A review of current bracken control and associated vegetation strategies in Great Britain

Abstract

Bracken is a major problem for livestock-based, extensive agriculture in many parts of the world. It also causes problems for conservation, recreation, game management and forestry and is hence subject to management in order to control it. This paper reviews current bracken control strategies in Great Britain to assess whether they can be improved, and reviews recent work on combining bracken control with vegetation restoration to derive guidelines for maximising the cost-effectiveness of these measures to increase biodiversity.

Bracken control in Great Britain is currently, mainly undertaken by aerial spraying of herbicide. A large-scale survey showed that only a small proportion (25%) of sites were likely to show long-term control, the developing vegetation was not that desired by the instigator of control, and there was a large geographic variation in success. The major conclusion was that large-scale treatment often exceeded the area that could be adequately treated by follow-up measures.

Experimental studies demonstrate that to obtain “desirable” vegetation (usually Calluna vulgaris-dominated heath in Great Britain) a number of steps usually have to be followed. However, the steps that have to be taken may differ between sites. Deep litter sites, where stock numbers are low, need the litter disturbed in some way and seed of suitable species added. On sites with higher stock numbers, litter disturbance has in effect already been carried out, so that management must involve seed addition and the exclusion/reduction of stock. It is not yet known how long or to what level stock must be removed before the vegetation is able to withstand grazing. It should be noted that management to reverse succession could prove less cost-effective than management that accelerates succession to woodland or forestry.

A set of points which highlight the considerations necessary at the commencement of an “integrated” bracken control programme are outlined. Targeting sites in western Britain or sites with residual vegetation present would provide the greatest gains for biodiversity in the short term. However, in many situations management for vegetation restoration must be seen as a key part of this strategy, not as something that will proceed unaided after bracken control has taken place.