Changes in the composition and diversity of forest vegetation from edge to interior.

Abstract

The effects of habitat edges may differ from habitat interiors in many variables including species composition, species diversity, and overall productivity. By using a forest edge bordered by a meadow habitat, we compared the edge and interior habitats in a northern deciduous forest at three distances from the forest edge. Overstory composition was similar at all three plots, but variations in subdominant species seemed to follow successional trends. Understory tree and tree seedling and sapling counts showed an increase in diversity from interior to edge. Evidence of past forest composition from snags and downed wood showed similarities to the present composition at each plot. No general trend in species diversity and composition could be applied to all strata of the habitats, but separate trends at the canopy and subcanopy levels were apparent. Lower producitivity and species diversity of the canopy nearer the edge may be direct results of edge effects. Increases in species diversity nearer the edge in the subcanopy levels, may be due to differences in canopy structure. Differences between canopy and subcanopy composition at the edge seemed to be due to effects of succession. Since successional factors probably influence the overall composition of edge and interior forest areas, separation of trends that are solely resultant of edge effects is difficult.