Abstract: The Black and Craggy Mountains of North Carolina consist of approximately 35,000 ha with a topographic relief of over 1219m, and include the highest mountain in eastern North America, Mt. Mitchell (2037m). The overall objectives of the study were (1) to inventory and analyze the flora and (2) to document the correlations between vegetation and environmental factors/gradients with the goal of determining those factors most likely controlling the vegetational variation.
The flora consists of 972 species in 115 families which indicates high floral diversity compared with other southern Appalachian areas. Sixty-four southern Appalachian endemics are found in the study area. These can be categorized into upper and lower-middle elevation species. The upper elevation species are mostly species of treeless open areas which probably became isolated in patchy subalpine barrens during the Pleistocene. The lower-middle elevation endemic species are species of acid soils, oak forests, and mesophytic forests. Disjunct patterns include disjunctions between the flora of the study area and Asia (26 genera), so-called Arcto-Tertiary refugia (37 genera) and the Coastal Plain (21 species). Separation of species during the Tertiary with subsequent distribution by migration best explains the Arcto-Tertiary disjunctions while the Coastal Plain-mountain disjuncts may represent jump dispersal during the Holocene.
The vegetation was studied through the combined use of numerical classification (TWINSPAN) and ordination DECORANA) analysis of 156 0.1 ha sample plots. The vegetation was classified into five community cover classes and 17 vegetation types, named primarily for canopy dominants. Vegetational composition was highly correlated with three complex gradients: (1) elevation, (2) topographic-moisture and, (3) soil nutrients-pH. These relationships were used to generate a vegetation-environmental gradient model of the Craggy and Black Mountains which is generally applicable to other southern Appalachian areas.
Species richness (number of species per 0.1ha) is greatest in moderately low elevation mixed forests in a mesic to dry-mesic position on the topographic-moisture gradient which are growing on soils slightly less nutrient rich than the richest soils. Soil reaction (pH) is a moderately good predictor of species richness (r$\sp2$ =.71).
Based on floristic differences the hypothesis is developed that grassy balds develop from fire meadows that have been grazed and trampled.
