Area: 18.3 hectares.
Description and Reasons for Notification:
This site displays a range of herb-rich mire and swamp communities, several of which are nationally scarce and restricted to southwest Britain. Several local plant species are also present.
Situated approximately 8 km from the coast and at an altitude of 120 metres, the site is subject to a strong oceanic climate. It occupies a gently sloping valleyside and flood plain of the upper reaches of the River Tamar. The clays derive from Carboniferous sediments and provide a slowly permable soil with attendant seasonal water-logging.
The low-lying wettest parts of the site support a mosaic of marshland plant communities. Here meadowsweet Filipendula ulmaria, wild angelica Angelica sylvestris, rushes Juncus effusus and J. acutiflorus, branched bur-reed Sparganium erectum and marsh marigold Caltha palustris are abundant, the last forming distinct sands in places. These species are accompanied by many others, including frequent horsetails Equisetum spp, greater bird’s-foot-trefoil Lotus pedunculatus, common valerian Valeriana officinal water mint Mentha aquatica and marsh cinquefoil Potentilla palustris. Beds of bladder-sedge Carex vesicaria, common sedge C. nigra, greater tussock-sedge C. paniculata and wood club-rush Scirpus sylvatica have developed in places, while the presence of yellow iris Iris pseudacorus and parsley water-dropwort Oenanthe crocata is indicative of the oceanic influence. wood club-rush, bladder-sedge and marsh cinquefoil are all uncommon plants in Devon, while the wavy St John’s-wort Hypericum undulatum which also occurs is nationally scarce.
In several places on the valley side quaking bogs have formed. These are characterised by a dominance of bog-mosses Sphagnum spp and the moss Aulacomnium palustre. Herbs include abundant bogbean Menyanthes trifoliata, star sedge C. echinata, marsh lousewort Pedicularis palustris and common cottongrass Eriophorum angustifolium. Roundleaved sundew Drosera rotundifolia, marsh violet Viola palustris, marsh pennywort hydrocotyle vulgaris and heath spotted-orchid Dactylorhiza maculata are frequent associates.
On slightly drier ground a rough grassland community occurs with a tussocky growth of purple moor-grass Molinia caerulea being dominant, with frequent meadow thistle Cirsium dissectum, devil’s-bit scabious Succisa pratensis, fen bedstraw Galium uliginosum, saw-wort Serratula tinctoria and sneezewort Achillea ptarmica. A heathy element is represented by occasional heather Calluna vulgaris, cross-leaved heath Erica tetralix and creeping willow Salix repens.
A further plant community present on the site is a type of rush pasture, where grasses such as bents Agrostis spp, sweet vernal-grass Anthoxanthum odoratum and Yorkshire fog Holcus lanatus are interspersed with rushes Juncus spp. Herbs such as cuckooflower Cardamine pratensis, bitter-vetch Lathyrus montanus, common marsh-bedstraw Galium palustre and ragged-robin Lychnis flos-cuculi are found here together with abundant whorled caraway Carum verticillatum, a local plant in Devon.
Otters Lutra lutra frequent the river bank, while breeding birds include tree pipit Anthus trivialis and reed bunting emberica schoeniclus.