Predicting species richness Ppatterns in the Chihuahuan Desert: A GIS analysis of spatial and ecological data
Dawson, Emma Mae Pamela
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ABSTRACT The Chihuahuan Desert is the largest North American Desert measuring more than 200,000 square miles. Its location crossing the US-Mexico border makes the desert and its resources of international importance. To achieve an efficient level of conservation, natural resource planning and management must be an integral part of the region's long-term development. With the aid of Geographic Information Systems (GIS), other digitized systems and traditional research methods, this project assesses the biodiversity (species richness) aspect of land use planning and sustainable development within the Mexican portion of the Chihuahuan Desert region. The research uses data generated by the Texas Gap Analysis Program (TX GAP) and other sources including the United States Geological Survey, The Nature Conservancy, Texas Parks and Wildlife, Mexico's National Commission for the Conservation and Use of Biodiversity (CONABIO) and the Instituto Nacional de Estadistica Geografia e Informatica (INEGI) to develop spatial models that predict species richness patterns in the desert region. Known spatial distribution of species (locality records), soil, climate, precipitation (rainfall), vegetation, and land use data was overlaid to see if habitat modeling based on environmental factors could be used to model and predict distribution of terrestrial vertebrate species. The geographical unit of measure used for Presence/Absence data was the Environmental Protection Agency's Ecological Mapping and Assessment Program (EMAP) hexagons each of which area approximately 635 km. Correlations between species distribution and the environmental variables were examined via Correspondence Analysis (CA). The resulting species distribution maps provide an overview of the estimated current distribution of over two hundred desert mammals. The results of this study also indicate that desert mammalian distributions are the functions of individualistic responses to environmental variables. The location of a proposed Chihuahuan Desert Biodiversity Reserve was then created based on maximum species diversity, rarity and complimentarity in each of the hexagons. The goal is to aid decision makers in the conservation and management of the desert's biological resources. The ResNet software used in this study was shown to be a feasible method in developing conservation sites based on species distributions. Gap analysis provides a proactive, conservation evaluation method for assessing the biodiversity in a given geographic area such as the Chihuahuan Desert. This dissertation produced critical data needed to assist decision makers and other stakeholders in conservation planning and management, and in the creation of biodiversity reserve networks in the Chihuahuan Desert.