Intrastand distribution patterns of southern Appalachian cove forest herbaceous species

Environmental data and quadrat samples of understory vegetation of cove forest were taken in the summers of 1975 and 1976 in the Great Smoky Mountains National Park, Tennessee, to explore variations in understory composition. Ordination and multiple regression analyses indicated that major intrastand gradients are degree of dominance of the tree canopy by Tsuga canadensis, moisture availability (indexed by mesotopographic and vegetational properties) and soil depth and microtopography. These gradients influence the distribution of herbaceous understory species and help determine understory community characteristics. Temporal changes in environment and disturbance are other significant intrastand gradients but were not directly included in this study. Association between pairs of 9 common species was measured using Cole's index of association, percent co-occurrence and Levins' measure of niche overlap. Niche breadth values were also calculated for common species. These analyses allowed recognition of four guilds of cove forest herbs, here defined as groups of species with similar intrastand distribution patterns: (1) species most dominant in Tsuga-dominated stands; (2) species of mesic, hardwood-dominated stands; (3) species restricted to wet-mesic sites, and (4) species adventive in disturbed areas. There are also a few generalists which do not fit into these guilds and occur in a wide variety of microhabitat types in cove forests.