A vegetation survey of the woodland complex was undertaken in 2007 and concluded that: "The woodland complex has a superb representation of the range of communities making up the lowland mixed Atlantic bluebell woods. Floristically this survey demonstrated the woodland flora is among the richest in England for woodland vascular plants." A total of 65 Ancient WoodlandIndicator plants have been recorded in the wood. Of special note is the population of narrow-leaved lungwort. This nationally scarce species is the rarest known vascular plant on the reserve and in Britain is limited to ancient woodlands on the shores and tributaries of the Solent. Other locally distributed ancient woodland specialities include green hellebore, greater butterfly orchid and thin spiked wood sedge.
Fauna
Mammals
Briddlesford Copses—the woodland areas that make up the majority of the woodland in the reserve—were designated a SAC in 1995 in recognition of the internationally important breeding population of Bechstein's bats that are resident there. The rare barbastelle bat also breeds in the woods, contributing to a total of eight bat species recorded at the site. These animals are particularly associated with woodpecker holes and crevices in mature ash trees at this site. The woods support both hazel dormice and red squirrels, and alongside the bats form a mammal assemblage that is unique to the UK. The dormice have been monitored in the woodland since at least 1996. Over 530 nest boxes are arranged in two grids that contribute data to the National Dormouse Monitoring Programme and inform the management of the woodlands.
Invertebrates
The invertebrate fauna of the reserve has been surveyed in detail in 2002 and 2012, and surveyors found a rich and diverse fauna with an abundance of ancient woodland associated species. A total of 650 species have been identified and the reserve is now known to be of SSSI quality for saproxylic invertebrates. Of special interest is the rare fungus weevil Pseudeuparius sepicola, a Red Data Book species. The nationally scarce wood-cricket Nemobius sylvestris is very common in Briddlesford Copse and a population of the ash-black slug was also recently discovered at the reserve - the largest terrestrial slug in the world. The rides and railway cuttings also provide a valuable habitat for a variety of woodland butterflies including silver-washed fritillary, white admiral ''and the dark crimson underwing moth.
Copses
Briddlesford Copse
Little Lynn Common
Great Lynn Common
Gunsight
Moor Wood
Sheepwash
Sandpit
Big Wood
Dunnage
Stockers Hole
Great Wood
Six Acre
Hurst Copse
Vicarage
Public access
There is a bridleway through the reserve and the parkland and Hurst Copse have permissive access.