Salt marshes are areas of periodically flooded low-lying coastal wetlands. They are often rich in plants, birds and animals.

A salt marsh begins life as an accumulation of mud and silt in a sheltered part of the coastline for example in lee of a spit or bar. As more deposition takes place, the mud begins to break the surface to form mudflats. Salt-tolerant plants such as cordgrass soon start to colonise the mudflats. These early colonisers are called pioneer plants. Cordgrass is tolerant of the saltwater and its long roots prevent it from being swept away by the waves and the tides. Its tangle of roots also helps to trap sediment and stabalise the mud.

As the level of the mud rises, it is less frequently covered by water. The conditions become less harsh as rainwater begins to wash out some of the salt and decomposing plant matter improves the fertility of the newly forming soil. New plant species such as sea asters start to colonise the area and gradually, over hundreds f years, a succession of plants develops. This is known as a vegetation succession.

Salt Marsh Vegetation Succession


Case study: Keyhaven Marshes
Make sure you can describe the threats to the ecosystem and management options there.