PARENT SESSION
Oral Session #100: Landscape Ecology.
Presiding: T. Crist
Friday, August 9. 9:00 AM to 12:00 PM. Gila Meeting Room, TCC.
Local and regional influence on taxonomic and ecological composition of herbaceous species in headwater wetlands.
HODSON, MICHAEL*,1, THRELKELD, STEPHEN1, 1 University of Mississippi, Oxford, MS
ABSTRACT- A GIS was used to test the influence of regional versus local influence on the taxonomic and ecological composition of herbaceous species in headwater riparian zones and wetlands. Satellite imagery, topography, and surficial geology in the Holly Springs National Forest were used to locate 57 first order streams dominated by groundwater input. A field survey using quadrat sampling and a visual search of the entire site was conducted once at each site. Approximately 150 species were encountered with an average of 28 species per site. On average visual searching added 7 species to the site total. The maximum number of species was 54 and the minimum number of species was 10. Although local conditions appear to affect site diversity, species turnover appears to increase with distance between sites. A GIS was constructed using satellite imagery, National Forest Service management and cover data, and a USGS Digital Elevation Model. This GIS was used to measure 12 indices of landscape structure describing both the regional setting and course scale local conditions. Local conditions are predominately controlled by the underlying geology, however regional setting appears to have some influence on both local conditions and species composition. Isolated sites tended to have a higher composition of facultative and upland species. The most frequent species were not always the most abundant but were generally wind dispersed species. The number of species dispersed by ingestion was generally higher in sites where the number of sites held within the surrounding area of continuous forest was high. In general, landscape structure appears to have an influence on both beta and gamma diversity.
KEY WORDS: Landscape Ecology, GIS, Wetland , Headwater