edge effect

views updated

edge effect The existence of more species in a region of overlap between two ecosystems than occur in either of those systems. It occurs because the overlap region supports some species from both adjacent ecosystems and some peculiar to itself. Ecologists now regard the edge effect as a sign of ecological deterioration. The fragmentation of habitats causes an increase in edge areas, but a decrease in the internal areas of ecosystems, leading eventually to a loss of species from all affected ecosystems and an increase in edge species, which are usually commonplace.