Sand dunes
Sand dunes develop behind large sandy beaches, which dry out at low tide allowing sand grains to be blown landward. Sand dunes are a dynamic habitat between coast and dry land. They range from embryonic and mobile dunes on the seaward side of the dune system to fixed or “grey” dunes that have been stabilised by plant roots. Marram grass plays a vital role in the colonisation and stabilisation of sand dunes. Grey dunes are then colonised by a range of drought-tolerant species. On older dunes, calcium may be leached out of the soils, leading to the development of acid dune grassland or dune heath. In wet depressions between dune ridges, dune slacks may develop which are often characterised by creeping willow and species of moss. Coastal grasslands occur to the leeward side of sand dunes and have a specialised calcareous and salt-tolerant species.
Sand dunes are widely distributed around the UK coast, covering approximately 12,000ha. In the Tees Valley, many of the sand dune systems are of national conservation importance, with approximately 88% of the 262 total designated as Sites of Special Scientific Interest (SSSI). The species rich coastal grassland is of local conservation importance. Key sites include Hart Warren Dunes, North Gare and Seaton Sands, South Gare and Coatham Sands.
