PARENT SESSION

Community Ecology 2 -- Session Chair: Kathleen Lyons-- Van Duzer Theater

RELATIONSHIPS BETWEEN TOPOGRAPHY, VEGETATION AND SMALL MAMMALS IN PALO DURO CANYON. Greg T. Lewellen, Raymond S. Matlack, Karah L. Gallagher, Rachel A. Spruance and Daniel P. Walker. Department of Life, Earth and Environmental Sciences, West Texas A&M University, Box 60808, Canyon, TX, US.

ABSTRACT- The influence of topography on the distribution of plant communities is evident along the eastern escarpment of the Llano Estacado, where the short-grass plains of the Llano gives way to the mixed-grass prairie of the Rolling Plains. The objectives of this study were to determine the influence of aspect on juniper patch characteristics and on the distribution and abundance of small mammals within the Palo Duro Canyon. The study was performed in Canoncita Ranch, a newly acquired portion of Palo Duro Canyon State Park. We established 8 transects in 2 habitats, north slopes and south slopes. Juniper patches were delineated from aerial photographs using ArcView 3.3 and patch characteristics were analyzed using Patch Analyst 3.0. Small mammals were sampled over 3,120 total trap nights from January 2003 to December 2003. We captured 77 individuals, including 50 Texas mice, 15 white-throated woodrats, 11 Palo Duro mice and 1 white-footed mouse. The number of shrub patches was higher on south slopes. North slopes had greater total shrub area, mean shrub patch size and mean patch edge. Overall, small mammal abundance was negatively related to the number of patches and edge density and positively related to the total shrub area, mean patch size and mean patch edge. Texas mouse abundance was positively related to total shrub area, mean patch size and mean patch edge. Topography influences the amount and distribution of shrub patches and the abundance and distribution of small mammals in this unique habitat.

KEY WORDS: vegetation, patch analysis, topography, GIS