As Seas Rise, a Florida Keys 'Ghost Forest' Makes A Last Stand
On a stretch of the Lower Keys, near an old borrow pit quarried during the construction of Big Pine, sea water and mud cover much of the rocky ground.
Poisonwood trees, whose sap was used by the Calusa to poison enemies, grow along the pit’s high berm. Clumps of pink-flowered pride-of-Big Pine, one of the planet’s most imperiled plants and found only in the Keys, also sprouts from the rare patch of high ground.
There’s something else, more ominous, too: bleached pine tree stumps, rising like tombstones.
A pine rockland forest once stood here, maybe a century ago. Not that long in tree years. The stumps still give off a sharp, tarry smell when gouged with a knife. Freshwater sawgrass could be found as recently as the 1990s. But now, it’s a stark and solemn warning about rising seas.
“It’s really kind of pathetic,” said Florida International University forest ecologist Michael Ross, who’s been studying the Keys pineland since the 1990s.
Just three decades ago, when he started studying the forests, healthy pineland grew on at least 10 islands. Today, the forests are thinning or gone. The only healthy tract stands on Big Pine.
Across the U.S. coast, sea rise has left behind swaths of skeletal ghost forests, pushing tracts of trees inland as oceans steal the land. Ecologists have watched as coastal forests steadily declined, unable to keep pace. A June study published in the journal Nature Climate found the Gulf Coast has lost about 57 square miles of forest over the last 120 years. With just over three feet of sea rise, the report found between 4,600 and 19,000 square miles of dry land up and down the U.S. coast will become tidal zones filled with wetlands.
But the story in the Keys is different. The underground freshwater lenses that once fed the pineland are shrinking. With no place to retreat, the forests are simply vanishing.
And when the pineland goes, a menagerie of rare plants and animals found only in the Keys may also disappear. Many, including the beloved Key deer, will lose up to 90 percent of their habitat at about two feet of sea rise. With the National Oceanic and Atmospheric Administration saying two feet is now possible by about 2050, the herd of dog-sized deer would likely be lost, according to a study by federal and state wildlife managers and the Nature Conservancy.
That’s put wildlife managers and ecologists in a race with time, struggling to come up with a plan to repair what’s been lost and conserve what’s left.
“It’s really daunting,” said Kevin Kalasz, the coastal program manager for the U.S. Fish and Wildlife Service. “We’ve been dealing with the recovery of the pine rockland for quite a long time. But we’re at a point now where we really want to change how we do things….with impending sea rise and species where there’s really no good option.”
The study, completed last year after a series of workshops, looked at tolerable sea levels for a range of protected species. That list also included the Lower Keys marsh rabbit, the Schaus butterfly and the two remaining populations of semaphore cactus. The effort was intended to gauge just how much time might be left and come up with feasible strategies for conservation. Florida’s Fish and Wildlife Conservation Commission is conducting a similar study that’s expected to be completed in the coming months.
“We recognize that sea level rise is eventually going to be the undoing of the terrestrial habitat in the Florida Keys and at the same time creating new habitat,” said Chris Bergh, the South Florida conservation director for The Nature Conservancy, who worked on the studies. “We think it’s important to buy as much time as we can.”
Managers are also pondering a more controversial option: building a Noah’s Ark for vanishing species. It’s not an untested strategy. Zoos have bred animals like pandas to build up wild populations. But the debate shifts when the habitat disappears.
“The Key deer are a product of evolving in the Florida Keys,” Bergh said. “When the Florida Keys are underwater, there will be no place for the Key deer to return to.”
Moving species is also counter to what most conservationists believe in, Ross said.
“Conservation is about improving habitat in place, and improving species within their range,” he said. “With sea level rise and climate change, if we're going to save the species, we're going to have to help them move.”
The question then becomes where would you put an animal like the deer, which can be found no place else on the planet.
“They were genetically isolated, and then suddenly we're going to move things up to the mainland where there's another sub species?” he said. “You're going to lose that genetic diversity. So that’s the question that they have to grapple with.”
Saving Florida’s pineland is not a new challenge. All but about two percent remains outside Everglades National Park. On the mainland, tracts disappeared under bulldozers as South Florida spread across the high ground where the pineland grew or deteriorated without the natural wildfires. But restrictions on development and protected refuges, like the Key Deer National Wildlife Refuge, ensured the preservation of large tracts in the Keys.
Ross first started studying the trees in order to look at damage caused by the lack of fire, setting up a study plot in one of the biggest stands on Sugarloaf.
Pineland evolved from the South Florida mean season, when booming lightning storms frequently ignite wildfires. Fires kept the canopy airy, so sunlight could wash across the forest floor, allowing unique ground herbs and other plants to flourish. The scarcity of water also helped make the region's pine wood especially hard.
Ross returned a decade later to look at sea rise and found a dramatic decline: 217 acres of pineland measured in 1935 had decreased to 74 acres by 2009.
“There were 10 islands with viable pine and they were all getting smaller and smaller,” Ross said.
Ross and researcher Danielle Ogurcak suspected sea rise was behind the decline, so Ogurcak began using old wells and digging new ones to measure the size of the lens.
“They were all wrapped together,” Ross said. “But I have to say sea level rise is probably the biggest factor.”
After Wilma, they found trees that survived wind died long after the storm passed. That’s because a hurricane, like Wilma or Irma, pushes storm surge across the island and contaminates the freshwater pools and groundwater. Two years after Irma, Ogurcak still found elevated levels of saltwater at the Blue Hole, an old quarry surrounded by pineland on Big Pine.
That can allow more salt tolerant plants to move in and, without fire, begin turning the stands into something else.
“Germination is not happening and essentially you end up with these relic stands of forests,” Ogurcak said. “That’s happening all over the east coast where you see changes in coastal forests first happening in the understory, with changes in salt tolerant species and a lack of regeneration.”
They also discovered it was possible to measure observable signs before the forest died. And that might help managers.
“Prior to seeing a ghost forest, a dead forest, there are things that are happening that aren't as dramatic,” Ogurcak said. “Trees themselves are under more stress so they're growing slower. Then you'll get a change in the understory of the salt tolerant plants colonizing in areas where they previously would not have been able to successfully compete.”
In a way, their work threw the forest a lifeline. If they could step in and help the forest by replanting trees, Ogurcak and Ross said, that could make the forest better able to withstand hits from hurricanes and give nature a chance to make a more natural transition. They just might avoid more catastrophic changes - like the rocky ground around the burrow pit - and give one functioning ecosystem time to replace another.
But repairing nature is expensive and convincing policy-makers can be complicated. The massive project to repair the Everglades, a $16 billion effort to fix damage from flood control in South Florida, is nearly 20 years old and far from completion.
To help win support, Kalasz has adopted a business approach and is drafting a cost-benefit analysis.
“We can say if we put in a minimum amount of funding, we’re gonna get this,” he said. “There’s no economies of scale, so we identify very explicitly what it’s going to take to achieve the desired future condition of the species or the habitats that we’re concerned about.”
He’s also looking at ways to expand pineland in the Keys and on the mainland, using maps and satellite imagery to identify public and private pineland where property owners might be willing to restore land or grant easements for pineland. He expects the plan will take two years to complete.
He’s also aware the looming expiration date for pineland, and the threat that comes with every hurricane season, means time is running out.
“There is certainly a sense of urgency,” he said.
As a land manager and forest ecologist, Ross said he cannot fathom giving up.
“Even though we may not be optimistic about whether it's going to be here 100 years from now, it may allow them to live longer,” he said. “There's some benefit to that. And that's what we do.”