated-corn watershed. The specific objectives included the following:

1. Analyze the trends in groundwater nitrate concentrations for the period of 1988 to 2006

2. Evaluate the effect of irrigation and nitrogen (N) inputs on groundwater nitrate concentrations using statistical approaches, including ArcGIS and cokriging and Bayesian Maximum Entropy …

Developing Slow-Release Persulfate Candles To Treat Btex Contaminated Groundwater, Ann Kambhu, Steve D. Comfort, Chanat Chokejaroenrat, Chainarong Sakulthaew

School of Natural Resources: Faculty Publications

The development of slow-release chemical oxidants for sub-surface remediation is a relatively new technol­ogy. Our objective was to develop slow-release persulfate-paraffin candles to treat BTEX-contaminated ground­water. Laboratory-scale candles were prepared by heating and mixing Na₂S₂O₈ with paraffin in a 2.25 to 1 ra­tio (w/w), and then pouring the heated mixture into circular molds that were 2.38 cm long and either 0.71 or 1.27 cm in diameter. Activator candles were prepared with FeSO₄ or zero-valent iron (ZVI) and wax. By treat­ing benzoic acid and BTEX compounds with slow-release persulfate and ZVI candles, we observed rapid …

Population Size Of Hatchery-Reared And Wild Pallid Sturgeon In The Lower Missouri River, Kirk D. Steffensen, Larkin A. Powell, Mark A. Pegg

School of Natural Resources: Faculty Publications

The population size of pallid sturgeon Scaphirhynchus albus is currently unknown throughout much of the Missouri River. Listed as federally endangered in 1990, the pallid sturgeon remains one of the rarest fishes in the Missouri and Mississippi River basins, and little to no natural recruitment occurs. Artificial population supplementation via a hatchery propagation program was initiated, necessitating the collection of sexually mature pallid sturgeon. Therefore, the Nebraska Game and Parks Commission maintained an intensive broodstock collection and mark– recapture effort from 2008 to 2010 to capture reproductively ready adults for the propagation program. Coordinated crews fished baited trotlines from the …

Operational Meris-Based Nir-Red Algorithms For Estimating Chlorophyll-A Concentrations In Coastal Waters — The Azov Sea Case Study, Wesley J. Moses, Anatoly A. Gitelson, Sergey Berdnikov, Vladislav Saprygin, Vasily Povazhnyi

School of Natural Resources: Faculty Publications

We present here results that strongly support the use of MERIS-based NIR-red algorithms as standard tools for estimating chlorophyll-a (chl-a) concentration in turbid productive waters. The study was carried out as one of the steps in testing the potential of the universal applicability of previously developed NIR-red algorithms, which were earlier calibrated using a limited set of MERIS imagery and in situ data from the Azov Sea and the Taganrog Bay, Russia, and data that were synthetically generated using a radiative transfer model. We used an extensive set of MERIS imagery and in situ data collected over …

Attendance Patterns And Survival Of Western Meadowlark Nests, Larkin A. Powell, Matthew D. Giovanni, Scott R. Groepper, Mitchell Reineke, Walter H. Schacht

School of Natural Resources: Faculty Publications

Biologists have linked nest attendance and nestling feeding rates to nest predation risk. Patterns of nest attendance also influence the success of methods designed to find nests for research use, such as rope drags. Very little has been published with regard to variation of attendance during the nesting period, but advances in video nest monitoring allow continuous data collection to provide this information. Our objectives were to (1) document attendance patterns at Western Meadowlark (Stumella neglecta) nests, (2) identify predator species of meadowlark nests, and (3) assess the effects of our camera system on nest survival. We used a solar-powered, …

Using Slow-Release Permanganate Candles To Remediate Pah-Contaminated Water, Lindy Rauscher, Chainarong Sakulthaew, Steve D. Comfort

School of Natural Resources: Faculty Publications

Surface waters impacted by urban runoff in metropolitan areas are becoming increasingly contaminated with polycyclic aromatic hydrocarbons (PAHs). Slow-release oxidant candles (paraffin–KMnO₄) are a relatively new technology being used to treat contaminated groundwater and could potentially be used to treat urban runoff. Given that these candles only release permanganate when submerged, the ephemeral nature of runoff events would influence when the permanganate is released for treating PAHs. Our objective was to determine if slow-release permanganate candles could be used to degrade and mineralize PAHs. Batch experiments quantified PAH degradation rates in the presence of the oxidant candles. Results …

Estimating The Abundance Of Long-Billed Curlews In Nebraska, Cory J. Gregory, Stephen J. Dinsmore, Larkin A. Powell, Joel G. Jorgensen

School of Natural Resources: Faculty Publications

Long-billed Curlews (Numenius americanus) are shorebirds of high conservation concern in North America. Populations have de­clined in the last 150 yr primarily due to habitat loss and conversion. We conducted a 2-yr study to estimate the density and state­wide abundance of breeding Long-billed Curlews in Nebraska during 2008 and 2009. Surveys were conducted during the prenest­ing period in April when Long-billed Curlews were likely to be detected. We used a simple random sample of roadside survey routes (N = 39), each consisting of 40 5-min point-counts at 800-m intervals. We modeled detection probability and found that wind …

2012 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 (2012). 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 habitat for two state and federally protected bird species, the Interior Least Tern (Sternula antillarum athalassos) and Piping Plover (Charadrius melodus). The Tern and Plover Conservation Partnership (TPCP), based at the University of Nebraska-School of Natural Resources, and the Nongame Bird …

Use Of Partially Fenced Fields To Reduce Deer Damage To Corn, Aaron M. Hildreth, Scott E. Hygnstrom, Erin E. Blankenship, Kurt C. Vercauteren

School of Natural Resources: Faculty Publications

White-tailed deer (Odocoileus virginianus) damage agricultural crops, often leading to significant economic losses for farmers. We used poly-mesh fence with wings to separate good deer cover from agricultural fields where crop damage by deer occurred primarily along this edge. In these cases, complete enclosure of the field with fencing may be unnecessary. The design used a 2.13-m-high polypropylene mesh fence erected along the wooded edge of a field with either 50-m or 150-m wings extending perpendicular from the fence line and wooded habitat. Fences reduced deer damage in cornfields 13.5% (F_1,6= _∞, P < 0.001). Average yield in fenced fields (10,211 kg/ha) was 1,708 kg/ha greater than in control fields, which, at US$0.155/kg, equals a net gain of US$265/ha. We found no difference in damage between fences with 50-m and 150-m wings (F …