The Appalachian/Blue Ridge Forests ecoregion encompasses major portions of Fenneman's (1938) Blue Ridge and Ridge and Valley physiographic provinces of the central and southern Appalachians. The region stretches north from northeastern Alabama and Georgia, through eastern Tennessee, western North Carolina, Virginia, and Maryland, and into central Pennsylvania.
The large variety of landforms, climate, soils, and geology, coupled with a long evolutionary history, has led to one of the most diverse assemblages of plants and animals found in the world's temperate deciduous forests (Stephenson et al. 1993). The Appalachians were once a large mountain range in the Paleozoic and have been relatively geologically stable since that period. Eroded ridges and valleys throughout the region run in a southwest-northeast direction. Climate differs across the ecoregion due to large variations in elevation, physiography, and latitude. Ancient limestones have eroded into extensive karst formations in some areas, creating a network of caves and unusual communities on limestone. During the Pleistocene glaciations, the Appalachians acted as a mesic and thermal refuge for a number of species and communities. In a similar manner, after the retreat of the glaciers, cold-adapted communities, such as cranberry bogs, remained in refugia in cooler portions of the Appalachians, well south of their usual range.
The Appalachian/Blue Ridge forests consist of two major community types, corresponding to elevational gradients. At lower elevations, between 250 and 1350 m, mixed oak (Quercus spp.) forests dominate. Old-growth cove forests at mid-elevations once supported massive tulip poplars (Liriodendron tulipifera), chestnuts (Castanea dentata), red spruce (Picea rubens), and oaks. Above 1350 m, spruce-fir forests develop and dominate the landscape (Stephenson et al. 1993). Along high elevation ridges, red spruce, the endemic Fraser fir (Abies fraseri), and balsam fir (A. balsamea) dominate.
Prior to 1890. the low-elevation dominant forest system of this region consisted of mixed oak and American chestnut communities. In the early 1900's the spread of the chestnut blight, caused by the fungus Cryphonectria parasitica, resulted in widespread loss of chestnut from the forest community. Chestnut trees once dominated much of the region’s lower elevation forest canopies. With its loss, red oak (Quercus rubra), hickory (Carya spp.), chestnut oak (Q. prinus), black oak (Q. velutina), locust (Robinia pseudoacacia), birch (Betula spp.), as well as red maple (Acer rubra), pines (Pinus spp.), and additional hardwood species proliferated (Whitney 1994). The decline of chestnuts was likely associated with a major loss of mast for wildlife.
This ecoregion, together with the adjacent Mixed Mesophytic Forests [NA0402], represents one of the world’s richest temperate broadleaf forests (only the temperate flora of central China is slighly richer). This ancient mesic forest type was formerly widespread in the Northern Hemisphere and is now represented by relictual ecosystems in eastern North America and eastern China. The related forests of the Appalachians and central and southwestern China share a large number of higher taxa and relict groups. Many genera and some species and families have disjunct distributions in these distant regions. Over 50 such genera of plants include magnolias, hickory, sassafras, ginseng, mayapple, skunk cabbage, several orchids, jack-in-the-pulpit, coffee-tree, stewartia, witch hazel, dogwoods, persimmons, hollies, sumacs, maples, and yellowood. Several animal taxa also show unique affinities with East Asian relatives, including copperheads (Agkistrodon spp.), hellbender salamanders (Cryptobranchidae family), some land snails, and paddlefish (Polyodon spathula). The taxonomic similarities between these two regions are paralleled by ecological similarities. These include dominance by woody, broad-leaved, deciduous plants, nonwoody plants with underground storage structures and spring blooming (1,400 species in the Great Smokies alone), early-leafing ephemeral herbs or shade-adapted perennials with buds that overwinter, and plant communities that vary predictably along environmental gradients (Constantz 1994).
The biodiversity of this ecoregion is also exceptional due to the broad range of microhabitats, presence of numerous relict species and communities, and geologic stability over long periods of evolutionary history to allow for diversification within taxa. Indeed, a number of plants, invertebrates, salamanders, crayfish, freshwater mussels and fish are restricted to single watersheds or peaks due to millions of years of isolation and favorable conditions. More than 158 tree species can be found within the region, ranking it among the highest ecoregions in North America for total floral diversity. In conjunction with the Appalachian Mixed Mesophytic Forests [NA0402], it contains the highest total amount of endemic flora and fauna species in North America. The Appalachians are the world’s center for Plethodontid salamander diversity, harboring 34 species of these lungless salamanders. Geographic diversification is pronounced with isolated and different species and populations on different peaks throughout the region. Several plethodontids exhibit a Mullerian mimicry complex in which several species have converged in appearance to warn predators of their general toxicity. Salamanders are often the most abundant vertebrate with the highest biomass in a given patch of forest, playing a significant role in ecological processes and food webs. Land snails and spiders are well-represented and contain a number of relictual and ancient taxa, many with disjunct relatives in the forests of eastern Asia. More than 225 terrestrial vertebrates occupy this ecoregion. The breeding bird community is dominated by neotropical migrants, inhabiting all the successional stages of forest structure.
The prevalent limestone and karst formations in this ecoregion are associated with a cave fauna of salamanders, fish, and invertebrates. The diversity and distribution of these species are not well known, but they appear to rival cave faunas around the world in richness and endemism.
Approximately 83 percent of the habitat in this ecoregion has been altered. Heaviest loss in habitat can be found in the ridge and valley provinces, particularly in limestone valleys that are most productive for agriculture. Habitat loss is greatest in low elevations, and diminishes with increased elevation. Lower elevations have milder slopes, and were preferentially selected for conversion to agriculture. In addition, suburban sprawl and urban development has occurred in the lower elevations. The vast majority of the region has been logged. Only a few blocks and patches of unlogged forest remain, with several larger blocks found in the Great Smokies region. Virtually all of Shenandoah National Park is regrowth, a situation repeated throughout the region where forests occur today. The extraordinary size of the trees and structural complexity of the ancient cove forests of the Great Smokies belies what has been lost throughout the region from centuries of deforestation and logging. The forests that have returned after logging have few, if any, large treees, no chestnuts, low structural complexity, and are uncharacteristically poor in wildflowers, land snails, salamanders, and other species normally abundant and diverse in undisturbed forests. Native wildflower communities have been severely reduced and altered throughout the region, with only a few areas that are a semblance of their former richness (J. Terborgh, pers. comm. 1996).
The spruce-fir forests and portions of the mixed oak forest were subject to intensive logging in the early 1900's. In the wake of poor management, heath balds spread over many ridge tops, thwarting plant and tree regeneration (White et al. 1993). Forests were also cleared for agriculture and pastures. However, these clearings have slowly been abandoned, and have subsequently begun to revert back to forest communities (Stephenson et al. 1993). High elevation forests consisting of red spruce, the endemic Fraser fir, and the more widespread balsam fir have been subject to environmental and anthropogenic stresses. These high elevation communities are naturally subject to increased atmospheric moisture, cooler temperatures and higher winds, but also now suffer from the effects of acid rain deposition, which tend to be exacerbated in high elevation communities, and from the depredations of an introduced homopteran insect, the wooly adelgid (Adelges spp.). In the early 1900's, short-sighted logging practices degraded these forests.
Remaining Blocks of Intact Habitat
Several blocks of more or less intact habitat remain as patches on the landscape. A large majority of them can be found within public lands. Larger and smaller patches of old-growth forest have been inventoried by Davis (1993). Some of the larger blocks are:
•The Great Smoky Mountains National Park - western North Carolina and eastern Tennessee
•Pennsylvania mountain ridges - central Pennsylvania
•South Mountain - south central Pennsylvania
•Shenandoah Mountain and Allegheny Front Range - northern Virginia
•Massanutten Mountain - northern Virginia
•Shenandoah National Park - central Virginia
•Thomas Jefferson National Forests - western Virginia
•Seneca Rocks, Spruce Knob, Panther Knob - eastern West Virginia
•Allegheny Mountains - central Pennsylvania
•Mt. Rogers highlands - southwestern Virginia
•Amphibolite Mountains - northwestern North Carolina
•Blue Ridge Escarpment - western North Carolina
•Brushy Mountains - northwestern North Carolina
•Roanoke Mountain highlands - western Virginia
•Nantahalah Mountains - western North Carolina
•Pisgah National Forest - western North Carolina
•The Escarpment Gorges - northwestern Georgia
•Ramsey's Draft Wilderness - western Virginia
Degree of Fragmentation
Fragmentation and isolation of remaining blocks of undisturbed habitat is severe. Secondary regrowth, however, has begun to offer opportunities for dispersal for a wide range of taxa, although significant movements of less vagile species such as salamanders, wildflowers, and land snails might require centuries. Regrowth areas are still highly fragmented from roads, power lines, and development. Opportunities for songbirds to nest in larger blocks of forests that are relatively undisturbed by cowbirds and mesopredators are few across the landscape.
Degree of Protection
Substantial acreage of forested land has been purchased by the federal and state governments for forests and parks during this century. Government agencies, corporations, absentee owners, and one percent of the local population control 53 percent of the land (Stephenson et al. 1993). Management of these areas depends on both the owning party and the political climate of the day. For example, on lands federally or state controlled, management plans dictate multiple-use management (e.g., timber harvest, recreation, wildlife). The best opportunities for the protection of large portions of this ecoregion lie in national and state forests. These forests are currently being managed for timber extraction, but changes in public demand and Forest Service policy may eventually balance consumptive use (timber extraction) with an increase in nonconsumptive uses (viewsheds, hiking, camping, biodiversity protection) (Stephenson et al. 1993).
Types and Severity of Threats
The major types of conversion threats for the ecoregion are timber and mineral extraction, conversion to developed lands, fire suppression, air pollution, acid precipitation, high densities of deer, and the introduction of exotic pests and diseases.
Timber extraction is a serious threat to habitat protection. While the demand for forest products will increase in the future, the abandonment of farms, demand for recreation, and support of the general public for forested lands should offset the extraction of the hardwood forests (Stephenson et al., 1993). However, the forest structure will change, becoming a younger, disturbed forest, which will support different faunal species than mature hardwood stands. Trees in much of the regrowing forests are beginning to grow into age classes that attract logging interests. Conservation action must take place now before plans for logging preclude potential opportunities to conserve well-connected, larger blocks of forest across the landscape.
Mining of coal and minerals continues to be a signficant threat to large tracts of habitat through direct destruction, and toxic runoff and deposition. Development also threatens the ecoregion. In the past 2 decades, natural lands have been increasingly developed for recreational resorts and second homes (Mardin and Schwartz 1981, Lovingood and Reiman 1988). This development has, for the most part, been unregulated at the government level in the past. Most of this developed land was converted from abandoned agricultural fields.
A by-product of increased urban and suburban development, even in distant regions, is an increase in air pollution and acidic precipitation. The ecological effects associated with acid rain deposition include a degradation of fitness and growth of trees and shrubs, a loss of resilience to natural stresses, and direct mortality of sensitive animal species. In particular, the Appalachian high elevation spruce-fir forest communities have experienced significant forest damage from air pollutants, and are highly susceptible to future degradation (de Steiguer et al. 1990).
The reduction and extirpation of large predators has caused rodents and deer to proliferate in abundance well above their estimated natural range. Browsing by deer and other abundant herbivores has been implicated in the extirpation of plant species and the alteration of communities throughout the region. Control programs must be intensified to reduce the impact of this pervasive threat. The reintroduction of large predators, such as the red wolf, and mountain lions, could help reestablish an ecological balance to the ecoregion.
The introduction of exotic pests and diseases poses a serious threat to portions of the habitat. The introduction of the gypsy moth (Lymantria dispar), spruce budworm (Choristoneura fumiferana), hemlock wooly adelgid (Adelges tsugae), balsam wooly-adelgid (A. piceae), as well as dogwood anthracnost fungi is altering the forest composition and habitat composition.
A number of species in this ecoregion are classified as rare, endangered or threatened. These include, but are not limited to, a number of land snails and salamanders, a variety of plant species including orchids and many herbaceous plants, the red-shouldered hawk (Buteo lineatus), the Virginia big-eared bat (Plecotus townsendii virginianus), the red wolf (Canis rufus) and the loggerhead shrike (Lanius ludovicianus) (Stephenson 1993).
Many cave fauna are threatened by altered hydrologic flows, toxicity and eutrophication from runoff, vandalization of caves and bat roosts, and alteration of cave openings, causing changes in environmental conditions.
Suite of Priority Activities to Enhance Biodiversity Conservation
•Larger blocks (greater than 100 km2) of relatively unfragmented and undisturbed forests need to be identified and protected.
•Linkage zones of appropriate habitats between larger blocks should be restored.
•Larger blocks need to be free of roads, powerline corridors, and other avenues for intrusions by cowbirds, racoons, and other predators of songbirds. Road closures and prohibition of road-building is greatly needed, particularly on public lands.
•Identification and protection of a regional system of large, undisturbed habitat blocks in order to maintain viable populations of migratory songbirds is urgently needed.
•Poaching of black bears, freshwater mussels, ginseng, and other economically valuable native plants and animals for commercial purposes must be curtailed.
•Reduction in deer populations is needed everywhere to prevent the extirpation of populations of many plant species across their ranges.
•Alabama Natural Heritage Program
•Georgia Natural Heritage Program
•Kentucky Natural Heritage Program
•National Park Service, Great Smoky Mountains National Park
•National Park Service, Shenandoah National Park
•The Nature Conservancy
•The Nature Conservancy - Southeast Regional Office
•The Nature Conservancy of Alabama
•The Nature Conservancy of Georgia
•The Nature Conservancy of Kentucky
•The Nature Conservancy of Maryland
•The Nature Conservancy of North Carolina
•The Nature Conservancy of Pennsylvania
•The Nature Conservancy of South Carolina
•The Nature Conservancy of Tennessee
•The Nature Conservancy of Virginia
•The Nature Conservancy of West Virginia
•The Sierra Club
•US Forest Service
•Virgina Division of Natural Heritage
•Western Pennsylvania Conservancy
•The Wildlands Project, SouthPAW
Relationship to other classification schemes
The ecoregion was based on Omernik's Central Appalachian Ridges and Valleys and Blue Ridge Mountains ecoregions. The ecoregion approximates Bailey's Northern Ridge and Valley section (M221A), the Blue Ridge Mountains section (M221D-although the northern sliver is left out), the Central Ridge and Valley section (221J), and captures smaller portions of several other sections (231c, 231D, 221H, 221H, M221C, M221B). The ecoregion covers a majority of Küchler's Appalachian Oak Forest as well as portions of the Oak-Hickory-Pine Forest found in West Virginia.
Prepared by: C. Loucks, D. Olson, E. Dinerstein, A. Weakley, R. Noss, J. Stritholt, K. Wolfe.