maritime forest sulivans island (copy)

A thick maritime forest on Sullivan's Island has grown on more than 100 acres of accreted land that has built up over decades. File/Staff

Maritime forests like the one that some residents want to trim back on Sullivan's Island might be the best defense they have against rising seas and storm surge.

Trees such as the wax myrtles and the underbrush the town is considering cutting have long been considered valuable erosion fighters. Now a study suggests planting more of them might be a better bet for coastal residents to protect their properties than other barriers because the trees bulk up the soil where they are planted.

The study, done in a mangrove forest in Florida, has ramifications all along the coast, said Professor Samantha Chapman, of Villanova University, one of the study authors.

"I think the science is there that 'green barriers' do the best job of building soil to keep pace (with sea rise)," she said.

Charleston landscaper Jeff Jackson of the South Carolina Native Plant Society couldn't agree more.

"Any vegetation will help hold sand in place far better than no vegetation," he said.

Beach renourishment advocates concur. Sea grasses and other plants to hold together renourished dunes are a routine installation during beach projects. Nicole Elko, South Carolina Beach Advocates director, called native vegetation a key element in beach preservation.

"For example, both Myrtle and Folly Beach are presently under beach nourishment. That will be followed by a dune restoration project that includes vegetation," she said. "The interwoven root system formed within dunes is critical in stabilizing South Carolina’s first line of defense from storm surge and waves."

The plantings have their limits, though.

"Dunes and dune vegetation are only effective on the part of the beach that is not regularly inundated by wave energy," Elko said. "Investment in dune vegetation for rapidly eroding beaches is not recommended, for example, where we know the beach will erode back to the seawall again. Dunes are no match for that kind of long-term chronic erosion."

And more vegetation means less beach, she said, particularly as erosion overtakes the renourishment before a new round is needed.

"The public thinks the beach is gone. There's nowhere to put the blankets at high tide," Elko said.

Chapman said mangroves are migrating north with warming seas and air and could reach South Carolina at least at the Georgia border by 2050.

But they'll be little help here, Elko said. Like other vegetation plantings, they don't stand up well to high wave energy beaches.

Reach Bo Petersen Reporter at Facebook, @bopete on Twitter or 1-843-937-5744.

Science and environment reporter. Author of Washing Our Hands in the Clouds.