SUCCESSIONAL CHANGES IN PLANT-SPECIES DIVERSITY AND COMPOSITION AFTERCLEARCUTTING A SOUTHERN APPALACHIAN WATERSHED

Watershed 7, a southwest-facing watershed in the Coweeta Basin, wester n North Carolina, USA, was clearcut in 1977. Twenty-four permanent plo ts were inventoried in 1974 before cutting and in 1977, 1979, 1984, an d 1993 after clearcutting. This study evaluates changes in species div ersity during early succession after clearcutting and differences in o verstory tree and ground flora response to disturbance by clearcutting and their interaction with previous disturbances and subsequent stand development, To quantify species diversity, we computed Shannon-Weave r's index of diversity (H') and Pielou's evenness index (J'). Woody sp ecies diversity remained relatively stable; however, woody species ric hness increased in the cove-hardwoods and hardwood-pines, but remained relatively constant in the mixed-oak hardwoods. Although revegetation was rapid, forest composition has changed through succession. Opportu nistic species, such as Liriodendron tulipifera, Robinia pseudoacacia, and Acer rubrum, increased in abundance, whereas Quercus velutina, Ca rya spp., and e. rubra decreased. Ground flora diversity declined in t he cove-hardwoods and mixed-oak hardwoods communities, but the decreas e in the hardwood-pines was not significant. The abundance (g biomass m(-2)) of ground flora was much lower in 1993 than in 1984; 79% less i n the cove-hardwoods, 90% less in the mixed-oak hardwoods, and 79% les s in the hardwood-pines. Watershed 7 is apparently in a transition sta te between early and late successional species abundance. Early succes sional, shade-intolerant species, such as Erechtites, Solidago, Eupato rium, Panicum, and Aster, have declined, whereas late successional, sh ade-tolerant species, such as Viola, Galium, Sanguinaria, Uvularia, an d Veratrum are not yet well established.