Ken Voorhis Photo
Why such a wondrous diversity? Mountains, glaciers, and weather are the big reasons. The park is the largest federally protected upland landmass east of the Mississippi River. Dominated by plant-covered, gently contoured mountains, the crest of the Great Smokies forms the boundary between Tennessee and North Carolina, bisecting the park from northeast to southwest in an unbroken chain that rises more than 5,000 feet for over 36 miles. Elevations in the park range from 875 to 6,643 feet. This range in altitude mimics the latitudinal changes you would experience driving north or south across the eastern United States, say from Georgia to Maine. Plants and animals common in the southern United States thrive in the lowlands of the Smokies while species common in the northern states find suitable habitat at the higher elevations.
The Great Smoky Mountains are among the oldest mountains in the world, formed perhaps 200-300 million years ago. They are unique in their northeast to southwest orientation, which allowed species to migrate along their slopes during climatic changes such as the last ice age, 10,000 years ago. In fact, the glaciers of the last ice age affected the Smoky Mountains without invading them. During that time, glaciers scoured much of North America but did not quite reach as far south as the Smokies. Consequently, these mountains became a refuge for many species of plants and animals that were disrupted from their northern homes. The Smokies have been relatively undisturbed by glaciers or ocean inundation for over a million years, allowing species eons to diversify.
In terms of weather, the park's abundant rainfall and high summertime humidity provide excellent growing conditions. In the Smokies, the average annual rainfall varies from approximately 55 inches in the valleys to over 85 inches on some peaks-more than anywhere else in the country except the Pacific Northwest. During wet years, over eight feet of rain falls in the high country. The relative humidity in the park during the growing season is about twice that of the Rocky Mountain region.
Some 100 species of native trees find homes in the Smokies, more than in any other North American national park. Almost 95% of the park is forested, and about 25% of that area is old-growth forest-one of the largest blocks of deciduous, temperate, old-growth forest remaining in North America. Over 1,500 additional flowering plant species have been identified in the park. The park is the center of diversity for lungless salamanders and is home to more than 200 species of birds, 66 types of mammals, 67 native fish species, 39 varieties of reptiles, and 43 species of amphibians. Mollusks, millipedes, and mushrooms reach record diversity here.
In recognition of the park's unique natural resources, the United Nations has designated Great Smoky Mountains National Park as an International Biosphere Reserve.
Great Smoky Mountains National Park: The Range of Life