Everglades National Park

Everglades National Park is an American national park that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the United States and the largest wilderness of any kind east of the Mississippi River. An average of one million people visit the park each year. Everglades is the third-largest national park in the contiguous United States after Death Valley and Yellowstone. UNESCO declared the Everglades & Dry Tortugas Biosphere Reserve in 1976 and listed the park as a World Heritage Site in 1979, and the Ramsar Convention included the park on its list of Wetlands of International Importance in 1987. Everglades is one of only three locations in the world to appear on all three lists.

Most national parks preserve unique geographic features; Everglades National Park was the first created to protect a fragile ecosystem. The Everglades are a network of wetlands and forests fed by a river flowing per day out of Lake Okeechobee, southwest into Florida Bay. The park is the most significant breeding ground for tropical wading birds in North America and contains the largest mangrove ecosystem in the Western Hemisphere. Thirty-six threatened or protected species inhabit the park, including the Florida panther, the American crocodile, and the West Indian manatee, along with 350 species of birds, 300 species of fresh and saltwater fish, 40 species of mammals, and 50 species of reptiles. The majority of South Florida's fresh water, which is stored in the Biscayne Aquifer, is recharged in the park.

Humans have lived for thousands of years in or around the Everglades. Plans arose in 1882 to drain the wetlands and develop the land for agricultural and residential use. As the 20th century progressed, water flow from Lake Okeechobee was increasingly controlled and diverted to enable explosive growth of the Miami metropolitan area. The park was established in 1934, to protect the quickly vanishing Everglades, and dedicated in 1947, as major canal-building projects were initiated across South Florida. The ecosystems in Everglades National Park have suffered significantly from human activity, and restoration of the Everglades is a politically charged issue in South Florida.

Geography

Everglades National Park covers , throughout Dade, Monroe, and Collier counties in Florida, at the southern tip of the Atlantic coastal plain. The elevation typically ranges from 0 to above sea level, but a Calusa-built shell mound on the Gulf Coast rises above sea level.

Geology

The terrain of South Florida is relatively and consistently flat. The limestone that underlies the Everglades is integral to the diverse ecosystems within the park. Florida was once part of the African portion of the supercontinent Gondwana. After it separated, conditions allowed a shallow marine environment to deposit calcium carbonate in sand, shells, and coral to be converted into limestone. Tiny bits of shell, sand, and bryozoans compressed over multiple layers forming structures in the limestone called ooids, which created permeable conditions that hold water.

The Florida peninsula appeared above sea level between 100,000 and 150,000 years ago. As sea levels rose at the end of the Wisconsin ice age, the water table appeared closer to land. Lake Okeechobee began to flood, and convection thunderstorms were created. Vast peat deposits south of Lake Okeechobee indicate that regular flooding had occurred about 5,000 years ago. Plants began to migrate, subtropical ones from the northern part of Florida, and tropicals carried as seeds by birds from islands in the Caribbean. The limestone shelf appears to be flat, but there are slight rises—called pinnacles—and depressions caused by the erosion of limestone by the acidic properties of the water. The amount of time throughout the year that water is present in a location in the Everglades determines the type of soil, of which there only two in the Everglades: peat, created by many years of decomposing plant matter, and marl, the result of dried periphyton, or chunks of algae and microorganisms that create a grayish mud. Portions of the Everglades that remain flooded for more than nine months out of the year are usually covered by peat. Areas that are flooded for six months or less are covered by marl. Plant communities are determined by the type of soil and the amount of water present.

Climate

According to the Köppen climate classification system, Royal Palm at Everglades National Park has a tropical monsoon climate (''Am''). Summers are long, hot, and very wet and winters are warm and dry.

Hydrography

While they are common in the northern portion of Florida, no underground springs feed water into the Everglades system. An underground reservoir called the Floridan aquifer lies about below the surface of South Florida. The Everglades has an immense capacity for water storage, owing to the permeable limestone beneath the exposed land. Most of the water arrives in the form of rainfall, and a significant amount is stored in the limestone. Water evaporating from the Everglades becomes rain over metropolitan areas, providing the fresh water supply for the region. Water also flows into the park after falling as rain to the north onto the watersheds of the Kissimmee River and other sources of Lake Okeechobee, to appear in the Everglades days later. Water overflows Lake Okeechobee into a river wide, which moves almost imperceptibly.

Ecosystems

At the turn of the 20th century, common concepts of what should be protected in national parks invariably included formidable geologic features like mountains, geysers, or canyons. As Florida's population began to grow significantly and urban areas near the Everglades were developed, proponents of the park's establishment faced difficulty in persuading the federal government and the people of Florida that the subtle and constantly shifting ecosystems in the Everglades were just as worthy of protection. When the park was established in 1947, it became the first area within the U.S. to protect flora and fauna native to a region as opposed to geologic scenery.Everglades National Park / Dry Tortugas National Park
Superintendent's Report, 2008 Fiscal Year. Retrieved on May 26, 2010. The National Park Service recognizes nine distinct interdependent ecosystems within the park that constantly shift in size owing to the amount of water present and other environmental factors.

Freshwater sloughs and marl prairies

Freshwater sloughs are perhaps the most common ecosystem associated with Everglades National Park. These drainage channels are characterized by low-lying areas covered in fresh water, flowing at an almost imperceptible per day.Robertson, p. 9. Shark River Slough and Taylor Slough are significant features of the park. Sawgrass growing to a height of or more, and broad-leafed marsh plants, are so prominent in this region that they gave the Everglades its nickname "River of Grass", cemented in the public imagination in the title for Marjory Stoneman Douglas's book (1947), which culminated years of her advocacy for considering the Everglades ecosystem as more than a "swamp". Excellent feeding locations for birds, sloughs in the Everglades attract a great variety of waders such as herons, egrets, roseate spoonbills (''Platalea ajaja''), ibises and brown pelicans (''Pelecanus occidentalis''), as well as limpkins (''Aramus guarauna'') and snail kites that eat apple snails, which in turn feed on the sawgrass. The sloughs' availability of fish, amphibians, and young birds attract a variety of freshwater turtles, alligator (''Alligator mississippiensis''), water moccasin (''Agkistrodon piscivorus conanti''), and eastern diamondback rattlesnake (''Crotalus adamanteus'').

Freshwater marl prairies are similar to sloughs but lack the slow movement of surface water; instead, water seeps through a calcitic mud called marl. Algae and other microscopic organisms form periphyton, which attaches to limestone. When it dries it turns into a gray mud. Sawgrass and other water plants grow shorter in freshwater marl than they do in peat, the other type of soil in the Everglades which is found where water remains present longer throughout the year. Marl prairies are usually under water from three to seven months of the year, whereas sloughs may remain submerged for longer than nine months and sometimes remain under water from one year to the next. Sawgrass may dominate sloughs, creating a monoculture. Other grasses, such as muhly grass (''Muhlenbergia sericea'') and broad-leafed water plants can be found in marl prairies. Animals living in the freshwater sloughs also inhabit marl prairies. Marl prairies may go dry in some parts of the year; alligators play a vital role in maintaining life in remote parts of the Everglades by burrowing in the mud during the dry season, creating pools of water where fish and amphibians survive from one year to the next. Alligator holes also attract other animals who congregate to feed on smaller prey. When the region floods again during the wet season, the fish and amphibians which were sustained in the alligator holes then repopulate freshwater marl prairies.

Tropical hardwood hammocks

Hammocks are often the only dry land within the park. They rise several inches above the grass-covered river and are dominated by diverse plant life consisting of subtropical and tropical trees, such as large southern live oaks ('' Quercus virginiana''). Trees often form canopies under which animals thrive amongst scrub bushes of wild coffee ('' Psychotria''), white indigoberry (''Randia aculeata''), poisonwood ('' Metopium toxiferum'') and saw palmetto ('' Serenoa repens''). The park features thousands of these tree islands amid sloughs—which often form the shape of a teardrop when seen from above (see park map) because of the slowly moving water around them—but they can also be found in pineland and mangroves. Trees in the Everglades, including wild tamarind (''Lysiloma latisiliquum