Contrasting Vegetation of Noses and Hollows in the Valley and Ridge Province, Southwestern Virginia

Abstract

STEPHENSON, S.L. (Department of Biology, Fairmont State College, Fairmont, WV 26554) AND H. H. MILLS (Department of Earth Sciences, Tennessee Technological University, Cookeville, TN 38505). Contrasting vegetation of nQses and hollows in the Valley and Ridge province, southwestern Virginia. J. Torrey Bot. Soc. 126: 197-212. 1999. The most prominent secondary landforms in the Valley and Ridge province are the small valleys and intervening ridges, commonly called hollows and noses, that corrugate the flanks of major ridges. Noses and hollows are relatively uniform both with respect to form and surficial materials on a given ridge flank. Knowledge of the distribution of vegetation associated with these landforms, therefore, is a key to the understanding of the overall pattern of vegetation in this province. We selected three study localities in southwestern Virginia that differed greatly in two or more of the following variables: bedrock, surficial deposits, elevation, and aspect. We described the vegetation in four hollows and on four noses at each of these three localities. Large differences between noses and hollows were found to exist in all three localities, differences that equal or exceed the differences between the study localities. For example, on a north-facing ridge flank with bouldery soils, Betula lenta had an importance value of 38.6 in hollows but only 0.6 on noses, whereas Quercus prinus displayed a value of 24.7 on noses but did not occur in hollows. On a south-facing ridge flank with bouldery soils, Quercus alba had an importance value of 37.4 on noses but was completely absent in hollows. On a northwest-facing ridge flank with steep-walled V-shaped hollows and thin shale-chip soil, Pinus pungens had an importance value of 31.2 on noses but did not occur in hollows. Compositional differences were even greater for shrubs and herbaceous plants. In addition, tree density, sapling density, shrub density, herb stratum cover, rock cover, and species richness differed significantly between noses and hollows at one or more study localities.