Dorset Heaths (Purbeck and Wareham) and Studland Dunes SAC 

General site character

Coastal sand dunes, Sand beaches, Machair (5%)

Inland water bodies (Standing water, Running water) (4%)

Bogs, Marshes, Water fringed vegetation, Fens (8%)

Heath, Scrub, Maquis and Garrigue, Phygrana (79%)

Dry grassland, Steppes (1%)

Broad-leaved deciduous woodland (1%)

Coniferous woodland (1%)

Mixed woodland (1%)

Habitats that are a primary reason for selection of this site:

Embryonic shifting dunes.

Embryonic shifting dunes initiate the very clear successional sequence of dune communities at Studland Dunes, which are representative of the habitat type in southern England. This is a part of the UK where this habitat type is rare, partly owing to intensive recreational use of the coast. The site is also of interest in that there are well-developed examples of both sand couch Elytrigia juncea and lyme-grass Leymus arenarius dominated communities. The former occurs discontinuously along the whole shoreline, while the latter is locally abundant in disturbed locations at the northern end of the site.

"Shifting dunes along the shoreline with Ammophila arenaria "white dunes"

Studland Dunes represents shifting dunes along the shoreline in southern England. Shifting dunes form one part of the very well-marked successional sequences. The seaward dune ridge supports marram Ammophila arenaria vegetation mainly of Ammophila arenaria mobile dune, Festuca rubra sub-community, though three other types are represented. There are transitions to embryonic dunes, which are rare on the south coast partly because of intense recreational pressure, and extensive transitions to decalcified fixed dunes and dune heath.

Atlantic decalcified fixed dunes (Calluno-Ulicetea)  * Priority feature.

Studland Dunes comprises the only large dune heath site in the south and south-west of Britain. The heathland occupies a series of dune ridges, which have developed over a period of several hundred years. The development of these ridges was the subject of a classic study (Diver 1933) and the processes are still active today. Structure and function of the dune heath communities are therefore well-conserved. The dry open heath is an important habitat for rare reptiles such as sand lizard Lacerta agilis. At the western margin of the dune ridges the dry dune heath grades into wet heath in which cross-leaved heath Erica tetralix is prominent, while at the northern end it grades into the southern heathland types of inland Dorset.

Humid dune slacks.

Studland Dunes is a large acidic dune system in south-west England with well-conserved structure and function. The site has been intensively studied. The structure and function of dune systems are well-represented with dune-building processes still active. These processes have resulted in the formation of acidic humid dune slack communities with a high water table, which lie in the parallel hollows between the dune ridges. In these slacks, acidic fen and reed beds have developed. Some areas are dominated by grey willow Salix cinerea and birch Betula sp. carr with the very local royal fern Osmunda regalis a conspicuous element. The dune slacks are linked to an area of open fresh water known as the Little Sea.

Oligotrophic waters containing very few minerals of sandy plains (Littorelletalia uniflorae)

Little Sea is a shallow lake at Studland Dunes in south-west England. It is of recent origin (<500 years old), formed as a large body of seawater became landlocked by the growing sand dunes (hence the name Little Sea). This water is now fresh and is replenished by acidic, oligotrophic water draining off the adjacent heathland, which then flows through the dune slacks and into the sea. The submerged vegetation is characterised by communities of alternate water-milfoil Myriophyllum alterniflorum, shoreweed Littorella uniflora and spring quillwort Isoetes echinospora, together with bladderwort Utricularia australis and less frequently six-stamened waterwort Elatine hexandra.

Northern Atlantic wet heaths with Erica tetralix.

The two Dorset Heaths SACs, together with the New Forest (also in southern England), contain a large proportion of the total UK resource of lowland northern Atlantic wet heaths. The habitat is of the Erica tetralix Sphagnum compactum wet heath type and occurs as well-developed transitions between dry heath and valley bog. This habitat type is important for rare plants, such as marsh gentian Gentiana pneumonanthe, brownbeak-sedge Rhynchospora fusca and great sundew Drosera anglica. The wet heaths and mires are also important for scarce Odonata, such as small red damselfly Ceriagrion tenellum and the Annex II species Southern damselfly Coenagrion mercuriale. The sites are an important transitional area between the more oceanic heathlands of the south-west peninsula and the semi-continental heathlands of eastern England.

Temperate Atlantic wet heaths with Erica ciliaris and Erica tetralix  * Priority feature.

The greatest concentration of Dorset heath Erica ciliaris in the UK is in Dorset on the heaths south of Poole Harbour, with outlying stands elsewhere in Dorset. Dorset Heaths (Purbeck and Wareham) and Studland Dunes has therefore been selected as it contains a high proportion of the total UK population of E. ciliaris.

European dry heaths.

This site in southern England has extensive stands of lowland dry heath vegetation. The types include Calluna vulgaris Ulex minor heath, Ulex minor – Agrostis curtisii heath and some areas of Ulex gallii – Agrostis curtisii heath. The communities are dominated by heather Calluna vulgaris growing in association with bell heather Erica cinerea and one of the dwarf gorse species – dwarf gorse Ulex minor or western gorse U. gallii. The heaths are rich in rare plants, invertebrates, birds and reptiles. Both of the Dorset Heath SACs and the New Forest are in southern England. All three areas are selected because together they contain a high proportion of all the lowland European dry heaths in the UK. There are, however, significant differences in the ecology of the two areas, associated with more oceanic conditions in Dorset and the continuous history of grazing in the New Forest.

Depressions on peat substrates of the Rhynchosporion.

The two Dorset Heaths cSACs, together with the New Forest, support a large proportion of the resource of Depressions on peat substrates of the Rhynchosporion within England. The habitat is widespread on the Dorset Heaths, both in bog pools of valley mires and in flushes. There are numerous valley mires within the Dorset Heaths, and the habitat type is most extensively represented here as part of a habitat mosaic. This location shows extensive representation of brown-beak sedge Rhynchospora fusca and is also important for great sundew Drosera anglica and bog orchid Hammarbya paludosa.

Bog woodland  * Priority feature.

The Dorset Heaths contain small pockets of wet woodland within valley mires but most of these appear to be of recent origin. However, at Morden Bog a Bog woodland stand is of ancient origin, as shown by its pollen record and old maps. The woodland is dominated by downy birch Betula pubescens with a ground flora consisting of greater tussock sedge Carex paniculata and purple moor-grass Molinia caerulea. There is a rich epiphytic lichen assemblage, again indicating the persistence of this area of bog woodland.

Annex I habitats present as a qualifying feature, but not a primary reason for selection of this site

Molinia meadows on calcareous, peaty or clayey-silt-laden soils (Molinion caerulea)

Calcareous fens with Cladium mariscus and species of the Caricion davallianae  * Priority feature.

Alkaline fens.

Old acidophilous oak woods with Quercus robur on sandy plains.

Species that are a primary reason for selection of this site:

Southern damselfly  Coenagrion mercuriale.

This site in southwest England, along with Dorset Heaths, represents the Dorset stronghold of southern damselfly Coenagrion mercuriale. The large size of the two cSACs, and a long history of records indicating well-established populations, should ensure the future viability of the small populations that occur here.

Species present as a qualifying feature, but not a primary reason for site selection:

Great crested newt  Triturus cristatus.

 

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