Area: 67.6 hectares.
The site is within the Dartmoor National Park.
Description and Reasons for Notification:
The site is a mixed valley mire containing a number of species rich communities of limited extent and distribution in Britain. It contains a complete transition of habitats from dry unimproved grassland through wet heath into mire itself.
Blackslade Mire is located near to the eastern limit of the Dartmoor Granite outcrop, remote from other mires of this type on the moor, at an altitude of approximately 400 metres. It is situated at the head of a valley and receives run off from the surrounding slopes.
The vegetation within the mire is a complex mosaic of soligenous mire types, characterised by a through flow of water, together with open bog pools. The soligenous mires have abundant soft rush Juncus effusus and sharp-flowered rush J. acutiflorus and bog mosses principally Sphagnum fallax, S. auriculatum, S. papillosum, S. capillifolium and S. pulchrum, together with a wide variety of herb species, especially in the areas of shorter vegetation. These herbs include bog asphodel Narthecium ossifragum, round-leaved sundew Drosera rotundifolia, bog pimpernel Anagallis tenella, pale butterwort Pinguicula lusitanica, several sedges mainly star sedge Carex echinata, common sedge Carex nigra, carnation sedge C. panicea and ivy-leaved bellflower Wahlenbergia hederacea. The bog pools characteristically contain abundant bog pondweed Potamogeton polygonifolius, bogbean Menyanthes trifoliata, marsh pennywort Hydrocotyle vulgaris, marsh lousewort Pedicularis palustris, marsh St John’s-wort Hypericum elodes and floating club-rush Eleogiton fluitans.
The surrounding wet heath has dwarf shrubs such as western gorse Ulex gallii, heather Calluna vulgaris, cross-leaved heath Erica tetralix, together with common cottongrass Eriophorum angustifolium and hare’s-tail cottongrass E. vaginatum. The dwarf shrub species form a mosaic with unimproved acidic grassland further up the valley sides with abundant purple moor-grass Molinia caerulea, bristle bent Agrostis curtisii, mat-grass Nardus stricta, green-ribbed sedge Carex binervis and heath rush Juncus squarrosus and many acidophilous herbs.