Windsor Hill SSSI
The site was notified as an SSSI in 1951. It is 61.8 hectares in area.
The site is featured in the Nature Conservation Review
The site is best known as one of three extant British locations for the Red Helleborine orchid, which is confined to a small section of the site; this section is managed as a nature reserve by the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust, and access to this area requires a permit.
The conspicuous knoll at the north-western extremity of the site is known as Kop Hill, whilst at the southern end of the site lies Pink Hill.
The Black Hedge is a hedgerow believed to be of Saxon origin, running along the base of Kop and Windsor Hills.
The beech woodlands incorporate communities characteristic of soils on the Clay-with-flints of the Chiltern plateau and the chalky deposits of the scarp slopes. Associated with the beech on the plateau are oak and occasional birch whilst on the slopes, the associated species are Ash and Whitebeam. Both even-aged and more mixed stands are represented, the latter typically with a shrub layer including Gorse and Honeysuckle on the plateau, and Elder and Hazel on the slopes.
On the plateau, brambles, Bracken and Rosebay willowherb occupy extensive patches, but a more mixed ground flora occurs between these, including Creeping Soft-grass Holcus mollis, Hairy Brome Bromus ramosus, Tufted Hair-grass Deschampsia cespitosa, Wood Millet Milium effusum and Wood Melick Melica uniflora. Pill Sedge Carex pilulifera, Hairy Wood-rush Luzula pilosa and Slender St. John's-wort Hypericum pulchrum are found in more heathy areas, and the rushes Juncus effusus and J. conglomeratus are present in damper areas.
On the slopes Dog's-mercury Mercurialis perennis and Woodruff Galium odoratum are abundant, while more local species include Nettle-leaved Bellflower Campanula trachelium, White Cephalanthera damasonium, Broad-leaved Epipactis helleborine and Narrow- lipped Helleborines E. leptochila, Yellow Bird's-nest Monotropa hypopitys and Scaly Male-fern Dryopteris affinis.
Juniper scrub occurs on Windsor Hill itself, where it is associated with various other typical chalk shrubs and chalk grassland with an abundance of the moss Pseudoscleropodium purum and Common Valerian Valeriana officinalis. There are patches of bare chalk with forget-me-nots Myosotis spp. and Common Mullein Verbascum thapsus.
On Kop Hill, hawthorn dominates the scrub, and the grassland is less mossy. Several localised plant species such as Squinancywort Asperula cynanchica Chalk Eyebright Euphrasia pseudokerneri, Horseshoe Vetch Hippocrepis comosa, Autumn Gentian Gentianella amarella and Clustered Bellflower Campanula glomerata occur. A further small area of chalk grassland dominated by Wood False-brome Brachypodium sylvaticum and Glaucous Sedge Carex flacca occurs at the foot of Pink Hill.
23 species of butterfly have been recorded, including Brown Hairstreak Thecla betulae, which requires scrub thickets and woodland edge habitats. The juniper colony supports several species of insect specific to this host plant. The snail fauna includes Abida secale, Helicella itala and Pomatias elegans.
- Natural England SSSI entry