Elstead Common is a Site of Special Scientific Interest, as are neighbouring Ockley and Royal commons (Walks with Rena post for the latter is here). All are managed by Surrey Wildlife Trust on behalf of the MOD. Elstead and Ockley commons are recognised as some of the finest remaining lowland heath in the south of England and are awash with heather, gorse and bracken. The woodlands on its perimeter are primarily made up of birch and Scots pine.
Royal Common, Forked Pond and Thursley Nature Reserve fringes
Royal Common, just outside Elstead, is part of the Longmoor Training Area owned by the Defence Estates, which also covers large parts of Hankley, Elstead and Ockley commons. Public access is allowed across the Defence Training Estate provided you adhere to the Surrey Commons Military Lands Byelaws 1978. Army training here (when it takes place) revolves around logistics and minor infantry manoeuvre exercises and you're unlikely to come to any harm, but make sure you follow the instructions of troops if you do encounter any.