The main coastal habitats are estuaries, marshes, cliffs, beaches and dunes, rocky shores and intertidal platforms. Underwater, there is an equally diverse and fascinating range of habitats and species (see Marine Ecology). Much of the coast is designated for its conservation importance, including European Special Protection Areas (SPA) and Special Areas of Conservation (SAC).

Many of Dorset’s rivers flow into estuaries. Some are very small and mostly reclaimed: e.g. the Brit at West Bay. Weymouth is now mainly an artificial shoreline, but reed swamps occur upstream at Radipole. Poole Harbour is large (over 3000 hectares) with extensive mudflats and salt marsh, much having been reclaimed around Poole and in the lower Frome and Piddle valleys. The salt marshes expanded most in the early 20th century when Spartina anglica colonised Poole Harbour. Many of the charts and aerial photographs show the changes in the marshes and channels particularly well.

Aerial Photograph of Wytch Heath (BUL).

There are some coastal freshwater lakes, such as Burton Mere, which were once part of a lagoon like the Fleet. The Fleet is Britain’s largest coastal lagoon.

Much of the Dorset coast is cliffed: low cliffs occur even around Poole Harbour and the Fleet. The cliffs are very important habitats. Taylor’s 1765 One Inch Scale map of Dorset shows well the pattern of woods and other features of the coastal landscape. Many of Dorset’s rarest plants are found on the cliffs, for example Nottingham Catchfly, Portland Spurge, Early Spider Orchid and Stinking Goosefoot. The cliffs are also the home for many birds, including Puffins, Guillemots, Rock Pipits and Peregrine Falcons.

The cliffs and undercliffs are one of the most natural habitats in Britain, home of Sand Lizards and one of our rarest butterflies, the Lulworth Skipper. The cliffs at Bournemouth and Poole, and to a lesser extent at Weymouth, have been planted with species which include pines, Ice Plant and Marram.

Examples of the cliff landscape prior to planting.

Watercolour painting of "The Water Chine" by Capt. John Vine-Hall (RCAGM).

Photograph of West Cliff in 1895 (BBC).

At Bournemouth, shrubs such as Euonymous japonica and Sallow were planted to provide stability to terraced and graded cliffs. At Highcliffe Castle, Holm Oaks were planted in the 19th century by Lady Bute. Extensive planting of salt-resistant grasses and shrubs formed part of the 1970s and 1980s coast protection scheme at Highcliffe.

The most important sandy beaches occur at Mudeford spit, Sandbanks and Studland. At Studland, the largest area of sand dunes on the south coast of England, accretion has taken place in cliff-foot dunes, spit and ridge development over the last 500 years. For the earliest detailed map of Studland, see Treswell's survey of 1585-6. The dune ridges are separated by lower brackish or fresh water environments. The most important shingle beach is Chesil beach, but rare species such as Shrubby Sea Blite grow on smaller gravel beaches for example within Poole Harbour.

There are extensive rocky shores beneath many of the cliffs and wide rock platforms at Kimmeridge and Lyme Regis (for more details see Marine Ecology).

Anita Diaz and Vincent May