Soil texture, land-use intensity, and vegetation of Fort Benning upland forest sites

DILUSTRO, J. J., B. S. COLLINS, L. K. DUNCAN, AND R. R. SHARITZ (Savannah River Ecology Laboratory, P. O. Drawer E, Aiken, S. C. 29802). Soil texture, land-use intensity, and vegetation of Fort Benning upland forest sites. J. Torrey Bot. Soc. 129: 289-297. 2002-Federal lands may harbor much of the diversity of upland pine-oak-hickory forests in the southeastern USA Fall Line Sandhills region. These forests are managed throughout the region; species composition is influenced by topography, soil composition, periodic natural and prescribed fires, and forest harvesting practices. Our objective was to describe the canopy and ground layer vegetation of upland sites at Fort Benning, Georgia that are managed primarily for longleaf pine (thinned, burned at 3 year intervals) and differ in soil texture (from sandy to clayey) and intensity of military training (lighter dismounted infantry vs. heavier mechanized training). We characterized surface soil texture and land-use disturbance of 32 sites, each 400 m x 400 m, and asked if canopy and ground layer community measures (species composition and richness, basal area, abundance) differed among sites on the basis of soil texture or land-use. There was significant interaction between land-use and soil texture, with a gradient of soil texture (% clay) from clayey sites within light training areas, to sandy sites in heavier training areas. Road-like features, including active and remnant trails, roads, and vehicle tracks or trails were the most frequent and abundant disturbance feature. Number of disturbance features per site did not differ among land-use/surface soil texture categories. Differences in ground layer and canopy composition among sites reflected disturbance intensity; differences in canopy composition also reflected the proportion of pine. Species richness of ground layer vegetation differed among surface soil texture/land-use categories. There was a richness gradient from heavily disturbed sites with clayey soil, through lightly disturbed sites, to heavily disturbed sites with sandy soil. Our results suggest upland pine-oak-hickory forests at Fort Benning range from sandhills scrub oak-pine to pine-hardwood to oak-hickory dominated forests, with greater species diversity in the ground layer of clayey sites. Forestry practices and disturbances associated with mechanized military training favor pine dominance, and maintain open-site, successional or fire-tolerant species in the ground layer. Although intense management toward pine monocultures can reduce within-stand diversity, federal installations such as Fort Benning may help conserve pine-oak-hickory forests in the rapidly developing Sandhills region.