Okefenokee Swamp

• Category: Inland Aquatic Biomes.
• Geographic Location: North America.
• Summary: Debates continue over how to best protect this richly inhabited major freshwater swamp from naturally occurring events such as droughts, lightning strikes, and forest fires.

The Okefenokee Swamp is the largest freshwater swamp in the United States, and is located in southern Georgia. The low pH balance, or high acidity, of the swamp leads to a limited flora, but supports numerous, diverse fauna.

The climate in South Georgia is subtropical; typically, summers are hot and rainy. In the drier winters, occasionally the temperature drops below freezing. The Okefenokee Swamp receives the majority of its water from precipitation throughout the 1,400-square-mile (3,600-square-kilometer) watershed. Surface springs also provide a minor contribution. The swamp itself covers an area of roughly 680 square miles (1,770 square kilometers).

Annual precipitation, which occurs mainly in the hot summer, averages 50 inches (125 centimeters); however, droughts are common throughout the region. The swamp is sometimes called the largest blackwater swamp in North America, the name referring to its tea-colored water. This color is produced by tannic acid, generated by decaying vegetation. Tannins cause the water pH to drop from a neutral 7.0 pH to an acidic 3.7 pH.

Water leaves the swamp either by evaporation or directly via two major rivers, the Suwannee and the St. Marys. The east side of the swamp has a natural barrier, called the Trail Ridge, that funnels a majority of the water into the Suwannee River, which then cuts across north-central Florida, draining into the Gulf of Mexico. The St. Marys River discharges east into the Atlantic Ocean. Despite the low pH of the swamp water, the rivers flow over calcareous limestone deposits, which eventually increase the pH and neutralize the river chemistry.

Flora and Fauna

The low pH and sandy soil limit the flora which can survive in Okefenokee Swamp. Naturally occurring floods and wildfires maintain the sensitive ecosystem. The most abundant tree in the swamp is the cypress (Taxodium ascendens). Although most of the cypress was logged in the early 1990s, some giant pond cypresses still exist. The pond cypress prefers lakes and ponds, whereas the bald cypress prefers to grow in moving waters. Less widespread trees such as the slash pine (Pinua elliotii), black gum (Nyssa sylvatica), water ash (Fraxinuscaroliniana), Ogechelme (Nyssa ogeche), loblolly-bay (Gordonia lasianthus), swamp-bay (Peresa plaustris), and sweet-bay (Magnolia virginiana) are also found here.

The lack of phosphate- and nitrogen-enriched soils have attracted many carnivorous plants. Carnivorous plants trap and ingest insects to survive. Three varieties of pitcher plants (Sarracenia flaua, S. minor, S. psittacina) survive in the swamp by first attracting flying insects into their pools of bacteria, then drowning them. Sundews (Droserarotunditolia) attract insects by use of their sticky hairs. Insects such as gnats become stuck and later ingested. Butterworts and species of bladderworts (family Lentibulariaceae) use similar strategies for attracting creatures living on the water surface.

The water lily (Nymphaea odorata) is one of the most common flowers found in the swamp. Vines such as the greenbriar (Smilax walteri) and the climbing heath (Pieris phillyreitolia) are also present here. Spanish moss is a notable “air plant” often seen hanging from tree branches.

Peat deposits up to 15 feet (5 meters) thick cover much of the Okefenokee floor. These deposits are so unstable in spots that trees and surrounding bushes may tremble if the adjacent surface is heavily trodden. It is this trembling ground that gave reason for the Choctaw to refer to the swamp as okafenoke, meaning “quivering Earth.” Floating peat batteries—mainly composed of decaying water lilies and cypress—form small islands. Up to 60 of these floating peat batteries can be found in the Okefenokee Swamp, and some of them will support the weight of a human.

It is estimated that over 400 species of vertebrate animals live in the Okefenokee Swamp, half of which are birds. This number reflects 39 fish, 37 amphibian, 64 reptile, 50 mammal, and 235 bird species. Several species are threatened or endangered, including the sandhill crane, wood stork, and great blue heron. The ivory-billed woodpecker (possibly extinct), Carolina parakeet, and passenger pigeon are no longer present in the swamp. The 235 bird species present in the swamp include both year-round and seasonal residents. Common birds include the white ibis (Eudocimus albus), anhinga (Anhinga anhinga), great egret (Casmerodius albus), various vultures, and warblers.

Amphibians require wetland depth fluctuation for proper reproduction, and have found such cycles suitable here. There are over 20 species of frogs and toads throughout the Okefenokee Swamp, including 10 members of the tree frog family. Salamanders are also plentiful in the swamp, with 16 types present. Additionally, two types of skink can be found.

Within the swamp, there are also 14 families of fish, featuring 36 species of freshwater fish. Some of the most common are the Florida gar, American eel, the Okefenokee pygmy, sunfish, bowfins (Amia calva), five species of catfish, and the chain pickerel (Esox niger).

Of the 64 species of reptiles present in the biome, the swamp alligator is the most common one specifically associated with the Okefenokee Swamp. Due to hunting in the middle of the 20th century, the alligator almost became extinct; it was listed as endangered in 1973. By 1984, the alligator population had recovered and it was removed from the Georgia Protected Species List. The 36 snake species (five of which are venomous) also contribute to the swamp’s fauna. The snake population includes the venomous pit viper and coral snake. Also found here are the rare rainbow snake and federally protected threatened species, the indigo snake. There are also 11 species of lizards and 14 species of turtles.

The Florida black bear, Ursus americanus floridianus, is the Okefenokee Swamp’s largest mammal. The majority of these bears live in the eastern region of the swamp, along the Trail Ridge Section. The bobcat (Felis rufus) and raccoon (Procyon lotor) are also quite common during the nighttime hours. Although there is an abundance and variety of animals living in the Okefenokee Swamp, no plant or animal is endemic, that is, unique to the region.

Human Impacts

Attempts were made in the late 1800s to drain parts of the swamp. Though the drainage projects were not successful, much of the swamp area was logged during the early 1900s. In 1936, the United States Biological Survey paid the Hebard Lumber Company for the approximate 470 square miles (1,200 square kilometers) which initially formed the basis for the Okefenokee Swamp reserve. In 1937, President Franklin D. Roosevelt signed an executive order establishing the Okefenokee National Wildlife Refuge. In 1960, the Suwannee River Sill was built to increase the water level in the swamp. By 1974, part of the swamp was designated as a part of the National Wilderness Preservation System. The swamp is now managed mainly by the Department of the Interior, Fish and Wildlife Services.

Fire is a dominant influence in the Okefenokee Swamp ecology. The Okefenokee Swamp has been classified as a high lightning-frequency area by the Forest Service. The naturally occurring swamp peat is about 85 percent combustible. An area with a high probability of lightning strikes that contains a large and combustible fuel source will have naturally occurring forest fires. Without natural fires, peat can accumulate and will eventually lead to invading shrubs and hardwoods.

As cypress and gum trees recover rapidly from fire damage, the present vegetative types cannot be sustained without fire. Human influence has not impacted the swamp in recent times as much as the naturally occurring wildfires. Although there is usually public demand to manage and quickly extinguish the wildfires, the naturally occurring swamp fires help with vegetative stability within the swamp.

The care of the swamp, in regards to unpredictable natural fires, remains a critical issue. Most neighbors and land owners in the area would prefer the government to control and prevent the natural spread of the fire. A wildfire which began with a lightning strike near the center of the refuge in May 2007 eventually merged with another wildfire that had begun earlier near Waycross, Georgia, due to a tree falling on a power line. By the end of the month, more than 935 square miles (2,400 square kilometers) had burned in the region, much of it in the refuge.

Again, in 2011, fire ravaged the area; some estimates are that 75 percent of the refuge was burned. The drought conditions that led to the spreading fires are believed to be related to global climate change. If so, this will be another factor to consider in terms of fire-control plans. However, many environmental groups would still prefer the National Wildlife Refuge to remain a naturally sustained ecosystem.

The Okefenokee Swamp Alliance is a conservation group that works for continued preservation of the swamp, which was named a Wetland of International Importance under the Ramsar Convention, and is on the United Nations Environmental, Scientific, and Cultural Organization (UNESCO) Tentative List for World Heritage Site status.

Conservationists have been working to prevent nearby industries from affecting the swamp area. They opposed a proposed mining operation, for example, over fears that it could affect wildlife and the peat beds. The peat stores significant amounts of carbon that could negatively impact the climate if water levels fall and the peat begins to decompose, releasing carbon. Mining threats continue to loom over the area. Twin Pines Minerals, an Alabama-based company, plans to strip-mine titanium from an area bordering Okefenokee National Wildlife Refuge, despite environmentalists' concerns and objections.

Bibliography

Lenz, Richard J. The Longstreet Highroad Guide to the Georgia Coast and Okefenokee. Marietta, GA: Longstreet Press, 1999.

McHugh, Paul, ed. Wild Places: 20 Journeys into the North American Outdoors. Emeryville, CA: Avalon Travel Publishers, 1996.

“New Strip Mining Operations Threaten the Okefenokee.” Environmental Action, 3 Apr. 2024, environmental-action.org/articles/new-strip-mining-operations-threaten-the-okefenokee/. Accessed 20 Nov. 2024.

Wilson, James. “The Okefenokee Swamp.” Georgia Wildlife Press: Natural Georgia Series 6, no. 1 (1997).

Yale Climate Connections. "Why Protecting the Okefenokee Swamp Matters for the Climate." Yale Climate Connections, 15 Nov. 2021, yaleclimateconnections.org/2021/11/why-protecting-the-okefenokee-swamp-matters-for-the-climate/. Accessed 20 Nov. 2024.