Fall 2005

Edge Effects

by Claire Payne

Fragmentation is the principal cause of ecological change in forested urbanizing landscapes, according to The Southern Forest Resource Assessment Summary Report. Editors, David Wear and John Greis, say designing development so some forest connectivity is retained could provide important habitat and other benefits, especially for neotropical migratory birds.

Sustainable forests include associated parts: trees, soil, water, plants, animals, timber, and minerals. These interdependent components are ecological capital. The infrastructure they create includes species biodiversity and human economic health. The ecological effects of fragmentation are most easily discerned at its edge.

Birds, Spiders, and Mammals

Susan Loeb, ecologist and project leader at the Southern Research Station (SRS) Endangered, Threatened, and Sensitive Wildlife and Plants in Southern Forests unit in Clemson, SC, found that early successional small mammals that live in vegetation regenerating after an area has been cleared, such as old-field mice and cotton rats, depend on patch size to maintain abundance and diversity. Populations on smaller patches are more susceptible to local extinction than on patches with larger population densities. Because large clearcuts may fragment latesuccessional forests to unacceptable levels, a balance must be maintained between the number and size of early and late-successional patches to maintain a full complement of species within an area. (...continued...)