This National Vegetation Classification (NVC) Phase 2 project and corresponding datasets are a collation of mapped saltmarsh habitats across Wales. This data was collected to provide an overview of saltmarshes across Wales. The surveys were conducted between 1990 and 2003. The dataset has been extensively validated and verified. However, habitat composition may change over time due to successional trends, land management or even planned developments. A record of a vegetation type or species in the digital data is therefore no guarantee that it is still extant on the ground.
Coastal saltmarshes in the UK comprise of the upper, vegetated portions of intertidal mudflats, lying approximately between mean high water neap tides and mean high water spring tides. Saltmarshes are usually restricted to comparatively sheltered locations in five main physiographic situations: in estuaries, in saline lagoons, behind barrier islands, at the heads of sea lochs, and on beach plains. The development of saltmarsh vegetation is dependent on the presence of intertidal mudflats. Communities are additionally affected by differences in climate, the particle size of the sediment and, within estuaries, by decreasing salinity in the upper reaches.
