Core, Corridor and Restoration Area Principles

The issue of fragmentation has been identified recently as one of the most pressing issues in wildlife management and the conservation of biodiversity (Solheim, Alverson and Waller, 1987; Wilcove, 1988). Briefly described, fragmentation is what occurs when a forested area is permeated with relatively smaller openings like roads, wildlife openings, and clearings created by even-aged timber management. Even though the majority of the area may still be covered by a forest canopy, "edge effects" such as those noted above penetrate beyond the edge itself. Such effects can adversely impact species of plants and animals that require interior forest habitat, leaving them with less useable habitat than the land cover would suggest, and isolating specific populations of such species from each other.

The problems of isolated populations of plants and animals have been described by researchers in conservation biology and island biogeography (Fahrig and Merriam, 1994). Isolated groups may have trouble maintaining the genetic integrity and variability needed for their continued evolutionary viability and prospects for long-term survival, if they cannot move to or be reached by other populations of their species. Such a situation occurs if there are no corridors of appropriate habitat for the species to move through. This is the situation for forest interior species in the fragmented forests of the Southern Appalachians.

The idea of cores, corridors and restoration areas has been proposed to remedy this problem (Cutler, 1991). The idea is to first protect from further fragmentation currently existing remnants of mature forest interior habitat; second, to restore corridors of similar habitat to link the remnants; and finally, to buffer all this from intensive human activity by way of restoration areas. To be fully effective, a design such as this watershed management proposal should be linked on a larger scale to other forest interior blocks in the region (Noss, 1992).

Wildlife corridors can help restore the proper ecosystem functions only if they are wide enough to constitute viable interior forest habitat. An "edge", such as between the forest and a maintained road or clearing, must be far enough away so that its various ecosystem effects do not reach all the way into the corridor. The distance that edge effects penetrate into the interior will vary, depending on which particular species and associated effects are focused on (see brood parasitism, nest predation, and microhabitat variations discussed above). Some researchers suggest that a distance of one-half mile from openings is needed to ensure that no edge effects penetrate into an interior forest wildlife corridor (Hamel, 1990).

In addition to land-based wildlife corridors, stream-side corridors have been promoted as a means of linking isolated habitats of some species. This strategy offers the benefits of protecting aquatic habitat and water quality, while at the same time serving the larger ecosystem's role (Naiman et al., 1993). Aquatic ecosystems are among the most threatened ecosystems in the country and are in need of immediate protective and restorative measures (Noss and Peters, 1995; Lydeard and Mayden, 1995)

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