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UF’s Sand Architects Try To Rebuild Coastal Dunes

By:
Cindy Spence

Source(s):
Mack Thetford
Deborah Miller (850) 983-2632

GAINESVILLE—The side panel on Deborah Miller and Mack Thetford’s state vehicle could easily read: Dunes R Us.

Instead, it carries the University of Florida logo as the two dune builders travel Northwest Florida beaches, renourishing sand dunes torn asunder by Hurricane Opal in 1995.

Dune architecture is a tricky thing, they’ve found. While any beachcombing old-timer will tell you, put a stick in the beach and sand will pile up around it, building whole dunes is just not that easy.

To collect entire dunes of sand, Miller and Thetford are trying different fencing materials and an assortment of configurations to determine which materials and methods work best, and fastest, in rebuilding.

The Panhandle’s mighty dunes — some as high as 30 feet and forming a nearly unbroken ridge down the coast — were blasted into grains of sand and carried away on Opal’s winds and storm surge. Because the dunes had not experienced such wholesale destruction in at least 90 years, no information was available on how to quickly restore them, said Thetford, a researcher at UF’s Institute of Food and Agricultural Sciences.

Left to Mother Nature, the dunes would rebuild, in time. But for the dune-dwelling wildlife, time is in short supply.

The Santa Rosa beach mouse, a candidate for listing as an endangered species, makes its home on the dunes. And for sea turtles, the dunes are a protective boundary, keeping them off coastal highways.

“Before the storm, we had a continuous system of dunes as high as 30 feet. It was a very complex dune system, with a primary dune, and then a wall of dunes behind that. With Opal, we had a 12- to 15-foot tidal surge and it flattened the dunes for long stretches,” said Miller, a wildlife ecologist who, like Thetford, is based at the West Florida Research and Education Center, inland at Jay.

“We need to reconnect the dune system, and we have to restore it as quickly as we can because the dunes are habitat and protection for creatures like beach mice and turtles,” Miller said. “And of course, dunes are of benefit to people.”

Miller and Thetford are monitoring elevation changes that occur with each type of fence, to see which works best along the coasts of Walton, Okaloosa and Santa Rosa counties. Among the configurations are zigzag patterns and a straight pattern with a perpendicular spur. The materials also vary and include a biodegradable fence.

“We have our baBy dunes already,” Miller said. “We’ve had great success, with almost 4 feet of buildup on our fences in a year.”

Miller and Thetford have found some differences between the patterns and materials in the last year of their research. So far, the best configuration appears to be a straight fence with a perpendicular spur behind it. The biodegradable fence, they found, lasted a year, but they are working on another biodegradable material that will stay in place longer.

But the sand architects say building dunes is only half of the task at hand. Once the miniature dunes are in place, they have to be stabilized and that calls for seaside vegetation. Trouble is, seaside plants are not exactly commercial nursery fare.

“Some of the things we needed to plant were not available commercially or were available at hefty prices. Beach rosemary, for instance, is a good dune-binding plant but can’t be found in nurseries,” Thetford said. “So we’ve had to come up with our own propagation and production techniques and are producing our own plants.

“We’ve had over 90 percent rooting success, and we’ll be putting the plants out on the dunes pretty soon,” Thetford said.

Sea oats and bitter panicum, a coastal grass, are being planted at the front of the dunes. In the rear, native trees and shrubs, such as myrtle oak and sand live oak, are being tried to hold the sand in place. All the plants will be monitored to see which survive and assist best in dune building.

“Right now, we don’t know which plants work best here, and we’re not even sure when to plant those plants. We have recommendations, but those recommendations do not come from this part of the coast,” Miller said. “So that’s part of what we’re trying to find out. When we should be planting and what we should be planting.”

In a year or two, the researchers say, they want to be able to make recommendations about the best reconstruction and replanting techniques.

“We want to learn as much as we can about dune restoration,” Miller said. “Then, after severe hurricanes like Opal, we can rapidly rebuild.”

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