Vegetation Dynamics of the Forest Edge -- Trends in Space and Successional Time

Forest herbs, shrubs, and tree seedlings were censused at five distances from human-generated edges at 14 sites in south-eastern Pennsylvania and northern Delaware, USA. Forest edges varied in orientation and in the degree of canopy closure, allowing comparisons of vegetation by aspect and successional stage. Soil depth and pH were measured at vegetation sampling points at a subset of sites; microclimate data were available from a parallel study. Edge-related pattern was observed in overall species composition, and in distributions of 15 individual species. At recently created forest edges, species abundances were correlated with steep climatic gradients. Although most edge-orientated species were clustered ≤ 5 m from the edge, some species consistently reached peak densities at distances up to 40 m, the greatest distance surveyed (...)