Studies on the Conservation of Lowland Calluna Heaths. II. Regeneration of Calluna, and its Relation to Bracken Infestation

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Abstract
(1) This paper investigates methods for restoring degenerate Calluna (Calluna vulgaris (L.) Hull) heath at Knettishall Heath in Breckland [England]. The treatments tested included disturbing the ground flora (cutting alone and in combination with burning and rotavating), and reducing the bracken (Pteridium aquilinum (L.) Kuhn.) density by fosamine application. (2) Calluna regeneration was entirely from seed, and was much greater where disturbance treatments were applied, with no significant difference between disturbance treatments. Seedling establishment was reduced in some plots where the bracken density was > 20 fronds m-2, and subsequent standing crops of Calluna were reduced by 50% at frond densities > 11 fronds m-2. (3) Seedling invasion of birch (Betula pendula Roth, and B. pubescens Ehrh.) and Scots pine (Pinus sylvestris L.) 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 bracken, but Scots pine was able to persist in greater densities (28 fronds m-2) than birch (20 fronds m-2). (4) Preliminary results suggest that at this site management for calluna regeneration should be confined to areas with a bracken density < 11 fronds m-2 in the first instance, and an outline plan for managing this type of degenerate heath is discussed.