Although sand dune systems are well represented around the Welsh coastline, they are much less well represented in Europe as a whole. The most important sites are located mostly along the Atlantic coast, i.e. in the UK, France, and Spain, and in The Netherlands. Virtually all phases of dune development are listed in Annex I of the EC Habitats Directive as threatened in Europe. The key dune habitats, and their reference ans modified states where relevant are described in the sections below.