Award Date

5-1-2012

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Committee Member

Scott Abella

Second Committee Member

Stanley Smith

Third Committee Member

James Deacon

Fourth Committee Member

Wesley Niles

Number of Pages

141

Abstract

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 the Newberry Mountains, Nevada." We compared measures of species abundance and measures of community composition between the survey years of 1979 and 2008 and further investigated if changes were related to numerous environmental gradients present in the mountain range. Community composition, as measured by relative cover, was the only abundance measure found significantly different between survey years (A= -0.0031, p=0.04). Mountain soils derived from granitic residuum and colluvium showed significantly higher community composition change compared to the alluvial soil of bajadas. Certain plant species, such as Coleogyne ramosissima, associated with specific soils and higher elevations report significant decreases across multiple abundance measures. Other species such as Ferocactus cylindraceus were found to have increased significantly across abundance measures. We address inferred scenarios for changes to species across environmental gradients as well as the suitability of each species and various abundance measures as early indicators of vegetation community change. Overall we found negligible change for most plant species and vegetation communities as represented by multiple abundance measures between survey years. In addition, the analysis provided useful information on the natural history and current status of species within this unique mountain range. Future resurvey efforts with permanently established plots and shorter intervals have exciting potential for more predictive information relating to vegetation change.

Keywords

Change; Climate; Climatic changes; Desert plants; Deserts; Ecology; Nevada – Newberry Mountains; Plant communities; United States – Mojave Desert; Vegetation; Vegetation and climate

Disciplines

Desert Ecology | Ecology and Evolutionary Biology | Environmental Monitoring | Environmental Sciences | Plant Sciences | Systems Biology

Language

English


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