Tennessee is a state in the Southeastern region of the United States. It is bordered by Kentucky to the north, Virginia to the northeast, North Carolina to the east, Georgia, Alabama, and Mississippi to the south, Arkansas to the southwest, and Missouri to the northwest. Tennessee's population as of the 2020 United States census is approximately 6.9 million.
Tennessee is within a temperate deciduous forest biome commonly known as the Eastern Deciduous Forest. It has eight ecoregions: the Blue Ridge, Ridge and Valley, Central Appalachian, Southwestern Appalachian, Interior Low Plateaus, Southeastern Plains, Mississippi Valley Loess Plains, and Mississippi Alluvial Plain regions. Due to its wide variety of terrains and ecosystems, Tennessee is the most biodiverse inland state. The Great Smoky Mountains National Park is the most biodiverse national park, and the state's Duck River is the most biologically diverse waterway in North America. The Nashville Basin is also renowned for its diversity of flora and fauna. Tennessee is home to 340 species of birds, 325 freshwater fish species, 89 mammals, 77 amphibians, and 61 reptiles.
Forests cover about 52% of Tennessee's land area, with oak–hickory the dominant type. Appalachian oak–pine and cove hardwood forests are found in the Blue Ridge Mountains and Cumberland Plateau, and bottomland hardwood forests are common throughout the Gulf Coastal Plain. Pine forests are also found throughout the state. The Southern Appalachian spruce–fir forest in the highest elevations of the Blue Ridge Mountains is considered the second-most endangered ecosystem in the country. Some of the last remaining large American chestnut trees grow in the Nashville Basin, and are being used to help breed blight-resistant trees. Middle Tennessee is home to many unusual and rare ecosystems known as cedar glades, which occur in areas with shallow limestone bedrock that is largely barren of overlying soil, and contain many endemic plant species.
Common mammals found throughout Tennessee include white-tailed deer, red and gray foxes, coyotes, raccoons, opossums, wild turkeys, rabbits, and squirrels. Black bears are found in the Blue Ridge Mountains and on the Cumberland Plateau. Tennessee has the third-highest number of amphibian species, with the Great Smoky Mountains home to the most salamander species in the world. The state also ranks second in the nation for the diversity of its freshwater fish species.