Ecology
Extending roughly 2000 miles from Canada’s Gaspe Peninsula to the hills of northern Georgia, the Appalachian Highlands form the geological backbone of the eastern United States. At its southern range the Blue Ridge Mountain Province of Georgia, the Carolinas, Tennessee, and Virginia the mountains increase significantly in mass and elevation. The cold, moist climate typical of these high elevations has created a unique ecological refuge for flora and fauna whose closest relatives are found in Canada and New England.
During the last glacial period some 10,000 to 12,000 years ago the polar ice cap extended as far south as Ohio and Long Island Sound. Consequently, the cold that accompanied the glaciers pushed the northern flora and fauna deep into the southeastern United States. By the time the Pleistocene came to a close temperatures were on the rise and glaciers were in full retreat. As the glaciers returned north so did the spruce, fir, and northern hardwood forests that accompanied them during the last glacial period. In conjunction with their withdraw north these forest communities also moved up the slopes of the southern mountains to eventually find refuge in the cool climates of the highest peaks and ridges where they exist today as disjunct communities (Simpson, 6).
A majority of the range is covered by medium to mature second-growth oak and pine forests. However, cove hardwoods and hemlock can be found on moist slopes and ravines.
Fraser fir and red spruce forests once occupied many of the highest mountain peaks in the Blue Ridge Province. The fir tree was found predominantly above 6,000 feet while the spruce occupied much of the terrain between 6,000 feet and 4,500 feet were it gives way to other forest types. Over the past one hundred years various factors such as logging, wild fires, balsam woolly adelgids, and airborne pollutants have destroyed more than 90 percent of the spruce-fir forests of the Southern Appalachians (Simpson, 13).
Northern hardwoods that include beech, yellow birch, sugar maple, red maple, northern red oak, fire cheery, and serviceberry are found along the lower border of the spruce-fir forests at elevations typically above 4,300 feet (Simpson, pg14).
In the southern Blue Ridge Mountains much of the forest land is dominated by various species of oak that reach their upper limits around 4,500 feet. The dominant species in these forests are white oak, scarlet oak, chestnut oak, black oak, and northern and southern red oaks. Other major tree species include red maple, various hickories, sourwood, white pine, pitch pine, Table Mountain pine, serviceberry, and black locust (Simpson, pg14).
In addition to the aforementioned species, oak forests often contain a variety of conifers. Particularly, at low to middle elevations in shallow, rocky, or poor soils; on dry ridges; and on steep, exposed slopes pines become one of the dominant tree species. These pine woodlands include a number of species such as pitch pine, Virginia pine, short leaf pine, Table Mountain pine, and white pine (Simpson, pg15).
Cove hardwood forests, which are the richest and most diversified of Appalachian forest types, are found at low and middle elevations in moist coves, ravines, and valleys. These forests rarely reach elevations of 4,500 feet and typically consist of eight to twelve species of trees that include tulip poplar, sugar maple, yellow, buckeye, yellow birch, red oak, red maple, white oak, basswood, white ash, beech, and black cheery. The most diverse cove hardwood forests are found in the Carolinas and Tennessee where many trees reach world-record sizes in areas of heavy rainfall such as the Smokies (Simpson, pg16).
Works Cited
Simpson Jr., Marcus B. Birds of the Blue Ridge Mountains. Chapel Hill and
London: The University of North Carolina Press, 1992.