"You have very shallow water in significant portions of the Okefenokee," Brian K. Meyer, a geologist and lecturer in Georgia State University's Department of Geosciences, explained.
In addition to the lack of water, deep layers of growth have formed, including plenty of peat, which is partially decayed vegetation and organic matter that accumulates over time in the swamp's substrate.
"It's usually two to four feet, but in some areas, it's 20 to 30 feet thick," Meyer said of the peat.
This is part of what helps fuel the fire.
"Peat is a precursor to coal – it's very combustible," he explained.
Deciding whether to fight the fire
In some cases, Okefenokee Swamp fires are simply allowed to burn.
Many variables go into the decision about whether to actively fight a swamp fire, according to fire behavior analyst Kelly Cagle of the U.S. Forest Service.
If the fire is in the center of the swamp and isn't threatening anyone, it may be allowed to burn out on its own. But if it moves further out to the edge, threatening communities and infrastructure, it will need to be actively fought, he said.
And once an Okefenokee swamp fire spreads, rain may not be much help in putting it out. In fact, it took Tropical Storm Barry to put out a 2007 swamp fire, a huge blaze in which two or three fires ultimately converged into one.
Small thunderstorms that move through in a day may be more of a curse than a blessing for swamp fires, Meyer said. Any lightning could cause another fire, and winds could help it spread.
As swamp fires grow and spread, they can have a large economic impact on surrounding communities, the state and the companies that own timber on adjacent lands. The 2007 fire in the swamp had perhaps the biggest impact, with a total cost of about $130 million, including $65 million in lost timber and $44 million in firefighting costs, Meyer said.
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Over 6,000 people were forced to evacuate their homes, and area schools closed, as did state roads and interstates. Fortunately, no lives were lost.
History of fires in the Okefenokee
Although the 2007 Okefenokee swamp fire may have been the biggest so far, it certainly hasn't been the only one.
"Fires have been in the Okefenokee since the Okefenokee existed," Meyer said.
Fires in the swamp have been reported as early as 1840, with another occurring in 1860. Three of the last nine fires have been within the past 25-30 years, including large blazes in 2007 and 2011. Meyer said this could be due to the fact that the area seems to have had more cycles of drought during this time period.
Drought conditions may have helped fuel the current fire by drying out plants and other flora.
"We are in a long-term drought," Joe Goudsward, an incident meteorologist with the National Weather Service, said. "We're about six to eight inches below normal precipitation in the swamp."
Fire activity today of the West Mims Fire in Okefenokee National Wildlife Refuge shot by firefighters from the Balcones Canyonlands National Wildlife Refuge in Texas.
Benefits of the fire
Although fires can threaten nearby communities, they're actually beneficial to the swamp itself, experts say.
"Fire helps a swamp stay a swamp," Cagle said. In the absence of fire, species such as hardwoods would encroach and knock back the swamp.
Without fires, the resulting change in the ecosystem would create a poor habitat for the swamp's wildlife, including the American alligator, wading birds, water fowl and migratory birds, Meyer said.
He tells his students that the fire is as much a part of the swamp as wildlife like the alligator.
Effects of fire on wildlife
Okefenokee swamp fires don't pose much of a threat to the habitat's wildlife in the short term, experts said. They relocate as best they can, with birds flying away and alligators moving to areas of the swamp with more water.
"Most are very adaptive," Cagle explained.