Flood & coastal defence • Pollution control & water quality • Biodiversity & conservation importance • Palaeoecology & Archaeology • Designations & conservation management

Biodiversity & conservation importance

The traditional view of saltmarsh habitat centres on specialist and geographically restricted salt tolerant plant communities. The rigours of the environment, notably caused by tidal inundation, restrict the range of plants able to tolerate the changes in salinity, desiccation and mechanical abrasion. However, despite this, in suitable conditions extensive areas of vegetation can sometimes develop, particularly where there is abundant sediment and shelter to allow the settlement of suspended particles from the water column onto the tidal flats. The resulting habitat is rare (with over 44,000ha in the United Kingdom) by comparison with peatland (1,300,000ha) or ancient semi-natural woodland (350,000ha) for example, and more comparable in size to other rare habitats such as calcareous grassland (43,500ha) and sand dunes (56,000ha).

In addition to the underlying interest of the specialist vegetation, saltmarshes support large numbers of both rare and abundant invertebrates and provide feeding and roosting areas for a large number of migrant and wintering wildfowl and waders. They also form one element in the mosaic of interrelated habitats which make up one of the most productive ecosystems in the world (estuaries).

The plant community mosaics that develop are obviously of interest; however, from a nature conservation perspective, their geographical range is also significant. Saltmarshes in the UK vary in composition from north to south, providing a floristic link between the saltmarshes of the Mediterranean and the Arctic. In addition, there are east/west gradients, which together provide a further contribution to the diversity of the plant interest. Understanding these natural distribution patterns is also important in determining the significance of the factors leading to change brought about by human activities. Information is also provided on;

• Evaluation of conservation importance of saltmarsh.
• Saltmarsh as a habitat
• Geographical range of variation
• Relationship with other habitats