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. 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. In addition to this it has helped contribute towards the monitoring of Special Area of Conservation, which includes: Carmarthen Bay and Estuaries / Bae Caerfyrddin ac Aberoedd; Glannau Môn: Cors heli / Anglesey Coast: Saltmarsh; Pembrokeshire Marine / Sir Benfro Forol; Pen Llyn a`r Sarnau / Lleyn Peninsula and the Sarnau; Dee Estuary / Aber Dyfrdwy and Severn Estuary / Môr Hafren. The surveys were conducted between 1990 and 2003. The dataset has been extensively validated and verified. Data collected by trained personnel, digitised by contractors, validated by NRW KMG, corrections made by contractors, validated again by NRW KMG, corrections made in-house in conjunction with relevant salt marsh specialist.
