Coastal Zone Restoration

Abstract

Coastal dunes and wetlands are dynamic ecosystems that exist at the interface between land and sea. The coastal environment is harsh. Dunes are buffeted by wind, salt spray, sandblast, and temperature extremes. Tidal wetlands are exposed to wave action, inundation that promotes soil anoxia, and salinity. Also, soils of dunes and tidal wetlands are low in nitrogen which limits plant growth. Dunes depend on a supply of sand, carried off the beach by onshore winds, and vegetation to catch the sand. Dune restoration involves placing a sand fence, woody brush, or some other obstacle to catch the sand initially, and vegetation to stabilize it. In the foredune zone, where sand actively accumulates, beach grass ( Ammophila sp.) and other species are planted to trap sand and hold it in place. Over time, the dune grows in size and woody vegetation colonizes the rear dune and initiates soil formation. Restoration of tidal marshes and mangroves usually involves planting vegetation, often Spartina spp., in the appropriate hydroperiod and salinity regimes, and time for vegetation to spread and cover the site. Restoration of wetland-dependent functions depends on accumulation of sufficient soil organic matter to support biogeochemical processes and food webs which takes about 5–15 years.