Life Sciences Commons^™

Informing Management Strategy For The Relict Leopard Frog (Rana Onca): Insights Into Breeding Biology And An Attempt To Improve Augmentation Success Through Pre-Exposure And Clearance Of An Emerging Amphibian Pathogen, Rebeca Rivera

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Relict Leopard Frog, Rana onca, is a species of conservation concern that suffered a decline sometime during the 20th century. Even after two decades of intensive management, the species currently only occupies 20 spring sites in southern Nevada and northwestern Arizona. The causes for the historical decline are mostly speculative, but relate to habitat loss, introduced predators, and emergent disease. Since 2001, R. onca has been under an intensive conservationprogram managed by a multiagency conservation team. There are several objectives specified in the program including the need to investigate the biology of the species and incorporate findings into management …

Effects Of Ecological Restoration Techniques In Glen Canyon National Recreation Area, Simone Ka-Voka Jackson

UNLV Theses, Dissertations, Professional Papers, and Capstones

A better understanding of key ecological restoration techniques can inform land management in the Southwest on restoration options for areas infested by invasive grasses that can pose threats to ecosystems, from changes in nutrient cycling to altered fire regimes. In the semi-arid desert of Glen Canyon National Recreation Area (GLCA), several exotic grasses pose risks to local ecosystems: Saccharum ravennae, a relatively new invasive perennial grass, and Bromus rubens and Bromus tectorum, widespread annual grasses. In this study, multiple ecological restoration techniques were implemented to assess their effects on native and nonnative vegetation on sites invaded by the non-native grasses …

Living On The Edge: Assessing The Effects Of Catastrophic Fire On Plants Utilized By Two Endemic Subspecies Of Spring Mountains Butterflies, Charles Ryan Herrmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the past few decades there has been an increase in catastrophic, high-intensity, large-scale wildfires globally due to the combination of climate warming with more than a century of fire suppression policy. One region that has been drastically affected is the Western United States, as there has been an increase in ‘mega-fires’ in the past few decades. The 2013 Carpenter 1 Fire in the Spring Mountains, Nevada was the largest fire in recorded history in these mountains, spreading out over 11,137 hectares. Catastrophic fire like the Carpenter 1 Fire can have potentially devastating effects on endemic species inhabiting refugia on …

Water Source Partitioning For Shrubland Transpiration In A Mixed Phreatophytic Plant Community, Amanda Jean Wagner

UNLV Theses, Dissertations, Professional Papers, and Capstones

Groundwater in the basins of east central Nevada (Great Basin Desert, NV) has been permitted for export to southern Nevada. These basins are also vulnerable to changes in climate that could lead to declining recharge. Any decline in groundwater levels no matter the driving force could significantly impact phreatophytes (deep rooted shrubs), which utilize water from both the vadose zone and the capillary fringe to meet plant water needs, to support growth, and for overall health. A reduction in groundwater due to these forces could have a significant impact on the decoupling of phreatophytes from what is normally a reliable …

Pronghorn (Antilocapra Americana) Offspring Recruitment On The Carrizo Plain National Monument: Evaluating The Effects Of Low Population Density And Marginal Habitat Quality., Diego Ramirez Johnson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Demographic fluctuation among ungulate populations is strongly linked to variability in recruitment. Rates of recruitment are subject to various forms of density-dependent and density-independent regulation. For species which benefit from the presence of conspecifics, reduced population density can decrease rates of recruitment and trigger a decline in per capita growth. Termed the Allee effect, this scenario can cause demographic collapse and population extinction. For many ungulate species, predation on juveniles is reduced when the timing and distribution of births is synchronized within a local population. Because birth synchrony is density-dependent, it may act as a mechanism for the Allee effect …

Restoration Of Biological Soil Crust On Disturbed Gypsiferous Soils In Lake Mead National Recreation Area, Eastern Mojave Desert, Lindsay P. Chiquoine

UNLV Theses, Dissertations, Professional Papers, and Capstones

Biological soil crusts (BSCs) are sensitive to anthropogenic disturbances. Natural recovery takes many years. Active restoration decreases recovery time. Native BSC inocula, which included lichens and mosses, salvaged from gypsiferous soil habitats in Lake Mead National Recreation Area (LMNRA) in the eastern Mojave Desert were stored dry for two years and applied to disturbed soil after a road reconstruction in LMNRA and also used in laboratory experiments to test inoculation technique effectiveness. After 18 months, field results revealed positive relationships between inoculation and the presence of macroscopic BSC cover, cyanobacteria abundance, soil stability, and ammonium concentrations. Chlorophyll fluorescence monitoring of …

Natural And Constructed Wetlands For Ecosystem And Engineering Services In The Arid And Semi-Arid Regions, Achyut Raj Adhikari

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Las Vegas Wash (LVW) has undergone significant wetlands degradation and soil erosion over the past thirty years due to increasing flow resulting from urbanization and large rainfall events in the Las Vegas Valley Watershed. The increased flow and associated pollution load in the LVW and its adverse impact in Lake Mead have alerted stakeholders to pay a greater attention to explore alternative measures for rehabilitation of wetland ecosystems. This dissertation, using the case of changes in LVW, analyzes and describes ecological and engineering services provided by wetlands in arid and semi-arid regions and provides a knowledge base that can …

Transforming Space Into Place: Development, Rock Climbing, And Interpretation In Red Rock Canyon National Conservation Area, 1960-2010, Megan Sharp Weatherly

UNLV Theses, Dissertations, Professional Papers, and Capstones

Though Americans tend to view wilderness as separate from nature, environmental historians have argued that wilderness is a cultural construct more than a quantifiable geographic category. Red Rock Canyon National Conservation Area (NCA), a 195,000-acre tract located west of Las Vegas, Nevada, is one such cultural construction. Since 1960, this BLM-managed parcel has served as a local and regional expression of broader, national trends in outdoor recreation, interpretation, and development and thereby forced visitors to engage (often unknowingly) in a cultural dialogue about consumerism, technology, and identity. With information from newspapers, archival collections, oral histories, and government documents, this thesis …

The Contribution Of Environmental Variables On Small Mammal Species Richness And Relative Abundance In Eastern Nevada, Stephanie Harris

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to determine how four environmental variables: elevation, latitude, soil type, and vegetation impact the relative abundance of Peromyscus maniculatus and the species richness of small mammal populations in Eastern Nevada. In order to complete this study, a survey of small mammals was completed in the following 8 Eastern Nevada valleys: Delamar, Dry Lake, Dry Lake- Muleshoe,Cave, Lake, Snake, Spring, White River. In each valley, transects of Sherman live traps will be set up for 3 consecutive nights (O'Farrell et al 1977). Data on elevation, latitude, soil type, and vegetation were taken at each trap …

Anaerobic Digester Use In Dairy Farms In The United States, Shaun Elsasser

UNLV Theses, Dissertations, Professional Papers, and Capstones

Anaerobic digestion is a highly efficient process, trapping the methane gas from cow manure and processing it into energy. The steep initial capital costs make anaerobic digesters short-term liabilities, but the long-term benefits far outweigh the long-term costs. An anaerobic digester unit will begin to show a profit after approximately five years of operation. During the lifetime of the unit, estimated at 15 years, the digester will have produced about $ 1,000,000 in profits for the dairy farm, while also providing invaluable benefits to society as a whole.

The Fate And Transport Of Nitrogen (N) And The Effect Of Emergent Plants On Natural Treatment Of N-Species At Las Vegas Wash, Nevada, Tanju Kiriscioglu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to analyze the effect of emergent plant communities at Las Vegas Wash (the System) using a system dynamics modeling approach. Understanding the dynamics of nitrogen (N —major polluting nutrient in the Wash) that enters the System is important because it occasionally causes algal blooms, choking Lake Mead through excessive eutrophication. Emergent plant communities are an integral part of wetland ecosystems and they play a crucial role in natural treatment of nutrients. This study is intended to test this hypothesis.

The study makes use of Wash data from reliable sources (Las Vegas Valley Water District, …

Observed Omnivory In The Herbivorous Blue Tilapia (Oreochromis Aureus), Stephen M. Oliveira Jr.

UNLV Theses, Dissertations, Professional Papers, and Capstones

Gila seminuda, a native endangered species, and Oreochromis aureus, a nonnative invasive species, share the same habitat in the form of the Reid Gardner Power Plant intake ponds. The purpose of this study is to characterize the feeding habits of Oreochromis aureus within the Reid Gardner Power Plant intake ponds and address the potential predation habits of Oreochromis aureus. Stomach contents of O. aureus were identified and analyzed using chi-square and log-likelihood ratio techniques, with respect to mass, length, girth, gender, or spatial distribution of samples. Results showed omnivorous behavior with a 7.00% predatory/prey relationship, and no difference of feeding …

Habitat Preferences Of Four Species Of Lizards Found At The Las Vegas Springs Preserve, Scott Garncarz

UNLV Theses, Dissertations, Professional Papers, and Capstones

Developing an understanding of the habitat usage of reptiles is important when trying to develop a management or restoration plan that is compatible with what is known of the reptile species that are being investigated. There are many lizard species found in the Mojave Desert, but there are only four known to inhabit the Las Vegas Springs Preserve (LVSP) in Las Vegas, Nevada. In the LVSP, sites are going to be restored with native Mojave Desert vegetation. Since there are many habitat types in the Mojave Desert, we must determine which types would be best suited for the four species …

Defining Soil Type And Habitat Characteristics Of The Arctomecon Californica, Philip S. Childers

UNLV Theses, Dissertations, Professional Papers, and Capstones

A. californica can be considered a rare endemic species, which is believed to be restricted by unique soil relationships. These relationships make the species vulnerable to anthropogenic habitat disturbance. Although A. californica is listed as critically endangered by the state of Nevada, further research is needed before the species can be listed as federally endangered or threatened. This study used primary observational data and secondary GIS compatible data to characterize A. californica habitat. Representative sampling techniques were used to select observations from derived soil types. Although a majority of A. californica populations were found to occur in gypsic soil types, …

Assessment Of Potential Environmental Impacts Of Nature-Based Tours Originating Within Clark County, Nevada, Beth Domowicz

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this thesis was to assess the potential magnitude of negative environmental damage of nature-based tours originating in Clark County, Nevada. An ordinal ranking system was used for assessment of five variables. These variables were resource use, noise pollution, soil degradation, vegetation degradation, and wildlife disturbance. There were two proposed answers. The first was that as distance increased, negative tour impact would increase. This was not supported, since tours had high impacts for destinations that were close by and far away. The second was that most tours were not causing high damage to the environment. This hypothesis was …

Green Sea Turtle (Chelonia Mydas) Hatchlings Success: The Effects Of Artificial Lights And Other Human Impacts, Hui-Yu Tracy Liang

UNLV Theses, Dissertations, Professional Papers, and Capstones

Sea turtles appeared more than 200 million years ago in the late Triassic period. They grow very slowly, taking an average of 25 years to reach sexual maturity, with a life span averaging 40-50 years. From May to October green sea turtles (Chelonia mydas) emerge during the night and follow light cues toward the sea. Recently, beachfront development has increased hatchling mortality rate. When hatchlings emerge from nest, high densities of artificial lights lead them toward the land where they either desiccate and die, or are preyed upon. Short-wavelength high intensity light and the distance of artificial light are the …

Vegetation Analysis: A Graphical Analysis Of Plant Succession In Desert Communities Affected By Fire, Jeff Lantow

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Mojave Desert is affected by fire every year. With each fire comes the removal of old growth and, in its place, new growth – consisting primarily of those species which thrive in disturbed areas. The focus of my research is to look at plant communities that have been disturbed by fire, and examine the successional pathway of these disturbed environments. The seven environments I analyzed were burned within the last twenty years and are found in the Coleogyne ramosissima ecotone throughout the Spring Mountain range near Las Vegas, Nevada. The data was collected with randomly chosen circle plots in …

Water Conservation In The Las Vegas Valley, Judith M. Keir

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis deals primarily with residential use of water in the Las Vegas Valley, an arid climate located in the Mojave Desert, and whether the education of people living here has any bearing on whether or not they conserve water. Many of the residents of the Las Vegas Valley have moved from other areas of the country, and perhaps are not aware of the fact that there is a limited supply of water available to the Valley. I believe that people are not necessarily wasteful, and that they would want to conserve water, if they were aware that conservation and …

The Real Cost Of Beef: A Monetary Assessment Of The Environmental Degradation Caused By Beef Production, Carolyn Babcock

UNLV Theses, Dissertations, Professional Papers, and Capstones

The environmental degradation caused by beef production is severe. The current literature assesses the ecological damage, but falls short of assigning a per pound dollar amount to reflect the real cost of beef. In the United States, most of the environmental focus has been centered around the use of public lands for grazing and the grazing fee the government considers appropriate. The fee covers the maintenance of the grazing program, which includes maintenance of the actual land. This paper will concentrate on beef-related environmental degradation and select specific damage for monetary valuation.