Area: 1,271.0 hectares.
The site is partly a Biogenetic Reserve. The site is a Nature Conservation Review site. The site is in Cornwall Area of Outstanding Natural Beauty. The site is partly a Lizard National Nature Reserve. This is a new site amalgamating four existing SSSIs: Goonhilly Downs and Bray’s Cot, Traboe Downs, Clahar and Trenoon and also a large area of land which has not previously been notified. Much of the site lies within the Lizard National Nature Reserve.
* These plants and insects are included in the Red Data Book listing of rare and endangered species.
Description and Reasons for Notification:
Goonhilly Downs are situated approximately 7 kilometres south of Helston on the Lizard Peninsula, the most southerly tip of mainland Britain. The site forms the central core of the Lizard heathlands, the largest remnant of a formerly more extensive serpentinite heathland. The site is mainly underlain by serpentinite, with small outcrops of granite gneiss and hornblende schist. Serpentinite is an ultra basic rock which weathers to form shallow, poorly drained gley soils. These typically support a basic lowland heath community dominated by Cornish heath Erica vagans, a Red Data Book (RDB) species (*), in the British Isles found only on the Lizard and County Fermanagh, Northern Ireland. In places the serpentinite is overlain by windblown loess deposits, giving rise to deeper, more acidic soils supporting a calcifuge heathland vegetation. The site comprises a range of heathland types, a number of pools and quarries and a system of ancient cart tracks which traverses the area. The unusual geology and soils of the area, combined with the mild oceanic climate have led to the development of flora and fauna unique to the Lizard district.
The dominant vegetation type of the serpentinite is ‘tall heath’ comprising Cornish heath, black bog-rush Schoenus nigricans and purple moor-grass Molinia caerulea. Associated species include tormentil Potentilla erecta, saw-wort Serratula tinctoria, devil’s-bit scabious Succisa pratensis, cross-leaved heath Erica tetralix, great burnet Sanguisorba officinalis and western gorse Ulex gallii. Common reed Phragmites australis often co-dominates in wetter areas where peat overlies the gleyed soils.
On the more acidic loess deposits, as ‘short heath’ community is dominant. This comprises heather Calluna vulgaris, bell heather Erica cinerea, western gorse, purple moor-grass, cross- leaved heath and bristle bent Agrostis curtisii.
‘Mixed heath’ occurs widely throughout the site on well-drained soils. It is the most species- rich of the heathland types and is typically dominated by gorse Ulex europaeus, western gorse and Cornish heath with bell heather, tormentil and betony Stachys officinalis.
A ‘wet heath’ community occurs in damp pockets, often around loess deposits. The community typically comprises Cornish heath, cross-leaved heath and purple moor-grass often in association with creeping willow Salix repens and bristle bent.
On the lower, flatter areas with deep, peaty soils, a diversity of wetland habitats is found. Tall fen vegetation, dominated in some places by greater tussock-sedge Carex paniculata occurs with sharp-flowered rush Juncus acutiflorus, grey willow Salix cinerea and of particular note bogbean Menyanthes trifoliata, marsh lousewort Pedicularis palustris and royal fern Osmunda regalis, together with yellow iris Iris pseudacorus, meadowsweet Filipendula ulmaria, hemlock water-dropwort Oenanthe crocata, ragged robin Lychnis flos-cuculi and fool’s water-cress Apium nodiflorum. Common reed and black bog-rush dominate stands along streams. Round- leaved sundew Drosera rotundifolia occurs locally in tussocks with common reed and Sphagnum capillifolium. Sea rush Juncus maritimus is also found, at its most inland site on the Lizard.
Many pools occur on the site, often the result of former quarries or bomb craters which have flooded to give open water bodies supporting a wide diversity of aquatic and semi-aquatic vegetation. Plant species include marsh pennywort Hydrocotyle vulgaris, common spike-rush Eleocharis palustris, shoreweed Littorella uniflora, pillwort Pilularia globulifera and floating club-rush Eleogiton fluitans. Rocky serpentinite outcrops and quarries which remain unflooded often support the RDB species (*), land quillwort Isoetes histrix, dwarf rush Juncus capitatus, and fringed rupturewort Herniaria ciliolata, and the nationally scarce autumn quill Scilla autumnalis and wild chives Allium schoenoprasum.
The system of ancient cart-tracks which crosses Goonhilly Downs supports a variety of species. The RDB species (*) pigmy rush Juncus pygmaeus and pillwort are found with the nationally scarce yellow centaury Cicendia filiformis and three-lobed crowfoot Ranunculus tripartitus along with chaffweed Anagallis minima and lesser water-plantain Baldellia ranunculoides.
The orchid flora is of particular note. Several species occur including the heath spotted-orchid Dactylorhiza maculata subsp. ericetorum, southern marsh-orchid D. praetermissa, fragrant orchid Gymnadenia conopsea and the green-winged orchid Orchis morio. In addition two rare heathers, the Dorset heath Erica ciliaris and the hybrid heath Erica williamsii, have been recorded at this site.
The open water areas, including Croft Pascoe Pool and Bray’s Cot Pool, provide an important habitat for dragonflies. At least thirteen species have been recorded on Goonhilly Downs, including the small red damselfly Ceriagrion tenellum and the nationally scarce black-tailed skimmer Orthetrum cancellatum. The heathland attracts other invertebrates. Four RDB (*) fly species Fannia latipalpus, Tipula grisescens, Urophora spoliata and Myopa extricata and seventeen regionally scarce species have been recorded. A rich beetle fauna includes the RDB species (*) Longitarsus rutilus and Graptodytes flavipes. Andrena falsifica (*), a mining bee species, has also been recorded on the site.
There are several stands of mixed conifers on the site, remnants of former plantations, now giving way to a mixed heath community. The mixture of conifer and heathland provides habitat for numerous bird species. The site is of particular importance as a breeding site for nightjar Camprimulgus europaeus. Other breeding birds include curlew Numenius arquata, lapwing Vanellus vanellus, stonechat Saxicola torquata and grasshopper warbler Locustella naevia. The Goonhilly site as a whole is a hunting ground for merlin Falco columbarius, kestrel Falco tinnunculus, buzzard Buteo buteo, short-eared owl Asio flammeus, barn owl Tyto alba, peregrine Falco peregrinus and hen harrier Circus cyaneus.