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Ecosystems in the Coastal Plain

The Atlantic-Gulf Coastal Plain is one of North America's major geographic provinces, forming the relatively level and exposed portion of the continental shelf in the East and South. On its northern frontier, the plain is narrow and strung with estuaries. It widens considerably southward to Florida, and reaches well inland in the lower Mississippi Valley and the West Gulf sections in Louisiana and Texas. The coastal plain supports a panoply of diverse ecosystems.

Swamps
- American alligators are common in the river swamps of the southern coastal plain.
  
  Rich bottomland swamp forests cloak the coastal plain's big black-water and brown-water rivers -- colored by tannic acid or sediments from Appalachian highlands, respectively. Biologically diverse, they are also bastions of wilderness in the eastern U.S. The names of many are legendary: Big Cypress, Okefenokee, Great Dismal Swamp. The Congaree Swamp of South Carolina, now protected in a national park, includes the most significant tract of old-growth bottomland woods left in the country. Its ancient trees, including water tupelo and sweetgum, are among the tallest of any temperate hardwood forest in the world. The country's biggest river swamp is southern Louisiana's Atchafalaya, with hundreds of thousands of acres of alligator-roamed cypress backwaters and bayous.
Pine Flatwoods
- Pine flatwoods are extensive in the coastal plain.
  
  Among the chief ecosystems of the coastal plain are its vast pine flatwoods. While dominant species of pine vary from north to south, these sandy woods, often so open as to be classified as savannas, share much scenic and ecological character from New Jersey to the southern tip of Florida, and west into Texas. Historically among the most extensive were the longleaf-pine savannas of the far Southeast, characterized by open, fire-pruned woodlands dominated by that stately conifer. The southern extension of the flatwoods are the so-called "pine rocklands" of South Florida, which are subtropical woodlands of char-barked slash pine, saw palmetto and cabbage palm on rugged limestone bedrock.
The Everglades
- Sawgrass flats and tree islands are among the unique ecosystems of the Everglades.
  
  One of the most unique and well-known ecosystems on the coastal plain is the Everglades and its associated landscapes. Defined by a slow-moving sheet of water draining the great Lake Okeechobee, the Everglades proper consist of vast sawgrass marshes and open sloughs, strung here and there with cypress domes and tropical hardwood hammocks. The freshwater sheet merges with brackish channels in the enormous mangrove forests of the South Florida coast and the shallows and keys of Florida Bay. The Big Cypress Swamp, a distinct ecosystem, adjoins the Everglades on the west. Its higher ground helps funnel the slow creep of water, as does the pinewood-studded Miami Rock Ridge to the east. In addition to tropical plants found nowhere else in the U.S., the Everglades is famous for its massive bird rookeries, panthers and crocodilians.
Other Ecosystems
- Mangroves line large parts of the Florida coast and its offshore keys.
  
  Coastal prairies and salt marshes are other significant ecosystems fringing seaside estuaries. Maritime forests of sand live oak, cabbage palm and other species help define dune edges and barrier islands. Florida supports one of the largest continuous mangrove forests in the world. These unique salt-adapted trees, which include white, red and black mangroves, provide important habitat for breeding birds and nursery grounds for marine organisms.

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