GRADIENT ANALYSIS OF SECONDARY FORESTS OF EASTERN WEST-VIRGINIA

Vegetation/environment relationships in two contiguous physiographic r egions in eastern West Virginia were examined to determine local and s ub-regional gradients underlying vegetation patterns. For 258 plots sa mpled in the Monongahela National Forest, West Virginia, broad vegetat ion patterns expressed along ordination axes were strongly related to elevation. Plots were ordered along the first ordination axis from hig h-elevation, mesic sites in the Allegheny Mountains to sandy, steep, l ower-elevation sites in the Ridge and Valley. A comparison of mean soi l-site factors between physiographic regions indicated that only depth of A horizon differed significantly. These similarities were reflecte d in the community types derived from TWINSPAN analysis. All seven com munity types were represented in both regions, although some regional affinity was apparent. Subsequent separate ordinations of plots within the Ridge and Valley and Allegheny Mountains showed community variati on correlated with elevation. In the Ridge and Valley, geographic loca tion, surface rock cover, topographic moisture and stand age were seco ndary gradients related to community distribution. In contrast, second ary gradients in the Allegheny Mountains included topographic moisture and solar radiation.