This report provides information on the structure and functions of saltmarsh, a habitat previously regarded as wasteland but which is now valued for its wide range of functions in relation to sea defence, nature conservation and supporting life in adjoining ecosystems.

 

The vertical development of the saltmarsh is dependent on the velocity of the water flow over the marsh. A cover of vegetation can have a major effect on marsh development by reducing the velocity and thus enhancing the deposition of sediment and reducing the possibility of sediment erosion.

 

Fluxes of organic matter, sediment and mineral nutrients can occur in most if not all saltmarshes. Generally young marshes will import nutrients but the nutrient reserves of older marshes are sufficient for there to be nutrient exports. Mature marshes can also export organic matter and if saltmarsh degeneration occurs they can release sediment.

 

A description is given of the history of the classification of British saltmarsh vegetation up to and including the development and application of the National Vegetation Classification. The 28 NVC communities making up the British saltmarsh vegetation are considered both in relation to the key plant species involved and in relation to factors affecting their distribution.

 

Sea level rise will increase the possibilities of both accretion and erosion with the whole coastal system becoming more dynamic. Climatic changes are likely to affect both the growth of saltmarsh plant species and their overall distribution. The ability of saltmarsh to adjust to climate change will be limited by the disjunct distribution of saltmarshes.

 

The coastline has seen widespread development with the spread of transport, industrial, residential and recreational facilities and all the associated infrastructure. In some cases the whole character of the estuary, including its geomorphology, has been changed as a result of large-scale reclamation and development.

The importance of monitoring rates of change and of developing suitable management techniques is emphasised. The first step in any programme for monitoring saltmarsh change is the establishment of detailed baselines against which future changes can be assessed. Baselines are needed both as the reference point for any monitoring programme and for making management decisions on the basis of that monitoring.

 

Suggestions are made regarding the possibilities for the development of advanced computer techniques for the formulation and application of saltmarsh management through the seamless integration of scientific data and saltmarsh process models within a Decision Support System (DSS).

The creation of new saltmarsh is likely to play an increasingly important role in the management of the coastal zone.

 

A number of specific research proposals are made relating to the effective management and creation of saltmarshes and saltmarsh ecosystems.