Vegetation distribution and site relationships in an Appalachian oak forest in southwest Virginia

One hundred and twenty-six stands were sampled using a stratified random design in a 6880 hectare Appalachian Oak Forest in southwest Virginia. The objective was to determine the present distribution patterns of tree species and community types and to relate their occurrence to site factors. Of the 52 tree species recorded, the dominants in order of decreasing importance were Acer rubrum, Quercus rubra, Liriodendron tulipifera, Quercus prinus, Acer saccharum and Quercus coccinea. Most site factors of importance, including elevation, lithology, landform, slope position, steepness, exposure, and soil depth appeared to influence the distribution of individual species and community types through their effect on local moisture and temperature conditions. Different site factors best explained the distribution of various species in a multiple regression analysis, thus suggesting that these species are distributed independently of each other. Stand history and interaction between site factors appeared to confound the species-site relationships examined and may explain the large portion of variation unaccounted for by the regressions.

Stands were placed in one of six community types with the aid of polar ordination. Three community types were dominated by oak and showed considerable intergradation of species and site preferences. The dominant oaks shifted from Quercus rubra to Quercus prinus to Quercus coccinea on progressively drier sites. Sugar maple-mixed hardwoods, Yellow-poplar, and Hemlock community types were more discrete when compared to the oak community types. Stands dominated by Acer saccharum or Tsuga canadensis occurred mostly in relatively cool, moist conditions at mid to upper elevations, while most stands dominated by Liriodendron tulipifera were in moist locations at lower elevations. Results indicate that shifts in the composition of forest stands when compared to presettlement forests may be attributed to selective logging practices and to the demise of American chestnut.