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In the southern Appalachian Mountains, compositions, structures, and dynamics of forest communities vary across steep topographic gradients, such as elevation and slope aspect, position on slope, steepness, and slope shape (Whittaker 1956). For instance, in mesic sites, the forest transitions across elevations from lower elevation cove hardwoods and hemlock forests to higher elevation northern hardwoods and, where the mountains surpass approximately 1,680 meters, spruce-fir forests. At mid and low elevations, cove forests on protected sites transition to oak-dominated forests on drier soils and finally to pine and xeric hardwood forests on exposed south- to west-facing sites. Despite a long history of human influence, remnant old-growth forests have survived across these landscape gradients and now comprise, in aggregate, one of the largest totals for old-growth acreage in eastern North America (Davis 1996). |
