Southern Chalk BCA

Biodiversity Character Areas have been developed by DERC to sit alongside Landscape Character Areas. They describe the landscape type and land use, main semi-natural habitats present and highlight species, species assemblages and features of particular interest.

Click here for a list of Key Species

The South Dorset Ridgeway is an open chalk landscape renowned for its abundance of Prehistoric monuments dating from the Neolithic. Maiden Castle is the largest Iron Age Hill Fort in Britain, and there are large ‘Celtic’ field systems at Newlands Warren and Valley of Stones. Protection of these features has also benefited biodiversity.

Inland unimproved downland is largely restricted to the steep slopes such as White Horse Hill and around Little Bredy. The turf sees a gradual shift from Sheep’s Fescue–dominated turf above the Bride Valley to Tor-grass–dominated swards near to, and along, the coast. Tor-grass is the larval foodplant of the Lulworth Skipper butterfly which is confined to Dorset and locally frequent on the coastal chalk. Shorter turf is favoured by Adonis Blue and Dingy Skipper.

The most connected area of chalk is that between White Nothe and Lulworth Cove where there is a variety of sward heights and it has the added interest of the coastal chalk which supports specialities including Nottingham Catchfly, Shaggy Mouse-ear Hawkweed and the endemic Dorset Sea-lavender. There is a more varied geology around Durdle Door and Mupe with small sections of slumping Wealden cliffs supporting an interesting invertebrate fauna. To the west, the change in geology from chalk through Greensand and Gault to Kimmeridge, the rotational landslips have produced a wild undercliff below White Nothe with a mosaic of grassland, scree, scrub and small wetlands with a diverse flora and fauna.

Around Bronkham Hill and Blackdown there is an outlying outcrop of the Poole Formation giving rise to acid grassland and heathland within an otherwise chalk landscape, the heath vegetation on Blackdown is unusual in Dorset in having an abundance of Bilberry. Acid grassland in the area has a rich assemblage of grassland fungi including a number of nationally uncommon species not known elsewhere in Dorset. 

There is very little ancient woodland in the area but there are extensive plantings around manor houses dating from the 19th and early 20th Century. As these plantations mature some of the trees are developing features of veterans and gaining species associated with deadwood features. There are also plantings of individual or small groups of trees in fields which support an important assemblage of epiphytic lichens.

The Southern Chalk BCA includes the Dorchester Downs (open chalk downland), South Dorset Downs (open chalk downland), Chaldon Downs (open chalk downland), South Dorset Escarpment (chalk ridge/escarpment) and West Dorset Escarpment (chalk ridge/escarpment) Landscape Character Areas and covers 16,660 hectares.

Summary of Key Features

  • Internationally important coastal chalk downland and chalk cliffs between Lulworth Cove and White Nothe with a very rich flora and fauna
  • Unimproved chalk downland on steep slopes inland, also on the ramparts of ancient monuments such as Maiden Castle
  • Stands of acid grassland and heathland on acid soils and superficial deposits around Abbotsbury Castle, Blackdown, Bronkham Hill and Valley of Stones
  • Nationally important clusters of Sarsen Stones in grassland around Portesham with specialised assemblages of bryophytes and lichens
  • South Winterbourne chalk stream
  • Landscape parklands around manor houses with veteran trees that support rare epiphytic lichens

Issues:

  • Lack of appropriate grazing to maintain the grassland habitats and species they support
  • Continuing decline of farmland birds and arable flora
  • Loss of field and pasture trees and lack of replacement
  • Enrichment of watercourses

Species assemblages of importance within the BCA

  • Plants of short, open chalk & limestone grassland
  • Bryophytes & lichens of short, open chalk & limestone grassland
  • Bryophytes & lichens of sarsen stones
  • Invertebrates of open, species-rich calcareous grassland
  • Butterflies and day-flying moths of chalk & limestone grassland
  • Grassland bees & bumblebees
  • Invertebrates of species-rich scrub & scrub edges
  • Plants of cliffs ledges & maritime grassland
  • Invertebrates of open sand & clay on slumping soft cliffs
  • Lichens & bryophytes of slumping clay & sand cliffs
  • Fungi of ancient and unimproved grasslands
  • Invertebrates of bare ground on sandy & clayey heaths
  • Plants of open, parched acid grassland
  • Breeding farmland birds
  • Wintering farmland birds
  • Lichens, fungi & bryophytes of mature and veteran wayside & pasture trees
  • Lichens & bryophytes of churchyards