A Natural History of the Central Appalachians

Chapter 04: Forests of the Central Appalachians

CHAPTER 04 FORESTS OF THE CENTRAL APPALACHIANS AS DISCUSSED IN CHAPTER 3, the forest vegetation that occurs over a landscape is best considered as a continuum, with the particular assemblage of tree species present at a given locality reflecting local environmental conditions. Where different localities have comparable environmental conditions and historical natural disturbances (e.g., windstorms or floods), they will have compositionally similar assemblages of species or forest communities. Only rarely does a sharp boundary (or ecotone) exist between two adjacent forest communities, and the usual situation is for one forest community to gradually intergrade into another. The most notable exceptions are seen when the underlying geology changes abruptly (e.g., from sandstone to limestone), where unique soil conditions exist (e.g., a transition from dry to wet), or where there was some disturbance event confined to only a portion of the landscape (e.g., logging). Nevertheless, it is possible to recognize a number of broadly defined forest community types for the Central Appalachian region. Several classification systems have been used for forests in eastern North America, including the region recognized here as the Central Appalachians. The first truly comprehensive treatment was provided by Braun in her classic book Deciduous Forests of Eastern North America (1950). Other, more recent treatments include Küchler’s Potential Natural Vegetation of the Conterminous United States (1964), Biodiversity of the Southeastern United States: Upland Terrestrial Communities (1993), by Martin, Boyce, and Echternacht, and Bailey’s Description of the Ecoregions of the United States (1995), although the second of these was limited to just the southeastern United States and thus includes only a portion of the region considered here. In brief, seven major forest community types can be distinguished in the Central Appalachians. These are (1) mixed mesophytic forests, (2) northern hardwood forests, (3) spruce and spruce-fir forests, (4) oak-dominated forests that once contained American chestnut, (5) oak-hickory-pine forests, (6) mixed hardwood forests, and (7) riparian forests. Several other distinctly different forest types are both limited in extent and appear in only a few localities. These will be discussed at the end of the chapter. MIXED MESOPHYTIC FORESTS The most diverse of the major forest community types is the mixed mesophytic forest. More than thirty species of trees can be major or minor components of the forest overstory or understory in this forest type. Mixed mesophytic forests are best developed on the Appalachian Plateau of West Virginia and the small portion of the Cumberland Plateau that extends into extreme southwestern Virginia. In West Virginia such forests are generally found at elevations below about 2,500 feet, but they also extend northward into western Maryland and northwestward into south central Pennsylvania. In his book Vegetation of West Virginia (1966), Earl Core described the forests of the “hilly section west of the mountains” in West Virginia as mixed mesophytic, but these forests are compositionally similar to those located in the more mountainous portion of the Appalachian Plateau in eastern West Virginia. The eastern boundary of the mixed mesophytic forest region is essentially the edge of the Appalachian Plateau, which more or less coincides with the border between West Virginia and Virginia. In the Ridge and Valley mixed mesophytic forests have a limited distribution and are restricted to a few high-elevation coves and ravines. These examples also contain fewer tree species than the Appalachian Plateau. Among the more widely distributed trees characteristically present in mixed mesophytic forests of the Cumberland Plateau, Appalachian Plateau, and Ridge and Valley are sugar maple, American beech, northern red oak, basswood, yellow poplar, White ash, cucumber magnolia, black walnut, chestnut oak, buckeye, red maple, white oak, black cherry, black birch, and eastern hemlock. In the Balsam Mountain portion of the southern Blue Ridge in extreme southwestern Virginia, mixed mesophytic forests are limited to open, north-facing slopes at elevations between 3,900 and 4,600 feet. These forests consist of various mixtures of the same species listed above, including basswood, sugar maple, American beech, white ash, yellow birch, buckeye, northern red oak, and red maple. Among the more common small trees are striped maple, serviceberry, mountain holly, and (particularly on rocky sites) mountain maple. Shrubs are not especially abundant, although witch hazel, hobblebush, and black elderberry are not uncommon, and great laurel is consistently present in moist sites such as those found in shallow ravines. The ground cover in a mixed mesophytic forest is often extraordinarily...