Ecology and Evolutionary Biology Commons^™

Assessing Growth Response To Climate Controls In A Great Basin Artemisia Tridentata Plant Community, Lorenzo F. Apodaca

UNLV Theses, Dissertations, Professional Papers, and Capstones

An assessment of the growth response of key vegetative species to climatic variability is vital to identifying possible local impacts on ecosystems faced with imminent climate change. With current climate projections in Nevada predicting a shift to an even more arid climate with greater year-to-year variability, the imperative exists to identify the effects of specific climatic controls on plant growth and to research methods to assess large-scale vegetative changes, especially in more remote areas where readily available data sets may be lacking. This study utilized annual growth ring indices constructed from big sagebrush (Artemisia tridentatassp.tridentata) stems collected in Spring Valley, …

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 …

Environmental Impact Of The Three Kids Mine Tailings, Henderson, Nv, Ji Hye Park

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research focused on the distribution of the Three Kids Mine tailings in surface soils in and around the mine in Henderson, Nevada. It is situated next to the communities of Calico Ridge and Lake Las Vegas Resort, and, just the west of the Lake Mead Recreation area. Even though the mine has been inactive for almost 50 years (1917-1961), tailing piles and other sources of contamination on the mine are currently exposed to the atmosphere. In this study, surface soil samples were collected along eight transects emanating from the center of Three Kids Mine tailing piles up to five …

Bryoecology In The American Southwest: Patterns Of Biodiversity And Responses To Global Change, John Carroll Brinda

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation combines investigation of the large-scale responses of bryophyte species diversity and distribution with small-scale physiological adaptations to global change. These two areas of inquiry are linked because one way to predict plant species responses to global change is to examine their distribution across current ecological gradients produced by factors such as latitude and elevation. By examining these biogeographic patterns one can identify those species that have a narrow tolerance and therefore are most sensitive to change. Selected bryophytes might then be used as indicator species in long-term monitoring programs. Where historical data exist, these can be used to …

Climate And Vegetation Change In The Newberry Mountains, Southern Clark County, Nevada, Ross Joseph Guida

UNLV Theses, Dissertations, Professional Papers, and Capstones

Ecological studies have shown worldwide that vegetation is being affected by climate change. Species are shifting to new elevations and physiographic positions to adapt to changes in their environment. More specifically, paleoecology studies in the Mojave Desert have shown shifting vegetation patterns in response to past warming and precipitation changes. Recent studies have shown mortality among desert plants related to extended drought and warming. However, few studies have shown how the geographic distribution of Mojave Desert species has changed during this most recent period of warming. This study addresses this gap in the literature by focusing on several plant species …

An Ecological Study Of Peregrine Falcons (Falco Peregrinus) At Lake Mead National Recreation Area, 2006-2010, Joseph Graham Barnes

UNLV Theses, Dissertations, Professional Papers, and Capstones

Peregrine Falcons (Falco peregrinus) represent an encouraging conservation biology success story in North America during the twentieth century. Their distribution and population size suffered major restrictions after the initiation of widespread application of the synthetic pesticide dichloro-diphenyl-trichloroethane (DDT) within the U.S. in the 1940s. The species was federally listed as endangered in the U.S. in 1969 and was then delisted in 1999 after DDT was banned in 1972. Herein, I present my ecological research of peregrines within Lake Mead National Recreation Area (LMNRA), concentrating on the years 2006-2010. This thesis is comprised of two chapters. In the first chapter, I …

Odonates At The Clark County Wetlands Nature Preserve: A Look At Habitat And Relative Abundance, Erin Jolley

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to identify the various species, relative abundance and habitat of dragonfly and damselfly larvae at the Clark County Wetlands Park Nature Preserve (WPNP). An accurate assessment of these insects can be useful in interpreting potential indications of environmental problems at the Wetlands. From this data, necessary improvements can be made to the dragonfly habitat as well as the habitat of other surrounding organisms. Habitat identification is considered especially important because it is "structured by instream and surrounding topographical features, and is a major determinant of aquatic community potential" (Southwood, 1977). For purposes of this …

The Effects Of Off-Road Vehicle Use In Desert Tortoise (Gopherus Agassizii) Habitats, Brent D. Clark

UNLV Theses, Dissertations, Professional Papers, and Capstones

The desert tortoise (Gopherus agassizii) populations have been in decline and have been placed on the endangered species list. No single factor is ultimately responsible for the tortoise decline. It is a combination of events that collectively have a negative impact. I chose to focus my study on only one factor, off-road vehicles. By evaluating the damage done to the terrain by off-road vehicles, a better understanding of their impact on the tortoise populations can be assessed and protective measures taken.

The amount of available vegetation does not seem to play a role in their decisions of which plants to …

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, …

The Effects Of Environmentally Relevant Doses Of Perchlorate (Clo4-) On Rana Pipiens Metamorphosis And Development, Andrea N. Golli

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study was to assess the effects of environmentally relevant concentrations of perchlorate on the development and growth of Rana pipiens. Ammonium perchlorate is a rocket fuel oxidizer that is known to interfere with the function of the thyroid gland and some of the highest United States surface water concentration exists in the Las Vegas Wash, NV. Perchlorate not only blocks the body’s ability to incorporate iodine into T3 and T4 hormones through the sodium iodine symporter system, but also depletes the thyroid glands’ internal stores of iodine. Many of the steps that regulate metamorphosis in amphibians …

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 …