Maritime grassland typically forms a fairly narrow band of habitat, sometimes no more than a few metres wide, between the rocks and cliffs of rocky shorelines and the less exposed grasslands and heaths further inland. The extent of the habitat can vary from year to year, depending on the degree of salt deposition during winter storms, which also limits the species composition to a relatively small number of salt-tolerant species (halophytes). As such, the habitat is invariably species-poor, and can be totally dominated by one or two species, such as red fescue (Festuca rubra), Plantago marittima, Plantago coronopus and Armeria maritima. The structure can vary considerably, however, from a closely cropped sward where sheep and rabbits graze, to a sward dominated by robust cushions of red fescue and little else. The most likely factors determining the structure of the sward are salt deposition, wind exposure, soil depth and grazing management. The three reference states are described below.