Deadwood

Dead and dying trees play an important role in the woodland ecosystem and are especially valuable in supporting biodiversity. Deadwood supports a vast food chain of species and as such is an important consideration in woodland management.

The term ‘deadwood’ is typically used to describe any accumulation of dead or dying wood. Deadwood includes whole or part standing dead trees (snags) and any fallen material such as tree trunks, branches, stumps or small twigs. The term is also used to describe the dying parts of a living tree such as rotten heart wood, rot holes or dead branches. Deadwood is generated by the natural ageing process of the tree and also by factors such as storms, drought and disease.

Dead and decaying wood provides a wide range of micro-habitats for many insects, mosses, lichens, plants and fungi involved in ‘decomposition’ or breaking down the woodland plant litter to help form the soil. These decomposer species also form part of the food chain and directly support many other plants, birds and animals.

Many species associated with deadwood habitats are rare and endangered. This is because most have evolved under specific conditions and will only make use of deadwood if it is a particular size, age, tree species, stage of decay, standing or fallen.

Standing deadwood
© D Cotton

Small pieces of deadwood 
© D Cotton

Beef steak fungus (Fistulina hepatica)
© Forestry Commission

Wood sorrel
© Forestry Commission

Crested tit
© Forestry Commission

Examples of deadwood habitat
The decaying wood of live veteran trees is particularly valuable in lowland broadleaf woodland providing homes for many kinds of invertebrates such as beetles, centipedes and woodlice. These in turn provide abundant food for cavity nesting birds such as tree creepers, redstarts and woodpeckers. Oak heartwood is broken down over many hundreds of years aided by wood decaying fungi of which the oak supports around 20 species. The beefsteak fungus is a well known example.

Among the fallen logs of upland broadleaf woodland the humid micro-climate provides a rich habitat for many species of moss and a niche for flowering plants such as Wood sorrel. Birch trees can die back as early as 80-100 years providing an early form of deadwood and the bracket fungi ‘Birch polypore’ are a common feature. Birch rots from the inside out, the trunk becoming a hollow tube; ideal for roosting bats.

The logs, stumps and crevices of dead pine wood in the northern woodlands of Britain provide a specialist habitat for many lichen species. Newly fallen wood is quickly inhabited by the aptly named timberman beetle and decaying snags and stumps provide ideal nesting space for crested tits.

Management of deadwood

As well as its value to wildlife and the woodland ecosystem in general, recent studies have shown that deadwood also forms part of the overall carbon store of a woodland. Deadwood has the ability to retain carbon for varying amounts of time depending upon the rate of decay. It is therefore an important factor to consider in sensitive and sustainable management of woodland.

Because of its enormous value, woodland grant schemes now provide specific guidelines on the recommended volumes of deadwood retained per hectare and advise that deadwood should be present across the whole woodland site; in the form of small and large pieces. For woodlands where nature conservation is the primary objective then the amount and variety of deadwood should be similar to that found in an unmanaged or ‘natural’ woodland. However, even in commercial systems it is possible to retain dead wood on track sides and margins.