Throughout its current range, the Cross Timbers forest ecosystem is vulnerable to land-use change. In this study, we examined the surrounding land use matrix on the vegetation structure, composition and regeneration of six Cross Timbers forest fragments in Denton County, Texas (north of the Dallas-Fort Worth metroplex). Two fragments adjacent to agricultural land, two to residential neighborhoods, and two formally protected forest sites were selected. In summer 2015, five 100 m2 plots were randomly established in each fragment at least 200 meters from the edge. In each plot, all live and dead trees ≥ 3 cm diameter were identified and their height and diameter at breast height (DBH at 1.3 m aboveground) measured. Evidence of dumping (presence of trash) was recorded as an index of human frequentation. Differences in vegetation structure among the forest fragments were found. Most notably, fragments adjacent to agriculture contained 25% to 50% fewer trees per hectare than all other sites (Kruskal-Wallis, p < 0.02), especially trees <10 cm DBH. However, residential fragments had fewer trees that were ≥15 cm DBH compared to the other fragments, indicating that these are the youngest of the forest patches surveyed. Trash was observed in 60% of plots surveyed at …

This study elucidates the underlying relationships for the distribution of oak landcover on bedrock and soil orders in two counties in Texas and one in Oklahoma. ESRI's ArcGis and ArcMap was used to create surface maps for Denton and Coke Counties, Texas and Choctaw County, Oklahoma. Attribute tables generated in GIS were exported into a spreadsheet software program and frequency tables were created for every formation and soil order in the tri-county research area. The results were both a visual and numeric distribution of oaks in the transition area between the eastern hardwood forests and the Great Plains. Oak distributions are changing on this transition area of the South Central Plains. The sandy Woodbine and Antlers formations traditionally associated with the largest oak distribution are carrying oak coverage of approximately 31-32% in Choctaw and Denton Counties. The calcareous Blackland and Grand Prairies are traditionally associated with treeless grasslands, but are now carrying oak and other tree landcover up to 18.9%. Human intervention, including the establishment of artificial, political and social boundaries, urbanization, farming and fire control have altered the natural distribution of oaks and other landcover of this unique georegion.

Nutritional quality and availability is thought to regulate geographic patterns of variability in animal body size due to phenotypic plasticity. The purpose of this study is to determine how vegetation quality, abundance and population density influence white-tailed deer (Odocoileus virginianus) body size on a subregional spatial scale at Fort Hood, Texas. Harvest and census records are used to test the hypothesis that white-tailed deer exhibit phenotypic plasticity (e.g. larger body size) in response to differences in vegetation quality and availability. Results from these analyses suggest that forage quality and abundance alone is not a main driver of white-tailed deer body size. Analysis of deer population density (generally) resulted in an inverse relationship with body size. Areas with high quality forage and low population density support larger deer while areas with low quality forage and high density support smaller than average deer. The few exceptions occur in areas exhibiting poor quality forage and low population density or high forage quality and high density. Results from this study suggest that continued overcrowding of deer within isolated areas may eventually lead to efficiency phenotypic conditions producing smaller sized deer. These results could prove useful in interpreting deer population responses to harvest management. For …

Archaeologically site catchment analysis produces valuable information regarding prehistoric subsistence strategies and social organization. Incorporating archaeological data into catchment analyses is an effective strategy to develop regional models of prehistoric site selection and settlement patterns. Digital access to data permits the incorporation of multiple layers of information into the process of synthesizing regional archaeology and interpreting corresponding spatial patterning. GIS software provides a means to integrate digital environmental and archaeological data into an effective tool. Resultant environmental archaeology maps facilitate interpretive analysis. To fulfill the objectives of this thesis, GIS software is employed to construct site catchment areas for archaeological sites and to implement multivariate statistical analyses of physical and biological attributes of catchments in correlation with assemblage data from sites. Guided by ecological, anthropological and geographical theories hypotheses testing evaluates patterns of prehistoric socio-economic behavior. Analytical results are summarized in a model of prehistoric settlement patterns in North Central Texas.