Hammocks are small pieces of dry land rising out of wet marshes. Salt marsh hammocks are found in the salt marshes that are located on the southeastern coast of the United States, where tides flood the lowlands twice a day. The salinity of the water gives salt marshes their own distinct marine habitat.
Salt marshes have been developing for approximately 18,000 years as melting glaciers caused rising sea levels, flooding the shallow areas between barrier islands and the mainland. As the water receded, sand and clay sediment was left behind. Over the years, the sediment accumulated, by the continual flow and receding of tides, reaching a level where the land was exposed during low tide. The environment of the salt marsh, exposure to both salt water and air on an intermittent basis plus soil that is very low in oxygen, makes life in the salt marsh difficult. While there are very few species that live full-time in the marsh, many species visit the salt marsh for food and shelter. The twice-daily tides, coming from tidal creeks and through estuaries, provide nourishment for marsh vegetation while the receding water carries nutritious products back to the estuaries where it provides sustenance for other marine life.
While salt marshes might appear to be simple flat expanses of grass, in reality the salt marsh is divided into zones that are defined by changes in elevation. As land rises, the depth of tide water covering the land becomes shallower and the length of time the water remains grows shorter. The zones range from the levee marsh, where the soil is regularly covered with tidal salt water, to the higher salt marsh hammock, an area of dry land within the salt marsh.
Marsh hammocks are islands, dry land within a marsh. Hammocks found in a salt marsh are called salt marsh hammocks. Plants commonly found growing on the hammocks include red cedar, wax myrtle, cactus, saw palmetto, yucca and holly. Hammocks can range in size from holding just a few trees to over 1,000 acres, supporting a maritime forest.
Salt marshes can be compared to nurseries. The varying depths of the salt marsh provide a home to many marine species. Crabs, mussels and snails are found in the levee and lower areas of the marsh. The waters of the marsh provide a safe place for the young of several marine species to feed, such as shrimp and oysters, allowing them to grow before they return to the sea. Salt marsh hammocks add an important piece to this ecological system by providing a home for birds, such as the bald eagle and the barn owl; reptiles; amphibians; and mammals, such as mink and deer.
