[1] The reserve is part of Rushbeds Wood and Railway Cutting, an 80.2-hectare (198-acre) biological Site of Special Scientific Interest.

This includes a section of the Chiltern Main Line railway cutting, which runs along the north-east side of the BBOWT reserve.

The invertebrate fauna are described by Natural England as "exceptional", including over thirty butterfly species, such as the nationally rare black hairstreak and the scarce wood white and purple emperor.

The woodland is wet ash and maple, with other trees including elm and hornbeam.

The understorey has species indicative of long tree cover, such as Poa nemoralis and wood millet.