Physical Sciences and Mathematics 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, …

Integrating, Developing, And Testing Methods To Generate More Cohesive Approaches To Biogeographic Inference, Mallory Elizabeth Eckstut

UNLV Theses, Dissertations, Professional Papers, and Capstones

As a fundamental component of the developing discipline of conservation biogeography, broadscale analyses of biotic assembly and disassembly across multiple temporal and spatial scales provide an enhanced understanding of how geologic transformations and climate oscillations have shaped extant patterns of biodiversity. As with any scientific field, there are limitations in the case of biogeographic historical reconstructions. Historical reconstructions are only as robust as the theoretical underpinnings of the methods of reconstruction (including data collection, quality, analysis, and interpretation). Nevertheless, historical reconstructions of species distributions can help inform our understanding of how species respond to environmental change.

My dissertation takes a …

The Evaluation Of Water Storage In Death Valley Using Grace Satellite Data, Maile Sweigart

UNLV Theses, Dissertations, Professional Papers, and Capstones

As drought conditions spread across the United States, concerns over water supplies, water use, and water management policies are growing and possible contributing environmental factors are continually being scrutinized. This thesis examines Death Valley as an analog for Southern Nevada and utilizes NASA EOS data, combined with ancillary climate data, to assess the effect of decadal climate variability on groundwater storage in the Death Valley area. Historical climate data, combined with satellite imagery observations, were compiled and calculated for analyses. Conclusions derived from statistical analyses infer trends between GRACE (Gravity Recovery and Climate Experiment) satellite data and fluctuating levels of …

Soil Moisture Recognition And The Spatial Distribution Of Storm Activity In The Mojave Desert Using High-Resolution Aster And Modis Imagery For Thermophysical Mapping, Russell J. Skuse

UNLV Theses, Dissertations, Professional Papers, and Capstones

Climate models suggest that the Mojave Desert ecoregion is vulnerable to becoming drier in the future, and as the human population grows and development increases, environmental stresses will likely increase. Determining the spatial distribution and variation of soil moisture on a regional scale is an essential component to climate change, hydrologic, and habitat analyses. Soil permeability and sediment stability are characteristics that have been shown to be measurable from remote sensing observations. The primary objective of this project is to map the mechanical composition of the surface materials in the Mojave Desert ecoregion with implications for soil permeability, sediment stability, …

Investigating Three Decades Of Vegetation Change In A Mojave Desert Mountain Range, Chris Lee Roberts

UNLV Theses, Dissertations, Professional Papers, and Capstones

This project is a vegetation change study spanning 29 years in the Newberry Mountains of Southern Nevada. Long term monitoring data are crucial for understanding the effects of climate change on vegetation dynamics. Successful management intervention in vegetation change will require identification of early indicator plant species and their responses to climatic cues. This project is one of the oldest comparisons of resurveyed Mojave vegetation community plots with repeatable methodology and the longest survey interval reported for the southeastern Mojave Desert. 103 plots were relocated and resurveyed based on data methods in Jim Holland's thesis titled "A Vegetative Analysis of …

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 …

Fluctuations In Chinook Salmon (Oncorhynchus Tshawytscha) Counts At Three Lower Columbia River Spawning Sites, Eric Michael Loomis

UNLV Theses, Dissertations, Professional Papers, and Capstones

Several hypotheses were developed to explore the pronounced increase in Chinook salmon (Oncorhynchus tshawytscha) returning to spawning grounds at the Cowlitz, Kalama, and Lewis Rivers, three tributaries of the lower Columbia River. The study was conducted using data compiled over a ten-year span from 1991-2001. Preliminary indications are that trends in climate are linked to these increases, with the absence of El Niño events and fluctuations in winter precipitation as likely explanations of these phenomena. The unique nature of Chinook life cycles causes them to utilize a variety of habitats that require ideal conditions for maximum survival rates. Correlations between …