Area: 45 hectares.
Owned by Devon County Council, managed as a Country Park. Mineral rights reserved.
Description and Reasons for Notification:
The main feature is a large lake dating from the late 18th century, regarded as displaying the best single example of this type of open water community in South West England, with no other single water body equivalent in size, naturalness or diversity in Devon. It is rich in invertebrates with many rare and local species.
The lake is approximately 200 years old, having been created as part of a landscape scheme in the grounds of Stover House and to supply water to the Stover Canal.
Extensive marshes have developed on the north and west sides exhibiting a classic hydrosere succession. The variety of marginal substrates produce a high floristic diversity. For example in areas affected by acid run off from adjacent conifer plantations the aquatic succession is modified, the increased acidity being reflected by species such as bog pondweed Potamogeton polygonifolius and bog myrtle Myrica gale.
The lake and its margins support a rich invertebrate fauna. Of 26 species of dragonflies (Odonata) occurring in Devon, 19 have been recorded at Stover. Of particular note are the hairy dragonfly Brachytron pratense and the scarce blue-tailed Ischnura pumilio, both vulnerable species. Migrant hawker dragonfly Aeshna mixta and red-eyed Damselfly Erythromma najas are scarce in Britain whilst the down emerald Cordulia aenea is at the western edge of its range here. Diptera of interest include a rare cranefly Tipula marginata breeding in the lakeside mud. Others of local occurrence are the lakeside fly Raphium longicorne, a snail-killing fly Pteromicra angustipennis, hoverflies Parhelophilus (Helophilus) versicolor, Anasimyia (Helophilus)frutetorum and A. contracta. A snipe fly Atherix ibis breeds in the outflow stream.
The woodland comprises mostly planted exotic species but there are areas of oak Quercus sp. and birch Betula pendula and scrub patches of common gorse Ulex europaeus and bramble Rubus fruticosus agg. Much of this woodland was planted when the lake was excavated and there are interesting old trees.
Despite their mainly imported content, these woods are of invertebrate interest, with species such as the broad-bordered bee hawk moth Hemaris fuciformis and the narrow-bordered bee hawk moth Hemaris tityus, both scarce and vulnerable, feeding at the rhododendron bushes. A good dead-wood fauna includes the rare cranefly Ctenephora pectinicornis and an uncommon horsefly Xylota florum. A nest of hornets Vespa crabro has been recorded.
Heathland dominated by ling Calluna vulgaris occupies open ground where the scarce plant-bugs Syromastus rhombeus and Corizus hyoscyami and a vulnerable hoverfly Microdon mutabilis have been recorded.