As Florida’s winter dry season stretched into a near rainless wet season, the central Everglades has withered into extreme drought conditions.
Water levels across sawgrass marshes dropped below normal, and in some places below ground. Water managers worry that with so little water, wading birds in the upcoming nesting season could go hungry. Parts of Florida Bay remain too salty, with too little water flowing from Everglades marshes. If that continues, seagrass could start dying.
Then this month wildfires ignited in parts of Everglades National Park hardest hit by the drought.
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On Wednesday, after nearly 24,000 acres burned, firefighters using helicopters brought the last and largest of the fires mostly under control. But the prolonged drought and fires have raised concerns over potentially cascading impacts.
”Normally, in a dry year, we might use helicopters [at] the end of spring, and then by July we're back on airboats,” said John Kominoski, a biology professor at Florida International University and principal investigator of the National Science Foundation’s long-term Everglades research program.
“But this year, our field crews stopped using airboats in January and they're still using helicopters to access field sites. So it's exceptionally dry out there.”
Relief could come from this year's El Nino rains, but those are not1 forecast to arrive until October at the earliest.
According to the National Weather Service, as the rest of South Florida has begun to emerge from the drought, extreme conditions remain in the central Everglades, between Shark River and Taylor Slough. Water levels at the sprawling water conservation area just north of Everglades National Park dropped to their lowest in early June. Going into July, levels started climbing, but still remain far below normal, scientists at the South Florida Water Management District told the district governing board in their briefing this month.
”Some of the rains are starting to develop over area one and area two, but area three continues to just bounce around the floor elevation,” chief engineer John Mitnik told board members, referring to Water Conservation Areas one, two and three that hold freshwater to provide flood control and protect water supplies in South Florida’s shallow aquifer. “ When you get below the floor elevation, then any water that leaves the conservation area has gotta be preceded by some inflows from the north.”
But With Lake Okeechobee still well below average and under water restriction rules, little water is flowing south.
Combine drought with fire and the backbone of the Everglades — its marshy peat soil — also becomes more vulnerable.
“ Globally, peat wetlands are tremendous carbon sinks. So when you have a carbon sink [destroyed], it's like robbing a bank,” Kominoski said. “You've got all this… storage of energy, and then all of a sudden it's gone.”
Scientists worry that when the thick layers of peat disappear, it can take a long time for the bank to reopen.
“It takes decades to hundreds to thousands of years to rebuild that,” he said.
Besides storing carbon to help fight climate change, Kominoski said peat also works to provide critical local services. The deep muck provides a cap for the shallow aquifer, helping to clean and filter freshwater that supplies drinking water for Miami-Dade, Broward, Monroe and parts of Palm Beach County. It helps fight coastal erosion. And, as long as it stays wet, peat can fend off saltwater intrusion fueled by sea rise.
”The peat is like a wet sponge, and a wet sponge will resist some of the water coming in that's salt water. But a dry sponge will wick it all the way in,” he said.
Like other parts of the Everglades, peat has also taken a hit from years of flood control that Everglades restoration aims to fix. At the southern end of the Everglades, where marshes and coastal wetlands are most starved for freshwater, peat has started to collapse, ripping open the shallow sawgrass marshes to leave behind deeper pits of open water.
”Because the peat overlays the limestone, and the limestone is irregular, if you start losing the peat, it can be too deep for sawgrass to regrow,” Kominoski said. “So that is also a big issue.”
With fire, peat faces a mortal enemy. If it burns too hot for too long, dried out peat incinerates.
Fire is part of the Everglades ecology — wildfire season coincides with the end of spring when stormy weather lightning strikes ignites marshes still dry from winter. But flood control and booming cities around the Everglades means that fire now has to be managed by the National Park Service.
”Typically with prescribed fires, they try to factor in the Goldilocks conditions, to be just right for the fire, and so that it's not gonna burn out of control,” Kominoski said. “Usually that coincides with where the water depth is, and that's almost never below the surface.”
Controlled burns can rid marshes of invasive plants and release beneficial phosphorus from burning sawgrass.
Although it’s not clear how much damage this month’s fires may have caused, in 2008, a fire that burned for nearly a month and covered 40,000 acres left a lasting mark. Parts of the Everglades where water flow is being restored have a better chance of recovering, Kominoski said. But with the drought, even restored areas, especially where the Tamiami Trail has been bridged to restore flow, could take longer.
“ It'll be a legacy effect, for sure,” he said. “We will be able to see the effect of these fires for years, in terms of plant recovery and possibly in terms of the chemistry [and] the chemical signatures in the landscape.”
