Bisham Woods

Also within

Berkshire County

Condition (Natural England)

Habitats

Ancient woodland, Bracken scrub, Coppiced woodland, Fast flowing river and stream

Geology & landscape

Rock Type: Chalk

Landscape processes: Glacial

Description

Area, 83.67 206.75 ac Description An extensive area of predominantly broad leaved woodland situated on a steep north west facing slope overlooking the River Thames at Marlow. Most of the site lies on the thin, freely drained soils of the chalk escarpment, which is dissected in places by dry valleys with sunken tracks, but the upper part of the wood is situated partly on wet clay soils of the Reading Beds and partly on base poor glacial sands and gravels. Most of the woodland consists of beech high forest and, as such, represents a southern outlier of the Chiltern beech woods. It is remarkable both for the diversity of its ground flora and the range of woodland types represented. Beech occurs with ash, cherry, wych elm, whitebeam, field maple, yew, holly and sycamore on the chalk slope and with oak, ash wych elm, birch, sweet chestnut and cherry on the more acid soils of the plateau. Shrubs include wild privet Ligustrum vulgare, wayfaring tree Viburnum lantana, guelder rose Viburnum opulus, elder Sambucus nigra, old man's beard Clematis vitalba, red currant Ribes rubrum and field rose Rosa arvensis. The wood has been modified in parts by the planting of conifers especially larch and other exotics and invasion by sycamore, which is locally dominant, but many interesting variations in structure and species composition occur. Examples include small patches of hazel coppice, alder woodland with sallow Salix caprea along the watercourse at the foot of the slope, some hornbeam on wood banks and occasional wild service trees Sorbus torminalis. The ground flora is one of the richest recorded from any Berkshire woodland site, although dog's mercury Mercurialis perennis and ivy Hedera helix are dominant over much of the escarpment and bramble Rubus fruticosus dominates much of the plateau with bracken Pteridium aquilinum on dry sandy areas. Species of interest include yellow bird's nest Hypopitys monotropa and bird's nest orchid Neottia nidus-avis in leaf litter under beech, thin spiked sedge Carex strigosa on the wetter clay soils, wood barley Hordelymus europaeus, tutsan Hypericum androsaemum, nettle leaved bellflower Campanula trachelium, wood goldilocks Ranunculus auricomus and four species of helleborine orchids Epipactis spp. The site supports an interesting mollusc fauna including some species characteristic of ancient woodland conditions and chalky soils. Snails recorded include Helicigona lapicida, Pomatias elegans, Cochlodina laminata, Lauria cylindracea, Acanthinula aculeata, Merdigera obscura and Abida secale.

Species mentioned

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.

Plant communities