Background on Smokies Natural History

This text is from the Tremont lesson manual, Connecting People and Nature: A Teacher's Guide.

Introduction | Geology | Climate | Forest Communities | Park Resource Management Issues

Introduction

Great Smoky Mountains National Park, containing 517,000 acres, is one of the largest protected land areas east of the Rocky Mountains. It has also been designated as an International Biosphere Reserve by the United Nations. As one of only forty-three such areas so designated in the United States, it was chosen with the primary objectives of coordinating environmental education, research and monitoring, and conserving genetic diversity.

The Smokies contain an enormous variety of plants and animals; this biological diversity is one of the park’s most unique features. Due to the elevation and orientation of the Great Smoky Mountains, tremendous variation occurs in a small amount of space. Changes in altitude and moisture conditions create entirely different ecosystems within a relatively small geographic area. In terms of diversity, a walk from valley to mountain peak (from 1500’ to 6500’) is often compared to the two thousand mile hike on the Appalachian Trail from Georgia to Maine.

The tremendous diversity is due in part to the Ice Age retreat of flora and fauna before the southward-advancing glaciers. Although the glaciers did not reach this area, their presence approximately two hundred fifty miles to the north caused a drop in temperature. Many northern species found suitable living conditions in the upper elevations of the Smokies, and continue to inhabit the park even after the glacial melt. Warmer-climate species are able to live in the lower elevations, thus creating an intricate interaction between ecosystems. Members of these ecosystems include over fourteen hundred flowering species; over four hundred species of mosses and liverworts; more than two thousand species of fungi; over one hundred twenty-five species of trees (more than occur in northern Europe); over two hundred different birds; at least sixty mammal species; over forty species of fish; thirty-eight reptilian species; numerous species of spiders, insects and butterflies; and fifty amphibian species, including at least thirty different types of salamanders. The Smokies hold the distinction of supporting the most diverse salamander community of any area of similar size in the world.

Species new to the scientific community are found in the park nearly every year, especially in the lesser studied groups such as the invertebrates.

Geology

The character and landscape of the Smoky Mountains are a result of the geologic processes that formed these mountains. The Smokies are round, but still rugged, mountains with few rock outcroppings, numerous stream drainages, and landslide scars. These topographic features reflect the ancient history of these mountains and the fact that they have been and continue to be shaped by the combined actions of thrust faults, uplifts, and erosion.

Most of the rocks encountered in the park are of a sedimentary type, some of which have been metamorphosed to varying degrees. Sandstone, siltstone, conglomerates and slates are the most common types. Limestone, found in a few areas, primarily in Cades Cove, tells of the ancient proto-Atlantic Ocean that once covered this land. Located in and near the park are a few caves which form special features in the area’s landscape.

Tectonic History

From the way rocks and mountains are forming today, geologists have developed ideas about how these mountains may have been formed. When early continents drifted apart during the Precambrian Era (four billion to six hundred million years ago), the proto-Atlantic Ocean was formed. Topographically, the ocean was a low area that eventually became the Appalachian geosyncline (a depositional basin of continental proportions that is filled with sediments over a large period of time). The Precambrian highlands, consisting of sandstones and quartzites, were eroded and washed into the ocean. Erosion continued through Cambrian and early Ordovician time (six hundred million to four hundred fifty million years ago). As erosion lowered the land, the ocean began to spread and cover some of the sediments previously deposited. In the shallow marine environment, carbonate deposits (later to become mostly limestone) were laid down as the shells of dead invertebrates drifted to the bottom and accumulated. The proto-Atlantic Ocean filled in with sediments and became land that eventually turned into the Appalachian Mountains.

During late Paleozoic time (three hundred twenty to two hundred twenty-five million years ago), Africa and what is now the southeastern United States collided, forming part of the supercontinent known as Pangaea. This collision lasted fifty million years and closed the proto-Atlantic Ocean, ending deposition into the Appalachian geosyncline. The force of this collision caused extensive folding, thrusting, and metamorphism (change in the rocks due to high temperatures and pressures). In the Smokies, the dominant effect was a thrusting of the older eastern rocks over the younger western rocks. The resulting Appalachian Mountains were enormous and probably resembled the current-day Rockies.

During the Mesozoic Era (two hundred twenty-five to sixty-five million years ago), Pangaea began to split up, and the present Atlantic Ocean basin began to form between the drifting continental plates. Erosion began to sculpt the mountains, and continued to do so throughout Cenozoic time (sixty-five million years ago to present). Erosion was speeded up due to climatic fluctuations occurring during the ice ages and interglacial periods. Glaciers did not extend into the Smoky Mountains, but increased biodiversity by pushing northern species southward as they fled the hostile colder climates.

Climate

The elevations in the park range from 800 to 6,643 feet. This topography can dramatically affect local weather. Temperatures regularly differ ten to twenty degrees Fahrenheit from mountain foot to top. Rainfall averages vary from fifty-five inches per year in the lowlands to eighty-five inches per year at Clingmans Dome.

Spring in the Smokies begins in March and extends through May. It is a season of unpredictable weather with changes often occurring rapidly. March is the month with the most radical changes; snow can fall at any time during the month, particularly in the higher elevations. The mean high for the park is sixty-one degrees and the mean low is forty-two degrees. April and May are warmer, with highs in the seventies and eighties, and rainfall averages over four inches during these months.

Summer heat and humidity dominate between June and August. Afternoon showers and thunderstorms are common. Temperatures increase with August afternoon highs in the nineties at the lower elevations. Higher in the mountains the temperatures are more pleasant. On Mt. LeConte (6593’), no temperature above eighty degrees has ever been recorded.

Autumn is the driest period of the year with only occasional rain showers. From September through mid-November clear skies, warm days, and cool nights dominate. The first frosts often occur in late September. By November the lows are usually near freezing and snow is a distinct possibility at higher elevations.

Winter runs from mid-November through February and is generally moderate. About half of the days in the winter have highs of fifty degrees or more. Most nights have lows at or below freezing. Snowfall is frequent high in the mountains and can accumulate up to two feet during a single storm. In the valleys and lower elevations, snowfalls of more than one inch usually occur three to five times per year.

Forest Communities

The Smokies support an amazing diversity of plant species. Groups of tree species that require similar environmental conditions tend to grow together and are referred to collectively as forest types. Forest types are named for the dominant species at the climax stage, when forest succession has run its course and the community is comparatively stable. The special habitats created by these groups of trees nourish a community of plants and animals unique to the particular forest type. There are five major forest types in the Smoky Mountains and two other types of plant communities of special note.

Cove hardwood forests occur in sheltered areas up to 4,500 feet in elevation. A characteristic feature is the diversity of tree species, with as many as fourteen to fifteen co-dominants. Some common species include sugar maple, yellow birch, tulip poplar, and silverbell.

Northern hardwood forests also contain broad-leaved trees but grow above 4,500 feet. The forests are so named because they closely parallel tree types that grow at lower elevations in the northern states. They are dominated principally by beech and yellow birch trees, with some maple trees. In the Smokies these forests are often found on north-facing slopes.

Spruce-fir forests often surround the northern hardwood forests, and are found at the same elevations, above 4,500 feet. The forest floor below the spruce and fir is often mossy.

Hemlock forests are typically restricted to sheltered areas along streams up to about 3000 feet, but they can occur on more exposed slopes and ridges up to about 4500 feet. Hemlock trees, often attaining heights of over one hundred feet, dominate. A dense understory of rhododendron is frequently found in this forest.

Pine and oak forests cover dry, exposed slopes and ridges at low to middle elevations, often in rocky terrain. Oaks and pines that dominate this forest type include white, red, chestnut and scarlet oak; and white, pitch, short-leaf, Table Mountain, and Virginia pines.

Old growth forests contain beautiful trees up to eight feet in diameter, and constitute up to twenty-five percent of the park’s forested area. These areas were spared the logging that occurred in the rest of the park from the late 1800s to 1930s.

Balds are located at middle to high elevations, with heath balds at the park’s eastern end and grassy balds at its western end. Their origins are debatable, but they have remained open, unforested areas, in part due to cattle and sheep grazing by early settlers. Many balds are shrinking or have returned to forest since the establishment of the park. Some of the balds are being actively maintained by the National Park Service.

Park Resource Management Issues

The management of any park is complex and involves difficult decisions on how to equitably spread limited resources for the improvement of the entire ecosystem. The problems facing the Smokies include, but are not limited to, increasing visitor numbers, poaching, exotic species, and endangered species.

Visitors
Located within a ten-hour drive of half of the nation’s population, the Smokies receive over ten million visits each year. While the National Park Service delights in increased interest, it sometimes seems that the Smokies are being literally “loved to death.”

The smog from traffic jams in Cades Cove and on the Little River Road, litter from tourists, feeding of wildlife, digging of plants for gardens, vehicle collisions with wildlife, overcrowded campgrounds, and overuse of backcountry sites all lead to the destruction of the area people come here to enjoy.

Park management is trying to reduce the impact on the park. The use of backcountry campsites has been limited through a permit system. They have also launched an educational campaign to teach visitors the ill effects of feeding wildlife and other destructive behaviors, such as throwing apple cores into the woods and defecating or urinating close to water sources.

Poaching
Poachers illegally kill or take a variety of animal and plant parts each year. The black bear and the ginseng root are two of the species that are subject to, and threatened by, poaching.

Poaching of the black bear is lucrative because an international market fetches high prices for paws, claws, and especially gall bladders. Parts are used as jewelry, gourmet delicacies, or for medicinal powers that they are believed to have. Gall bladders, used in traditional medicines, sell for exorbitantly high prices and are an easy item to hide since they are small and easily transported. Often a bear is killed and the entire body left to rot, with only the gall bladder removed.

Black bears
Black bears (Ursus americanus) weigh eight ounces and measure a few inches at birth. They grow into adults of up to three hundred pounds in weight (in the park average weight is closer to one hundred fifty pounds) and six feet in length with a height, at the shoulder, of up to three feet. They eat mostly berries, nuts, fish and carrion. There are approximately two thousand bears in the park (1999 figures). They range over all elevations, are good tree climbers, swim very well, can run up to thirty miles per hour, and have color vision and an extremely keen sense of smell. The life span of an average bear is twelve to fifteen years. Most activity occurs during early morning and late evening hours. Bears mate in June, but implantation of the fetus into the uterus is delayed until the female bear has gained sufficient weight to enable her to support the extra life throughout a winter of denning. One to four cubs are born seven months after conception, and remain with the mother for about eighteen months or until she mates again. Mother bears are fiercely protective of their young.

Exotic Species
Exotic species are those species which are not native to a continent but have been introduced by humans. Exotic species tend to be destructive. They usually have no controls, such as predators, or limits on their range, diet, and reproductive capacities, because these have not evolved within the native ecosystem. Since exotic species tend to take over and force out native populations, they threaten to reduce the biological diversity of the ecosystem.

Exotic species may be introduced accidentally, because traveling is so common, and seeds, spores, or larvae are not very apparent to the unwitting transporter; or intentionally, because somebody believed that a good reason for introduction existed, and neglected to examine the possible negative effects. Some of the introduced species that have adversely affected the park ecosystem are wild hogs, balsam woolly adelgid, rainbow and brown trout, kudzu, lespedeza, and mimosa.

Wild Hog
The wild hog (Sus scrofa) is native to Europe, Asia, northern Africa, Japan, and the Malayan Islands. In 1912 a shipment of European wild hogs was transported to a private game preserve in western North Carolina, only fifteen miles southwest of the current park boundary. Some of the wild hogs escaped from the preserve, interbred with domestic hogs, and reached the park by the late 1940s.

Although the maximum weight for a wild hog is three hundred pounds, most male hogs in the Smokies weigh about one hundred twenty-five pounds, with females weighing slightly less. Hogs are three and a half to five feet long and stand two to three feet tall at the shoulder. Both sexes have forty-four teeth, including a well-developed set of canine teeth. The upper tusks act as “whetstones” to keep sharp edges on the lower ones. Adult coat color varies from gray to black, and most piglets have longitudinal stripes until they are about four months old. Hogs have poor eyesight, but a keen sense of smell and hearing.

Wild hog piglets weigh about two pounds at birth. After three or four months, the piglets are weaned and become independent from the sow. Family groups usually break up once the young reach sexual maturity, which is usually within a year of birth for both males and females. Gestation is approximately one hundred to one hundred twenty-five days, and most litters have three to eight piglets. Average life expectancy is about eight years. The rapid rate of reproduction, combined with relatively large litters and early sexual maturity, means that hog populations increase rapidly, thus adding to the threat they pose.

Hogs are omnivorous, and consume the foods that are normally eaten by native inhabitants of the system. Whereas native animals will often selectively choose their food, hogs root up large areas with their snouts and tusks to obtain food. They also create large muddy wallows as they rid their bodies of mites. The disturbed areas are usually devoid of all plants, thus adding erosion to the list of problems created by the hog. Also, hogs have been known to eat red-cheeked salamanders (Plethodon jordani), which are endemic to the park (i.e., this is their only known habitat on earth).

National Park Service policy is that “manipulation of populations of exotic plant and animal species, up to and including total eradication, will be undertaken whenever such species threaten the protection or interpretation of resources being preserved by the park” (from National Park Service information flyer on wild hogs). Since the invasion of the wild hog in the late 1940s, over eight thousand eight hundred hogs have been removed by trapping or shooting. Of the total number of animals taken, over seven thousand six hundred have been removed since the removal program started in earnest in 1978. The majority of hogs removed from the park are trapped and transported to wildlife management areas to be released for hunting purposes.

Balsam Woolly Adelgid
The balsam woolly adelgid (Adelges piceae) is an insect that infests and kills stands of Fraser fir (Abies fraseri) in the spruce-fir forest type. This fir used to be the dominant tree at the highest elevations. It is the only fir which occurs naturally in the Smokies and is endemic to this region. The adelgid was introduced on trees imported from Europe, and the Fraser fir has no natural defense against it.

After finding a suitable feeding site, the adelgid inserts a long, needle-like stylet below the bark. A substance within the insect’s saliva diffuses into the cells surrounding the stylet, causing them to enlarge abnormally. The saliva is believed to encourage the flow of nutrients to the feeding site, thus providing for the adelgid and the few surrounding cells while starving the rest of the tree. An infested tree may serve as host for thousands of these tiny insects. Death may take from two to seven years and results from the disruption in the transport of water and minerals from the roots to the rest of the tree. To date (January 1999), researchers estimate that over ninety-five percent of the mature Fraser fir trees have been killed by the adelgids.

In more northerly climates, the adelgid has been partly suppressed by the greater severity of winter weather and temperature. They reproduce rapidly, have no natural predators, and are easily transported by the wind.

Researchers have tried various methods of control with little practical success. Introduced predators would not feed exclusively or reliably upon the adelgids. Most pesticides are banned because of their adverse affect upon native insects. A mild soap which effectively removes a protective coating from the adelgids and leaves them to die by dehydration is too costly to put into widespread use because it requires individual coating of each limb of each tree. For the time being, seeds are being collected for gene preservation in hopes that in the future a solution will be discovered and the firs may be reintroduced.

Exotic plants
There are over three hundred species of exotic plants in Great Smoky Mountains National Park. Problems caused by these include competition with native plants for resources, ability to change succession patterns, interbreeding with closely-related native species, and out-competing rare native plants that require specialized habitats.

Fish
Among the introduced fish species are the rainbow trout and the brown trout, which offer stiff competition for the native brook trout. These larger fish apparently compete with the native brook trout and eventually displace the “brookies” in marginal and less desirable habitats. The brook trout’s range has been reduced by seventy-five percent since 1900.

Endangered Species
Unfortunately, the Smokies, as everywhere, have a number of native endangered species. Threats include exotics, acid rain, and loss of habitat. Endangered and threatened species include the red-cockaded woodpecker, northern flying squirrel, Indiana bat, Florida gray bat, red-cheeked salamander, brook trout, and eleven or more species of plants, including the Table Mountain pine and the Fraser fir. Some animals, such as the river otter, the peregrine falcon and the smoky madtom (a small catfish), have been successfully reintroduced.

Red Wolf Recovery Program
The red wolf, Canis rufus, is a shy, solitary species that once roamed throughout the Southeast, but aggressive predator-control programs and the clearing of essential habitat combined to bring the red wolf to the brink of extinction. To save the species, the U. S. Fish and Wildlife Service captured as many red wolves as possible in 1975. These animals were bred in captivity with the goal of reestablishing the species in its original range.
Successful releases in eastern North Carolina and on coastal islands in South Carolina, Mississippi, and Florida gave biologists optimism that the red wolf could once again thrive in the Smokies. Four wolves, consisting of a mated pair and two pups, were released in 1991 in the Cades Cove area. In 1992 the experimental release efforts were deemed a success and a permanent release was begun. The program continued until December of 1998, but ultimately closed down due to a lack of pup survival and the inability of the wolves to establish home ranges within park boundaries. The animals still in the wild were recaptured, to be either put back into the captive breeding program or released at another reintroduction site.

Extinct and Extirpated Species
A few species which are missing from the Smokies are:

Extinct Species: Passenger pigeon, 1914

Extirpated species (native species that are locally extinct or driven to other habitats) include:
American bison, 1825; mountain lion, 1910;
Grey Wolf, 1900; Fishers, 1850; Red Wolf, 1905, 1998

All Taxa Biodiversity Inventory
Great Smoky Mountains National Park is considered to be the most biologically diverse park in the continental United States, and has been designated an International Biosphere Reserve by the United Nations. It is estimated that the park may contain over one hundred thousand living species, excluding bacteria, yet less than ten thousand had been identified as of 1998. The All Taxa Biodiversity Inventory (ATBI) is a long-term project initiated in 1998 and expected to last for ten to fifteen years. It is being managed by the National Park Service in cooperation with many universities, museums, other government agencies, and volunteers.

The project will tap the expertise of taxonomists (scientists who differentiate and classify plants and animals), data specialists, biologists, botanists, and ecologists. Once completed, the ATBI will provide a baseline from which to measure change. This type of comprehensive scientific survey has never been undertaken on such a scale anywhere in the world, and it is intended to serve as a model for future projects in other national parks and protected areas. The effort is founded on the notion that knowledge is essential for effective preservation.

This survey will also provide many educational opportunities. Students and volunteers will learn about research and the life of the Smokies while they take part in the inventory work. As species are studied, web pages and interactive keys will be developed to help park visitors identify what they find. There is no telling what benefits may result from a better understanding of this part of our world.