Everglades: Flora and Fauna
Authored By: K. McPherson
The Everglades consists of several different plant communities. The general aspect of the Everglades is a large herbaceous wetland with scattered tree islands. The distribution of these communities is dynamic in time and space and is controlled primarily by the hydrologic regime, but disturbances such as fires are also important. The most extensive plant community of the historic Everglades was sawgrass marsh, (intermediate hydroperiod marsh flooded for 7 – 11 months/year (Lockwood et al. 2003)) also called swale (FNAI 1990), and accounts for approximately 2/3 of the plant cover in the region (Wade et al 1980). This community is dominated by sawgrass (Cladium jamaicense), a sedge. Sawgrass marsh often grows where there is 10-20 cm of standing water (Gunderson and Loftus 1993). Dense nearly monotypic stands of sawgrass reaching 3m (10ft) in height with standing biomass up to 28,0000 kg/ha (25,000 lbs/acre) are located on the deep soils of the central Everglades . More commonly, on shallower soils sawgrass stands are shorter, and less dense intermixed with up to 14 other plant species (Olmstead and Loope 1984). Common associates in these stands include maidencane (Panicum hemitomon) and arrowhead (Sagittaria lancifolia) or other plant species. Sawgrass is tolerant of prolonged flooding, fire and nutrient poor, and oxygen poor sites. Monospecific stands of cattail have recently become more and more common displacing sawgrass, particularly in some of the water conservation areas (Davis Everglades are the long hydroperiod marshes (called slough by FNAI (1990)). These communities have a longer hydroperiod than sawgrass marsh, often flooded for more than 11 months per year (Lockwood et al. 2003). One of three plants is usually dominant in long hydroperiod marsh: spikerush (Eleocharis cellulosa), beakrush (Rhynchospora tracyi) or maidencane (Gunderson 1994, Wade et al. 1980). Up to 25 other plants including submerged aquatics, have been found in these associations (Gunderson 1994). Periphyton is common. Sloughs are the wettest and include all associations of floating aquatic plants. Marl Tree Islands Everglades (Wade et al. 1980). These islands are composed of bayheads, a type of swamp forest, but can also include tropical hardwood forests on the highest elevation sites (Gunderson 1994). Bayhead tree islands are usually 0.5 to 1 m higher than their surroundings with a hydroperiod of 2 to 6 months per year. The larger tear-drop shaped tree islands develop where there is bedrock near the surface over which peat accumulates. Smaller, circular tree islands probably formed on floating “batteries” of peat that were colonized by hardwoods. Common plant species include red bay (Persea borbonia), swamp bay (Magnolia virginiana), dahoon holly (Ilex cassine), wax myrtle (Myrica cerifera), and pond apple (Annona glabra). A dense shrub layer is found beneath the canopy commonly of cocoplum (Crysobalanus icaco), but can include others. Herbaceous plants, when present, are composed mostly of epiphytes including some rare plants (Gunderson 1994). Tropical hammocks are often dominated by Live oak (Quercus virginiana), hackberry (Celtis laevigata) or stangler fig (Ficus aurea) or others and rarely flood (Wade et al. 1980). Several other communities make up a minor portion of the Everglades . Willow heads, dominated by willow (Salix caroliniana) are found on sites with a history of severe soil disturbance. Cypress forests (discussed elsewhere) are a minor feature of the Everglades , but are a dominant community to the west in the Big Cypress swamp. Pond apple forests that once stood on the rim of Lake Okeechobee are largely gone, having been converted to agricultural lands (Gunderson 1994). Some authors consider the pine forests dominated by south Florida Everglades . The largest remnant of pine rockland Florida Everglades National Park Florida Everglades . Old world climbing (Lygodium microphyllum) fern grows in most habitats including on tree islands and sawgrass marsh (Wade et al 1980, Ferriter 2001.). Disturbed habitats such as roadsides and canal banks are also heavily infested with exotics. Animals of the Everglades tend to be less diverse than the animals of the rest of the Florida Everglades invertebrates. Some groups of invertebrates are relatively diverse, such as water beetles, while others, larger invertebrates, are species poor; only one species each of crayfish, prawn and amphipod have been found (Gunderson and Loftus 1993). The tendency is for a few taxa to become very abundant as exemplified by mosquito populations. Fish assemblages are common in the wetlands of the Everglades . Thirty species of fish have been found in the freshwater marshes (Loftus and Kushlan 1987). The most dominant fish is the mosquito fish (Gambusia affinis) (Kushlan 1990). Small species of fishes include livebearers (Poeciliidae), killifishes (Cyprinodontidae) and sunfishes (Centrarchidae). Larger fishes use deeper water habitats including holes excavated by alligators. Deeper water habitats are also important as refugia for fishes when water draws down, and can also serve as wading bird feeding sites, as fishes are concentrated there in draw down. Exotic fishes are becoming a larger proportion of Everglades fauna and have begun to invade intact communities of the Everglades . As of 1994, 7 or more exotic fish species were known from the Everglades (Robertson and Frederick 1994). Reptiles and amphibians of the Everglades marshes tend to be similar to those in much of the rest of peninsular Florida Everglades is world renown. Historically it was known for the seemingly endless abundance of wading birds during the plume-hunting era. Today it is known for precipitous declines in wading bird densities. Nesting success of wading birds has been particularly hard hit in recent years (Robertson and Fredrick 1994). Besides wading birds, waterfowl, passerines, and raptors including the endangered snail kite use the Everglades . Approximately 25 species of birds are known to nest in the Everglades (Robertson and Fredrick 1994). Densities of birds are much higher in winter than summer reflecting use by overwintering birds (Kushlan 1990). The Cape Sable seaside sparrow is one federally listed bird that uses muhly grass marshes in more coastal locations (See the section salt marsh birds for more info). Mammals of marshes are more limited with carnivores making up a large percentage of mammalian fauna (Gunderson and Loftus 1993). Small mammals such as the round tailed muskrat (Neofiber alleni), cotton rats (Sigmodon hispidus) and marsh rabbits (Sylvilagus palustris) and medium sized mammals like opossum (Didelphis virginiana) and raccoon (Procyon lotor) are all found within the Everglades . White tailed deer (Odocoileus virginianus) use marshes extensively. The previous animals form part of the prey base for the endangered Florida Panther (Felis concolor var. cori).
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Encyclopedia ID: p269
