Studies on the conservation of lowland Calluna heaths. II. Regeneration of Calluna, and its relation to bracken infestation.
Abstract
Methods for restoring degenerate Calluna vulgaris heath at Knettishall Heath in Breckland were studied. The treatments tested included disturbing the ground flora (cutting alone and in combination with burning and rotavating) and reducing Pteridium aquilinum density by fosamine application. Calluna regeneration was entirely from seed and was much greater where disturbance treatments were applied, with no difference between disturbance treatments. Seedling establishment was reduced in some plots where the P. aquilinum density was >20 fronds/m2, and subsequent standing crops of Calluna were reduced by 50% at frond densities >11 fronds/m2. Seedling invasion of Betula pendula, B. pubescens and Pinus sylvestris was mainly confined to the 3 years after disturbance, being reduced as the Calluna increased. Numbers of tree seedlings tended to be reduced in the higher densities of P. aquilinum, but P. sylvestris was able to persist in greater densities (28 fronds/m2) than Betula (20 fronds/m2). Preliminary results suggest that at this site, management for Calluna regeneration should be confined to areas with a P. aquilinum density <11 fronds/m2 in the first instance, and an outline plan for managing this type of degenerate heath is discussed.