Ecological Systems

Tennessee is an Upper South state approximately 432 miles long and 112 miles wide, constituting 42,244 square miles, with elevations ranging from peaks of over 6,000 feet to sea level, containing a wide variety of natural and human environments. A growing season that ranges from an average of 160 days in the mountainous east to 260 days in the southwestern corner provides another source of variation. The state contains significant portions of three of the major ecological regions, or biomes, of North America. Within each of those larger zones are also smaller environmental areas.

Much of the Unaka, or Great Smoky, Mountains of East Tennessee is in the Boreal, or Conifer Zone, where the climate and environment, due to the high altitude, more nearly resembles that of upstate New York than that of the Upper South. Consequently, trees commonly associated with more northern climes–firs, spruce, hemlock–are native. The area's topographical complexity of peaks, ridges, valleys, and coves creates a setting for a wide variety of plant life, including some 1,300 species of flowering plant and 131 species of trees, compared to 85 for all of Europe. In the heart of the region is the Cherokee National Forest (625,350 acres), which includes the Great Smoky Mountains National Park (241,206 acres), one of the region's most popular parks.

At the opposite end of the state are the Mississippi River Bottomlands, which are some 50 miles wide and contain over 900 square miles. A swampy, deciduous forest is the ecological system dominating this geophysical region. Its almost subtropical appearance is typified by Reelfoot Lake, approximately 14 miles long and five miles wide, with its cypress and abundant waterfowl, including egrets and herons. Reelfoot Lake, in fact, is one of the state's few bald eagle nesting areas. This ecological zone, together with much of the rest of West Tennessee and the western portion of the Tennessee River Valley, is crucial to the Mississippi Flyway. Consequently the U.S. Fish and Wildlife Service maintains seven National Wildlife Refuges, totaling 91,073 acres, in the region.

The vast majority of the state's territory, ranging from the Valley of East Tennessee through the Gulf Coastal Plain bordering on the Mississippi Bottoms, is within the Deciduous Forest Zone. This zone is characterized by oaks, maples, beech, walnut, hickory, poplar, and other hardwoods mixed with pine and cedar. The wildlife complex–deer, raccoon, opossum, and turkey–is typical for the American South. Given the zone's topological diversity and its complex drainage patterns and varying soils, there is considerable environmental variation.

West of the Unaka Mountains is the Valley of East Tennessee, varying in width from 30 to 60 miles and containing some 9,000 square miles drained by the eastern reaches of the Tennessee River and its tributaries. It is an undulating region of small farms with two major urban centers, Knoxville and Chattanooga. Forest patches are frequent. West of the Valley is the Cumberland Plateau, portions of which reach an elevation of 2,000 feet. To the south the Sequatchie Valley bifurcates the plateau as far north as the Crab Orchard Mountains. The Cumberland Plateau, totaling 4,300 square miles, is also cut by deep and sometimes wide river valleys which create some of the most spectacular vistas in the state. The Cumberland Plateau descends into the Eastern Highland Rim, averaging 1,000 feet above sea level. This region of some 2,500 square miles is reasonably fertile, except for the western edges where poor drainage and soils create broad “barrens” and where forests develop and recover more slowly than in other nearby regions.

The Great Central or Nashville Basin (5,000 square miles), with its average elevation just over 500 feet and scattered hills termed “knobs,” is often called the “Garden of Tennessee” for its relative fertility. It is a region of larger farms and cattle operations, comparatively cleared of forest. Nashville is the hub of the region. It is well drained by portions of the Tennessee and Cumberland Rivers and their tributaries including the Duck, Caney Fork, Buffalo, and Harpeth Rivers. To the south and west are the Western Highland Rim (7,500 square miles with an average elevation of 1,000 feet) and the Tennessee River Valley, which are much more heavily forested than the Basin. Between the Tennessee River Valley and the Mississippi Bottoms is the Gulf Coastal Plain (9,000 square miles) of West Tennessee. Parallel to the Tennessee River in the eastern portion of the plain is a belt of sand hills and mixed pine and hardwood forests about 35 miles wide where farming is difficult. Much of this land is in the Tennessee National Wildlife Refuge. The bulk of the Coastal Plain is both flatter and more fertile and, consequently, more heavily farmed than other areas of the state.

Human occupation and exploitation, of course, have had a massive impact on these natural environments. Agriculture is the greatest of these influences. There were approximately ninety-one thousand farms in Tennessee in 1999, constituting about 45 percent of the state's land area, despite the fact that around one-third of the state's territory is unfit for farming. About 20 percent of this farmland is in woodland and forest rather than field and pasture. Tennessee's forests, public and private, were sufficient to allow the cutting of 960 million board feet of hardwood in 1999, making the state one of the nation's leaders in hardwood production, along with another 156 million board feet in softwood. According to 1995 estimates, one-half of the state's area is wooded, with some 200 species of trees, of which one-third have commercial value. There are more acres (156,000) in Tennessee's thirteen state forests than in any other southern state. The Tennessee State Park system contains over 131,000 acres.

The rivers, streams, and lakes are vital parts of the state's ecological systems. The Tennessee Valley Authority operates seventeen dams on the Tennessee and its tributaries, while the U.S. Army Corps of Engineers has built seven on the Cumberland. These projects for flood control and hydroelectric power have created a series of slack water lakes of ecological value as well as of recreational and economic importance. Also the state's five largest cities have, over the last twenty years, increasingly recognized the importance of urban ecology. For instance, there have been projects to preserve green areas and provide better public access to riverfronts for recreational and cultural uses.

Enforcement of state environmental laws and regulations rests mainly with the Department of Environment and Conservation. Created in 1991 to consolidate programs from a variety of departments and agencies, the department oversees the state park system, air and water pollution control, and solid waste management. The Wildlife Resources Agency is independent while the Forestry Division is part of the Department of Agriculture and maintains the state forests.

Citation Information

The following information is provided for citations.

  • Article Title Ecological Systems
  • Author
  • Website Name Tennessee Encyclopedia
  • URL
  • Access Date July 25, 2024
  • Publisher Tennessee Historical Society
  • Original Published Date
  • Date of Last Update March 1, 2018