A Spatially Explicit Model of Vegetation-Habitat Interactions on Barrier Beaches

ISLAND is a model designed to simulate annual changes in vegetation, geomorphology, water table depth, and average ground water salinity on a cross-sectional transect, running from ocean to lagoon, on a barrier beach. The model is composed of three submodels; (1) a vegetation submodel which simulates the development of a four "species" plant community consisting of two grasses, an annual and a perennial shrub, (2) a geomorphology submodel which simulates the redistribution of sand by water and wind, and (3) a ground water submodel which simulates the average depth of the water table and the salinity of the ground water. Information calculated in each of the submodels is reevaluated and made available to the other submodels after each time iteration. The model works on a one year time step and acts on five meter sections along the transect. It is assumed that each five meter section is homogeneous with respect to vegetation, height above sea level, water table depth, and ground water salinity.