Wednesday, December 17, 2008

Sullivan's Island

The southern side of Sullivan's Island is growing
or accreting, while to the northeast the northern end of neighboring Isle of Palms is eroding. Property owners in Wild Dunes are
seeing their land disappear into the sea, while the Town of Sullivan's Island has seen its property expand by approximately 200 acres. The march of sand from the northern end to the southern end has been a characteristic of barrier islands ever since there were barrier islands along our nation's southeastern coast. This movement of sand, due to a combination of longshore current and the angle that waves tend to hit the beach, was not a concern of humans until humans began to construct homes on the barrier islands.

The mission of the National Audubon Society "is to conserve and restore natural ecosystems, focusing on birds, other wildlife, and their habitats for the benefit of humanity and the earth's biological diversity." No plants have
adapted to grow at the beach/ocean interface, but just inland from that interface, plants can begin to take hold. Decaying smooth cordgrass (Spartina alterniflora) from marshes (often located between barrier islands and the mainland) is washed onto the beach where it forms a wrack line at the high tide line. Windblown sand begins to accumulate around the wrack line along with plant seeds, which find the perfect mulch in the decaying spartina. As plants begin to grow, their roots provide an anchor in the shifting sand, which continues to accumulate around the base of the plant. Slowly, a more stable zone begins to form and larger plants, including trees, can take root. This is what has occurred on the southern face of Sullivan's Island although not all of the accreted land has been treated in a similar fashion. Some homeowners have cut the vegetation to a height of six feet in the 200-yard stretch between their homes and the beach. Note the shadows in the forest to the left and right of the push pin denoting higher vegetation in the form of trees and the lack of shadows throughout the swath surrounding the push pin.

Although this severe pruning maintains a view of the ocean, it significantly degrades the habitat and prevents the natural development of the maritime forest. Maritime forests absorb much of the heat on barrier islands and offer protection from extreme temperatures, an abundance of food, and nesting areas to a variety of organisms. Low-lying areas of the maritime forest trap and hold rainwater and are thus a source of fresh water for many inhabitants. (Of Sand and Sea: Teachings From the Southeastern Shoreline, Paula Keener-Chavis & Leslie Reynolds Sautter, 2000, p. 63) These maritime forests are critical stop-over sites for migrating birds, especially as similar sites along our coast disappear to development.

Audubon South Carolina supports efforts on Sullivan's Island to protect the vital maritime forest and dune habitats for birds and other wildlife.

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