woodland, with some pasture fields. Like much of the Mid Cheshire Ridge, the Bickerton Hills are rather cooler than the surrounding Cheshire Plain, with an accumulated temperature of 1375–1649 day °C compared with 1650–1924 day °C. The soil is slightly moist, with a similar moisture level to that of the surrounding area. Sites of Special Scientific Interest Bickerton Hill An area of of the birch woods and heathland of the southerly hill has been designated a Site of Special Scientific Interest (SSSI). With the exception of several areas of farmland and former quarries, the SSSI covers the northmost (Kitty Stone) high point and the Maiden Castle area of the southern high point, together with the intervening col. It also extends over Cuckoo Rock, a lower area to the west of the southern high point, which lies to the south of the hamlet of Brown Knowl. It excludes the southwest of the hill, including part of Hether Wood as well as an area of farmland. A total of of the southerly hill, covering 90% of the SSSI, are owned and managed by the National Trust. The lowland heath habitat (heathland below 300 metres elevation) of Bickerton Hill is considered particularly valuable. Lowland heath is an internationally scarce habitat that is rare within Cheshire; a survey in 1995 found only 60 Ha in the administrative county. Bickerton Hill is the largest of the four lowland heath SSSIs in the county. A semi-natural habitat, heathland requires active management, such as grazing, to avoid succession to scrub and woodland. Flora Within the heathland areas, the predominant community types are Calluna vulgaris (common heather)–Deschampsia flexuosa (wavy hair grass) (H9) and heather–Ulex gallii (western gorse) (H8). Bilberry (Vaccinium myrtillus) is also widespread, with some patches of bracken (Pteridium aquilinum), and less frequently bell heather (Erica cinerea), cross leaved heath (Erica tetralix) and broom (Cytisus scoparius). The woodland is dominated by silver birch, with aspen, holly, rowan, sessile oak and wild cherry also present. The undergrowth includes heather and bilberry, with patches of broad buckler-fern (Dryopteris dilatata). Over two hundred plants of the nationally rare fern, Lobed Maidenhair Spleenwort (Asplenium trichomanes subsp pachyrachis), were discovered in 1997, growing on calcareous sandstone at two different locations; this is possibly the largest population of the subspecies in Britain. A few plants have since been recorded at Raw Head. Fauna The area is rich in wildlife. Insects found here that