Researchers Restore Lost Wetlands

Wetlands and streams—pieces of North Carolina’s natural landscape—have been lost over time as land across the state has been cultivated for farming, paved for transportation, or built into residential and commercial property. But NC State researchers are working to restore the natural order to some of these areas, improving wildlife habitats and water quality in the process.

“Streams in North Carolina have been hammered for quite some time. We’re just trying to fix the damage.”

“We’re working together to focus on ecological systems,” says Dr. Greg Jennings. A professor and extension specialist in the Department of Biological and Agricultural Engineering (BAE), Jennings has repaired broken streams statewide, and the protocols his team developed are being copied elsewhere. The three-step process rebuilds streams from the bottom up. First, maps and computer models help determine the proper size and shape of the channel and surrounding flood plain. After heavy machinery shapes and sculpts that plain, rocks and logs are set as reinforcement to keep the stream in place and create pools for fish. Finally, native shrubs and trees are planted along the banks to restore a natural buffer, limit erosion, and create animal habitat. “Streams in North Carolina have been hammered for quite some time,” Jennings says. “We’re just trying to fix the damage.”

“Restoration science is relatively new. We need to continue studying these areas for years to get a long-term picture.”

Although Jennings has done projects in the mountains—an avid fly fisherman, he’s too often distracted by the flow of a trout stream to catch anything—his most challenging project is right outside his office. Rocky Branch runs through the NC State campus and downtown Raleigh, and stormwater runoff from parking lots had clogged the stream with sediment and eroded the banks to the point that nearby sidewalks were crumbling. He has worked with a large team over the past 10 years to rebuild the stream into a healthy ecosystem. “You can’t have an instant restoration,” he says. “It takes years for an area
to heal.”

Wetland restoration is likewise a long-range proposition. Dr. Mike Burchell, a BAE assistant professor and extension specialist, has been working for more than six years to design, build, and study about 350 acres of restored wetlands in Carteret County that had been drained for farmland. The project is part of a planned 4,000-acre restoration by the North Carolina Coastal Federation to re-establish diverse wetland habitat and improve water quality in the North River and surrounding estuaries. “We’re trying to find the most cost-efficient means possible to recreate wetlands,” he says, “without sacrificing the structure or ecological function of the system.”

“Ecological restoration seems like a simple idea, but it’s very effective for protecting wildlife habitat and our water quality.”

Burchell and his team have studied three design and construction methods that allow land to revert to wetlands. In one area, they just plugged up drainage ditches and planted vegetation. Elsewhere, they also used tractors to till the land in meandering patterns. Finally, they used heavy machinery in some areas to remove sloped crowns used to improve the surface drainage of fields. All three methods work to some extent, he says, adding that removing the crowns produces the wettest areas—the leveled surface is closer to the water table—while roughing up the ground can improve water storage and helps diversify vegetation. “We’re not to the point where there’s a cookbook for doing this,” says Burchell, whose interest in wetlands dates to a childhood fascination with the swamps he saw going to and from family beach vacations. “All sites are different, and restoration science is relatively new. We need to continue studying these areas for years to get a long-term picture.”

The National Oceanic and Atmospheric Administration recently reported the U.S. is losing about 59,000 acres of wetlands each year, primarily because of development. “Some of it is from large projects, but most is nibbling,” says Dr. Doug Frederick, a professor of forestry and environmental resources. “The cumulative effect of an acre or two here and there can be devastating.” That’s why wetland banking is critical to preserving functioning wetland systems for water quality and wildlife habitats, he says.

Wetland banking allows a developer to pay to restore wetlands elsewhere in exchange for those destroyed by new subdivisions, shopping centers, or roads. Frederick created North Carolina’s first private wetland mitigation bank in the mid-1990s, working with conservation groups and investors to buy land, convert it to wetland, and sell the credits for the restoration. He also helped implement NC State’s only wetlands bank by overseeing the restoration of 388 acres of Hofmann Forest in Onslow County, which is owned by a foundation in the College of Natural Resources. Frederick uses his expertise in forestry to advise landowners what types of hardwoods to plant and how to manage the growth of the restored sites. “Ecological restoration seems like a simple idea,” he says, “but it’s critical for protecting wildlife habitat and our water quality.”

 

Dr. Greg Jennings has worked with a team to restore Rocky Branch on NC Stateís campus in recent years. Stormwater had eroded the stream bed and banks and caused unhealthy water quality conditions.

Restoration work continues on sections of Rocky Branch, with stones and logs used to maintain the stream channel and natural plants used on the banks as buffers and to control erosion.

Drs. Mike Burchell and Doug Frederick, left to right, use their expertise to transform cultivated areas into wetlands.

Burchellís applied research led to the resculpting of this former agricultural plot, now filtering nutrient-laden runoff from an adjacent Carteret County farm before the water flows into the North River. Eventually, this site will return to wetland habitat.