THE CONSERVATION VALUE OF BRACKEN PTERIDIUM-AQUILINUM (L) KUHN-DOMINATED COMMUNITIES IN THE UK, AND AN ASSESSMENT OF THE ECOLOGICAL IMPACT OF BRACKEN EXPANSION OR ITS REMOVAL

Bracken Pteridium aquilinum is generally regarded by farmers, foresters and conservationists as a problem species. Bracken stands are usually poor floristically, except where they protect a relict, woodland vernal flora. Similarly, bracken generally has a poor fauna; in some instances stands can provide cover for some birds and animals, but have a high conservation value only in a few specific cases. Further spread of bracken will lead to the loss of many areas of other habitats with a high conservation value, e.g. moorland and lowland heathland, and thus a decline in many uncommon species. There is therefore a choice between allowing the continuing spread of bracken and thus reducing the ecological and landscape diversity of Britain, or controlling it on a large scale. Bracken can be controlled by herbicide use or mechanical means, both give the same on-site selectivity and intensity of treatment, but are expensive. Irrespective of how it is controlled there will be difficulties with revegetation of semi-natural communities, The release of alien biological control agents is an alternative strategy; this could be cheap and offers the possibility of reducing bracken vigour on a countrywide scale. However, there would be no control over which sites were affected or the effects at a particular site.