Extensive and fragmented, these heathland areas are centred around the estuary of Poole Harbour and are adjacent to the urban conurbation of Bournemouth and Poole. The heathland contains numerous examples of wet heath and acid valley mire, habitats that are restricted to the Atlantic fringe of Europe. These heath wetlands are among the best of their type in lowland Britain. There are also transitions to coastal wetland and fen habitat types. The wetland flora and fauna includes a large assemblage of nationally rare and scarce species, especially invertebrates.
1. Contains particularly good examples of (i) northern Atlantic wet heaths with cross-leaved heath Erica tetralix and (ii) acid mire with Rhynchosporion.
Contains largest example in Britain of southern Atlantic wet heaths with Dorset heath Erica ciliaris and cross-leaved heath Erica tetralix.
2. Supports 1 nationally rare and 13 nationally scarce wetland plant species, and at least 28 nationally rare wetland invertebrate species.
3. Has a high species richness and high ecological diversity of wetland habitat types and transitions, and lies in one of the most biologically-rich wetland areas of lowland Britain, being continuous with three other Ramsar sites: Poole Harbour, Avon Valley and The New Forest.
The Dorset Heathlands cover an extensive complex of heathland sites at the western edge of the Hampshire Basin in southern England. The area is centred around the large estuary of Poole Harbour and lies in close proximity to the urban conurbation of Bournemouth and Poole. Past losses of the heathland (an estimated 75% during the 20th century to development, agriculture and afforestation) have left the remaining heaths in a highly fragmented state. Despite this decline and fragmentation, the heaths show a high degree of ecological cohesion. They contain large areas of dry heath, wet heath and acid valley mire, all habitats that are restricted to the Atlantic fringe of Europe. The examples of the Dorset Heathlands are among the best of their type in the UK. There are also transitions to coastal wetlands and floodplain fen habitats.
General ecological features
This site contains large areas of dry heath, wet heath and valley mire, and these often occur together in mosaics and zonations of heathland vegetation. Typically the wet heath occupies areas of impeded drainage on the lower valley sides and less steeply-sloping ground. The vegetation is mostly of the Erica tetralix -Sphagnum compactum type, locally characterised by Drosera spp. and Rhynchospora spp. In almost all instances the wet heath gives way to base-poor, acid mire vegetation in the valley bottoms. The mires are commonly dominated by Molinia caerulea, with scattered areas of the more floristically rich Rhynchospora alba habitat.
South of Poole Harbour, Erica tetralix is joined by Erica ciliaris, which occurs extensively and often in abundance, growing on moist soils ranging from wet heath to mire situations. Outlying stands of Erica ciliaris occur towards the north and west of the site.
In places conditions are influenced by sources of base-enriched water, giving rise to rich fens. Several types of vegetation occur, and these include valley mire communities characterised by Schoenus nigricans and, where there is livestock grazing, flood plain fen and fen-meadow characterised by Carex rostrata or Molinia caerulea - Cirsium dissectum vegetation. Adjacent to Poole Harbour there is Cladium mariscus fen and transitions to intertidal areas of Phragmites australis swamp.
Nationally important species occurring on the site.
Erica ciliaris, Cicendia filiformis, Gentiana pneumonanthe, Hammarbya paludosa, Illecebrum verticillatum, Rhynchospora fusca, Deschampsia setacea, Elatine hexandra, Isoetes echinospora, Pilularia globulifera, Lycopodiella inundata.
Sphagnum pulchrum, Sphagnum flexuosum and Cladopodiella francisci.
Species currently occurring at levels of national importance: Species regularly supported during the breeding season:
Dartford warbler , Sylvia undata, Europe 418 pairs, representing an average of 26.1% of the GB population (Three count mean 1991-2 and 1994)
Species with peak counts in winter:
Hen harrier, Circus cyaneus, Europe 20 individuals, representing an average of 2.6% of the GB population (Count as at 1991/2)
Merlin , Falco columbarius, Europe 15 individuals, representing an average of 1% of the GB population (Count as at 1991/2)
Species occurring at levels of international importance.
Southern Damselfly Coenagrion mercuriale.
Nationally important species occurring on the site. Invertebrates.
Minutest diving beetly Bidessus unistiatus, Buckleria paludum, Chrysops sepulchralis, Crambus silvella, Cryptocephalus biguttatus, Cyclophora pendularia, Donacia bicolora, Eristalis cryptarum, Formica candida (=transkaucasia), Graphoderus cinereus, Graptodytes flavipes, Heliothis maritima, Hydroporus cantabricus, Libellula fulva, Longitarsus nigerrimus, Nabis brevis, Pachybrachius luridus, Parhelophilus consimilis, Phragmataecia castaneae, Plecocera tricincta, Sphaerophoria loewi, Stenoptilia graphodactyla, Stenus kiesenwetteri, Stethophyma grossum, Tipula marginata, Zora armillata, Sedina buettneri.