Vegetation and soils of a serpentine barren in western North Carolina

<p>Vegetation of a pine-savanna on an olivine-serpentine outcrop is described. Soil characteristics, community structure, species composition, species richness, and representation of life-forms and geographic areas are discussed and compared with those of oak-mixed hardwood vegetation growing on mica gneiss slopes in the same area. The pine-savanna differs from the oak-mixed hardwoods in the following ways: canopy closure is incomplete, whereas a closed canopy is observed on mica gneiss; the pine-savanna has somewhat fewer species; hemicryptophytes and chamaephytes are more important life-forms in the flora of the pine-savanna than in that of the oak-mixed hardwood type; the flora of the pine-savanna displays an affinity with that of midwestern regions of the United States, represented by a disjunct element (6%), whereas the oak-mixed hardwood type is more closely allied with southern Appalachian flora; the serpentine soils are more variable morphologically, are higher in cation exchange capacity and percentage base saturation, and are lower in acidity, the ratio of calcium to magnesium, and difference in water retention between -33 and -1500 kPa. The pine-savanna is physiognomically similar to vegetation occurring elsewhere on serpentine, particularly in the northwestern United States, and contains range disjunctions and morphological variants such as typify serpentine vegetation on many continents. It appears to be a stable edaphic climax as are some of the other barrens, limestone cedar glades, and prairie-like communities occurring outside the prairie region proper.</p>