Along U.S. coastlines, tidal forested wetlands—a powerful natural ally in the fight against climate change—are disappearing because of logging, draining, and land-use conversions. But there’s still time to reverse that trend and restore and protect these valuable ecosystems, according to experts who participated in an Oct. 1 webinar hosted by The Pew Charitable Trusts.
Tidal forested wetlands, including brackish tidal swamps, are ecological transition zones, influenced by both marine tides and inflowing freshwater. This habitat features woody plants that sequester “blue carbon”—carbon captured from the atmosphere and surrounding water and stored in branches, leaves, roots, and soils. Tidal forested wetlands provide many benefits to people and nature, including storing significant amounts of carbon, filtering water, buffering coastal communities from storms and flooding, and providing habitat for economically and ecologically important fish, birds, and other wildlife.
However, a staggering 95% of tidal forested wetlands have been lost from some regions of the U.S. over the past century, according to researchers, due to the factors mentioned above and rising sea levels, saltwater intrusion, increased development, and recently decreased federal wetland protections.
Although tidal forested wetlands are distinct ecosystems, local, state and federal decision-makers may overlook them because of their transitional nature between freshwater and saltwater environments, said webinar panelist Ken Krauss, a research ecologist with the U.S. Geological Survey's Wetland and Aquatic Research Center.
And because of insufficient mapping, scientists and policymakers don’t know the habitat’s true extent or how much greenhouse gases it removes from the environment, Krauss said. For example, 1990s data suggested these ecosystems covered 2,000 square kilometers in the Southeast. But as one example showed, that estimate was low: Recent mapping increased the extent of tidal forested wetlands in South Carolina’s Winyah Bay, a coastal estuary where the Waccamaw River flows into the Atlantic Ocean, by 17%-- from 397 to 463 square kilometers. This suggests that tidal forested wetlands cover a much broader swath of the southeastern U.S. than previously known.
To further help produce accurate estimates, Krauss said scientists must also agree on standardized terminology for the habitat. He noted that experts have least seven terms for tidal forested wetlands, and to prove his point, he used three in his webinar presentation. Having one standard term and definition would enable more-precise mapping and communication, which could support policies to conserve tidal forested wetlands as blue carbon ecosystems.
The 2023 U.S. Supreme Court ruling Sackett v. EPA removed federal protection for about 50% of U.S. wetlands previously safeguarded under the Clean Water Act--a gap that states should move to fill with their own rules, said Josh Eagle, a University of South Carolina School of Law professor.
“Some states already had their own permitting systems in place, but more will now need to step up,” Eagle told attendees. “There's potential here for building a diverse constituency to get new state laws, and maybe a new federal law,” he added, noting that anyone who relies on clean water has a stake in protecting wetlands.
South Carolina has the largest distribution of tidal forested wetlands in the Southeast, and the state’s Waccamaw National Wildlife Refuge includes some of the most diverse freshwater wetlands in North America. Established in 1997, the refuge has grown to about 38,000 acres through voluntary land sales to the state, refuge manager Craig Sasser said. When the U.S. Fish and Wildlife Service (USFWS) asked him to suggest ways to streamline the land acquisition process, he said, “It was really important to convey an economic value for what we’re doing.”
One benefit is demonstrating how habitat conservation can save money. For example, in Horry County, South Carolina, land acquired by the refuge has spurred lower flood insurance premiums that save about $1 million annually. The National Flood Insurance Program sets flood insurance premiums via a “ community rating system” that lowers premiums for better managed floodplains.
The refuge is also building resiliency in its managed wetlands by reconnecting historic rice fields to the river, allowing them to absorb floodwaters. This project has gained support from The Gullah/Geeche Nation, descendants of enslaved Africans with deep ties to their rice cultivation heritage. “We couldn't manage these places without all our partners,” said Sasser.
Michelle Moorman, a field biologist with USFWS, told webinar attendees about a half-day pilot workshop she recently co-led using the federally developed “ resist, accept, direct” (RAD) framework to brainstorm ways the policymakers could conserve the Waccamaw River Basin. RAD is a tool resource managers employ to plan for and respond to climate and development pressures by resisting the changes, accepting them wholesale, or using them to shape a new, beneficial reality.
Moorman said her workshop generated a six-fold increase in the number of actions resource managers could take to protect the basin and demonstrated how important it is to collaborate with diverse audiences and integrate the values, rules, and knowledge of communities into potential solutions. “What we want to do is build those relationships that happen each time we talk about climate adaptation.”
Tidal forested wetlands are vital for carbon storage, flood protection, and biodiversity. Efforts in Winyah Bay and Waccamaw National Wildlife Refuge show that proactive management can help these landscapes endure—and continue to help communities—in a changing climate.
Jazmin Dagostino is an associate with The Pew Charitable Trusts’ U.S. conservation project.