Landscape variation in species diversity and succession as related to topography, soils and human disturbance

Three hundred and thirty-two plots have been sampled on the Wayne National Forest of southeastern Ohio, for the purpose of developing an ecological classification system (ECS). The ECS will be based on the herbaceous and woody vegetation, soils and topography of mature (80-140 year-old), relatively-undisturbed forests. Species diversity changes little across this landscape. Forty-eight woody tree species were identified among all plots and species richness (R) varied from two to thirteen on individual plots. Although variable within landform type, R varied similarly across landform type, with slightly greater variability on moderately steep slopes (3-13) than on steep slopes (3-10). Ridgetops (4-11) were comparable to sideslopes while ravines generally had fewer species (2-9) than other landforms. Again, although variable, R and species diversity (H) were not highly different across areas with differing soils characteristics. However, higher values of R and H were associated with severe, xeric sites having sandy soils; and mesic to dry-mesic sites that had evidence of nearby disturbance.