The Great Smoky Mountains are a mountain range rising along the Tennessee–North Carolina border in the southeastern United States. They are a subrange of the Appalachian Mountains, and form part of the Blue Ridge Physiographic Province. The range is sometimes called the Smoky Mountains and the name is commonly shortened to the Smokies. The Great Smokies are best known as the home of the Great Smoky Mountains National Park, which protects most of the range. The park was established in 1934, and, with over 11 million visits per year, it is the most visited national park in the United States.
The Great Smokies are part of an International Biosphere Reserve. The range is home to an estimated 187,000 acres (76,000 ha) of old growth forest, constituting the largest such stand east of the Mississippi River. The cove hardwood forests in the range's lower elevations are among the most diverse ecosystems in North America, and the Southern Appalachian spruce-fir forest that coats the range's upper elevations is the largest of its kind. The Great Smokies are also home to the densest black bear population in the Eastern United States and the most diverse salamander population outside of the tropics.
Along with the Biosphere reserve, the Great Smokies have been designated a UNESCO World Heritage Site. The U.S. National Park Service preserves and maintains 78 structures within the national park that were once part of the numerous small Appalachian communities scattered throughout the range's river valleys and coves. The park contains five historic districts and nine individual listings on the National Register of Historic Places.
The name "Smoky" comes from the natural fog that often hangs over the range and presents as large smoke plumes from a distance. This fog is caused by the vegetation emitting volatile organic compounds, chemicals that have a high vapor pressure and easily form vapors at normal temperature and pressure.
Heavy logging in the late 19th century and early 20th century devastated much of the forests of the Smokies, but the National Park Service estimates 187,000 acres (760 km2) of old growth forest remains, comprising the largest old growth stand in the Eastern United States. Most of the forest is a mature second-growth hardwood forest. The range's 1,600 species of flowering plants include over 100 species of native trees and 100 species of native shrubs. The Great Smokies are also home to over 450 species of non-vascular plants, and 2,000 species of fungi.
Appalachian balds—patches of land where trees are unexpectedly absent or sparse—are interspersed through the mid-to-upper elevations in the range. Balds include grassy balds, which are highland meadows covered primarily by thick grasses, and heath balds, which are dense thickets of rhododendron and mountain laurel typically occurring on narrow ridges. Mixed oak-pine forests are found on dry ridges, especially on the south-facing North Carolina side of the range. Stands dominated by the Eastern hemlock (Tsuga canadensis) are occasionally found along streams and broad slopes above 3,500 feet (1,100 m).
The Great Smoky Mountains are home to 66 species of mammals, over 240 species of birds, 43 species of amphibians, 60 species of fish, and 40 species of reptiles. The range has the densest black bear population east of the Mississippi River. The black bear has come to symbolize wildlife in the Smokies, and the animal frequently appears on the covers of the Great Smoky Mountains National Park's literature. Most of the range's adult eastern black bears weigh between 100 pounds (45 kg) and 300 pounds (140 kg), although some grow to more than 500 pounds (230 kg).
Other mammals in the Great Smokies include the white-tailed deer, the population of which drastically expanded with the creation of the national park. The bobcat is the range's only remaining wild cat species, although sightings of cougars, which once thrived in the area, are still occasionally reported. The coyote is not believed to be native to the range, but has moved into the area in recent years and is treated as a native species. Wolf packs do not roam this region due to extirpation. They modernly reside in Alaska, portions of the Great Lakes region, all northwestern American states and Canada. Two species of fox (red fox and the gray fox) are found within the Smokies, with red foxes being documented at all elevations.
European boar, introduced as game animals in the early 20th century, thrive in Southern Appalachia but are considered a nuisance due to their tendency to root up and destroy plants. The boars are seen as taking food resources away from bears as well, and the park service has sponsored a program that pays individuals to hunt and kill boars and leave their bodies in locations frequented by bears.
The Smokies are home to over two dozen species of rodents, including the endangered northern flying squirrel, and 10 species of bats, including the endangered Indiana bat. The National Park Service has successfully reintroduced river otters and elk into the Great Smokies. An attempt to reintroduce the red wolf in the early 1990s ultimately failed. These wolves were removed from the park and relocated to the Alligator River National Wildlife Refuge in North Carolina.
The Smokies are home to a diverse bird population due to the presence of multiple forest types. Species that thrive in southern hardwood forests, such as the red-eyed vireo, wood thrush, wild turkey, northern parula, ruby-throated hummingbird, and tufted titmouse, are found throughout the range's lower elevations and cove hardwood forests. Species more typical of cooler climates, such as the raven, winter wren, black-capped chickadee, yellow-bellied sapsucker, dark-eyed junco, and Blackburnian, chestnut-sided, and Canada warblers, are found in the range's spruce-fir and northern hardwood zones.
Ovenbirds, whip-poor-wills, and downy woodpeckers live in the drier pine-oak forests and heath balds. Bald eagles and golden eagles have been spotted at all elevations in the park. Peregrine falcon sightings are also not uncommon, and a peregrine falcon eyrie is known to have existed near Alum Cave Bluffs throughout the 1930s. Red-tailed hawks, the most common hawk species, have been sighted at all elevations in the range. Owl species residing in the Smokies include the barred owl, eastern screech-owl, and northern saw-whet owl.
Timber rattlesnakes—one of two venomous snake species in the Smokies—are found at all elevations in the range. The other venomous snake, the copperhead, is typically found at lower elevations. Other reptiles include the eastern box turtle, the eastern fence lizard, the black rat snake, and the northern water snake.
The Great Smokies are home to one of the world's most diverse salamander populations. Five of the world's nine families of salamanders are found in the range, consisting of up to thirty-one species. A type of Jordan's salamander known as the redcheeked salamander is found only in the Smokies. The imitator salamander is found only in the Smokies and the nearby Plott Balsams and Great Balsam Mountains.
Two other species—the southern gray-cheeked salamander and the Southern Appalachian salamander—occur only in the general region. Other species include the shovelnose salamander, blackbelly salamander, eastern red-spotted newt, and spotted dusky salamander. The legendary hellbender inhabits the range's swifter streams. Other amphibians include the American toad and the American bullfrog, wood frog, upland chorus frog, northern green frog, and spring peeper.
Fish inhabiting the streams of the Smokies include trout, lamprey, darter, shiner, bass, and sucker. The brook trout is the only trout species native to the range, although northwestern rainbow trout and European brown trout were introduced in the first half of the 20th century. The larger rainbow and brown trout outcompete the native brook trout for food and habitat at lower elevations. As such, most of the brook trout found in the park today are in streams above 3,000 feet in elevation. Trout in the Smokies are generally smaller than other members of their species in different locales. Protected fish species in the range include the smoky and yellowfin madtom, the spotfin chub, and the duskytail darter.
The lightning-bug firefly Photinus carolinus, whose synchronized flashing light displays occur in mid-June, is native to the Smoky Mountains with a population epicenter near Elkmont, Tennessee.
Air pollution is contributing to increased Red Spruce tree mortality at higher elevations and oak decline at lower elevations, while invasive hemlock woolly adelgids attack Hemlocks and balsam woolly adelgids attack Fraser firs. Pseudoscymnus tsugae, a type of beetle in the ladybug family, Coccinellidae, has been introduced in an attempt to control the pests.
Visibility now is dramatically reduced by smog from both the Southeastern United States and the Midwest, and smog forecasts are prepared daily by the Environmental Protection Agency for both nearby Knoxville, Tennessee and Asheville, North Carolina.
Environmental threats are the concern of many non-profit environmental stewardship groups, especially The Friends of the Smokies. Formed in 1993, the friends group assists the National Park Service in its mission to preserve and protect the Great Smoky Mountains National Park by raising funds and public awareness, and providing volunteers for needed projects.