Habitat and ecosystem transitions

Coastal habitats rarely exist in isolation. In fact many coastal systems are made up of a complex of individual habitats. Shingle structures, may enclose and shelter tidal areas. This in turn can create conditions where sediment is deposited. Saltmarsh succession occurs as plants become established. These help to trap new sediment, raising the level of the marsh to a point where the tidal influence is limited or non-existant. A similar sequence can be defined for sand dunes when sand grains are blown inland. Sand dune succession occurs as vegetation helps the build up of sand and grassland, heath and finally woodland may develop. These processes and those for reedbed and shingle appear at any one time as transitions. At their margins these transitions can be particularly rich in species. Examples include the high level saltmarsh communities, which have a much wider range of plants and animals than earlier stages of succession (as is exemplified by the Natura 2000 communities). Where freshwater seeps onto the marsh transitions to reedbed may occur introducing a further element of biodiversity. These can, in their turn exist in an number of complex reedbed forms with a further range of species.