Woodland habitat audit

This audit includes all semi-natural plant communities dominated by trees or shrubs. Although there are a few intermediate habitats, the dominance of woody species generally distinguishes woodland and scrub from grasslands and marshes. London's better woodlands have been described before, but this audit can take account of more recent information on both the woodlands and their community types, provide borough by borough statistics and identify the issues that will need to be addressed in action for London's woodlands and scrub.

There is no doubt that London was very largely clothed in woodland before the activities of man induced the other ancient habitats. Even nowadays, after millennia of management, the composition of the ground flora of the older woodlands is derived from this wildwood. But there have been many losses, and the composition of woodland canopies more reflects their long history of management, so that species like hornbeam, sweet chestnut, field maple and hazel are more abundant than they would be naturally.

Many wet woodlands have a dense structure, often with fallen trees, difficult ground conditions and mosquitoes. This makes them more difficult to enjoy and so less appreciated by the public than 'bluebell woods'. They are threatened with changes in the water regime through drainage or flood control work, succession to drier habitat and toxic water pollutants/ The tradition of pond maintenance to arrest succession to wet woodland prevents the development of many small wet woodlands.

There has been a national drive for woodland planting, manifest in and around London in the Watling and Thames Chase projects. The aims of these projects extend far beyond biodiversity conservation, but they provide an excellent basis for the development of new woodlands for people to enjoy. There are also less obvious opportunities, such as allowing wetlands to develop into wet woodland through natural succession, which would be appropriate in disused mineral workings. Tree planting can, however, cause harm to nature conservaton, as trees shade out other valuable plant communities in grassland, heath, wasteland or marsh. It is vital therefore that new woodland planting is undertaken only after survey of the existing plant communitiy confirms that it is of no species value for nature conservation.