Area: 687.3 hectares
Description and Reasons for Notification:
The Lynher estuary forms the western arm of the Tamar-Tavy-Lynher drowned river valley (ria) complex lying west of Plymouth. Unusually for a ria system the Lynher Estuary has developed, particularly on its northern shores, fairly extensive saltmarsh, which together with the adjacent highly productive mud flats provide important feeding and roosting grounds for large populations of wintering wildfowl and waders. In addition, freshwater input from the rivers Tiddy and Lynher give rise to a gradient of salinity along which transitional marsh communities have developed ranging from saltmarsh to freshwater fen and willow carr. Elsewhere exposures of Devonian slate support fringing brown-algal beds, backed by narrow shale beaches and low rock cliffs with stunted trees and scrub. Sheviock and Wacker Woods are important remnants of former extensive ancient woodland.
A variety of salt marsh vegetation communities are found on the Lynher Estuary. These range from pioneer stands of Townsend's cord-grass Spartina townsendii and sea aster Aster tripolium through lower-mid marsh with common saltmarsh-grass Puccinellia maritima and sea-purslane Halimione portulacoides, to mid-upper marsh and transition fresh-water inundation communities. The largest and most diverse stands, exhibiting a range of structural characteristics are the areas of mid-upper marsh, as seen around Erth Island, where common saltmarsh-grass, sea club-rush Scirpus maritimus, saltmarsh rush Juncus gerardi and English scurvygrass Cochlearia anglica are frequent with scattered sea-milkwort Glaux maritima, sea plantain Plantago matitima, sea arrowgrass Triglochin maritima and long-bracted sedge Carex extensa. Higher parts are dominated by sea rush Juncus maritimus and red fescue Festuca rubra, whilst thrift Armeria maritima flourishes in old salt-pans. Of particular note is the presence of the locally distributed parsley water-dropwort Oenanthe lachenalii. Sea couch Elytriga atherica forms a distinct drift line and fresh water inlets support yellow iris Iris pseudacorus and hemlock waterdropwort Oenanthe crocata.
Further up river, as salinity decreases the marshes become progressively less species rich and are dominated by creeping bent Argostis stolonifera with patches of sea aster and sea club-rush. Important populations of the nationally rare bulbous foxtail Alopecurus bulbosus thrive here. Eventually, freshwater inundation communities occur with fool's water-cress Apium nodiflorum, marsh marigold Caltha palustris, common reed Phragmites australis and bulrush Typha latifolia. Small areas of willow Salix spp carr complete the transition.
The ancient woodlands of Sheviock and Wacker are dominated by coppiced sessile oak Quercus petraea over a holly Ilex aquifolium and hazel Corylus avellana understorey with frequent bramble Rubus fruticosus. The ground flora on these acidic soils consists largely of great wood-rush Luzula sylvatica with bluebell Hyacinthoides non-scripta and occasional bilberry Vaccinium myrtillus and heather Calluna vulgaris.
The Tamar-Tavy-Lynher complex is of national importance for its wintering populations of around 6,000 wildfowl and 10,000 waders. The extensive Lynher Estuary marsh system provides important roosting areas for up to 5,000 wigeon Anas penelope which feed on the eel grass Zostera spp beds on nearby St John's Lake. Teal Anas crecca, mallard A. platyrhynchos, shelduck Tadorna tadorna and pintail Anas acuta all occur in high numbers. The soft mud flats attract a nationally important population of black-tailed godwit Limosa limosa which regularly winter in numbers up to 150, 3–4% of the British wintering population. Other waders which feed on the productive mud flats include up to 5,000 dunlin Calidris alpina, 800 curlews Numenius arquata, 500 oystercatchers Haematopus ostralegus and 200 redshank Tringa totanus. Turnstone Arcenaris interpres, grey plover Pluvialis squatarola, ringed plover Charadrius hiaticula and spotted redshank Tringa erythropus also frequent the site. In addition there is a large gull roost of up to 4,000 black-headed gulls Larus ridibundus.
Mute swan Cygnus olor, grey heron Ardea cinerea, shelduck and mallard all breed here.