The SSSI, notified in 1979, is located north of the hamlet of Rosenannon within the civil parish of St Wenn, south-west of the town of Wadebridge. The streams rising on this site feed into the River Camel Valley and Tributaries SSSI. The nature reserve is owned and managed by the CornwallWildlife Trust. The Downs have been leased by the Trust from 1999 and were bequeathed to them in 2009 by Theresa Knowles.
History
To the north of the site are three Bronze Age barrows, dated to around 2500 BC. The SSSI was previously named Rosenannon Bog, but was renamed after the site was expanded to its current limits. The Downs have not been grazed since the 1960s, although a proposal to reintroduce this is going ahead.
Wildlife and ecology
Flora
The two main types of habitat on the site are heathland and bogland, which support a wide variety of species. The dry heath comprises five main species of plant, of which the common heather is the most prolific with bell heather and western gorse also dominant; bristle bent and purple moor-grass to a lesser extent. Other species found in this habitat are heath milkwort, lousewort, saw-wort, deer grass and the heath spotted-orchid. The wet heath areas also contain purple moor-grass along with bog myrtle and cross-leaved heath as the three most prolific species. Black bogrush are prominent in the wetter, more base-rich parts, whereas bog mosses and the insectivorous round-leaved sundew can be found in the wet hollows. Along with cross-leaved heath and purple moor-grass the valley bog habitat supports bog asphodel, bog pimpernel, common cottongrass, lesser skullcap, pale butterwort and white beak-sedge. Royal fern and wavy St. John's-wort, species which are not common within Britain, can also be found in the bogland. A broad-leaved woodland surrounds the valley bog which mainly contains sessile oak, and willows. An area of scrub is present on the southern edge of the Downs, which supports Cornish bladderseed.
The Cornwall Wildlife Trust has been given permission by the Secretary of State for Environment to allow the site to be fenced in order to re-introduce cattle grazing on the site for management purposes. This is to be carried out in order to reduce the chance of uncontrolled fires and to benefit the small pearl-bordered fritillary butterfly, whose larva feed mainly on marsh violet on the mid–Cornwall moors; a low–growing plant which is out competed by the more vigorous purple moor-grass. Fencing to enable cattle grazing was started in December 2011. For the third year in the last four there has been an uncontrolled fire on the reserve which is thought to be arson; the latest in March 2012 burnt.
