Terrestrial
Appalachian mountain forests span over 1,500 miles of Canada and the Eastern U.S. and serve as a critical migration corridor and breeding habitat for migratory birds, including neotropical migrant species such as the cerulean warbler, hooded warbler, and wood thrush. Many of the priority migratory birds are considered to be area-sensitive, requiring continuous forested tracts. Many also avoid forest edges during nesting and therefore are considered forest interior species.
The Appalachian-Blue Ridge forests consist of two major forest community types, corresponding to elevation gradients. At lower elevations, between 250 and 1350 meters, mixed oak forests dominate. Old-growth cove forests at mid-elevations once supported massive tulip poplars, chestnuts, red spruce, and oaks. Above 1,350 m, spruce-fir forests develop and dominate the landscape. Along high elevation ridges, red spruce, the endemic Fraser fir, and balsam fir dominate.
Understory plants in the Southern Appalachians are incredibly diverse but many are highly susceptible to alteration of the forest canopy. More than 2,000 species of vascular plants occur in the Southern Appalachians, making it one of the most botanically diverse regions in the temperate zone, and therefore an area considered to have high potential for future medicinal plant research and development. Hundreds of these species, including herbaceous understory plants such as the federally listed endangered small whorled pogonia, are at risk of extinction due to land use practices and development. Many species have restricted ranges and occur in specialized habitats, or require intact canopy and moist understory conditions, which are destroyed by logging.
Spruce-fir forests have a coniferous overstory. Fraser fir is endemic to the southern Appalachians and can form almost pure stands on the highest peaks. This community type is a Pleistocene relic that is now confined to a limited number of high mountains in southwestern Virginia, eastern Tennessee, and western North Carolina. A number of breeding bird species associated with the northern boreal forest occur in these communities: northern saw-whet owl, winter wren, golden-crowned kinglet, red-breasted nuthatch, and common raven. Spruce-fir is the least abundant forest community type in the southern Appalachians and is separated into disjunct patches due to its elevational limits. There is concern about the persistence of some endemic species such as the northern flying squirrel and the spruce-fir moss spider. The Spruce-fir moss spider is a federally listed endangered species of spider found at high elevations in the southern Appalachian Mountains. First identified in 1923, they inhabit moss that grows on rocks underneath the forest canopy.
