Climate change takes hold in North Carolina’s ghost forests
As sea levels rise and storms become more intense, scientists are racing to study the rapid loss of trees and marshland along the Outer Banks
Lanier first came here to work for the U.S. Fish and Wildlife Service in the mid-1980s and stayed several years before heading to postings around the Southeast. When he returned in 2006, a singular question reverberated in his mind as he drove around:
“What happened to the trees?”
The startling transformation he witnessed then has only accelerated in recent years. “It has changed dramatically,” he says, “and it has changed very quickly.”
Few examples of climate change are as unmistakable and arresting as the “ghost forests” proliferating along parts of the East Coast — and particularly throughout the Albemarle-Pamlico Peninsula of North Carolina.
Places where Lanier once stood on dry ground are now in waist-deep water. Forests populated by towering pines, red maple, sweet gum and bald cypress have transitioned to shrub land. Stretches of shrub habitat have given way to marsh. And what once was marsh has succumbed to the encroaching sea.
As sea levels rise, droughts deepen and storms become more intense, saltier water makes its way into these woodlands more readily from surrounding water bodies, as well as deeper into the sprawling network of drainage ditches and irrigation canals created long ago to support the expansion of agriculture.
Persistently wet conditions can weaken existing trees. And episodes of saltwater intrusion can push already stressed forests to the breaking point, poisoning the freshwater on which they depend and hastening the death of trees not only at the water’s edge, but in some cases far inland. The result are expanses of dead or dying trees, known as “snags,” that stand as grim monuments to a shifting ecosystem.
“This has happened over and over before in geologic time,” says Marcelo Ardón, an ecologist at North Carolina State University. “But now it is happening faster.”
Ghost forests have existed for decades. But as they proliferate, scientists are racing to better understand the factors driving the changes, what humans might do to slow the demise of such forests and what consequences lie ahead if the trend continues.
They are investigating what the profound changes to coastal systems might mean for the migrating birds, mammals, reptiles and plants that call them home.
And they worry about what will come of the massive stores of carbon these landscapes hold, huge amounts of which could be released back into the atmosphere as forests die and the land retreats — a shift that could further complicate efforts to slow the warming of the planet.
“I still feel like we are just scratching the surface and trying to figure out how much of an impact this is,” Ardón says, “and how big of an area is being affected.”
‘Something’s not right’
Emily Ury was haunted by what she saw when she began to travel the coastal stretches of North Carolina, where in certain spots the ashen skeletons of trees spread as far as she could see.
“You just know looking at it that something’s not right,” said Ury, who at the time was a doctoral student at Duke University, studying the ecology of wetlands. “The most fundamental questions haven’t been answered,” she added. “Where is this happening? Why is this happening? To what extent is it happening?”
To help answer that last question, Ury and other researchers turned to Google Earth, where they examined visible changes over the past 35 years to the Alligator River National Wildlife Refuge.
In a paper published last year, they found that despite its protected status nearly a third of the refuge — or more than 47,000 acres — had transformed from forest habitat to shrub land or marsh over that period. Nearly 3,000 more acres were “lost to the sea.” And as much as 11 percent of the refuge became ghost forest, dominated by dead trees and fallen trunks.
While the greatest forest losses occurred where the refuge met the Croatan and Pamlico sounds, the researchers noted, tree deaths “also occurred much further inland in low-elevation areas and alongside major canals.”
Specific events have clearly played a role. For instance, researchers observed a spike in deaths after Hurricane Irene in 2011 forced enormous amounts of salty water into forests already strained by years of drought. But the problem continued in the years that followed.
In their findings, Ury and her colleagues saw a glimpse of what lies ahead for areas beyond this corner of North Carolina, where sea levels have risen roughly a foot over the past century. The eerie phenomenon has unfolded along the Atlantic seaboard, from the swamps of Louisiana to the Chesapeake Bay, from the white cedar forests of New Jersey to the St. Lawrence estuary in Canada.
“These unprecedented rates of deforestation and land cover change due to climate change may become the status quo for coastal regions worldwide,” they wrote, “with implications for wetland function, wildlife habitat, and global carbon cycling.”
Ury knows that many people might not grasp the long-term threats posed by their transformation, even as the sight of stricken trees is difficult to miss. Saltwater intrusion has inflicted damage in more immediate and visceral ways, such as contaminating aquifers and tainting once fertile farm land in the region.
But even less obvious changes are significant.
“People just don’t really care about swamp forests. They are not really populated,” said Ury, now a postdoctoral fellow at the University of Waterloo in Ontario. “But they are experiencing this massive shift, and it’s a loss of an ecosystem that’s underappreciated but still has a lot of value for water quality and wildlife habitat and storing carbon.”
“And it’s definitely a canary in the coal mine for coastal change.”
On a sun-splashed spring morning, Ardón, the ecologist, stands knee deep in the cold water of the Albemarle Sound.
“It’s happening right here,” he says of climate change. He nods toward the stumps of fallen trees poking out of the water, some of them 50 feet or more from the shoreline. “That was probably land 20 years ago.”
After a short hike inland, Ardón reaches one of many testing sites he and colleagues maintain inside the Palmetto-Peartree Preserve. Year after year, they track whether the soil is accumulating or subsiding.
In this spot, as in others, the forest floor is adding mass a millimeter at a time, but at a much slower pace than the local rate of sea level rise.
“Bad math,” Ardón calls it. “Over time, these forests are going to get swallowed by the sound.”
Scientists say that transition from forested wetlands to marsh and eventually to open water raises daunting questions about what will happen to the habitat for a range of species, including red-cockaded woodpeckers and many other birds, black bears, river otters and critically endangered red wolves.
It also has serious implications for climate change.
Researchers have found that an estimated 27 million tons of carbon are stored in the trees and other biomass along the Albemarle-Pamlico Peninsula.
A 2020 study detailed how ghost forests had crept across roughly 15 percent of the area’s unmanaged public land from 2001 to 2014. During that time, the authors calculated, the changes allowed an estimated 130,000 tons of carbon to escape into the atmosphere that otherwise would have remained sequestered. Those emissions further fuel the planet’s warming and make it harder to avoid future disasters.
A separate study last year found that the “amount of carbon lost from forest mortality is far greater than that gained by the growing marsh soils.” The time it would take for wetlands to make up for the carbon-related impact of dying trees, the authors wrote, “is at the scale of centuries, which is approximately the same amount of time predicted for marshes to drown from rising sea levels.”
In other words, more evidence of bad math.
“If you were to lose this forest and all this carbon above ground, how long would it take for the marsh to recover the carbon that is lost? It’s on the order of 200 to 600 years,” Ardón says.
Neither marshes nor humans have that kind of time to stave off climate change, he said, as he surveyed the forest and the creeping shoreline beyond.
“In that time, this is going to be underwater.”
Trying to slow the inevitable
Researchers from Florida to New Jersey and from Louisiana to Maryland are busy trying to learn more about the causes and consequences of ghost forests — from their impact on wildlife and water quality to whether dead trees emit greenhouse gases through their strawlike trunks.
Meanwhile, state and federal wildlife officials, along with groups such as the Nature Conservancy, are trying to slow down the rapid transition, even as they know the land probably will never be what it once was.
In North Carolina, that has meant an array of efforts such as sowing oyster reefs to combat erosion, planting more saltwater-tolerant plants and trees, and engineering specialized ditch-draining structures meant to prevent saltwater from penetrating deep into the forests and vegetation that remain.
“If we do nothing, the forest could collapse rapidly and go from being forested to being open water,” said Brian Boutin, director of the Albemarle-Pamlico Sounds Program at the Nature Conservancy. “We’re buying time to allow it to transition to something that’s still going to be functional and still provide habitat for a wide variety of species.”
But the future is perilous for this landscape and others like it, as researchers wrote in one study last summer: “At the current rate of deforestation, in the absence of widespread protection or restoration efforts, coastal forested wetlands may not persist into the next century.”
Emily Bernhardt, a Duke ecologist and professor and co-author of that study and others on ghost forests, says even as scientists continue to study the problem, they must help policymakers, farmers and other residents consider how to make the best out of the decades to come.
Scientists have documented the changes that have already happened and those that are likely to come. “The question is, can we go there in an intelligent, intentional way that’s protective of livelihoods and biodiversity? Or are we going to go there in a very catastrophic way?”
They are questions Lanier ponders often as he nears the home stretch of his career.
As the manager of the Alligator River National Wildlife Refuge, the vast majority of which lies barely two feet above sea level, he knows the person in his job could face “a very different thing” in only a handful of decades. If current trends continue, he said, the majority of the refuge could be underwater within a century.
“It’s sobering to see a landscape you are trying to manage for wildlife die out,” he said.
But Lanier and others who care about this place are not content to sit idle. There is wildlife that depends on this habitat, humans who rely on its water filtration benefits and a planet that relies in part on its ability to store carbon.
“We’re trying to find out what we can do to make sure the place is as resilient as we can,” he said. “To try to slow down the change as long as it’s possible.”