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Articles 901 - 930 of 1872

Full-Text Articles in Terrestrial and Aquatic Ecology

Sandhill Crane Collisions With Wind Turbines In Texas, Laura Navarrete, Kerry L. Griffis-Kyle Jan 2016

Sandhill Crane Collisions With Wind Turbines In Texas, Laura Navarrete, Kerry L. Griffis-Kyle

Proceedings of the North American Crane Workshop

The High Plains of the United States have been experiencing a large increase in wind energy generation sites with the American Wind Energy Association reporting an increase across America from 10 total installed gigawatts in 2006 to 60 total installed gigawatts in 2012. (American Wind Energy Association 2012). The High Plains also coincides with the Central Flyway in North America which is used by numerous bird species during migration, some with large bodies and high wing loading including the sandhill cranes (Grus canandensis), whooping cranes (G. americana), and waterfowl. Species such as these tend to be more vulnerable to mortality …


Proceedings Of The Thirteenth North American Crane Workshop Frontmatter, David A. Aborn, Richard Urbanek Jan 2016

Proceedings Of The Thirteenth North American Crane Workshop Frontmatter, David A. Aborn, Richard Urbanek

Proceedings of the North American Crane Workshop

List of previous Proceedings of the North American Crane Workshops

Suggested citation formats

PREFACE: The North American Crane Working Group (NACWG) is an organization of professional biologists, aviculturists, land managers, non-professional crane enthusiasts, and others interested in and dedicated to the conservation of cranes and crane habitats in North America. Our group meets approximately every 3 years to exchange information pertaining to sandhill cranes and whooping cranes and occasionally reports about some of the other cranes species. Our meeting in Lafayette, Louisiana, 14-17 April 2014, celebrated the return of whooping cranes to Louisiana for the first time in 60 years. …


Winter And Migratory Habitat Use Of Six Eastern Greater Sandhill Cranes, Hillary L. Thompson, Anne E. Lacy Jan 2016

Winter And Migratory Habitat Use Of Six Eastern Greater Sandhill Cranes, Hillary L. Thompson, Anne E. Lacy

Proceedings of the North American Crane Workshop

To better understand non-breeding ecology of sandhill cranes (Grus canadensis tabida), we harnessed 6 satellite GPS transmitters to adult cranes from 1 central Wisconsin breeding area. Using location data from these transmitters, we investigated non-breeding movements, including the routes and timing of migration. By combining satellite GPS data with a national land cover dataset, we also described habitat use on stopovers and wintering areas. Sandhill cranes tended to use larger home ranges on long stopovers (>3 days) than on short stopovers (3 days or less). The durations of northward migrations were longer and had more stopovers than …


The Utility Of Census Or Survey For Monitoring Whooping Cranes In Winter, Bruce H. Pugesek, Thomas V. Stehn Jan 2016

The Utility Of Census Or Survey For Monitoring Whooping Cranes In Winter, Bruce H. Pugesek, Thomas V. Stehn

Proceedings of the North American Crane Workshop

We discuss recent changes in the monitoring program for endangered whooping cranes (Grus americana) on their winter habitat in Texas. A 61-year annual census was replaced in the winter of 2011-2012 with a distance sampling procedure. Justification for the change was, in part, based on criticism of the previous methods of counting cranes and the assessment of crane mortality on the wintering grounds. We argue here that the arguments, methods, and analyses employed to discount the census procedure and mortality estimates were applied incorrectly or with flawed logic and assertions. We provide analysis and logical arguments to show …


Protocol And Results From The First Season Of Captive-Rearing Whooping Cranes For A Non-Migratory Release In Louisiana, Glenn H. Olsen, Jane N. Chandler Jan 2016

Protocol And Results From The First Season Of Captive-Rearing Whooping Cranes For A Non-Migratory Release In Louisiana, Glenn H. Olsen, Jane N. Chandler

Proceedings of the North American Crane Workshop

The principal historic range of the whooping crane (Grus americana) consisted of the tall grass prairies and wetlands of southwest Louisiana, Texas, and parts of Mexico (Allen 1952). Whooping cranes migrated there from Illinois, Iowa, Minnesota, Dakotas, Manitoba, Saskatchewan, Alberta, and breeding grounds of the remnant flock in and near Wood Buffalo National Park, Canada.


Habitat Selection By Breeding Sandhill Cranes In Central Wisconsin, Tamara P. Miller, Jeb A. Barzen Jan 2016

Habitat Selection By Breeding Sandhill Cranes In Central Wisconsin, Tamara P. Miller, Jeb A. Barzen

Proceedings of the North American Crane Workshop

We used compositional analysis to describe habitat use for a dense population of breeding sandhill cranes (Grus canadensis tabida) in central Wisconsin at 2 spatial scales: selection of home range within a study area and selection of habitats within the home range. Habitat use and home range size were estimated from radio-telemetry data from 12 breeding sandhill crane pairs. Research in Wisconsin that was performed on the landscape level suggests that breeding cranes depend on wetlands and do not select upland habitats. Evaluating habitat selection at different spatial levels, such as during different stages of the breeding season, …


Historic And Recent Winter Sandhill Crane Distribution In California, Gary L. Ivey, Caroline P. Herziger, David A. Hardt, Gregory H. Golet Jan 2016

Historic And Recent Winter Sandhill Crane Distribution In California, Gary L. Ivey, Caroline P. Herziger, David A. Hardt, Gregory H. Golet

Proceedings of the North American Crane Workshop

Understanding the geographic distribution and long-term dynamics of winter foraging areas and night roost sites of sandhill cranes (Grus canadensis) is important to their conservation and management. We studied sandhill crane distribution in California’s Central Valley from December 2012 through February 2013. We mapped observed flock and night roost locations. Flock locations occurred between Tehama County in the north and Kern County in the south. Flocks were concentrated in the northern Sacramento Valley, the Sacramento-San Joaquin Delta, the northern San Joaquin Valley south of Tracy to Mendota (including the lower Stanislaus and Tuolumne River floodplains and the Grasslands …


A Review Of Fall Sandhill Crane Migration Through Indiana, Allisyn-Marie T. Y. Gillet Jan 2016

A Review Of Fall Sandhill Crane Migration Through Indiana, Allisyn-Marie T. Y. Gillet

Proceedings of the North American Crane Workshop

The Indiana Division of Fish and Wildlife conducts surveys from October to December to collect long-term data on greater sandhill cranes (Grus canadensis tabida). Results from these censuses contribute to a fall index of the Eastern Population, which informs wildlife management decisions and research priorities. Recent findings from the annual U. S. Fish and Wildlife Service Fall Sandhill Crane Migration Survey demonstrate a decline in the number of cranes observed at fall staging areas throughout Indiana since 1979. However, nationwide data exhibit a trend of population increase. I provide evidence to show that the apparent decline in the …


A Guide To The Freshwater Mussels Of Nebraska, Steven C. Schainost Jan 2016

A Guide To The Freshwater Mussels Of Nebraska, Steven C. Schainost

Nebraska Game and Parks Commission: White Papers, Conference Presentations, and Manuscripts

This print-ready pdf includes information on the anatomy, life history, identification of and threats to Nebraska's freshwater mussels. Species accounts include maps and photos.


Hawks And Owls, Brian E. Washburn Jan 2016

Hawks And Owls, Brian E. Washburn

Wildlife Damage Management Technical Series

Human-Wildlife Conflicts: Hawks and owls can negatively impact a variety of human interests, including important natural resources, livestock and game bird production, human health and safety, and companion animals. Conflicts between raptors and people generally are localized and often site-specific. However, the economic and social impacts to the individuals involved can be severe. Despite the problems they may cause, hawks and owls provide important benefits and environmental services. Raptors are popular with birdwatchers and much of the general public. They also hunt and kill large numbers of rodents, reducing crop damage and other problems.

Damage Identification

Management Methods

Economics

Species …


Territoriality And Inter-Pack Aggression In Gray Wolves: Shaping A Social Carnivore's Life History Rudyard Kipling's Law Of The Jungle Meets Yellowstone's Law Of The Mountains, Kira A. Cassidy, Douglas W. Smith, L. David Mech, Daniel R. Macnulty, Daniel R. Stahler, Matthew C. Metz Jan 2016

Territoriality And Inter-Pack Aggression In Gray Wolves: Shaping A Social Carnivore's Life History Rudyard Kipling's Law Of The Jungle Meets Yellowstone's Law Of The Mountains, Kira A. Cassidy, Douglas W. Smith, L. David Mech, Daniel R. Macnulty, Daniel R. Stahler, Matthew C. Metz

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

When Rudyard Kipling wrote The Jungle Book in 1894 and included the famous line "For the strength of the Wolf is the Pack, and the strength of the Pack is the Wolf," he would have had no idea that over a century later, scientific research would back up his poetic phrase. Recent studies in Yellowstone have found that both the individual wolf and the collective pack rely on each other and play important roles in territoriality. At a time when most fairy tales and fables were portraying wolves as demonic killers or, at best, slapstick gluttons, Kipling seemed to have …


Wolf (Canis Lupus) Generation Time And Proportion Of Current Breeding Females By Age, L. David Mech, Shannon M. Barber-Meyer, John Erb Jan 2016

Wolf (Canis Lupus) Generation Time And Proportion Of Current Breeding Females By Age, L. David Mech, Shannon M. Barber-Meyer, John Erb

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

Information is sparse about aspects of female wolf (Canis lupus) breeding in the wild, including age of first reproduction, mean age of primiparity, generation time, and proportion of each age that breeds in any given year. We studied these subjects in 86 wolves (113 captures) in the Superior National Forest (SNF), Minnesota (MN), during 1972–2013 where wolves were legally protected for most of the period, and in 159 harvested wolves from throughout MN wolf range during 2012–2014. Breeding status of SNF wolves were assessed via nipple measurements, and wolves from throughout MN wolf range, by placental scars. In …


Differential Wolf-Pack-Size Persistence And The Role Of Risk When Hunting Dangerous Prey, Shannon M. Barber-Meyer, L. David Mech, Wesley E. Newton, Bridget L. Borg Jan 2016

Differential Wolf-Pack-Size Persistence And The Role Of Risk When Hunting Dangerous Prey, Shannon M. Barber-Meyer, L. David Mech, Wesley E. Newton, Bridget L. Borg

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

Risk to predators hunting dangerous prey is an emerging area of research and could account for possible persistent differences in gray wolf (Canis lupus) pack sizes. We documented significant differences in long-term wolf-pack-size averages and variation in the Superior National Forest (SNF), Denali National Park and Preserve, Yellowstone National Park, and Yukon, Canada (p < 0.01). The SNF differences could be related to the wolves’ risk when hunting primary prey, for those packs (N = 3) hunting moose (Alces americanus) were significantly larger than those (N = 10) hunting white-tailed deer (Odocoileus virginianus) (F1,8 = 16.50, p = 0.004). Our data support the hypothesis that differential pack-size persistence may be …


A Desert In Disguise: The Resilience Of The Nebraska Sandhills, Jeff Hartman Dec 2015

A Desert In Disguise: The Resilience Of The Nebraska Sandhills, Jeff Hartman

School of Natural Resources: Dissertations, Theses, and Student Research

The Nebraska Sandhills are the largest sand dune system in the Western Hemisphere, and are unique because they remain relatively undisturbed from row crop agriculture. Research in the past two decades demonstrated that the Sandhills are dynamic on millennial timescales, switching between stabilized, vegetated states to non-vegetated, mobilized states. The Sandhills are currently stabilized, but understanding how ecological processes are altered as sand dunes transition from stabilized to mobilized states, provides insight into the thresholds, stability, and resilience of this grassland ecosystem. My research investigated the impacts of vegetation disturbances on ecological processes and the sand dune surface stability. For …


Effects Of Wind Turbine Noise On Male Greater Prairie-Chicken Vocalizations And Chorus, Cara E. Whalen Dec 2015

Effects Of Wind Turbine Noise On Male Greater Prairie-Chicken Vocalizations And Chorus, Cara E. Whalen

School of Natural Resources: Dissertations, Theses, and Student Research

Wind energy facilities are constructed without full knowledge of their effects on birds, and the noise generated by wind turbines is a particular concern. I investigated the effects of wind turbine noise on male Greater Prairie-Chicken (Tympanuchus cupido pinnatus) vocalizations and chorus near Ainsworth, NE, USA in 2013 and 2014. I studied 14 leks located in the area surrounding a 36-turbine wind energy facility. I used two main approaches in this study. First, I recorded Greater Prairie-Chicken boom, cackle, whine, and whoop vocalizations at each of the study leks and measured the duration, sound pressure level, peak frequency, …


Occupancy Analysis And Density Estimation Of Kori Bustards (Ardeotis Kori) And Helmeted Guineafowl (Numida Meleagris) For Use In Landscape Conservation Planning In The Northern Tuli Game Reserve, Botswana, Kathryn R. Mccollum Dec 2015

Occupancy Analysis And Density Estimation Of Kori Bustards (Ardeotis Kori) And Helmeted Guineafowl (Numida Meleagris) For Use In Landscape Conservation Planning In The Northern Tuli Game Reserve, Botswana, Kathryn R. Mccollum

School of Natural Resources: Dissertations, Theses, and Student Research

For understudied species, more informed conservation planning and decision-making on both the local and landscape levels may be attained through the use of occupancy and abundance estimations. Here, we focus on two iconic bird species in eastern Botswana, kori bustards (Ardeotis kori) and helmeted guineafowl (Numida meleagris). The overall goal of this project was to better understand the hierarchy of factors that influence occupancy (ψ) and density of kori bustard and helmeted guineafowl populations within the Northern Tuli Game Reserve and how these factors may interact to affect landscape conservation and usage. We performed distance sampling …


Expansion Of The Chlorovirus Genus By Studies On Virus Natural History And Chlorella Host Metabolism, Cristian F. Quispe Dec 2015

Expansion Of The Chlorovirus Genus By Studies On Virus Natural History And Chlorella Host Metabolism, Cristian F. Quispe

School of Biological Sciences: Dissertations, Theses, and Student Research

Inland waters cover about 2.5 percent of our planet and harbor huge numbers of known and unknown microorganisms including viruses. Viruses likely play dynamic, albeit largely undocumented roles in regulating microbial communities and in recycling nutrients in the ecosystem. Phycodnaviruses are a genetically diverse, yet morphologically similar, group of large dsDNA-containing viruses (160- to 560-kb) that inhabit aquatic environments. Members of the genus Chlorovirus are common in freshwater. They replicate in eukaryotic, single-celled, chlorella-like green algae that normally exist as endosymbionts of protists in nature. Very little is known about the natural history of the chloroviruses and how they achieve …


Estudios En Biodiversidad, Volumen I, Griselda Pulido-Flores, Scott Monks, Maritza López-Herrera Nov 2015

Estudios En Biodiversidad, Volumen I, Griselda Pulido-Flores, Scott Monks, Maritza López-Herrera

Zea E-Books Collection

Este libro es el producto del trabajo colegiado que han desarrollado los profesores, investigadores, y estudiantes que conforman la Red Temática de Calidad Ambiental y Desarrollo Sustentable, a través del macroproyecto “Evaluación del impacto ambiental por actividades antropogénicas: Alternativas de mitigación”. El cual fue apoyado con recursos financieros por parte del Programa para el Desarrollo Profesional Docente (PRODEP), de la Secretaria de Educación Pública (SEP) en México. Las instituciones de educación superior y cuerpos participantes en la red temática son la Universidad Autónoma del Estado de Hidalgo (Uso, Manejo y Conservación de la Biodiversidad UAEHCA- 10; Ciencias Ambientales UAEH-CA-59); Universidad …


When An Invasive Plant Fails To Invade, Stephen L. Young Oct 2015

When An Invasive Plant Fails To Invade, Stephen L. Young

West Central Research and Extension Center, North Platte

In 2012, much of the US Midwest was gripped in one of the most severe droughts on record. While conducting experimental fieldwork at a site in Nebraska during June of that year, I noticed a single musk thistle (Carduus nutans; Figure 1) that appeared to be in the bolt or early flowering stage, which is typical for the species at that time. Here, however, two things were unusual: this plant was less than 1 meter tall (with adequate moisture and light, musk thistle typically grows to heights of 1–2.5 meters before flowering), and was only 3 months old (the bolt …


Spreading Holiday Spirit And Northwestern Salamanders, Ambystoma Gracile (Baird 1859) (Caudata: Ambystomatidae), Across The Usa, Michael R. Rochford, Jeffrey M. Lemm, Kenneth Krysko, Louis A. Somma, Robert W. Hansen, Frank J. Mazzotti Sep 2015

Spreading Holiday Spirit And Northwestern Salamanders, Ambystoma Gracile (Baird 1859) (Caudata: Ambystomatidae), Across The Usa, Michael R. Rochford, Jeffrey M. Lemm, Kenneth Krysko, Louis A. Somma, Robert W. Hansen, Frank J. Mazzotti

Papers in Herpetology

Introduced species of amphibians and reptiles are of growing conservation concern (Bury and Luckenbach 1976; Krysko et al. 2011; Meshaka 2011). Unintentional introductions result largely from individuals escaping from enclosures or hitch-hiking in cargo or on vehicles, whereas intentional introductions occur primarily because a species is perceived to be of value to humans or from deliberately releasing sick or unwanted animals, including pets (Kraus 2009; Krysko et al. 2011). In Florida, most known introductions are directly related to the pet trade, but about 12% are related to the cargo pathway (Krysko et al. 2011). In this paper, we report the …


Resilience Thinking And Structured Decision Making In Social–Ecological Systems, Noelle M. Hart Aug 2015

Resilience Thinking And Structured Decision Making In Social–Ecological Systems, Noelle M. Hart

School of Natural Resources: Dissertations, Theses, and Student Research

Natural resource management may be improved by synthesizing approaches for framing and addressing complex social-ecological issues. This dissertation examines how structured decision making processes, including adaptive management, can incorporate resilience thinking. Structured decision making is a process for establishing a solid understanding of the problem, values, management options, and potential consequences. Adaptive management is a form of structured decision making in which uncertainty is reduced for iterative decisions through designed monitoring and review. Resilience thinking can help conceptualize complex social-ecological systems and draws attention to the risks of managing for narrowly-focused objectives.

This dissertation provides practical advice to managers and …


Discovery And Delimitation: Criconematid Nematodes Of North American Grasslands, Magdalena Jean Olson Jul 2015

Discovery And Delimitation: Criconematid Nematodes Of North American Grasslands, Magdalena Jean Olson

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Approximately 200 years ago, North American landscapes were dominated by vast expanses of grassland. The Great Plains, an ecologically complex and diverse ecoregion, extended from Canada to the Gulf of Mexico, and from the Rocky Mountains to the border of the eastern hardwood forest in Indiana. Now the original tallgrass prairie exists in small widely dispersed remnant patches surrounded by agroecosystems. This study is an effort to characterize soil nematode diversity and population structure within those remnant patches. The plant parasitic nematode family Criconematidae serves as our indicator for nematode diversity, due to its global distribution, high abundance in natural …


Mammalian Records From Southwestern Kansas And Northwestern Oklahoma, Including The First Record Of Crawford’S Desert Shrew (Notiosorex Crawfordi) From Kansas, Cody A. Dreier, Keith Geluso, Jennifer D. Frisch, Brittney N. Adams, Alyx R. Lingenfelter, Anthony E. Bridger, Patricia Freeman, Cliff Lemen, Jeremy A. White, Brett R. Andersen, Hans W. Otto, Curtis J. Schmidt Jul 2015

Mammalian Records From Southwestern Kansas And Northwestern Oklahoma, Including The First Record Of Crawford’S Desert Shrew (Notiosorex Crawfordi) From Kansas, Cody A. Dreier, Keith Geluso, Jennifer D. Frisch, Brittney N. Adams, Alyx R. Lingenfelter, Anthony E. Bridger, Patricia Freeman, Cliff Lemen, Jeremy A. White, Brett R. Andersen, Hans W. Otto, Curtis J. Schmidt

School of Natural Resources: Faculty Publications

Mammalian distributions are constantly changing. Some distributional shifts reflect habitat change, climate change, and human transplantations; thus, such shifts are due to actual expansions or contractions of populations. However, other species ranges that appear to shift as the result of new records being added to known distributional limits actually might reflect populations that previously were undetected due to a lack of past surveys or species that are difficult to detect. In 2013, multiple techniques were employed to document mammalian distributional records in southwestern Kansas and northwestern Oklahoma. We discovered three new county records in Morton County, Kansas (Crawford’s Desert Shrew, …


At Home And At Large In The Great Plains: Essays And Memories, Paul A. Johnsgard Jul 2015

At Home And At Large In The Great Plains: Essays And Memories, Paul A. Johnsgard

Zea E-Books Collection

This volume presents fourteen essays (some updated) that originally appeared in Prairie Fire, a monthly free newspaper that for seven years (as of 2015) has carried important messages of social, environmental, and economic issues in a mature and nonpartisan manner to tens of thousands of residents of Nebraska, western Iowa, eastern Colorado, and southern South Dakota, and by mail to subscribers in the rest of the world. These essays discuss the North American east-west ecological boundaries, spring migration events, birds at the bird feeder, feathered survivors of a glacial past, the threatened sharp-tailed grouse of Nebraska and South Dakota, and …


Carbon Storage Potential Of Windbreaks On Agricultural Lands Of The Continental United States, William Ballesteros Possu Jul 2015

Carbon Storage Potential Of Windbreaks On Agricultural Lands Of The Continental United States, William Ballesteros Possu

School of Natural Resources: Dissertations, Theses, and Student Research

Agricultural production systems face major challenges under climate change scenarios in terms of expected negative impacts on productivity and persistence of the crops. Greenhouse gases from agriculture continue to rise although not as fast as from other fossil fuel-based human activities. Windbreaks perform several ecosystems functions that improve the local and regional capacity of crop systems to increase yields and offer environmental services by minimizing the negative effects of extreme weather events. Windbreaks also represent an important means of mitigating greenhouse gas emissions. This is predominantly accomplished by the windbreak trees storing carbon (C) in their above and belowground woody …


Introducing Green Manures In An Organic Soybean–Winter Wheat–Corn Rotation: Effects On Crop Yields, Soil Nitrate, And Weeds, Katja Koehler-Cole Jul 2015

Introducing Green Manures In An Organic Soybean–Winter Wheat–Corn Rotation: Effects On Crop Yields, Soil Nitrate, And Weeds, Katja Koehler-Cole

School of Natural Resources: Dissertations, Theses, and Student Research

In organic soybean– winter wheat – corn rotations, animal manure is a common choice to maintain high yields, but leguminous crops grown as green manures after wheat harvest and incorporated into the soil before corn planting, can be an alternative when animal manure is not accessible. Forage legumes with high dry matter (DM) production and high biological N fixation have been shown to meet corn N demand. However, in Eastern Nebraska, lack of precipitation can reduce green manure growth and N fixation, leading to an insufficient N supply for corn, but corn growth can also be impacted by green manure …


Acute Toxicity Of Β-N-Methylamino-L-Alanine (Bmaa) To Fathead Minnow (Pimephales Promelas) And Zebrafish (Danio Rerio), Jiayi Wang May 2015

Acute Toxicity Of Β-N-Methylamino-L-Alanine (Bmaa) To Fathead Minnow (Pimephales Promelas) And Zebrafish (Danio Rerio), Jiayi Wang

School of Natural Resources: Dissertations, Theses, and Student Research

β-N-methylamino-L-alanine (BMAA) is a neurotoxic amino acid produced by most species of cyanobacteria. Exposure to BMAA has been hypothesized as a cause of ALS and possibly Parkinson’s and Alzheimer’s diseases for several decades. Both in vitro and in vivo experiments revealed that exposure to elevated concentrations of BMAA can damage motor neurons and cause motor dysfunctions. However, the exact mechanism of BMAA-induced neurotoxicity has not been well understood.

Based on the available literature and in spite of its water-soluble and non-protein nature, BMAA appears to be able to bioaccumulate in organisms. The ubiquity of cyanobacteria and the potential for bioaccumulation …


Genetic And Morphological Variation In Ecuadorian Astroblepid Catfishes, Katherine M. Lawry May 2015

Genetic And Morphological Variation In Ecuadorian Astroblepid Catfishes, Katherine M. Lawry

School of Natural Resources: Dissertations, Theses, and Student Research

The Andean ichthyofauna remains a poorly understood component of Neotropical biodiversity, and stands in stark contrast to the lowland ichthyofauna in terms of number of species and range of distribution. The Climate Variability Hypothesis (CVH) predicts rapid turnover of species along elevational gradients in tropical climates, but it remains unclear whether stream fishes follow this pattern. Astroblepid catfishes represent a distinctive assemblage of species that inhabit high elevation streams throughout the Andes from Panama to Bolivia, and constitute the only native fish family present in the Ecuadorian highland region. In this research, population samples of Astroblepids collected throughout Ecuador’s Napo …


Plant Diversity Affects Performance Of Invasive Thistles In Restored Nebraska Grasslands, Katilyn J. Price May 2015

Plant Diversity Affects Performance Of Invasive Thistles In Restored Nebraska Grasslands, Katilyn J. Price

School of Natural Resources: Dissertations, Theses, and Student Research

Invasive plant species threaten native grasslands, affecting nutrient cycling, biodiversity, wildlife habitat, and usable land for production. Consequently, preventing establishment of invasive species is critical before removal becomes difficult and expensive. The purpose of this study was to examine the effects of grassland plant diversity on musk thistle (Carduus nutans) and Canada thistle (Cirsium arvense) establishment and determine which environmental factors (light penetration, soil moisture, plant diversity, and soil nitrogen) account for resistance to invasions. In a field experiment at The Nature Conservancy’s Wood River site (Nebraska), the two invasive thistle species were planted into replicated …


Coupling Soil Oxygen And Greenhouse Gas Dynamics, Karla M. Jarecke May 2015

Coupling Soil Oxygen And Greenhouse Gas Dynamics, Karla M. Jarecke

School of Natural Resources: Dissertations, Theses, and Student Research

Dynamic soil hydrology triggers important shifts in soil biogeochemical and physical processes that control greenhouse gas (GHG) emissions. Soil oxygen (O2), a direct control on biogenic GHG production (e.g. nitrous oxide-N2O, carbon dioxide-CO2 and methane-CH4), may serve as both an important proxy for determining sudden shifts in subsurface biogenic GHG production as well as the physical transport of soil GHG to the atmosphere. Recent technological advancements offer opportunities to link in-situ, near-continuous measurements of soil O2 concentration to soil biogeochemical processes and soil gas transport. Using high frequency data, this study …