After driving for hours in the sun, Marcelo Ardón hit a bumpy gravel road leading to a coastal forest where rising sea levels are visibly changing the landscape. Flies swarmed as he got out of the truck and started walking down a thick, overgrown path.
Dodging cobwebs, Ardón left the trail in a muddy area where he and his research team placed equipment that monitors ground elevation, helping them predict the fate of this swampy forest, located in the Palmetto-Peartree Reserve on the Albemarle. Its from North Carolina.
“We’re monitoring whether the ground is rising or falling – that will tell us if the wetland is going to be able to keep up with sea level rise, or if it’s going to drown,” said Ardón, associate professor of forest and environmental resources at the North Carolina State University.
Ardón has already witnessed changes in this forest since he started studying it about 15 years ago. At that time, Ardón only wore ordinary boots. He is now wearing rubber waders because the water has gotten so high.
“I saw the forest changing right before my eyes,” Ardón said. “We saw all the trees dying. The canopy was opening. All of the understory vegetation was changing; a different vegetation, more aquatic, was coming. That’s why I’m still working on this site and why we’ve started looking at Ghost Forests more broadly.
Ardón studies the drivers and downstream impacts of the transition from rainforests to so-called ghost forests.
“So we studied: what are the drivers of these changes? he said. “What are the consequences? On what timescales do these changes appear to occur?”
When the water rises too fast
Follow the seeker’s trail to the end and you reach Albemarle Sound. Dead tree stumps and snags mark the shore.
“It’s what we call a ghost forest,” Ardón said, after wading through shoreline vegetation and wading to stand waist-deep among the snags. “This area looked like the forest we just walked through earlier.”
You get a graveyard of dead stumps when water floods the land too quickly, Ardón explained, and the swamp vegetation can’t keep up. In previous work from his lab, researchers tracked the saltwater threshold that different plants can withstand.
“So what’s happened here is we’re right next to Albemarle Sound, and the water has been rising faster than this system has had time to migrate,” he said. -he declares.
Ardón pointed to the base of a nearby tree. He would have stood at tree level if the forest was intact. Instead, he was waist deep in water. This soil, and the carbon-based organic matter it contains, has been lost.
“So we lost that amount of soil and that amount of carbon,” he said. “We lost him. Some of it may have fallen off and it’s buried in the background of the sound and some of it may be in the atmosphere.
While he said there has been a “dance” between forested wetlands and marshes in the past, the issue now is how quickly this is happening.
“So the sea level is rising and there are more storms; there are more droughts – all of these things stress the trees and the vegetation,” Ardón said.
The trees, in death, still carry gases
Ardón placed his hand on the trunk of one of the dead trees – a trunk which, although dead, can still transport gases through the vascular system remaining within.
In a recent study, Ardón and his team looked at the role trees play in releasing or retaining gases in the soil of ghost forests.
“We now find that they work like filtered straws, because they facilitate the movement of certain gases, but they also help to filter some of them,” Ardón said. “They help filter out methane, which is a very potent greenhouse gas.”
He waded to the edge of where the last stump was in the sound. He said that around 1990 the shoreline was about 80 feet from where it is now.
“You can see the change on satellite images if you go to Google Earth, and use the time-lapse tool to put a pin on where the shoreline is right now,” he said. “Then you turn the clock back and it will show you footage that goes back to 1987, 1990. You can see that change yourself.”
Volunteers helping track Ghost Forest transitions
Back on land, Ardón took a walk down the Scuppernong River. Inside the Pocosin Lakes National Wildlife Refuge in Columbia, North Carolina, the boardwalk winds between blooming native flowers and gnarled cypress trees.
Ardón stopped at a sign along the boardwalk, overlooking a forest beyond. He placed his phone on a small ledge on the panel and took a picture. The site is part of a citizen science project Ardón has launched to track forests in transition.
Volunteers can take photos at the sites and email them to NC State researchers. The idea is to use the photos to track forests over time.
“I love studying ghost forests because they are a very clear indication that climate change is here, climate change is happening, and it’s here and now,” Ardón said.
In addition to involving citizen scientists in his work, Ardón has also researched solutions to sea level rise, including a wetland restoration effort.
“These systems have changed a lot since I studied them, and I know they will continue to change as my children grow up,” he said. “But I’m sure our research can help reduce the uncertainties that land managers already face.”
To read a Q&A with Ardón on the Citizen Science Project, click here. To see the photos collected so far, click here.
