Area: 217.6 hectares.
Boundary amended by extension and deletion. Previously known as Haresdown and Knowstone Moors SSSI.
Reasons for Notification:
This is the largest area of diverse lowland-heathland remaining in North Devon. It supports both species-rich and species-poor heaths and some plant associations that are nationally rare. The rich flora and fauna include several uncommon and local species. The site represents a habitat that used to be widely distributed in England but is now very local and confined to the south-west.
The heathland overlies the Culm Measures which give rise to nutrient-poor acidic, impermeable soils with local base-rich areas. Much of the vegetation consists of species-rich, wet, dwarf-shrub heath dominated by purple moor-grass Molinia caerulea, with cross-leaved heath Erica tetralix, ling Calluna vulgaris and western gorse Ulex gallii sub-dominant. Other species include heath grass Danthonia decumbens, bristle bent Agrostis curtisii, devil’s-bit scabious Succisa pratensis, bog asphodel Narthecium ossifragum and heath-spotted orchid Dactylorhiza maculata subsp. ericetorum. A moss layer dominated by Sphagnum occurs over most of the area with S. papillosum and S. compactum being the commonest species.
Drier areas support habitats which range from species-poor dwarf-shrub heath, to more diverse heathland communities with common tormentil Potentilla erecta, heath grass, saw-wort Serratula tinctoria, sneezewort Achillea ptarmica, bell heather Erica cinerea, meadow thistle Cirsium dissectum, velvet bent Agrostis canina, sheep’s fescue Festuca ovina and lousewort Pedicularis sylvatica. In these drier areas the moss layer is poorly developed; there are small areas of bracken Pteridium aquilinum and gorse Ulex europaeus.
Draining down the slopes to the River Sturcombe and a number of smaller streams which cross the site, are a number of flushes dominated by purple moor-grass with soft-rush Juncus effusus and sharp-flowered rush J. acutiflorus as sub-dominants. Associated species include wild angelica Angelica sylvestris, creeping bent Agrostis stolonifera, marsh thistle Cirsium palustre, bog violet Viola palustris, marsh bedstraw Galium palustris, ivy-leaved bell-flower Wahlenbergia hederacea and floating sweet-grass Glyceria fluitans. Bottle sedge Carex rostrata is locally abundant in the flushes on Rackenford Moor, growing in and amongst the purple moor-grass tussocks. The lower slopes of Rackenford Moor support scattered clumps of grey willow Salix cinerea and in the valley bottoms are small stands of the greater tussock-sedge Carex paniculata associated with mineral-rich ground water welling up to the surface.
Bog communities also occur, with bogbean Menyanthes trifoliata, bog pimpernel Anagallis tenella, white beak-sedge Rhynchospora alba, star sedge Carex echinata, common sedge C. nigra, marsh St John’s-wort Hypericum elodes and the insectivorous round-leaved sundew Drosera rotundifolia and pale butterwort Pinguicula lusitanica.
A rich invertebrate fauna has been recorded here including the local small pearl-bordered fritillary Boloria selene, pearl-bordered fritillary Boloria euphrosyne, silver-washed fritillary Argynnis paphia, marsh fritillary Eurodryas aurinia, green hairstreak Callophrys rubi, purple hairstreak Quercusia quercus, marbled white Melanargia galathea, grizzled skipper Pyrgus malvae butterflies the silver-studded blue butterfly Plebejus argus and the nationally scarce weevil Apoderus coryli.
The site supports an excellent complement of lowland breeding birds including curlew Numenius arquata, lapwing Vanellus vanellus and nightjar Caprimulgus europaeus. Wintering birds include Jack snipe Lymnocryptes minimus and woodcock Scolopax rusticola. The common lizard Lacerta vivipara, common toad Bufo bufo, common frog Rana temporaria and adder Vipera berus have all been recorded. Red deer Cervus elaphus are found in the area.