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.