Other Environmental Sciences Commons^™

Evaluation Of Acoustic Telemetry Grids For Determining Aquatic Animal Movement And Survival, Richard T. Kraus, Christopher M. Holbrook, Christopher S. Vandergoot, Taylor R, Stewart, Matthew D. Faust, Douglas A. Watkinson, Colin Charles, Mark A. Pegg, Eva C. Enders, Charles C. Krueger

School of Natural Resources: Faculty Publications

1. Acoustic telemetry studies have frequently prioritized linear configurations of hydrophone receivers, such as perpendicular from shorelines or across rivers, to detect the presence of tagged aquatic animals. This approach introduces unknown bias when receivers are stationed for convenience at geographic bottlenecks (e.g. at the mouth of an embayment or between islands) as opposed to deployments following a statistical sampling design.

2. We evaluated two-dimensional acoustic receiver arrays (grids: receivers spread uniformly across space) as an alternative approach to provide estimates of survival, movement and habitat use. Performance of variably spaced receiver grids (5–25 km spacing) was evaluated by simulating …

Variability Of Rainfall Erosivity And Erosivity Density In The Ganjiang River Catchment, China: Characteristics And Influences Of Climate Change, Xianghu Li, Xuchun Ye

School of Natural Resources: Faculty Publications

Soil erosion is one of the most critical environmental hazards in the world. Understanding the changes in rainfall erosivity (RE) and erosivity density (ED), as well as their affecting factors, at local and catchment scales in the context of climate warming is an important prerequisite of soil erosion prevention and soil loss risk assessment. The present study identified the variability and trends of RE and ED in terms of both time and space in the Ganjiang River catchment over the period of 1960–2012, and also analyzed and discussed the impact of climate change. The results show that RE and ED …

Can Genomic Variation Explain The Extinction Of The Passenger Pigeon?, Chih-Ming Hung, R. M. Zink, Shou-Hsien Li

School of Natural Resources: Faculty Publications

No abstract provided.

Hybrid Speciation In Birds, With Special Reference To Darwin's Finches, G. E. Hill, R. M. Zink

School of Natural Resources: Faculty Publications

No abstract provided.

Gene Flow From Single And Stacked Herbicide-Resistant Rice (Oryza Sativa): Modeling Occurrence Of Multiple Herbicide-Resistant Weedy Rice, Joseph Dauer, Andrew Hulting, Dale Carlson, Luke Mankin, John Harden, Carol Mallory-Smith

School of Natural Resources: Faculty Publications

Background: Provisia™ rice (PV), a non-genetically engineered (GE) quizalofop-resistant rice, will provide growers with an additional option for weed management to use in conjunction with Clearfield® rice (CL) production. Modeling compared the impact of stacking resistance traits versus single traits in rice on introgression of the resistance trait to weedy rice (also called red rice). Common weed management practices were applied to 2-, 3- and 4-year crop rotations, and resistant and multiple-resistant weedy rice seeds, seedlings and mature plants were tracked for 15 years.

Results: Two-year crop rotations resulted in resistant weedy rice after 2 years with abundant populations (exceeding …

Dominant Plant Species Shape Soil Bacterial Community In Semiarid Sandy Land Of Northern China, Shaokun Wang, Xiaoan Zuo, Xueyong Zhao, Tala Awada, Yongqing Luo, Yuqiang Li, Hao Qu

School of Natural Resources: Faculty Publications

Plant species affect soil bacterial diversity and compositions. However, little is known about the role of dominant plant species in shaping the soil bacterial community during the restoration of sandy grasslands in Horqin Sandy Land, northern China. We established a mesocosm pots experiment to investigate short-term responses of soil bacterial diversity and composition, and the related soil properties in degraded soils without vegetation (bare sand as the control, CK) to restoration with five plant species that dominate across restoration stages: Agriophyllum squarrosum (AS), Artemisia halodendron (AH), Setaria viridis (SV), Chenopodium acuminatum (CA), and Corispermum macrocarpum (CM). We used redundancy analysis …

Urban Stream Microbial Communities Show Resistance To Pharmaceutical Exposure, E. J. Rosi, H. A. Bechtold, D. D. Snow, M. Rojas, A. J. Reisinger, J. J. Kelly

School of Natural Resources: Faculty Publications

Residues of pharmaceuticals are increasingly detected in surface waters throughout the world. In four streams in Baltimore, Maryland, USA, we detected analgesics, stimulants, antihistamines, and antibiotics using passive organic samplers. We exposed biofilm communities in these streams to the common drugs caffeine, cimetidine, ciprofloxacin, and diphenhydramine. Respiration rates in the least urban stream were suppressed when exposed to these drugs, but biofilm functioning in the most urban stream was resistant to drug exposure. Exposure to the antibiotic ciprofloxacin altered bacterial community composition at all sites, with the greatest change occurring in the most urban stream. These results indicated that continuous …

Rainfall Simulation Experiments In The Southwestern Usa Using The Walnut Gulch Rainfall Simulator, Viktor O. Polyakov, Jeffry Stone, Chandra Holifield Collins, Mark A. Nearing, Ginger Paige, Jared Buono, Rae-Landa Gomez-Pond

School of Natural Resources: Faculty Publications

This dataset contains hydrological, erosion, vegetation, ground cover, and other supplementary information from 272 rainfall simulation experiments conducted on 23 semiarid rangeland locations in Arizona and Nevada between 2002 and 2013. On 30% of the plots, simulations were conducted up to five times during the decade of study. The rainfall was generated using the Walnut Gulch Rainfall Simulator on 2m by 6m plots. Simulation sites included brush and grassland areas with various degrees of disturbance by grazing, wildfire, or brush removal. This dataset advances our understanding of basic hydrological and biological processes that drive soil erosion on arid rangelands. It …

Field-Scale Mapping Of Evaporative Stress Indicators Of Crop Yield: An Application Over Mead, Ne, Usa, Yang Yang, Martha C. Anderson, Feng Gao, Brian D. Wardlow, Christopher R. Hain, Jason A. Otkin, Joseph Alfieri, Yun Yang, Liang Sun, Wayne Dulaney

School of Natural Resources: Faculty Publications

The Evaporative Stress Index (ESI) quantifies temporal anomalies in a normalized evapotranspiration (ET) metric describing the ratio of actual-to-reference ET (f_RET) as derived from satellite remote sensing. At regional scales (3–10 km pixel resolution), the ESI has demonstrated the capacity to capture developing crop stress and impacts on regional yield variability in water-limited agricultural regions. However, its performance in some regions where the vegetation cycle is intensively managed appears to be degraded due to spatial and temporal limitations in the standard ESI products. In this study, we investigated potential improvements to ESI by generating maps of ET, …

Understanding Deer, Bear, And Forest Trends In The North Georgia Mountains: The Value Of Long-Term Data, Andrew R. Little, Gino J. D'Angelo, Charlie H. Killmaster, Kristina L. Johannsen, Karl V. Miller

School of Natural Resources: Faculty Publications

Most state wildlife agencies collect harvest data to inform management decisions. However, these data are typically considered across relatively short time periods and are rarely revisited. We present a case study using historical records to investigate potential agents (i.e., harvest, predation, and forest change) influencing the declining white-tailed deer (Odocoileus virginianus) population in the north Georgia mountains. We used long-term black bear (Ursus americanus) and deer harvest data, and indices of forest stand conditions from 1979–2015 on eight Wildlife Management Areas (WMAs) in the north Georgia mountains. During 1979–2015, harvest of male and female deer declined by 85% and 97%, …

Reproductive Ecology Of Interior Least Tern And Piping Plover In Relation To Platte River Hydrology And Sandbar Dynamics, Jason S. Alexander, Joel G. Jorgensen, Mary B. Brown

School of Natural Resources: Faculty Publications

Historical and contemporary use of large, economically important rivers by threatened and/or endangered species in the United States is a subject of great interest to a wide range of stakeholders. In a recent study of the Platte River in Nebraska, Farnsworth et al. (2017) (hereinafter referred to as “the authors” or “Farnsworth et al.”) used distributions of nest initiation dates taken mostly from human-created, off-channel habitats and a model of emergent sandbar habitat to evaluate the hypothesis that least terns (Sternula antillarum) and piping plovers (Charadrius melodus) are physiologically adapted to initiate nests concurrent with the …

Assessing Decadal Trends Of A Nitrate-Contaminated Shallow Aquifer In Western Nebraska Using Groundwater Isotopes, Age-Dating, And Monitoring, Martin J. Wells, Troy E. Gilmore, Aaron R. Mittelstet, Daniel D. Snow, Steven S. Sibray

School of Natural Resources: Faculty Publications

Shallow aquifers are prone to nitrate contamination worldwide. In western Nebraska, high groundwater nitrate concentrations ([NO₃^–]) have resulted in the exploration of new groundwater and nitrogen management regulations in the North Platte Natural Resources District (NPNRD). A small region of NPNRD (“Dutch Flats”) was the focus of intensive groundwater sampling by the United States Geological Survey from 1995 to 1999. Nearly two decades later, notable shifts have occurred in variables related to groundwater recharge and [NO₃^–], including irrigation methods. The objective of this study was to evaluate how changes in these variables, in part …

Effects Of Patch Size And Basal Area On Avian Taxonomic And Functional Diversity In Pine Forests: Implication For The Influence Of Habitat Quality On The Species–Area Relationship, Myung-Bok Lee, John P. Carroll

School of Natural Resources: Faculty Publications

Relationships between avian diversity and habitat area are assumed to be positive; however, often little attention has given to how these relationships can be influenced by the habitat structure or quality. In addition, other components of biodiversity, such as functional diversity, are often overlooked in assessing habitat patch value. In the Sandhills Ecoregion of Georgia, USA, we investigated the relationship between avian species richness and functional diversity, forest basal area, and patch size in pine forests using basal area as a surrogate for overstory structure which in turn impacts vegetation structure and determines habitat quality within a patch. We conducted …

Juvenile Rockfish Show Resilience To Co2-Acidification And Hypoxia Across Multiple Biological Scales, Brittany E. Davis, Lisa M. Komoroske, Matthew J. Hansen, Jamilynn B. Poletto, Emily N. Perry, Nathan A. Miller, Sean M. Ehlman, Sarah G. Wheeler, Andrew Sih, Anne E. Todgham, Nann A. Fangue

School of Natural Resources: Faculty Publications

California’s coastal ecosystems are forecasted to undergo shifting ocean conditions due to climate change, some of which may negatively impact recreational and commercial fish populations. To understand if fish populations have the capacity to respond to multiple stressors, it is critical to examine interactive effects across multiple biological scales, from cellular metabolism to species interactions. This study examined the effects of CO₂-acidification and hypoxia on two naturally cooccurring species, juvenile rockfish (genus Sebastes) and a known predator, cabezon (Scorpaenichthys marmoratus). Fishes were exposed to two PCO₂ levels at two dissolved oxygen (DO) levels: ~600 …

Kori Bustards (Ardeotis Kori) Respond To Vegetation Density And Elevation In The Northern Tuli Game Reserve, Botswana L'Abondance De L'Outarde Kori (Ardeotis Kori) Varie Selon La Végétation Et L'Élévation Dans La Réserve De Chasse De Northern Tuli, Botswana, Kathryn R. Mccollum, Larkin A. Powell, Andrei Shyman, Mary Bomberger Brown, John P. Carroll

School of Natural Resources: Faculty Publications

Conservation planning and decision making for species of concern requires precise information on abundance and habitat associations. We conducted transect surveys throughout the Northern Tuli Game Reserve, Botswana during June–July 2014 and May– July 2015 to estimate the occupancy and abundance of Kori Bustards (Ardeotis kori). The probability of occupancy of Kori Bustards was greater in areas with tree canopy cover ≤ 50% (ψ2014 = 0.37, SE ± 0.09; ψ2015 = 0.39, SE ± 0.06) when compared with areas with tree canopy cover > 50% (ψ2014 = 0.00, SE ± 0.00; ψ2015 = 0.00, SE ± 0.00). Densities of Kori Bustards …

Population Genomic Analysis Of North American Eastern Wolves (Canis Lycaon) Supports Their Conservation Priority Status, Elizabeth Heppenheimer, Ryan J. Harrigan, Linda Y. Rutledge, Klaus-Peter Koepfli, Alexandra L. Decandia, Kristin E. Brzeski, John F. Benson, Tyler Wheeldon, Brent R. Patterson, Roland Kays, Paul A. Hohenlohe, Bridgett M. Von Holdt

School of Natural Resources: Faculty Publications

The threatened eastern wolf is found predominantly in protected areas of central Ontario and has an evolutionary history obscured by interbreeding with coyotes and gray wolves, which challenges its conservation status and subsequent management. Here, we used a population genomics approach to uncover spatial patterns of variation in 281 canids in central Ontario and the Great Lakes region. This represents the first genome-wide single nucleotide polymorphism (SNP) dataset with substantial sample sizes of representative populations. Although they comprise their own genetic cluster, we found evidence of eastern wolf dispersal outside of the boundaries of protected areas, in that the frequency …

Ecological Drought: Accounting For The Non-Human Impacts Of Water Shortage In The Upper Missouri Headwaters Basin, Montana, Usa, Jamie Mcevoy, Deborah J. Bathke, Nina Burkardt, Amanda E. Cravens, Tonya Haigh, Kimberly R. Hall, Michael J. Hayes, Theresa Jedd, Marketa Podebradska, Elliot Wickham

School of Natural Resources: Faculty Publications

Water laws and drought plans are used to prioritize and allocate scarce water resources. Both have historically been human-centric, failing to account for non-human water needs. In this paper, we examine the development of instream flow legislation and the evolution of drought planning to highlight the growing concern for the non-human impacts of water scarcity. Utilizing a new framework for ecological drought, we analyzed five watershed-scale drought plans in southwestern Montana, USA to understand if, and how, the ecological impacts of drought are currently being assessed. We found that while these plans do account for some ecological impacts, it is …

Exploring The Role Of Relational Practices In Water Governance Using A Game-Based Approach, Piotr Magnuszewski, Karolina Krolikowska, Anna Koch, Michal Pajak, Craig R. Allen, Victoria Chraibi, Anil Giri, Danielle Haak, Noelle Hart, Michelle Hellman, Donald Pan, Nathan Rossman, Jan Sendzimir, Maggi S. Sliwinski, Joanna Stefanska, Tharsi Taillieu, Denise Marie Weide, Ilonka Zlatar

School of Natural Resources: Faculty Publications

The growing complexity and interdependence of water management processes requires the involvement of multiple stakeholders in water governance. Multi-party collaboration is increasingly vital at both the strategy development and implementation levels. Multi-party collaboration involves a process of joint decision-making among key stakeholders in a problem domain directed towards the future of that domain. However, the common goal is not present from the beginning; rather, the common goal emerges during the process of collaboration. Unfortunately, when the conflicting interests of different actors are at stake, the large majority of environmental multi-party efforts often do not reliably deliver sustainable improvements to policy …

The Spatial Sensitivity Of The Spectral Diversity–Biodiversity Relationship: An Experimental Test In A Prairie Grassland, Ran Wang, John A. Gamon, Jeannine Cavender-Bares, Philip A. Townsend, Arthur I. Zygielbaum

School of Natural Resources: Faculty Publications

Remote sensing has been used to detect plant biodiversity in a range of ecosystems based on the varying spectral properties of different species or functional groups. However, the most appropriate spatial resolution necessary to detect diversity remains unclear. At coarse resolution, differences among spectral patterns may be too weak to detect. In contrast, at fine resolution, redundant information may be introduced. To explore the effect of spatial resolution, we studied the scale dependence of spectral diversity in a prairie ecosystem experiment at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Our study involved a scaling exercise comparing synthetic pixels resampled from …

Habitat Associations Of Shovelnose Sturgeon Scaphirhynchus Platorynchus (Rafinesque, 1820) In The Lower Platte River, Nebraska, Jeremy J. Hammen, Martin J. Hamel, M. L. Rugg, Mark A. Pegg

School of Natural Resources: Faculty Publications

Human induced alterations of river systems are ubiquitous throughout the world. Alterations have reduced riverine habitat and negatively affected riverine species; therefore, it is crucial to understand what habitats are important to riverine fish at multiple scales. Most research has focused around microhabitats (i.e., depth) with little effort on how the reach scale habitat (i.e., geomorphic landscape) influences riverine fish abundance. We examined habitat associations of shovelnose sturgeon sampled with two gears (trotlines and trammel nets) at multiple spatial scales in the lower Platte River, NE, a system that has not been overtly altered in physical description. At a microhabitat …

Spring Warming In Yukon Mountains Is Not Amplified By The Snow Albedo Feedback, Scott N. Williamson, Faron S. Anslow, Garry K. C. Clarke, John A. Gamon, Alexander H. Jarosch, David S. Hik

School of Natural Resources: Faculty Publications

Decreasing spring snow cover may amplify Arctic warming through the snow albedo feedback. To examine the impact of snowmelt on increasing temperature we used a 5,000 m elevation gradient in Yukon, Canada, extending from valley-bottom conifer forests, through middle elevation tundra, to high elevation icefields, to compare validated downscaled reanalysis air temperature patterns across elevational bands characterized by different patterns of spring snowmelt. From 2000 to 2014 we observed surface warming of 0.01 °C/a·1,000 m in May (0.14 °C/a at 1,000 m to 0.19 °C/a at 5,000 m), and uniform cooling of 0.09 °C/a in June at all elevations. May …

A Modis Photochemical Reflectance Index (Pri) As An Estimator Of Isoprene Emissions In A Temperate Deciduous Forest, Iolanda Filella, Chao Zhang, Roger Seco, Mark Potosnak, Alex Guenther, Thomas Karl, John A. Gamon, Stephen Pallardy, Lianhong Gu, Saewung Kim, Manuela Balzarolo, Marcos Fernandez-Martinez, Josep Penuelas

School of Natural Resources: Faculty Publications

The quantification of isoprene and monoterpene emissions at the ecosystem level with available models and field measurements is not entirely satisfactory. Remote-sensing techniques can extend the spatial and temporal assessment of isoprenoid fluxes. Detecting the exchange of biogenic volatile organic compounds (BVOCs) using these techniques is, however, a very challenging goal. Recent evidence suggests that a simple remotely sensed index, the photochemical reflectance index (PRI), which is indicative of light-use efficiency, relative pigment levels and excess reducing power, is a good indirect estimator of foliar isoprenoid emissions. We tested the ability of PRI to assess isoprenoid fluxes in a temperate …

Imaging Spectroscopic Analysis Of Biochemical Traits For Shrub Species In Great Basin, Usa, Yi Qi, Susan L. Ustin, Nancy F. Glenn

School of Natural Resources: Faculty Publications

The biochemical traits of plant canopies are important predictors of photosynthetic capacity and nutrient cycling. However, remote sensing of biochemical traits in shrub species in dryland ecosystems has been limited mainly due to the sparse vegetation cover, manifold shrub structures, and complex light interaction between the land surface and canopy. In order to examine the performance of airborne imaging spectroscopy for retrieving biochemical traits in shrub species, we collected Airborne Visible Infrared Imaging Spectrometer—Next Generation (AVIRIS-NG) images and surveyed four foliar biochemical traits (leaf mass per area, water content, nitrogen content and carbon) of sagebrush (Artemesia tridentata) and …

Road Induced Edge Effects On A Forest Bird Community In Tropical Asia, Daphawan Khamcha, Richard T. Corlett, Larkin A. Powell, Tommaso Savini, Antony J. Lynam, George A. Gale

School of Natural Resources: Faculty Publications

Background: Edge effects cause changes in bird community richness, abundance, and/or distribution within a landscape, but the avian guilds most influenced can vary among regions. Although Southeast Asia has the highest rates of deforestation and projected species loss, and is currently undergoing an explosive growth in road infrastructure, there have been few studies of the effects of forest edges on avian communities in this region.

Methods: We examined avian community structure in a dry evergreen forest in northeastern Thailand adjacent to a five-lane highway. We evaluated the richness and abundance of birds in 11 guilds at 24 survey points on …

Validation Of A Process-Based Agro-Ecosystem Model (Agro-Ibis) For Maize In Xinjiang, Northwest China, Tureniguli Amuti, Geping Luo, Gang Yin, Qi Hu, Elizabeth A. Walter-Shea

School of Natural Resources: Faculty Publications

Agricultural oasis expansion and intensive management practices have occurred in arid and semiarid regions of China during the last few decades. Accordingly, regional carbon and water budgets have been profoundly impacted by agroecosystems in these regions. Therefore, study on the methods used to accurately estimate energy, water, and carbon exchanges is becoming increasingly important. Process-based models can represent the complex processes between land and atmosphere among agricultural ecosystems. However, before the models can be applied they must be validated under different environmental and climatic conditions. In this study, a process-based agricultural ecosystem model (Agro-IBIS) was validated for maize crops using …

The Spatial Sensitivity Of The Spectral Diversity–Biodiversity Relationship: An Experimental Test In A Prairie Grassland, Ran Wang, John A. Gamon, Jeannine Cavender-Bares, Philip A. Townsend, Arthur I. Zygielbaum

School of Natural Resources: Faculty Publications

Remote sensing has been used to detect plant biodiversity in a range of ecosystems based on the varying spectral properties of different species or functional groups. However, the most appropriate spatial resolution necessary to detect diversity remains unclear. At coarse resolution, differences among spectral patterns may be too weak to detect. In contrast, at fine resolution, redundant information may be introduced. To explore the effect of spatial resolution, we studied the scale dependence of spectral diversity in a prairie ecosystem experiment at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Our study involved a scaling exercise comparing synthetic pixels resampled from …

Extreme Group Sizes In A Colonial Bird Favored During A Rare Climatic Event, Charles R. Brown, Mary B. Brown

School of Natural Resources: Faculty Publications

What maintains stasis in animal group-size distributions is an unresolved problem in behavioral ecology. One potential driver could be rare climatic events that favor certain group sizes in ways that do not occur in normal conditions. We investigated mortality among colonially nesting cliff swallows (Petrochelidon pyrrhonota) during a rare climatic event in western Nebraska in 1996 that led to the starvation of thousands of adult birds. Colonies at the extreme end of the size distribution exhibited less size reduction (higher adult survival) than those of intermediate size. That this event resulted in disruptive selection on colony size was …

Enhancing Quantitative Approaches For Assessing Community Resilience, W. C. Chuang, A. Garmestani, T. N. Eason, T. L. Spanbauer, H. B. Fried-Peterson, C. P. Roberts, S. M. Sundstrom, J. L. Burnett, D. G. Angeler, B. C. Chaffin, L. Gunderson, D. Twidwell, C. R. Allen

School of Natural Resources: Faculty Publications

Scholars from many different intellectual disciplines have attempted to measure, estimate, or quantify resilience. However, there is growing concern that lack of clarity on the operationalization of the concept will limit its application. In this paper, we discuss the theory, research development and quantitative approaches in ecological and community resilience. Upon noting the lack of methods that quantify the complexities of the linked human and natural aspects of community resilience, we identify several promising approaches within the ecological resilience tradition that may be useful in filling these gaps. Further, we discuss the challenges for consolidating these approaches into a more …

Tiered Approach To Resilience Assessment, Igor Linkov, Cate Fox-Lent, Laura Read, Craig R. Allen, James C. Arnott, Emanuele Bellini, Jon Coaffee, Marie-Valentine Florin, Kirk Hatfield, Iain Hyde, William Hynes, Aleksandar Jovanovic, Roger Kasperson, John Katzenberger, Patrick W. Keys, James H. Lambert, Richard Moss, Peter S. Murdoch, Jose Palma-Oliveira, Roger S. Pulwarty, Dale Sands, Edward A. Thomas, Mari R. Tye, David Woods

School of Natural Resources: Faculty Publications

Regulatory agencies have long adopted a three-tier framework for risk assessment. We build on this structure to propose a tiered approach for resilience assessment that can be integrated into the existing regulatory processes. Comprehensive approaches to assessing resilience at appropriate and operational scales, reconciling analytical complexity as needed with stakeholder needs and resources available, and ultimately creating actionable recommendations to enhance resilience are still lacking. Our proposed framework consists of tiers by which analysts can select resilience assessment and decision support tools to inform associated management actions relative to the scope and urgency of the risk and the capacity of …

River Otter Distribution In Nebraska, Nathan R. Bieber, Samuel P. Wilson, Craig R. Allen

School of Natural Resources: Faculty Publications

The river otter (Lontra canadensis) was extirpated from Nebraska, USA, in the early 1900s and reintroduced starting in 1986. Information is needed regarding the distribution of river otters in Nebraska before decisions can be made regarding its conservation status. Understanding distribution of a species is critically important for effective management. We investigated river otter distribution in Nebraska with occupancy modeling and maximum entropy (Maxent) modeling using 190 otter sign observations on Nebraska’s navigable rivers and 380 historical otter records from November 1977 to April 2014. Both methods identified the Platte River, Elkhorn River, central and eastern Niobrara River, …