Everglades National Park, Florida, United States Photograph by Deborah Gainer   Southeastern North America: Southeastern United States (Florida) Flooded Grasslands and Savannas   7,800 square miles (20,100 square kilometers) -- about the size of Massachusetts Vulnerable

· River of Grass
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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River of Grass

The Everglades is the most famous wetland in the United States and one of the most distinct in the world. It is unique among the world's large wetlands because it derives its water directly from rainfall. Other large and famous wetlands, such as the Pantanal of South American, the Okavango of Botswana, and the Llanos in Venezuela and Colombia, derive most of their water and nutrient inputs from river flooding. The unique "sheet flow," the slow flow of water over shallow, broad tracts of marsh, inspired environmentalist Marjory Stoneham Douglas to name the Everglades the "River of Grass."

In addition to sheet flow, there is a groundwater connection to Lake Okeechobee, the second largest freshwater lake entirely within the United States. The links between the Everglades, Lake Okeechobee, and the Kissimmee River, which provides 80 percent of the surface flow into Lake Okeechobee, are crucial to maintaining this ecoregion.

Special Features

The Everglades are subtropical, meaning the climate is not quite as hot and wet as the tropics, but the area still gets a large amount of rainfall. The ecoregion is also exposed to hurricanes, most frequently between August and October. The occasional small hills that rise above the wetland are called hammocks, and it is here that clusters of trees that need drier areas can grow. Species growing on these tree islands include red bay, pond apple, cypress, and a variety of palms. Some tree snails are endemic to the hammocks.

The amazing American alligator can grow to be up to 18 feet (5.4 m) long and weigh up to 500 pounds (225 kg)! As a result of unregulated hunting, this species almost became extinct. When the seriousness of the situation was realized, the American alligator was listed as a federally endangered species in 1967. A conservation program, supported by the United States Endangered Species Act, fined people harming alligators or their eggs. The program was so successful that, in 1987, the American alligator was removed from the endangered species list.

Wild Side

Fascinating creatures can be found in all areas of the Everglades -- alligators swimming in the water and snail kites flying overhead. This ecoregion is home to many wading birds, as well as lots of insects, from mosquitoes to tropical butterflies. Trees include many tropical species that are very different from those found in other parts of the United States but are found further south in Central America and the Caribbean. Mangroves are coastal trees uniquely adapted to living in partially submerged brackish conditions. In the open water areas, floating plants including water lilies and spatter dock are found, while a complex of submerged plants are dominated by bladderwort . Fourteen species of plants and nine vertebrates (animals with backbones) are federally listed endangered species, including the Florida panther.

Cause for Concern

The Everglades have been described as one of the most endangered ecoregions, having suffered from a long history of human manipulation. It is estimated that only 2 percent of the original Everglades ecosystem is truly intact. Wetlands have been drained and cleared, which can affect foraging areas for wading birds. The most widespread impact on the ecoregion has been the disruption of natural water flow as a result of practices such as the straightening of rivers and construction of canals. Changing natural water levels makes fire more likely. Invasive species such as Brazilian pepper tree and the Australian Melaleuca tree, have taken over some of the habitat.

Florida is one of the fastest-growing states in terms of human population; between 1940 and 1980, the populations of Dade, Broward, and West Palm Beach Counties increased by 830 percent! This puts great stress on the Everglades, especially through the use of water. Population growth has resulted in the destruction of the eastern 12 percent of the Everglades. There has been a decline of approximately 90 percent of the wading birds in the last 100 years. Poaching of deer, alligators, and panthers continues.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.