Ham Street Woods is part of the larger Orlestone Forest, a fragmented area of woodland that is the remnant of a continuous oak forest that once covered the Weald.
As well as being one of the first National Nature Reserves to be designated in 1952, Ham Street Woods is nationally designated as a Site of Special Scientific Interest because it includes a series of broadleaved woodlands supporting outstanding bird and invertebrate communities.
Ham Street Woods is home to rare moths (such as the triangle and silky wave moths), and butterflies (such as the White Admiral); breeding birds, including rare ones such as the nightingale and hawfinch; and also to 2 protected species: the great crested newt and the dormouse.
Oak, sweet chestnut, birch, aspen and hornbeam flourish in the higher parts of the site, whilst in the damper soil of the valleys ash, hawthorn, hazel and alder are found. Hornbeam trees are easy to spot as they have been coppiced so have multiple stems. Wild Service, or ?chequer? trees are also found in the woods; they are an indicator of ancient woodland.
In spring the floor of the woods is filled with primrose, white wood anemones and bluebells, whilst autumn is the perfect time for appreciating the fabulous fungi and autumnal leaves.
There are 3 way-marked trails (varying between 2.5 and 5 kilometres) through the reserve. There is a map and information board at the entrance.