Structure and Composition of Vegetation of Longleaf Pine Plantations Compared to Natural Stands Occurring along an Environmental Gradient at the Savannah River Site

Fifty-four plots in 33-43 year old longleaf pine plantations were compared to 30 remnant plots in longleaf stands on the Savannah River Site in South Carolina. Within these stands, the structure and composition of primarily the herb layer relative to a presumed soil moisture or soil texture gradient was studied using the North Carolina Vegetation Survey methodology. Data were also collected on soils and landform variables. Based on ordination and cluster analyses, both plantation plots and natural stand plots were separated into three distinct site units (xeric, sub-xeric, and sub-mesic). The plantation plots had an overall classification rate of 78 percent while the natural plot classification rate was 87 percent. The xeric end of the gradient demonstrated the most similarity between the remnant and plantation plots. Among all the plots, presence or absence of a B horizon was the most discriminating environmental factor. On the plantation sites, 265 species were found as compared to 297 species on the remnant natural sites. Overall species richness was significantly greater on the remnant sites with a mean of 74.00 species per 0.1 hectare compared to 57.11 for the plantation sites. However, of the 265 species found on plantation sites, roughly 90 percent were judged to be representative of natural or native longleaf pine communities. This lack of a major compositional difference between xeric plantation and natural longleaf sites suggests that restoration of the herbaceous layer may not be as complex as once thought. This provides reasonable encouragement for the restoration of the longleaf pine ecosystem. 1 Graduate Research Assistant, Associate Professor, Department of Forest Resources, Clemson University, Clemson, SC 29634; Research Ecologist, USDA Forest Service, Southern Research Station, Clemson, SC 29634, respectively. Citation for proceedings: Outcalt, Kenneth W., ed. 2002. Proceedings of the eleventh biennial southern silvicultural research conference. Gen. Tech. Rep. SRS–48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 622 p.