Geography and ecology of the Everglades
Encyclopedia
The geography and ecology of the Everglades involve the complex elements affecting the natural environment throughout the southern region of the U.S. state of Florida
. Before drainage
, the Everglades
were an interwoven mesh of marsh
es and prairie
s covering 4000 square miles (10,360 km²). The Everglades is simultaneously a vast watershed
that has historically extended from Lake Okeechobee
100 miles (160.9 km) south to Florida Bay
(around one-third of the southern Florida peninsula), and many interconnected ecosystems within a geographic boundary. It is such a unique meeting of water, land, and climate that the use of either singular or plural to refer to the Everglades is appropriate. When Marjory Stoneman Douglas
wrote her definitive description of the region in 1947, she used the metaphor "River of Grass" to explain the blending of water and plant life.
Although sawgrass
and slough
s are the enduring geographical icons of the Everglades, other ecosystems are just as vital, and the borders marking them are subtle or nonexistent. Pinelands and tropical hardwood hammock
s are located throughout the sloughs; the trees, rooted in soil inches above the peat
, marl
, or water, support a variety of wildlife. The oldest and tallest trees are cypress
es, whose roots are specially adapted to grow underwater for months at a time. The Big Cypress Swamp is well-known for its 500-year-old cypresses, though cypress domes can appear throughout the Everglades. As the fresh water from Lake Okeechobee makes its way to Florida Bay, it meets salt water from the Gulf of Mexico
; mangrove
forests grow in this transitional zone, providing nursery and nesting conditions for many species of birds, fish, and invertebrates. The marine environment of Florida Bay is also considered part of the Everglades because its sea grasses and aquatic life are attracted to the constant discharge of fresh water.
These ecological systems are always changing due to environmental factors. Geographic features such as the Western Flatwoods, Eastern Flatwoods, and the Atlantic Coastal Ridge affect drainage patterns. Geologic elements, climate, and the frequency of storms and fire are formative processes for the Everglades. They help to sustain and transform the ecosystems in the Shark River Valley, Big Cypress Swamp, coastal areas and mangrove forests. Ecosystems have been described as both fragile and resilient. Minor fluctuations in water levels have far-reaching consequences for many plant and animal species, and the system cycles and pulses with each change.
At only 5,000 years of age, the Everglades is a young region in geological terms. Its ecosystems are in constant flux due to three factors: the type and amount of water present, the geology of the region, and the frequency and severity of fires.
Water is the dominant element in the Everglades, and it shapes the land, vegetation, and animal life of South Florida. The South Florida climate was once arid
and semi-arid
, interspersed with wet periods. Between 10,000 and 20,000 years ago, sea levels rose, submerging portions of the Florida peninsula and causing the water table
to rise. Fresh water saturated the limestone
, eroding some of it and creating spring
s and sinkhole
s. The abundance of fresh water allowed new vegetation to take root, and through evaporation formed thunderstorm
s. Limestone was dissolved by the slightly acidic rainwater. The limestone wore away, and groundwater came into contact with the surface, creating a massive wetland ecosystem. Although the region appears flat, the wearing away of the limestone in some areas created slight valleys and plateaus—a difference of inches in elevation—that affected not only the flow of water, but also types of vegetation present.
The Everglades are unique; no other wetland system in the world is nourished primarily from the atmosphere. Before the first attempt at draining the Everglades in 1882, the entire watershed
extended from Orlando
to Florida Bay
comprising the Kissimmee
–Lake Okeechobee
–Everglades (KLOE) watershed. Kissimmee River outlets flow into Lake Okeechobee, which sits 18 feet (5.5 m) above sea level. Only two seasons exist in the Everglades: wet (May to November) and dry (December to April). Average annual rainfall in the Everglades is approximately 62 inches (157.5 cm), though fluctuations of precipitation are normal. Droughts, floods, and tropical storms are normal occurrences in the area. When Lake Okeechobee exceeds its water storage capacity during the wet season, it pours slowly over the southern rim and flows for 100 miles (160.9 km) to Florida Bay. The gradient change is so slight that the river moves only 2 foot (0.6096 m) a minute. Sawgrass thrives in this river, dominates freshwater marshes and sloughs
, and is the main characteristic of the region.
Severe weather, in the form of tropical storms and hurricanes
, also affects the structure of the Everglades. Between 1871 and 2003, 40 tropical cyclones struck the Everglades, usually every one to three years. These storms alter the coastline, flush decaying vegetation from estuaries
, strip weakened branches from trees, and disperse seeds, pollen, and plant material. Hurricane Donna
in 1960 affected 120 square miles (310.8 km²) of mangrove
forests by depositing marl
over the roots and depriving the trees of oxygen. It also eradicated orchid
s, bromeliad
s, and other epiphyte
s that once flourished in the mangroves; their reappearance may take a century or more. Donna also significantly spread buttonwood
, saltwort
, and glasswort, and epiphytes began to grow in new areas. Although the lasting effects remain to be seen, Hurricane Andrew
in 1992 also destroyed mangrove forests and snapped slash pines in half. However, regrowth occurred quickly, and sand deposited by the storm surge improved nesting conditions for crocodile
s and sea turtle
s.
were compressed by ocean water, making limestone. Fossilized bryozoa
ns and tiny shells, or ooids, make the limestone porous. Water is stored in the rock, sometimes from one year to the next. The length of time that a region in the Everglades remains flooded, called a hydroperiod, determines what particular soils and vegetation are present.
Shorter hydroperiods of three or four months promote the growth of periphyton
: algae and other microscopic organisms covered with calcium carbonate crystals. Periphyton is the basic building block of marl, a calcitic mud. In areas with hydroperiods of longer than nine months, peat
builds up over hundreds or thousands of years due to many generations of decaying plant matter. Peat and marl are considered nutrient-poor soils that foster the growth of specialized vegetation depending on the length of the regional hydroperiod.
Five types of peat appear in the Everglades system; each type supports a specific type of vegetation, such as sawgrass, tree islands, or custard apple trees. Peat buildup is possible because water prevents oxygen from quickly decomposing plant matter. Once peat buildup reaches the surface, oxygen reacts with the microorganisms to decay the peat rapidly in a process called subsidence
. Initial attempts at developing agriculture near Lake Okeechobee were successful, but the nutrients in the peat quickly deteriorated by drying, and were broken down by bacteria in the soil. The dried peat burned or was degraded into carbon dioxide
and water by microorganisms. Some homes built near early farms had to restructure their foundations on stilts as the peat deteriorated; other areas lost approximately 8 feet (2.4 m) of soil depth. Between the 1880s and 2005, an estimated 3.4 billion metric tons of soil has been lost in the Everglades due to oxidation. Most of that loss occurs in the Everglades Agricultural Area; the least amount of loss is found in Everglades National Park.
strikes from thunderstorm
s during the wet season. Their effects are largely superficial, and serve to foster further plant growth: sawgrass
will burn above water, but the roots are preserved. Fire in the sawgrass marshes serves to keep out larger bushes and trees, and releases nutrients from decaying plant matter more efficiently than decomposition
. Large burned areas also affect waterflow, since wind and water are undeterred by the eradicated sawgrass; water may flow two to three times faster in recently burned areas. During the wet season only dead plant matter and the tips of plants are burned; however, the effects of fire are much more significant in the dry season, as fire may be fed by organic peat
and burn deeply, destroying root systems. The only impediment to the spread of fire in the Everglades is the presence of water. It takes around 225 years for one foot (0.3 m) of peat to develop, but the peat is not as dense as it should be for the 5,000 years of the Everglades' existence. Scientists point to fire as the reason.
Researchers have noted that fires appear in cycles associated with those of the hydroperiods. The first cycle is the annual wet-season fires that occur with rapid frequency during the summer, but are quickly extinguished. Dry-season fires are rarer due to the lack of lightning, but their damage may be more pervasive. A longer fire cycle spanning ten to fourteen years coincides with similar water cycles affected by global climate conditions. Fires in this cycle may be numerous and have little effect, or rare and have catastrophic consequences. The third cycle appears in a 550-year frequency associated with severe drought. Layers of charcoal
have been detected inside peat in parts of the Everglades, indicating the region endured severe fires for years at a time, although this trend seems to have abated since the last occurrence around 940 BCE.
The Everglades are dominated by sawgrass
in water; this is the titular "River of Grass" popularized by Marjory Stoneman Douglas
in 1947. This river contains a wide variety of plant and animal life. An early American environmentalist named Gifford Pinchot
said of the Everglades, "It is a region so different that it hardly seems to belong to the United States. It is full of the most vivid and most interesting life on land, in the air, and in the water. It is a land of strangeness, separate and apart from the common things we all know so well."
The sawgrass grows in prairies or strands, in between channels of water in a shallow river 100 miles (160.9 km) long and 60 miles (96.6 km) wide flowing from Lake Okeechobee to Florida Bay. Some authors refer to the sawgrass and water combination as the "true Everglades" or just "the Glades". Prior to the first drainage attempts in 1905
, the sheetflow, or the wide shallow river starting in Lake Okeechobee, occupied nearly a third of the lower Florida peninsula. Though sawgrass remains the main feature of the Everglades, other ecosystems are scattered among the marshes and prairies, and their borders are sometimes imperceptible.
known as Cladium
, or sawgrass in common terminology. The sedge is a three-dimensional v-shaped stalk with upward-pointing teeth. Sawgrass thrives in the slowly moving water, but may die if oxygen is unable to reach its roots and is particularly vulnerable to floods immediately after a fire. Some of the sawgrass can grow up to 6 feet (1.8 m) tall, and directly south of Lake Okeechobee
it has grown to 10 feet (3 m). Farther south, where the peat is not as rich, it typically grows 4 feet (1.2 m) tall in patches, as opposed to the prairies of the upper glades. The hydroperiod for the marsh is usually nine months but can last longer. In shorter hydroperiods, marl
may form instead of peat.
Where sawgrass grows densely, few animals or other plants thrive, although alligator
s often choose these locations for nesting. Where there is more room, periphyton
grows, appearing as mats or brown sausage-shaped chunks. Periphyton is predominantly algae
, although over 100 different microorganisms help create it. Larval insects and amphibians are supported by periphyton; these in turn provide food for birds, fish, and reptiles. Periphyton also absorbs calcium
from the water, which creates marl where sawgrass takes root.
), or spatterdock (Nuphar lutea
). Major sloughs in the Everglades system include the Shark River
Slough draining to Florida Bay, Lostmans Slough bordering The Big Cypress, and Taylor Slough
in the eastern Everglades.
and water-marsh community. Wet prairies are slightly elevated like sawgrass marshes, but contain abundant plant diversity. Marl prairies are located where marl covers limestone that may protrude as pinnacles or erode into solution holes: depressions formed by the same processes that create sinkhole
s. Solution holes, however, do not meet the water table; they are filled with rain water. The surface is covered only three to seven months of the year, but the water is usually just 4 inches (10.2 cm) deep. Marl is created by layers of periphyton loosely attached to the limestone, and forms a grey or white crumbly mud when it dries. When flooded, the marl can support a variety of water plants, and dwarf cypresses may grow for hundreds of years though not exceed 10 feet (3 m) in height. Solution holes may remain flooded even when the prairies are dry, and they support aquatic invertebrates such as crayfish and snails, as well as larval amphibians which feed young wading birds
. Where the predominant soil is peat, a water-marsh community exists. Its hydroperiod is longer than the marl prairie, although its plants are less diverse. These regions tend to be on the border between sloughs and sawgrass marshes.
Alligators have created an ecological niche in wet prairies; they dig at low spots with their claws and snouts and create ponds free of vegetation that remain submerged throughout the dry season. Alligator holes are integral to the survival of aquatic invertebrates, turtles, fish, small mammals, and birds during extended drought periods. Alligators feed upon animals that visit the hole.
s. They may rise between 1 and 3 ft (0.3048 and 0.9144 m) above water level in freshwater sloughs, sawgrass prairies, or pineland. These islands illustrate the difficulty of characterizing the climate of the Everglades as tropical or subtropical. Hammocks in the northern portion of the Everglades consist of more temperate plant species, but closer to Florida Bay the trees are tropical and smaller shrubs are more prevalent. Tropical trees like the West Indian mahogany (Swietenia mahagoni
) were probably spread by birds carrying seeds from the West Indies.
These hammocks form on slightly elevated areas unharmed by deep peat fires or limestone plateaus rising several inches above the surrounding peat. Hardwood hammocks exhibit a mixture of subtropical and hardwood trees that grow in very dense clumps, such as Southern live oak (Quercus virginiana), gumbo limbo (Bursera simaruba
), royal palm (Roystonea
), and willow bustic (Dipholis salicifolia
). Near the bases of hammocks sharp saw palmettos (Serenoa repens) flourish, making the hammocks very difficult to penetrate. Water in sloughs flow around the islands creating moat
s. Though some ecosystems are maintained and promoted by fire, hammocks may take decades or centuries to recover; the moats are therefore essential for protection. Islands vary in size, but most range between 1 and 10 acre (0.404686 and 4 ha); the water slowly flowing around them limits their size and gives them a teardrop appearance from above. The height of the trees is limited by factors such as frost, lightning, and wind: the majority of trees in hammocks grow no higher than 55 feet (16.8 m).
Florida strangler figs (Ficus aurea
) are common in hammocks, and find particular ease in rooting at the heads of cabbage palms (Sabal palmetto
). After taking root into the ground, they build complex frameworks around the host tree, eventually squeezing out light and nutrients, and essentially taking its place. A variety of invertebrates including beetles, ants, spiders, and tree snail
s support a food chain that includes frogs, owls and other birds of prey, snakes, rodents, bobcat
s, and raccoon
s. There are more than 50 varieties of tree snails in the Everglades; the color patterns and designs unique to single islands may be a result of the isolation of certain hammocks.
Tropical hardwood hammocks in the Everglades have been harvested for lumber, particularly by shipbuilders seeking West Indian mahogany and black ironwood (Krugiodendron ferreum
). The largest and most mature of these trees had been removed by the late 18th century. Seminole
s made their villages in hammocks in the late 19th and early 20th centuries; they lived in groups of chickee
s numbering half a dozen, with one central chickee for cooking and another for eating. Dugout canoes, cookware, still
s, and sewing machines may still be found in remote locations.
), wax myrtle (Myrica cerifera
), and cocoplum (Chrysobalanus icaco
). Willowheads, dominated by willow trees (Salix caroliniana
), take hold where the hydroperiod is long, usually around solution or alligator holes, and may surround the holes, giving them a donut
appearance from above.
to the east, directing it southwesterly into Florida Bay. The South Florida metropolitan area
is located on a portion of the Atlantic Coastal Ridge, and much of the landscape has changed drastically within the past 100 years as a result of urban growth.
substrate
s that contain pinnacles and solution holes. There are three primary locations of pine rocklands: the Miami Ridge, which runs from Miami into Long Pine Key near the main entrance of Everglades National Park
; the lower Florida Keys; and the Big Cypress Swamp. The most significant feature of the pine rockland ecosystem is the South Florida slash pine (Pinus elliotti var densa
; also called Dade County pine) that reaches a height of 22 feet (6.7 m). Pine rockland communities require fire for maintenance; they have adapted to promote and resist fire at the same time. These communities are located in the highest part of the Everglades with little to no hydroperiod, although some floors may have flooded solution holes or puddles for a few months at a time. The sandy floor of the pine rocklands is covered with dry pine needles that are highly flammable. South Florida slash pines are insulated by their bark to protect them from heat. Fire eliminates competing vegetation on the forest floor, and opens pine cones to germinate seeds. A period without significant fire can turn pineland into hardwood hammock as larger trees overtake the slash pines. The understory shrubs in pine rocklands include fire-resistant species like saw palmetto (Serenoa repens), cabbage palm (Sabal palmetto
), and West Indian lilac (Tetrazygia bicolor
). The most diverse group of plants in the pine community are herbs, of which two dozen species exist. These plants contain tuber
s and other mechanisms allowing for quick sprouts after charring.
Wildlife in pine rockland communities is diverse. In some forests, 15 species of birds can be found. Common among them are the pine warbler (Dendroica pinus), the red-bellied woodpecker (Melanerpes carolinus), and the eastern meadowlark (Sturnella magna). More than 20 species of reptiles and amphibians have been noted, such as the green anole (Anolis carolinensis), southern leopard frog (Rana sphenocephala), and southern black racer (Coluber constrictor priapus
). Mammals such as the critically endangered
Florida panther (Puma concolor coryi), Florida black bear (Ursus americanus floridanus), and several types of bats also live in the pine rocklands.
Before urban development of the South Florida region, pine rocklands covered around 161660 acres (654.2 km²) in Miami-Dade County
. Pine forests were extensively cleared by urban developers and the lumber industry in the 1930s and 1940s. Within Everglades National Park, 19840 acres (80.3 km²) of pine rockland communities are protected, but outside the park, 1780 acres (7.2 km²) of pine forests remain as of 1990, averaging 12.1 acre (0.048967006 km²) in size. Dade County pine has a remarkable longevity and has proven to be termite
-resistant, though dense enough to make driving nails difficult. In 1984 they were protected by a county ordinance
, after many pine areas had been depleted. A misunderstanding of fire's role also played a part in the disappearance of pine forests, as natural fires were put out and pine rocklands transitioned into hardwood hammocks. Today prescribed fires occur in Everglades National Park in pine rocklands every three to seven years.
; at its most limited measurement, the swamp measures 1200 square miles (3,108 km²), but its hydrological boundary is nearly twice as large. The Big Cypress is slightly elevated at 22 feet (6.7 m) at its highest point and slopes gradually to the coastline for approximately 35 miles (56.3 km). Because the defining feature of The Big Cypress is the abundance of trees, it is considered a swamp rather than a marsh, in which grass is the main characteristic.
The basin for The Big Cypress receives on average 55 inches (139.7 cm) of water in the rainy season. Most of The Big Cypress sits atop a bedrock covered by a thin layer of limestone that contains quartz
, creating a sandy soil that hosts a variety of vegetation. The majority of trees are bald cypress (Taxodium distichum
) and not true cypresses (Cupressaceae
). Cypresses are conifers that are uniquely adapted to thrive in flooded conditions, with buttressed trunks and root projections that protrude out of the water, called "knees".
Cypress trees in the area can live for hundreds of years; some giants grow to 130 feet (39.6 m) and are 500 years old. Still, they may be only seventh- or eighth-generation cypresses. Few massive trees survived the logging operations that took place in the 1930s and 1940s. As a result, much of The Big Cypress is protected by various federal or state agencies that include Big Cypress National Preserve
, Corkscrew Swamp Sanctuary
, Fakahatchee Strand State Preserve and two Indian reservations.
Although The Big Cypress is the largest growth of cypress swamps in South Florida, such swamps—as well as portions of sawgrass marshes—can be found near the Atlantic Coastal Ridge and between Lake Okeechobee and the Eastern flatwoods. Hardwood hammocks and pineland are often interspersed with the cypress ecosystem. Much like tree islands that are colloquially referred to as "heads", cypress trees grow in formations that resemble domes, with the tallest and thickest trunks in the center, rooted in the deepest peat. As the peat thins out, cypresses continue to grow, but are smaller and thinner, giving the small forest the appearance of a dome. They also grow in strands, slightly elevated on a plateau of limestone and surrounded on two sides by sloughs. Other hardwood trees can be found in cypress domes, such as red maple (Acer rubrum), swamp bay (Persea palustris
), and pop ash (Fraxinus caroliniana
). If cypresses are removed, hardwoods take over, and the ecosystem is recategorized as a mixed swamp forest.
Because the cypress domes and strands retain moisture and block out much of the sunlight, plants such as orchids, bromeliads, and fern
s thrive in cypress domes and strands. Orchids bloom throughout the year in cypress heads, and bromeliads appear in many varieties; on Fakahatchee Strand alone, thirteen species have been documented. Bromeliads collect moisture from rain and humidity in the bases of their leaves, which also nurture frogs, lizards and various insects. Wood storks (Mycteria americana) nest almost exclusively in cypress forests and in the past 100 years have seen a dramatic decline, probably due to lack of reproduction tied to controlled water
. Wood storks' reproductive cycles coincide with the dry season, when small fish and amphibians are trapped in shallow pools and puddles. When water from canals or locks is released too soon or not at all, storks are unable to find enough food for themselves and their offspring. An estimated 20,000 wood storks nested in The Big Cypress in the 1930s, but by the 1990s less than 2,000 were counted.
trees thrive, adapted as they are to both kinds of water. This brackish mixture of water and mangrove systems, crisscrossed by hundreds of tidal creeks, harbors a very productive ecosystem. The depth of these zones is dependent on how much water flows from the Everglades. In the wet season, fresh water pours into Florida Bay and sawgrass appears near the coastline. In dryer years, salt water creeps inland to the coastal prairie, an ecosystem that buffers the freshwater marshes by absorbing sea water. Mangrove trees grow in fresh water ecosystems when the salt water flows far enough inland. The Everglades have the most extensive contiguous system of mangroves in the world. The mangrove forests of the Ten Thousand Islands cover almost 200000 acres (809.4 km²).
), black (Avicennia germinans
), and white (Laguncularia racemosa
), although all are from different families. All have the same characteristics: they are tolerant of salt, brackish, and fresh water; they grow in oxygen-poor soil; and they can survive drastic water-level changes. Black and white mangroves excrete salt from under their leaves, and red mangroves filter the salinity of sea water. All species are integral to coastline protection during severe storms. Red mangroves, for example, have far-reaching roots that trap sediments. The trees not only stabilize coastlines, but add land as more sand and decaying vegetation is trapped in the root systems. All three mangroves also absorb the energy of waves and storm surge
s.
The estuaries act as fisheries for fry and nurseries for crustacean
s. Shrimp, oyster
s, crabs, whelk
s, cockle
s, and snails thrive in these waters, as do primordial horseshoe crabs (Limulus polyphemus). The region supports a $59 million-a-year Tortugas pink shrimp (Farfantepenaeus duorarum) industry, and a $22 million-a-year stone crab (Menippe mercenaria) industry. Between 80 and 90 percent of species that are harvested commercially in Florida are born or spend time in the shallow waters near the Everglades. Oysters and mangroves work in tandem to build up the coastline. The sand around the coastline has minute white particles of quartz and fine shells. When currents are right, oysters grow in colonies or beds, and deposit their shells, reinforcing the bed. Mangrove seeds, called propagule
s, are full embryo
s and float in water until they reach a favorable location and take root, often on oyster beds. They shed skin and litter, ensuring other trees will not compete for space and nutrients.
Mangroves also serve as excellent rookeries for birds. Wading birds, such as roseate spoonbills (Platalea ajaja), egret
s, and tricolored herons (Egretta tricolor) use the mangroves as a nursery, due to the proximity of food sources and the protection offered from most prey. Thousands of birds can nest in the mangroves at once, making a noisy and messy colony, but their droppings fertilize the mangrove trees. Shorebirds like rail
s, tern
s and gull
s; diving birds such as pelican
s and grebe
s; and birds of prey such as osprey
s, hawk
s and vulture
s are among the more than 100 species of birds that use Everglades mangrove trees to raise their young.
Because much of the coast and inner estuaries are built by mangroves—and there is no border between the coastal marshes and the bay—the ecosystems in Florida Bay
are considered part of the Everglades. More than 800 square miles (2,072 km²) of Florida Bay is protected by Everglades National Park
, representing the largest body of water in the park boundaries. There are approximately one hundred key
s in Florida Bay, many of which are mangrove forests. Larger islands may be taken over by hardwood hammocks. The outer rims of the Ten Thousand Islands and Cape Sable
share characteristics of the intertwining saltwater bays and fresh water marshes.
The fresh water entering Florida Bay from the Everglades creates ideal conditions for vast beds of turtle grass
and algae formations that foster animal life in the bay. Sea turtle
s and manatees (Trichechus manatus latirostris) eat the grass, while invertebrates such as worms, clams, and other mollusks consume algae formations and microscopic plankton
. Female sea turtles return annually to nest on the shore, and manatees spend the winter months in the warmer water of the bay. The Calusa
Indians had various uses for shells of marine invertebrates, due to the lack of dense rock with which to make tools. They used the horse conch (Pleuroploca gigantea
), left-handed whelk (Busycon contrarium), and the Florida crown conch (Melongena corona
) as drinking vessels, picks, hammers, knives and awls.
Sea grasses stabilize sea beds and protect shorelines from erosion by absorbing energy from waves. Shrimp, spiny lobster
s, and sea urchin
s live in and among the grasses and feed on phytoplankton
; they in turn feed larger predators such as shark
s, ray
s, barracuda
, and king mackerel (Scomberomorus cavalla). Due to shallow water and abundant sunlight, Florida Bay hosts communities of coral reef
s and sponges, although the majority of the state's reefs are closer to the Florida Keys
. Everglades keys that foster mangroves also support nurseries for wading birds such as the Great white heron (Ardea herodias), which was almost wiped out in the Labor Day Hurricane of 1935
(only 146 were counted afterward). After recovering to number more than 2,000, they were further endangered by Hurricane Donna
in 1960, which decreased their numbers by 35 to 40 percent.
Sea floor patterns of Florida Bay are formed by currents and winds. However, since 1932, sea levels have been rising at a rate of 1 foot (0.3048 m) per 100 years. Though mangroves serve to build and stabilize the coastline, seas may be rising more rapidly than the trees are able to build.
For example, Florida apple snails (Pomacea paludosa
) are an amphibious fresh water mollusk. They have a single gill and lung, and live on stalks of sawgrass in water depths no more than 20 inches (50.8 cm). They are the primary food of the endangered Everglades snail kite (Rostrhamus sociabilis) and limpkin (Aramus guarauna) as well as the raccoon, otter, and young alligator. Apple snails lay their eggs on sawgrass stalks about 6 inches (15.2 cm) above the water line, and they are intolerant of being submerged for long periods of time. When the eggs hatch, young snails must enter the water quickly or face death. When water levels are too low or rise too quickly while snail eggs are developing, apple snails do not flourish, affecting the many reptiles, mammals, and birds that feed on them. With regard to the ecology of trophic dynamics, or food chains, the 174 species of invertebrates play a vital role in the Everglades. Crayfish
, insects, scorpions, and other invertebrates also support a web of animals.
The group of animals most integral to the overall success of Everglades wildlife is freshwater fish. Few places in the Everglades stay submerged from one year to the next, so alligator holes and deep clefts in the limestone are vital to the survival of fish, and the animal community as a whole. Freshwater fish are the main diet of most wading birds, alligators, and otters, and require large areas of open water in order to repopulate. Young amphibians also play an important role in the food chain. Tadpole
s spread quickly in isolated areas where fish do not have the time or access to reproduce in numbers necessary to support larger animals. Hundreds of species of amphibians are found in the Everglades, and their availability helps support wildlife during short hydroperiods or in remote locations.
These smaller animals support communities of larger animals, including 70 species of land birds that breed within the Everglades, and 120 water birds, of which 43 breed in the area. Many of these birds go on to migrate through the West Indies and North America. Several dozen species of mammals also thrive in the region, from tiny bats and shrews to midsize raccoons (Procyon lotor), otters (Lontra canadensis), opossums (Didelphis virginiana), and foxes. The largest include white tailed deer (Odocoileus virginianus), the Florida black bear, and the Florida panther.
Although slight changes in water level affect many species, the system as a whole also cycles and pulses with each change. Some transformations to the diversity of plant and animal life are natural, caused by fire or storms, and some are induced by humans, such as urban encroachment, the introduction of exotic species, and rapid global warming
. Environmental conditions in the Everglades favor no particular species. Some species, such as snail kites and apple snails, do well in wet conditions, but wood storks and Cape Sable seaside sparrows (Ammodramus maritimus mirabilis) do well in dryer circumstances.
grew exponentially, the result caused chaos in ecosystems throughout the Everglades. By the 1990s, the diminishing quality of life in many of these urban areas was linked to the degraded local environment. The State of Florida and the U.S. government devised and passed a plan in 2000 to restore as much of the Everglades to pre-drainage conditions as possible. It is the costliest and most comprehensive environmental restoration project in history.
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. Before drainage
Draining and development of the Everglades
The history of draining and development of the Everglades dates back to the 19th century. During the Second Seminole War beginning in 1836, the United States military's mission was to seek out Seminole people in the Everglades and capture or kill them. Those missions gave the military the...
, the Everglades
Everglades
The Everglades are subtropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large watershed. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee...
were an interwoven mesh of marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
es and prairie
Prairie
Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...
s covering 4000 square miles (10,360 km²). The Everglades is simultaneously a vast watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
that has historically extended from Lake Okeechobee
Lake Okeechobee
Lake Okeechobee , locally referred to as The Lake or The Big O, is the largest freshwater lake in the state of Florida. It is the seventh largest freshwater lake in the United States and the second largest freshwater lake contained entirely within the lower 48 states...
100 miles (160.9 km) south to Florida Bay
Florida Bay
Florida Bay is the bay located between the southern end of the Florida mainland and the Florida Keys. Its area is variously stated to be , or , or . Nearly all of Florida Bay is included in Everglades National Park. The southern edge, along the Florida Keys is in the Florida Keys National Marine...
(around one-third of the southern Florida peninsula), and many interconnected ecosystems within a geographic boundary. It is such a unique meeting of water, land, and climate that the use of either singular or plural to refer to the Everglades is appropriate. When Marjory Stoneman Douglas
Marjory Stoneman Douglas
Marjory Stoneman Douglas was an American journalist, writer, feminist, and environmentalist known for her staunch defense of the Everglades against efforts to drain it and reclaim land for development...
wrote her definitive description of the region in 1947, she used the metaphor "River of Grass" to explain the blending of water and plant life.
Although sawgrass
Cladium
Cladium is a genus of large sedges, with a worldwide distribution in tropical and temperate regions...
and slough
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
s are the enduring geographical icons of the Everglades, other ecosystems are just as vital, and the borders marking them are subtle or nonexistent. Pinelands and tropical hardwood hammock
Hammock (ecology)
Hammocks are dense stands of hardwood trees that grow on natural rises of only a few inches higher than surrounding marshland that is otherwise too wet to support them. Hammocks are distinctive in that they are formed gradually over thousands of years rising in a wet area through the deposits of...
s are located throughout the sloughs; the trees, rooted in soil inches above the peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...
, marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
, or water, support a variety of wildlife. The oldest and tallest trees are cypress
Taxodium
Taxodium is a genus of one to three species of extremely flood-tolerant conifers in the cypress family, Cupressaceae...
es, whose roots are specially adapted to grow underwater for months at a time. The Big Cypress Swamp is well-known for its 500-year-old cypresses, though cypress domes can appear throughout the Everglades. As the fresh water from Lake Okeechobee makes its way to Florida Bay, it meets salt water from the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
; mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
forests grow in this transitional zone, providing nursery and nesting conditions for many species of birds, fish, and invertebrates. The marine environment of Florida Bay is also considered part of the Everglades because its sea grasses and aquatic life are attracted to the constant discharge of fresh water.
These ecological systems are always changing due to environmental factors. Geographic features such as the Western Flatwoods, Eastern Flatwoods, and the Atlantic Coastal Ridge affect drainage patterns. Geologic elements, climate, and the frequency of storms and fire are formative processes for the Everglades. They help to sustain and transform the ecosystems in the Shark River Valley, Big Cypress Swamp, coastal areas and mangrove forests. Ecosystems have been described as both fragile and resilient. Minor fluctuations in water levels have far-reaching consequences for many plant and animal species, and the system cycles and pulses with each change.
Water
Water is the dominant element in the Everglades, and it shapes the land, vegetation, and animal life of South Florida. The South Florida climate was once arid
Arid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
and semi-arid
Semi-arid
A semi-arid climate or steppe climate describes climatic regions that receive precipitation below potential evapotranspiration, but not extremely...
, interspersed with wet periods. Between 10,000 and 20,000 years ago, sea levels rose, submerging portions of the Florida peninsula and causing the water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...
to rise. Fresh water saturated the limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
, eroding some of it and creating spring
Spring (hydrosphere)
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...
s and sinkhole
Sinkhole
A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks or suffosion processes for example in sandstone...
s. The abundance of fresh water allowed new vegetation to take root, and through evaporation formed thunderstorm
Thunderstorm
A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...
s. Limestone was dissolved by the slightly acidic rainwater. The limestone wore away, and groundwater came into contact with the surface, creating a massive wetland ecosystem. Although the region appears flat, the wearing away of the limestone in some areas created slight valleys and plateaus—a difference of inches in elevation—that affected not only the flow of water, but also types of vegetation present.
The Everglades are unique; no other wetland system in the world is nourished primarily from the atmosphere. Before the first attempt at draining the Everglades in 1882, the entire watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
extended from Orlando
Orlando, Florida
Orlando is a city in the central region of the U.S. state of Florida. It is the county seat of Orange County, and the center of the Greater Orlando metropolitan area. According to the 2010 US Census, the city had a population of 238,300, making Orlando the 79th largest city in the United States...
to Florida Bay
Florida Bay
Florida Bay is the bay located between the southern end of the Florida mainland and the Florida Keys. Its area is variously stated to be , or , or . Nearly all of Florida Bay is included in Everglades National Park. The southern edge, along the Florida Keys is in the Florida Keys National Marine...
comprising the Kissimmee
Kissimmee River
The Kissimmee River is a river in south-central Florida, United States.-Course:The Kissimmee River arises in Osceola County as the outflow from East Lake Tohopekaliga, passing through Lake Tohopekaliga, Lake Cypress, Lake Hatchineha and Lake Kissimmee...
–Lake Okeechobee
Lake Okeechobee
Lake Okeechobee , locally referred to as The Lake or The Big O, is the largest freshwater lake in the state of Florida. It is the seventh largest freshwater lake in the United States and the second largest freshwater lake contained entirely within the lower 48 states...
–Everglades (KLOE) watershed. Kissimmee River outlets flow into Lake Okeechobee, which sits 18 feet (5.5 m) above sea level. Only two seasons exist in the Everglades: wet (May to November) and dry (December to April). Average annual rainfall in the Everglades is approximately 62 inches (157.5 cm), though fluctuations of precipitation are normal. Droughts, floods, and tropical storms are normal occurrences in the area. When Lake Okeechobee exceeds its water storage capacity during the wet season, it pours slowly over the southern rim and flows for 100 miles (160.9 km) to Florida Bay. The gradient change is so slight that the river moves only 2 foot (0.6096 m) a minute. Sawgrass thrives in this river, dominates freshwater marshes and sloughs
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
, and is the main characteristic of the region.
Severe weather, in the form of tropical storms and hurricanes
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
, also affects the structure of the Everglades. Between 1871 and 2003, 40 tropical cyclones struck the Everglades, usually every one to three years. These storms alter the coastline, flush decaying vegetation from estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
, strip weakened branches from trees, and disperse seeds, pollen, and plant material. Hurricane Donna
Hurricane Donna
Hurricane Donna in the 1960 Atlantic hurricane season was a Cape Verde-type hurricane which moved across the Leeward Islands, Puerto Rico, Hispanola, Cuba, The Bahamas, and every state on the East Coast of the United States...
in 1960 affected 120 square miles (310.8 km²) of mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
forests by depositing marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
over the roots and depriving the trees of oxygen. It also eradicated orchid
Orchidaceae
The Orchidaceae, commonly referred to as the orchid family, is a morphologically diverse and widespread family of monocots in the order Asparagales. Along with the Asteraceae, it is one of the two largest families of flowering plants, with between 21,950 and 26,049 currently accepted species,...
s, bromeliad
Bromeliaceae
Bromeliaceae is a family of monocot flowering plants of around 3,170 species native mainly to the tropical Americas, with a few species found in the American subtropics and one in tropical west Africa, Pitcairnia feliciana...
s, and other epiphyte
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
s that once flourished in the mangroves; their reappearance may take a century or more. Donna also significantly spread buttonwood
Conocarpus
Conocarpus is a genus of two species of flowering plants in the family Combretaceae, native to tropical regions of the world. One of the species is a widespread mangrove species, the other is restricted to a small area around the southern Red Sea coasts, where it grows alongside seasonal...
, saltwort
Saltwort
Saltwort is a common name for several genera of flowering plants, including:*Batis, family Bataceae*Salicornia and Salsola, family Amaranthaceae*Salsola kali, prickly saltwort...
, and glasswort, and epiphytes began to grow in new areas. Although the lasting effects remain to be seen, Hurricane Andrew
Hurricane Andrew
Hurricane Andrew was the third Category 5 hurricane to make landfall in the United States, after the Labor Day Hurricane of 1935 and Hurricane Camille in 1969. Andrew was the first named storm and only major hurricane of the otherwise inactive 1992 Atlantic hurricane season...
in 1992 also destroyed mangrove forests and snapped slash pines in half. However, regrowth occurred quickly, and sand deposited by the storm surge improved nesting conditions for crocodile
American Crocodile
The American crocodile is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas. Populations occur from the Atlantic and Pacific coasts of southern Mexico to South America as far as Peru and Venezuela. It also lives...
s and sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...
s.
Geology
A vast marshland could only have been formed due to the underlying rock formations in southern Florida. The floor of the Everglades formed between 25 million and 2 million years ago when the Florida peninsula was a shallow sea floor. The peninsula has been covered by sea water at least seven times since the earliest bedrock formation. The rock that makes up the Everglades floor was created as layers of calcium carbonateCalcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
were compressed by ocean water, making limestone. Fossilized bryozoa
Bryozoa
The Bryozoa, also known as Ectoprocta or commonly as moss animals, are a phylum of aquatic invertebrate animals. Typically about long, they are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia...
ns and tiny shells, or ooids, make the limestone porous. Water is stored in the rock, sometimes from one year to the next. The length of time that a region in the Everglades remains flooded, called a hydroperiod, determines what particular soils and vegetation are present.
Shorter hydroperiods of three or four months promote the growth of periphyton
Periphyton
Periphyton are a complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus that are attached to submerged surfaces in most aquatic ecosystems. It serves as an important food source for invertebrates, tadpoles, and some fish. It can also absorb contaminants; removing them from...
: algae and other microscopic organisms covered with calcium carbonate crystals. Periphyton is the basic building block of marl, a calcitic mud. In areas with hydroperiods of longer than nine months, peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...
builds up over hundreds or thousands of years due to many generations of decaying plant matter. Peat and marl are considered nutrient-poor soils that foster the growth of specialized vegetation depending on the length of the regional hydroperiod.
Five types of peat appear in the Everglades system; each type supports a specific type of vegetation, such as sawgrass, tree islands, or custard apple trees. Peat buildup is possible because water prevents oxygen from quickly decomposing plant matter. Once peat buildup reaches the surface, oxygen reacts with the microorganisms to decay the peat rapidly in a process called subsidence
Groundwater-related subsidence
Groundwater-related subsidence is the subsidence of land resulting from groundwater extraction, and a major problem in the developing world as major metropolises swell without adequate regulation and enforcement, as well as a being a common problem in the developed world...
. Initial attempts at developing agriculture near Lake Okeechobee were successful, but the nutrients in the peat quickly deteriorated by drying, and were broken down by bacteria in the soil. The dried peat burned or was degraded into carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and water by microorganisms. Some homes built near early farms had to restructure their foundations on stilts as the peat deteriorated; other areas lost approximately 8 feet (2.4 m) of soil depth. Between the 1880s and 2005, an estimated 3.4 billion metric tons of soil has been lost in the Everglades due to oxidation. Most of that loss occurs in the Everglades Agricultural Area; the least amount of loss is found in Everglades National Park.
Fire
Fire is another important element in the maintenance of the Everglades. The majority are caused by lightningLightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
strikes from thunderstorm
Thunderstorm
A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...
s during the wet season. Their effects are largely superficial, and serve to foster further plant growth: sawgrass
Cladium
Cladium is a genus of large sedges, with a worldwide distribution in tropical and temperate regions...
will burn above water, but the roots are preserved. Fire in the sawgrass marshes serves to keep out larger bushes and trees, and releases nutrients from decaying plant matter more efficiently than decomposition
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
. Large burned areas also affect waterflow, since wind and water are undeterred by the eradicated sawgrass; water may flow two to three times faster in recently burned areas. During the wet season only dead plant matter and the tips of plants are burned; however, the effects of fire are much more significant in the dry season, as fire may be fed by organic peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...
and burn deeply, destroying root systems. The only impediment to the spread of fire in the Everglades is the presence of water. It takes around 225 years for one foot (0.3 m) of peat to develop, but the peat is not as dense as it should be for the 5,000 years of the Everglades' existence. Scientists point to fire as the reason.
Researchers have noted that fires appear in cycles associated with those of the hydroperiods. The first cycle is the annual wet-season fires that occur with rapid frequency during the summer, but are quickly extinguished. Dry-season fires are rarer due to the lack of lightning, but their damage may be more pervasive. A longer fire cycle spanning ten to fourteen years coincides with similar water cycles affected by global climate conditions. Fires in this cycle may be numerous and have little effect, or rare and have catastrophic consequences. The third cycle appears in a 550-year frequency associated with severe drought. Layers of charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...
have been detected inside peat in parts of the Everglades, indicating the region endured severe fires for years at a time, although this trend seems to have abated since the last occurrence around 940 BCE.
Ecosystem characteristics
Cladium
Cladium is a genus of large sedges, with a worldwide distribution in tropical and temperate regions...
in water; this is the titular "River of Grass" popularized by Marjory Stoneman Douglas
Marjory Stoneman Douglas
Marjory Stoneman Douglas was an American journalist, writer, feminist, and environmentalist known for her staunch defense of the Everglades against efforts to drain it and reclaim land for development...
in 1947. This river contains a wide variety of plant and animal life. An early American environmentalist named Gifford Pinchot
Gifford Pinchot
Gifford Pinchot was the first Chief of the United States Forest Service and the 28th Governor of Pennsylvania...
said of the Everglades, "It is a region so different that it hardly seems to belong to the United States. It is full of the most vivid and most interesting life on land, in the air, and in the water. It is a land of strangeness, separate and apart from the common things we all know so well."
The sawgrass grows in prairies or strands, in between channels of water in a shallow river 100 miles (160.9 km) long and 60 miles (96.6 km) wide flowing from Lake Okeechobee to Florida Bay. Some authors refer to the sawgrass and water combination as the "true Everglades" or just "the Glades". Prior to the first drainage attempts in 1905
Draining and development of the Everglades
The history of draining and development of the Everglades dates back to the 19th century. During the Second Seminole War beginning in 1836, the United States military's mission was to seek out Seminole people in the Everglades and capture or kill them. Those missions gave the military the...
, the sheetflow, or the wide shallow river starting in Lake Okeechobee, occupied nearly a third of the lower Florida peninsula. Though sawgrass remains the main feature of the Everglades, other ecosystems are scattered among the marshes and prairies, and their borders are sometimes imperceptible.
Sawgrass marsh
Most marshes in the Everglades are dominated by the sedgeCyperaceae
Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...
known as Cladium
Cladium
Cladium is a genus of large sedges, with a worldwide distribution in tropical and temperate regions...
, or sawgrass in common terminology. The sedge is a three-dimensional v-shaped stalk with upward-pointing teeth. Sawgrass thrives in the slowly moving water, but may die if oxygen is unable to reach its roots and is particularly vulnerable to floods immediately after a fire. Some of the sawgrass can grow up to 6 feet (1.8 m) tall, and directly south of Lake Okeechobee
Lake Okeechobee
Lake Okeechobee , locally referred to as The Lake or The Big O, is the largest freshwater lake in the state of Florida. It is the seventh largest freshwater lake in the United States and the second largest freshwater lake contained entirely within the lower 48 states...
it has grown to 10 feet (3 m). Farther south, where the peat is not as rich, it typically grows 4 feet (1.2 m) tall in patches, as opposed to the prairies of the upper glades. The hydroperiod for the marsh is usually nine months but can last longer. In shorter hydroperiods, marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
may form instead of peat.
Where sawgrass grows densely, few animals or other plants thrive, although alligator
Alligator
An alligator is a crocodilian in the genus Alligator of the family Alligatoridae. There are two extant alligator species: the American alligator and the Chinese alligator ....
s often choose these locations for nesting. Where there is more room, periphyton
Periphyton
Periphyton are a complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus that are attached to submerged surfaces in most aquatic ecosystems. It serves as an important food source for invertebrates, tadpoles, and some fish. It can also absorb contaminants; removing them from...
grows, appearing as mats or brown sausage-shaped chunks. Periphyton is predominantly algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, although over 100 different microorganisms help create it. Larval insects and amphibians are supported by periphyton; these in turn provide food for birds, fish, and reptiles. Periphyton also absorbs calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
from the water, which creates marl where sawgrass takes root.
Freshwater sloughs
Sloughs are channels of free-flowing water in between the sawgrass marshes. Sloughs are deeper than sawgrass marshes, about 3 foot (0.9144 m), and may stay flooded for at least 11 months out of the year if not multiple years in a row. The peat beds that support sawgrass are slightly elevated and may begin abruptly creating ridges of grass. The borders between these systems are called "ridge-and-slough" landscapes. Aquatic animals such as turtles, young alligators, snakes, and fish live in sloughs and they usually feed on aquatic invertebrates, such as the Florida apple snail. Plants grow here, usually submerged or floating like bladderwort (Utricularia), waterlily (NymphaeaceaeNymphaeaceae
Nymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...
), or spatterdock (Nuphar lutea
Nuphar lutea
Nuphar lutea is an aquatic plant of the family Nymphaeaceae, native to temperate regions of Europe, northwest Africa, and western Asia.-Growth:...
). Major sloughs in the Everglades system include the Shark River
Shark River (Florida)
The Shark River is a major distributary of the Harney River in the southwestern portion of Everglades National Park. It is located in Monroe County, Florida, United States. The river is entirely sea level. The mouth of the river is at Ponce de Leon Bay, part of the Gulf of Mexico. The river is only...
Slough draining to Florida Bay, Lostmans Slough bordering The Big Cypress, and Taylor Slough
Taylor Slough
Taylor Slough, located in the southeastern corner of the Florida Everglades, along with the much larger Shark River Slough farther to the west, are the principal natural drainages for the freshwater Everglades....
in the eastern Everglades.
Wet prairie
Two kinds of wet prairies thrive in the Everglades: marlMarl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
and water-marsh community. Wet prairies are slightly elevated like sawgrass marshes, but contain abundant plant diversity. Marl prairies are located where marl covers limestone that may protrude as pinnacles or erode into solution holes: depressions formed by the same processes that create sinkhole
Sinkhole
A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks or suffosion processes for example in sandstone...
s. Solution holes, however, do not meet the water table; they are filled with rain water. The surface is covered only three to seven months of the year, but the water is usually just 4 inches (10.2 cm) deep. Marl is created by layers of periphyton loosely attached to the limestone, and forms a grey or white crumbly mud when it dries. When flooded, the marl can support a variety of water plants, and dwarf cypresses may grow for hundreds of years though not exceed 10 feet (3 m) in height. Solution holes may remain flooded even when the prairies are dry, and they support aquatic invertebrates such as crayfish and snails, as well as larval amphibians which feed young wading birds
Wader
Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...
. Where the predominant soil is peat, a water-marsh community exists. Its hydroperiod is longer than the marl prairie, although its plants are less diverse. These regions tend to be on the border between sloughs and sawgrass marshes.
Alligators have created an ecological niche in wet prairies; they dig at low spots with their claws and snouts and create ponds free of vegetation that remain submerged throughout the dry season. Alligator holes are integral to the survival of aquatic invertebrates, turtles, fish, small mammals, and birds during extended drought periods. Alligators feed upon animals that visit the hole.
Tropical hardwood hammock
Islands of trees featuring dense temperate or tropical trees are called tropical hardwood hammockTropical hardwood hammock
Tropical hardwood hammocks are closed canopy forests, dominated by a diverse assemblage of evergreen and semi-deciduous tree and shrub species, mostly of West Indian origin...
s. They may rise between 1 and 3 ft (0.3048 and 0.9144 m) above water level in freshwater sloughs, sawgrass prairies, or pineland. These islands illustrate the difficulty of characterizing the climate of the Everglades as tropical or subtropical. Hammocks in the northern portion of the Everglades consist of more temperate plant species, but closer to Florida Bay the trees are tropical and smaller shrubs are more prevalent. Tropical trees like the West Indian mahogany (Swietenia mahagoni
Swietenia mahagoni
Swietenia mahagoni, commonly known as the West Indies Mahogany, is a species of Swietenia native to southern Florida, USA, The Bahamas, Cuba, Jamaica, and Hispaniola. It is the species from which the original mahogany wood was produced....
) were probably spread by birds carrying seeds from the West Indies.
These hammocks form on slightly elevated areas unharmed by deep peat fires or limestone plateaus rising several inches above the surrounding peat. Hardwood hammocks exhibit a mixture of subtropical and hardwood trees that grow in very dense clumps, such as Southern live oak (Quercus virginiana), gumbo limbo (Bursera simaruba
Bursera simaruba
Bursera simaruba, commonly known as the Gumbo-limbo, is a tree species in the family Burseraceae, native to tropical regions of the Americas from the southeasternmost United States south through Mexico and the Caribbean to Brazil and Venezuela...
), royal palm (Roystonea
Roystonea
Roystonea is a genus of eleven species of monoecious palms, native to the Caribbean Islands, and the adjacent coasts of Florida, Central and South America. Commonly known as the royal palms, the genus was named for Roy Stone, a U.S. Army engineer...
), and willow bustic (Dipholis salicifolia
Dipholis salicifolia
Dipholis salicifolia, commonly called willow bustic or White Bully, is a species of flowering plant native to Florida, the West Indies and Central America. It was previously considered a member of the genus Sideroxylon, with the binomial Sideroxylon salicifolium...
). Near the bases of hammocks sharp saw palmettos (Serenoa repens) flourish, making the hammocks very difficult to penetrate. Water in sloughs flow around the islands creating moat
Moat
A moat is a deep, broad ditch, either dry or filled with water, that surrounds a castle, other building or town, historically to provide it with a preliminary line of defence. In some places moats evolved into more extensive water defences, including natural or artificial lakes, dams and sluices...
s. Though some ecosystems are maintained and promoted by fire, hammocks may take decades or centuries to recover; the moats are therefore essential for protection. Islands vary in size, but most range between 1 and 10 acre (0.404686 and 4 ha); the water slowly flowing around them limits their size and gives them a teardrop appearance from above. The height of the trees is limited by factors such as frost, lightning, and wind: the majority of trees in hammocks grow no higher than 55 feet (16.8 m).
Florida strangler figs (Ficus aurea
Ficus aurea
Ficus aurea, commonly known as the Florida strangler fig , golden fig, or higuerón, is a tree in the family Moraceae that is native to the U.S. state of Florida, the northern and western Caribbean, southern Mexico and Central America south to Panama...
) are common in hammocks, and find particular ease in rooting at the heads of cabbage palms (Sabal palmetto
Sabal palmetto
Sabal palmetto, also known as cabbage palm, palmetto, cabbage palmetto, palmetto palm, blue palmetto, Carolina palmetto, common palmetto, swamp cabbage and sabal palm, is one of 15 species of palmetto palm . It is native to the southeastern United States, Cuba, and the Bahamas...
). After taking root into the ground, they build complex frameworks around the host tree, eventually squeezing out light and nutrients, and essentially taking its place. A variety of invertebrates including beetles, ants, spiders, and tree snail
Tree snail
Tree snail is a common name that is applied to various kinds of tropical air-breathing land snails, pulmonate gastropod mollusks that have shells, and that live in trees, in other words, are exclusively arboreal in habitat....
s support a food chain that includes frogs, owls and other birds of prey, snakes, rodents, bobcat
Bobcat
The bobcat is a North American mammal of the cat family Felidae, appearing during the Irvingtonian stage of around 1.8 million years ago . With twelve recognized subspecies, it ranges from southern Canada to northern Mexico, including most of the continental United States...
s, and raccoon
Raccoon
Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...
s. There are more than 50 varieties of tree snails in the Everglades; the color patterns and designs unique to single islands may be a result of the isolation of certain hammocks.
Tropical hardwood hammocks in the Everglades have been harvested for lumber, particularly by shipbuilders seeking West Indian mahogany and black ironwood (Krugiodendron ferreum
Krugiodendron ferreum
Krugiodendron ferreum, commonly known as the Black Ironwood or Leadwood, is a species of tree in the buckthorn family, Rhamnaceae. It is found in southern Florida, throughout the Caribbean and from southern Mexico to Honduras...
). The largest and most mature of these trees had been removed by the late 18th century. Seminole
Seminole
The Seminole are a Native American people originally of Florida, who now reside primarily in that state and Oklahoma. The Seminole nation emerged in a process of ethnogenesis out of groups of Native Americans, most significantly Creeks from what is now Georgia and Alabama, who settled in Florida in...
s made their villages in hammocks in the late 19th and early 20th centuries; they lived in groups of chickee
Chickee
Chikee or Chickee is a shelter supported by posts, with a raised floor, a thatched roof and open sides. The chickee style of architecture — palmetto thatch over a bald cypress log frame — was adopted by Seminoles during the Second and Third Seminole War as U.S...
s numbering half a dozen, with one central chickee for cooking and another for eating. Dugout canoes, cookware, still
Still
A still is a permanent apparatus used to distill miscible or immiscible liquid mixtures by heating to selectively boil and then cooling to condense the vapor...
s, and sewing machines may still be found in remote locations.
Bayheads and willowheads
Some hammocks are dominated by types of vegetation that grow in relation to the amount of water or type of soil present. The majority of hardwood hammocks create a thin poor soil covering the limestone called humus, made of decaying plant matter and moisture trapped by the structure of the trees. When peat forms the layer atop the limestone of a tree island, bayheads develop, dominated by bay trees such as sweetbay magnolia (Magnolia virginiana) and others like swamp holly (Ilex deciduaIlex decidua
Ilex decidua is a species of holly native to the United States.-Description:...
), wax myrtle (Myrica cerifera
Myrica cerifera
Myrica cerifera is a small tree or large shrub native to North America. Its common names include Wax myrtle, Bayberry, Candleberry, Bayberry tree, and Tallow shrub...
), and cocoplum (Chrysobalanus icaco
Chrysobalanus icaco
Chrysobalanus icaco, the cocoplum, Paradise Plum and icaco , is found near sea beaches and inland throughout the tropical Americas and the Caribbean, including Cuba, southern Florida, and the Bahamas. The inland subspecies is Chrysobalanus icaco pellocarpus.-Description:Chrysobalanus icaco is a...
). Willowheads, dominated by willow trees (Salix caroliniana
Salix caroliniana
Salix caroliniana, commonly known as the coastal plain willow, is a shrub or small tree native to the southeastern United States, Mexico and parts of Central America and the Caribbean. It is an obligate wetland species and grows as an emergent species in the Everglades. In the absence of fire, S....
), take hold where the hydroperiod is long, usually around solution or alligator holes, and may surround the holes, giving them a donut
DONUT
DONUT was an experiment at Fermilab dedicated to the search for tau neutrino interactions. Even though the detector operated only during a few months in the summer of 1997, it was largely successful. By detecting the tau neutrino, it confirmed the existence of the last lepton predicted by the...
appearance from above.
Flatwoods and the Atlantic Coastal Ridge
The prairies and sloughs of the Everglades system are bordered by two areas of poorly drained sandy soil on both sides of Lake Okeechobee: the Eastern Flatwoods and the Western Flatwoods just north of Big Cypress Swamp. The predominant ecosystem in the Flatwoods is pine forest, but there are also cypress swamps and sloughs in the Eastern Flatwoods. Along the eastern border of the Everglades is the Atlantic Coastal Ridge, rising 20 feet (6.1 m) in elevation, and curving to the southwest, gradually decreasing in elevation until it meets Taylor Slough. The Coastal Ridge prevents Everglades water from flowing into the Atlantic OceanAtlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
to the east, directing it southwesterly into Florida Bay. The South Florida metropolitan area
South Florida metropolitan area
The South Florida metropolitan area, also known as the Miami metropolitan area, and designated the Miami–Fort Lauderdale–Pompano Beach, FL Metropolitan Statistical Area by the U.S...
is located on a portion of the Atlantic Coastal Ridge, and much of the landscape has changed drastically within the past 100 years as a result of urban growth.
Pine rockland
Pine rocklands (also called pinelands) are found on uneven limestoneLimestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
substrate
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
s that contain pinnacles and solution holes. There are three primary locations of pine rocklands: the Miami Ridge, which runs from Miami into Long Pine Key near the main entrance of Everglades National Park
Everglades National Park
Everglades National Park is a national park in the U.S. state of Florida that protects the southern 25 percent of the original Everglades. It is the largest subtropical wilderness in the United States, and is visited on average by one million people each year. It is the third-largest...
; the lower Florida Keys; and the Big Cypress Swamp. The most significant feature of the pine rockland ecosystem is the South Florida slash pine (Pinus elliotti var densa
Slash Pine
Pinus elliottii, commonly known as the Slash Pine, is a pine native to the southeastern United States, from southern South Carolina west to southeastern Louisiana, and south to the Florida Keys....
; also called Dade County pine) that reaches a height of 22 feet (6.7 m). Pine rockland communities require fire for maintenance; they have adapted to promote and resist fire at the same time. These communities are located in the highest part of the Everglades with little to no hydroperiod, although some floors may have flooded solution holes or puddles for a few months at a time. The sandy floor of the pine rocklands is covered with dry pine needles that are highly flammable. South Florida slash pines are insulated by their bark to protect them from heat. Fire eliminates competing vegetation on the forest floor, and opens pine cones to germinate seeds. A period without significant fire can turn pineland into hardwood hammock as larger trees overtake the slash pines. The understory shrubs in pine rocklands include fire-resistant species like saw palmetto (Serenoa repens), cabbage palm (Sabal palmetto
Sabal palmetto
Sabal palmetto, also known as cabbage palm, palmetto, cabbage palmetto, palmetto palm, blue palmetto, Carolina palmetto, common palmetto, swamp cabbage and sabal palm, is one of 15 species of palmetto palm . It is native to the southeastern United States, Cuba, and the Bahamas...
), and West Indian lilac (Tetrazygia bicolor
Tetrazygia bicolor
Tetrazygia bicolor is a species flowering plant in the glory bush family, Melastomataceae, that is native to southern Florida in the United States and the Caribbean. Common names include Florida Tetrazygia and West Indian Lilac.T. bicolor is a shrub that reaches a height of...
). The most diverse group of plants in the pine community are herbs, of which two dozen species exist. These plants contain tuber
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
s and other mechanisms allowing for quick sprouts after charring.
Wildlife in pine rockland communities is diverse. In some forests, 15 species of birds can be found. Common among them are the pine warbler (Dendroica pinus), the red-bellied woodpecker (Melanerpes carolinus), and the eastern meadowlark (Sturnella magna). More than 20 species of reptiles and amphibians have been noted, such as the green anole (Anolis carolinensis), southern leopard frog (Rana sphenocephala), and southern black racer (Coluber constrictor priapus
Coluber constrictor priapus
The Southern Black Racer is one of the more common subspecies of nonvenomous snakes in the Southeastern United States. The name priapus refers to the proximal spines of the hemipenes being much enlarged into basal hooks, which is characteristic of this subspecies. These snakes are quite active...
). Mammals such as the critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
Florida panther (Puma concolor coryi), Florida black bear (Ursus americanus floridanus), and several types of bats also live in the pine rocklands.
Before urban development of the South Florida region, pine rocklands covered around 161660 acres (654.2 km²) in Miami-Dade County
Miami-Dade County, Florida
Miami-Dade County is a county located in the southeastern part of the state of Florida. As of 2010 U.S. Census, the county had a population of 2,496,435, making it the most populous county in Florida and the eighth-most populous county in the United States...
. Pine forests were extensively cleared by urban developers and the lumber industry in the 1930s and 1940s. Within Everglades National Park, 19840 acres (80.3 km²) of pine rockland communities are protected, but outside the park, 1780 acres (7.2 km²) of pine forests remain as of 1990, averaging 12.1 acre (0.048967006 km²) in size. Dade County pine has a remarkable longevity and has proven to be termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
-resistant, though dense enough to make driving nails difficult. In 1984 they were protected by a county ordinance
Local ordinance
A local ordinance is a law usually found in a municipal code.-United States:In the United States, these laws are enforced locally in addition to state law and federal law.-Japan:...
, after many pine areas had been depleted. A misunderstanding of fire's role also played a part in the disappearance of pine forests, as natural fires were put out and pine rocklands transitioned into hardwood hammocks. Today prescribed fires occur in Everglades National Park in pine rocklands every three to seven years.
The Big Cypress
West of the sawgrass prairies and sloughs lies the Big Cypress Swamp, commonly called "The Big Cypress", referring to its size rather than the height or diameter of its trees. It takes up the majority of Collier CountyCollier County, Florida
Collier County is a county located in the U.S. state of Florida. As of 2000, the population was 251,377. The U.S. Census Bureau 2007 estimate for the county is 315,839...
; at its most limited measurement, the swamp measures 1200 square miles (3,108 km²), but its hydrological boundary is nearly twice as large. The Big Cypress is slightly elevated at 22 feet (6.7 m) at its highest point and slopes gradually to the coastline for approximately 35 miles (56.3 km). Because the defining feature of The Big Cypress is the abundance of trees, it is considered a swamp rather than a marsh, in which grass is the main characteristic.
The basin for The Big Cypress receives on average 55 inches (139.7 cm) of water in the rainy season. Most of The Big Cypress sits atop a bedrock covered by a thin layer of limestone that contains quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, creating a sandy soil that hosts a variety of vegetation. The majority of trees are bald cypress (Taxodium distichum
Taxodium distichum
Taxodium distichum is a species of conifer native to the southeastern United States.-Characteristics:...
) and not true cypresses (Cupressaceae
Cupressaceae
The Cupressaceae or cypress family is a conifer family with worldwide distribution. The family includes 27 to 30 genera , which include the junipers and redwoods, with about 130-140 species in total. They are monoecious, subdioecious or dioecious trees and shrubs from 1-116 m tall...
). Cypresses are conifers that are uniquely adapted to thrive in flooded conditions, with buttressed trunks and root projections that protrude out of the water, called "knees".
Cypress trees in the area can live for hundreds of years; some giants grow to 130 feet (39.6 m) and are 500 years old. Still, they may be only seventh- or eighth-generation cypresses. Few massive trees survived the logging operations that took place in the 1930s and 1940s. As a result, much of The Big Cypress is protected by various federal or state agencies that include Big Cypress National Preserve
Big Cypress National Preserve
Big Cypress National Preserve is a United States National Preserve located in southern Florida, about 45 miles west of Miami. The Big Cypress, along with Big Thicket National Preserve in Texas, became the first national preserves in the United States National Park System when they were...
, Corkscrew Swamp Sanctuary
Corkscrew Swamp Sanctuary
Corkscrew Swamp Sanctuary is a National Audubon Society sanctuary located in southwest Florida, north of Naples, Florida and east of Bonita Springs, in the United States. The sanctuary was established to protect one of the largest remaining stands of Bald Cypress and Pond Cypress Corkscrew Swamp...
, Fakahatchee Strand State Preserve and two Indian reservations.
Cypress head
Persea palustris
Persea palustris, commonly known as the swampbay, is a tree native to eastern North America, from Texas eastwards to Florida and then extending north to Delaware, mostly on the Gulf Coastal Plain and Atlantic Coastal Plain but extending into the Piedmont somewhat. Its range also includes the...
), and pop ash (Fraxinus caroliniana
Fraxinus caroliniana
Fraxinus caroliniana, commonly known as the Pop ash, Florida ash, Swamp ash, or Water ash, is a species of ash tree native to the southeastern United States. It was originally described by the botanist Philip Miller. It is a small tree about 40 ft...
). If cypresses are removed, hardwoods take over, and the ecosystem is recategorized as a mixed swamp forest.
Because the cypress domes and strands retain moisture and block out much of the sunlight, plants such as orchids, bromeliads, and fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
s thrive in cypress domes and strands. Orchids bloom throughout the year in cypress heads, and bromeliads appear in many varieties; on Fakahatchee Strand alone, thirteen species have been documented. Bromeliads collect moisture from rain and humidity in the bases of their leaves, which also nurture frogs, lizards and various insects. Wood storks (Mycteria americana) nest almost exclusively in cypress forests and in the past 100 years have seen a dramatic decline, probably due to lack of reproduction tied to controlled water
Restoration of the Everglades
The restoration of the Everglades is an ongoing effort to remedy damage inflicted on the environment of southern Florida during the 20th century. It is the most expensive and comprehensive environmental repair attempt in history. The degradation of the Everglades became an issue in the United...
. Wood storks' reproductive cycles coincide with the dry season, when small fish and amphibians are trapped in shallow pools and puddles. When water from canals or locks is released too soon or not at all, storks are unable to find enough food for themselves and their offspring. An estimated 20,000 wood storks nested in The Big Cypress in the 1930s, but by the 1990s less than 2,000 were counted.
Mangrove and Coastal prairie
Water from Lake Okeechobee and The Big Cypress eventually flows to the ocean. At a transitional zone where fresh water meets salt water, mangroveMangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
trees thrive, adapted as they are to both kinds of water. This brackish mixture of water and mangrove systems, crisscrossed by hundreds of tidal creeks, harbors a very productive ecosystem. The depth of these zones is dependent on how much water flows from the Everglades. In the wet season, fresh water pours into Florida Bay and sawgrass appears near the coastline. In dryer years, salt water creeps inland to the coastal prairie, an ecosystem that buffers the freshwater marshes by absorbing sea water. Mangrove trees grow in fresh water ecosystems when the salt water flows far enough inland. The Everglades have the most extensive contiguous system of mangroves in the world. The mangrove forests of the Ten Thousand Islands cover almost 200000 acres (809.4 km²).
Mangrove
Three species of mangrove trees exist in the region: red (Rhizophora mangleRhizophora mangle
Rhizophora mangle, known as the red mangrove, is distributed in estuarine ecosystems throughout the tropics. Its viviparous "seeds," in actuality called propagules, become fully mature plants before dropping off the parent tree...
), black (Avicennia germinans
Avicennia germinans
Avicennia germinans, commonly known as the black mangrove, is a species of flowering plant in the acanthus family, Acanthaceae.A. germinans grows in tropical and subtropical regions of the Americas, on both Atlantic and Pacific coasts, and on the Atlantic coast of tropical Africa, where it thrives...
), and white (Laguncularia racemosa
Laguncularia racemosa
Laguncularia racemosa is a species of flowering plant in the leadwood tree family, Combretaceae...
), although all are from different families. All have the same characteristics: they are tolerant of salt, brackish, and fresh water; they grow in oxygen-poor soil; and they can survive drastic water-level changes. Black and white mangroves excrete salt from under their leaves, and red mangroves filter the salinity of sea water. All species are integral to coastline protection during severe storms. Red mangroves, for example, have far-reaching roots that trap sediments. The trees not only stabilize coastlines, but add land as more sand and decaying vegetation is trapped in the root systems. All three mangroves also absorb the energy of waves and storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
s.
The estuaries act as fisheries for fry and nurseries for crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s. Shrimp, oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s, crabs, whelk
Whelk
Whelk, also spelled welk or even "wilks", is a common name used to mean one or more kinds of sea snail. The species, genera and families referred to using this common name vary a great deal from one geographic area to another...
s, cockle
Cockle (bivalve)
Cockle is the common name for a group of small, edible, saltwater clams, marine bivalve molluscs in the family Cardiidae.Various species of cockles live in sandy sheltered beaches throughout the world....
s, and snails thrive in these waters, as do primordial horseshoe crabs (Limulus polyphemus). The region supports a $59 million-a-year Tortugas pink shrimp (Farfantepenaeus duorarum) industry, and a $22 million-a-year stone crab (Menippe mercenaria) industry. Between 80 and 90 percent of species that are harvested commercially in Florida are born or spend time in the shallow waters near the Everglades. Oysters and mangroves work in tandem to build up the coastline. The sand around the coastline has minute white particles of quartz and fine shells. When currents are right, oysters grow in colonies or beds, and deposit their shells, reinforcing the bed. Mangrove seeds, called propagule
Propagule
In horticulture, a propagule is any plant material used for the purpose of plant propagation. In asexual reproduction, a propagule may be a woody, semi-hardwood, or softwood cutting, leaf section, or any number of other plant parts. In sexual reproduction, a propagule is a seed or spore...
s, are full embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s and float in water until they reach a favorable location and take root, often on oyster beds. They shed skin and litter, ensuring other trees will not compete for space and nutrients.
Mangroves also serve as excellent rookeries for birds. Wading birds, such as roseate spoonbills (Platalea ajaja), egret
Egret
An egret is any of several herons, most of which are white or buff, and several of which develop fine plumes during the breeding season. Many egrets are members of the genera Egretta or Ardea which contain other species named as herons rather than egrets...
s, and tricolored herons (Egretta tricolor) use the mangroves as a nursery, due to the proximity of food sources and the protection offered from most prey. Thousands of birds can nest in the mangroves at once, making a noisy and messy colony, but their droppings fertilize the mangrove trees. Shorebirds like rail
Rallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
s, tern
Tern
Terns are seabirds in the family Sternidae, previously considered a subfamily of the gull family Laridae . They form a lineage with the gulls and skimmers which in turn is related to skuas and auks...
s and gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s; diving birds such as pelican
Pelican
A pelican, derived from the Greek word πελεκυς pelekys is a large water bird with a large throat pouch, belonging to the bird family Pelecanidae....
s and grebe
Grebe
A grebe is a member of the Podicipediformes order, a widely distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter...
s; and birds of prey such as osprey
Osprey
The Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...
s, hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
s and vulture
Vulture
Vulture is the name given to two groups of convergently evolved scavenging birds, the New World Vultures including the well-known Californian and Andean Condors, and the Old World Vultures including the birds which are seen scavenging on carcasses of dead animals on African plains...
s are among the more than 100 species of birds that use Everglades mangrove trees to raise their young.
Florida Bay
Florida Bay
Florida Bay is the bay located between the southern end of the Florida mainland and the Florida Keys. Its area is variously stated to be , or , or . Nearly all of Florida Bay is included in Everglades National Park. The southern edge, along the Florida Keys is in the Florida Keys National Marine...
are considered part of the Everglades. More than 800 square miles (2,072 km²) of Florida Bay is protected by Everglades National Park
Everglades National Park
Everglades National Park is a national park in the U.S. state of Florida that protects the southern 25 percent of the original Everglades. It is the largest subtropical wilderness in the United States, and is visited on average by one million people each year. It is the third-largest...
, representing the largest body of water in the park boundaries. There are approximately one hundred key
Cay
A cay , also spelled caye or key, is a small, low-elevation, sandy island formed on the surface of coral reefs. Cays occur in tropical environments throughout the Pacific, Atlantic and Indian Oceans , where they provide habitable and agricultural land for hundreds of thousands of people...
s in Florida Bay, many of which are mangrove forests. Larger islands may be taken over by hardwood hammocks. The outer rims of the Ten Thousand Islands and Cape Sable
Cape Sable
Cape Sable, Florida is the southernmost point of the US mainland and mainland Florida. It is located in southwestern Florida, in Monroe County, and is part of the Everglades National Park. The cape is a peninsula issuing from the southeastern part of the Florida mainland, running west and curving...
share characteristics of the intertwining saltwater bays and fresh water marshes.
The fresh water entering Florida Bay from the Everglades creates ideal conditions for vast beds of turtle grass
Seagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...
and algae formations that foster animal life in the bay. Sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...
s and manatees (Trichechus manatus latirostris) eat the grass, while invertebrates such as worms, clams, and other mollusks consume algae formations and microscopic plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
. Female sea turtles return annually to nest on the shore, and manatees spend the winter months in the warmer water of the bay. The Calusa
Calusa
The Calusa were a Native American people who lived on the coast and along the inner waterways of Florida's southwest coast. Calusa society developed from that of archaic peoples of the Everglades region; at the time of European contact, the Calusa were the people of the Caloosahatchee culture...
Indians had various uses for shells of marine invertebrates, due to the lack of dense rock with which to make tools. They used the horse conch (Pleuroploca gigantea
Pleuroploca gigantea
Pleuroploca gigantea, common name the Florida horse conch, is a species of extremely large predatory subtropical and tropical sea snail, a marine gastropod mollusk in the family Fasciolariidae, the spindle snails, tulip snails and their allies....
), left-handed whelk (Busycon contrarium), and the Florida crown conch (Melongena corona
Melongena corona
Melongena corona, common name the Florida crown conch, is an edible species of sea snail, a marine gastropod mollusk in the family Melongenidae, the crown conches and their allies.-Description:...
) as drinking vessels, picks, hammers, knives and awls.
Sea grasses stabilize sea beds and protect shorelines from erosion by absorbing energy from waves. Shrimp, spiny lobster
Spiny lobster
Spiny lobsters, also known as langouste or rock lobsters, are a family of about 45 species of achelate crustaceans, in the Decapoda Reptantia...
s, and sea urchin
Sea urchin
Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
s live in and among the grasses and feed on phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
; they in turn feed larger predators such as shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s, ray
Rajiformes
Rajiformes is one of the four orders of batoids, flattened cartilaginous fishes related to sharks.Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion...
s, barracuda
Barracuda
The barracuda is a ray-finned fish known for its large size and fearsome appearance. Its body is long, fairly compressed, and covered with small, smooth scales. Some species could reach up to 1.8m in length and 30 cm in width...
, and king mackerel (Scomberomorus cavalla). Due to shallow water and abundant sunlight, Florida Bay hosts communities of coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
s and sponges, although the majority of the state's reefs are closer to the Florida Keys
Florida Keys
The Florida Keys are a coral archipelago in southeast United States. They begin at the southeastern tip of the Florida peninsula, about south of Miami, and extend in a gentle arc south-southwest and then westward to Key West, the westernmost of the inhabited islands, and on to the uninhabited Dry...
. Everglades keys that foster mangroves also support nurseries for wading birds such as the Great white heron (Ardea herodias), which was almost wiped out in the Labor Day Hurricane of 1935
Labor Day Hurricane of 1935
The 1935 Labor Day Hurricane was the strongest tropical cyclone of the 1935 Atlantic hurricane season, and one of the most intense hurricanes to make landfall in the United States in recorded history...
(only 146 were counted afterward). After recovering to number more than 2,000, they were further endangered by Hurricane Donna
Hurricane Donna
Hurricane Donna in the 1960 Atlantic hurricane season was a Cape Verde-type hurricane which moved across the Leeward Islands, Puerto Rico, Hispanola, Cuba, The Bahamas, and every state on the East Coast of the United States...
in 1960, which decreased their numbers by 35 to 40 percent.
Sea floor patterns of Florida Bay are formed by currents and winds. However, since 1932, sea levels have been rising at a rate of 1 foot (0.3048 m) per 100 years. Though mangroves serve to build and stabilize the coastline, seas may be rising more rapidly than the trees are able to build.
Biodiversity
Ecosystems in the Everglades have been described as both fragile and resilient. Author Michael Grunwald wrote about the observations of the Everglades' first American visitors: "If the Grand Canyon was a breathtaking painting, the Everglades was a complex drama, and everything in it had a role." An estimated 11,000 species of seed-bearing plants and 400 species of land or water vertebrates live in the Everglades, but slight variations in water levels affect many organisms and reshape land formations. The health and productivity of any ecosystem relies on the number of species present: the loss of one species weakens the entire ecosystem.For example, Florida apple snails (Pomacea paludosa
Ampullariidae
Ampullariidae, common name the apple snails, is a family of large freshwater snails, aquatic gastropod mollusks with a gill and an operculum...
) are an amphibious fresh water mollusk. They have a single gill and lung, and live on stalks of sawgrass in water depths no more than 20 inches (50.8 cm). They are the primary food of the endangered Everglades snail kite (Rostrhamus sociabilis) and limpkin (Aramus guarauna) as well as the raccoon, otter, and young alligator. Apple snails lay their eggs on sawgrass stalks about 6 inches (15.2 cm) above the water line, and they are intolerant of being submerged for long periods of time. When the eggs hatch, young snails must enter the water quickly or face death. When water levels are too low or rise too quickly while snail eggs are developing, apple snails do not flourish, affecting the many reptiles, mammals, and birds that feed on them. With regard to the ecology of trophic dynamics, or food chains, the 174 species of invertebrates play a vital role in the Everglades. Crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
, insects, scorpions, and other invertebrates also support a web of animals.
The group of animals most integral to the overall success of Everglades wildlife is freshwater fish. Few places in the Everglades stay submerged from one year to the next, so alligator holes and deep clefts in the limestone are vital to the survival of fish, and the animal community as a whole. Freshwater fish are the main diet of most wading birds, alligators, and otters, and require large areas of open water in order to repopulate. Young amphibians also play an important role in the food chain. Tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s spread quickly in isolated areas where fish do not have the time or access to reproduce in numbers necessary to support larger animals. Hundreds of species of amphibians are found in the Everglades, and their availability helps support wildlife during short hydroperiods or in remote locations.
These smaller animals support communities of larger animals, including 70 species of land birds that breed within the Everglades, and 120 water birds, of which 43 breed in the area. Many of these birds go on to migrate through the West Indies and North America. Several dozen species of mammals also thrive in the region, from tiny bats and shrews to midsize raccoons (Procyon lotor), otters (Lontra canadensis), opossums (Didelphis virginiana), and foxes. The largest include white tailed deer (Odocoileus virginianus), the Florida black bear, and the Florida panther.
Although slight changes in water level affect many species, the system as a whole also cycles and pulses with each change. Some transformations to the diversity of plant and animal life are natural, caused by fire or storms, and some are induced by humans, such as urban encroachment, the introduction of exotic species, and rapid global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
. Environmental conditions in the Everglades favor no particular species. Some species, such as snail kites and apple snails, do well in wet conditions, but wood storks and Cape Sable seaside sparrows (Ammodramus maritimus mirabilis) do well in dryer circumstances.
Human impact
People have lived in the Everglades region for thousands of years. Within the past 100 years however, they have changed the natural landscape dramatically. Settlement of urban areas in South Florida was facilitated by large drainage projects intended to create more land. The drainage was often implemented without a full understanding of the intricacies of ecosystems and shaping processes of the Everglades. Though the South Florida metropolitan areaSouth Florida metropolitan area
The South Florida metropolitan area, also known as the Miami metropolitan area, and designated the Miami–Fort Lauderdale–Pompano Beach, FL Metropolitan Statistical Area by the U.S...
grew exponentially, the result caused chaos in ecosystems throughout the Everglades. By the 1990s, the diminishing quality of life in many of these urban areas was linked to the degraded local environment. The State of Florida and the U.S. government devised and passed a plan in 2000 to restore as much of the Everglades to pre-drainage conditions as possible. It is the costliest and most comprehensive environmental restoration project in history.
See also
- Indigenous people of the Everglades regionIndigenous people of the Everglades regionThe indigenous people of the Everglades region arrived in the Florida peninsula approximately 15,000 years ago, probably following large game. The Paleo-Indians found an arid landscape that supported plants and animals adapted to desert conditions...
- Draining and development of the EvergladesDraining and development of the EvergladesThe history of draining and development of the Everglades dates back to the 19th century. During the Second Seminole War beginning in 1836, the United States military's mission was to seek out Seminole people in the Everglades and capture or kill them. Those missions gave the military the...
- Restoration of the EvergladesRestoration of the EvergladesThe restoration of the Everglades is an ongoing effort to remedy damage inflicted on the environment of southern Florida during the 20th century. It is the most expensive and comprehensive environmental repair attempt in history. The degradation of the Everglades became an issue in the United...