Oak polypore  (Piptoporus quercinus)

Provisionally classified as Endangered in Great Britain, and fully protected in the UK under Schedule 8 of the Wildlife and Countryside Act 1981 (1).

This fungus causes a brown rot of the heartwood of mature or dead oak trees. The stemless bracket-like fruit bodies (the visible part of the fungus) have a smooth upper surface, which feels velvety when young (6). As the fruit body matures, pores develop on the underside (6), and the colour changes from white to pale-yellow and then brown with a white border in mature specimens (6).

This species is widespread but rare in Europe, and the range extends as far east as Japan. It is currently in decline in central Europe and has already become extinct in many areas of northern Europe. In Britain, the species is only known in England, where it has been recorded from 22 sites, ten of them (from Sussex north to Yorkshire) since 1970 (6).

You can view distribution information for this species at the National Biodiversity Network Gateway.

This fungus occurs on the limbs and trunks of living or dead veteran oak trees (i.e. trees which are 250 - 800 years old), or on fallen heartwood (6). Typical habitats include medieval forests, deer parks, wood pasture and wooded commons (6).

Fungi are neither plants nor animals but belong to their own kingdom. They are unable to produce their own food through the process of photosynthesis, as plants do; instead, they acquire nutrients from living or dead plants, animals, or other fungi, as animals do. In many larger fungi (lichens excepted) the only visible parts are the fruit bodies, which arise from a largely unseen network of threads called ‘hyphae’. These hyphae permeate the fungus’s food source, which may be soil, leaf litter, rotten wood, dung, and so on, depending on the species.

In the oak polypore, the hyphae occur within the heartwood of living or dead trees (6). The oak polypore is one of the few species able to live in oak heartwood, which contains a number of toxic or antifungal compounds (6). The fruit bodies of this species occur in July or August, either singly or in clusters, and persist for just a few weeks (6). Old fruit bodies, however, can sometimes persist into the following year in a blackened, decaying or mummified state (6).

In many woodlands, the age structure of the trees has become skewed towards old specimens, and very little regeneration of new trees occurs. This threatens the long-term future survival of the oak polypore, as there may come a time when oaks of a suitable age will not be present. Felling of old and dead oak trees, often for reasons of 'tidiness' or 'health and safety', has also affected the species, as has clearance of fallen wood (1).

The oak polypore fungus is a UK Biodiversity Action Plan (UK BAP) priority species, and is included in English Nature's Species Recovery Programme. The Species Action Plan for this fungus aims to maintain all known populations, and establish five new colonies by 2010 from ex-situ cultivated stocks. In areas where the species exists, pollarding oaks and protecting saplings will help to ensure a supply of suitably aged oaks in the future. In addition, current host trees, dead or alive, must not (and cannot legally) be destroyed, nor can fallen host dead wood be cleared (1). Sherwood Forest (one of the known sites for the fungus) is a Site of Special Scientific Interest, and a candidate Special Area of Conservation (4). Furthermore, the species is one of just four non-lichenized fungi to be protected by law; Schedule 8 of the Wildlife and Countryside Act deems that it is an offence to pick, uproot, cut, destroy, collect or sell any listed species (5).

There may be further information about this species available via the National Biodiversity Network Gateway.

For further information on the conservation of British fungi, see:

• Association of British Fungus Groups:
  http://www.abfg.org/