RELATIONSHIPS BETWEEN NATIVE PLANT COMMUNITIES, GEOMORPHOLOGY AND SOILS IN A RARE PIEDMONT WET PRAIRIE, NORTH CAROLINA
The surficial geology of Suther Prairie was mapped, and soil pits were excavated on each geomorphic unit. The 7-acre site was surveyed at a 5 meter resolution with a laser theodolite and a 10x10m grid was established. Soil samples were collected from 0-15cm and 16-30cm depth at each grid point. These samples were analyzed for moisture, pH, texture, and carbon. In the spring and fall of 2006, the abundance of dominant plant species (>1% coverage) was collected by the pin-drop method at 69 sites within the grid. All data were inputted into ARC/GIS, and vegetation and soil data were additionally analyzed using PC-ORD.
Suther Prairie consists of 4 primary geomorphic units: floodplain, tributary alluvial fan, hillslope underlain by typical Piedmont saprolite, and an anthropogenic ridge which dissects the western margin of the floodplain. Plant communities are statistically differentiable in both spring and fall and correlate well with geomorphic units and soil moisture. Andropogon gerardii (Big Bluestem) and Tripsacum dactyloides (Gamma Grass) dominate the alluvial fan and upland hillslope. The floodplain of the prairie consists primarily of Carex stricta (Tussock Sedge) and Cephalanthus occidentalis (Button Bush). Overall drier sites are dominated by Big Bluestem and Gamma Grass, while wetter areas consist of Tussock Sedge and Button Bush. Relationships between vegetation and other measured soil properties are less clear. The soils and geomorphology of the Suther Prairie site are typical of many Piedmont floodplains. We therefore conclude that similar sites could be found and restored with native prairie ecosystems.