The role of catastrophic death of Calluna in heathland dynamics

In the Breckland heaths of East Anglia large patches of Calluna are often killed by adverse climatic conditions or insect attack. This paper studies one site, Cavenham Heath, where large areas of Calluna were killed between 1976–1979, and shows that older stands were most affected, and recovery was slowest compared to either younger stands, or stands with an uneven-aged structure. Moreover, where Calluna death was most severe, directional succession to birch woodland was accelerated. At this site, although Calluna regeneration has been previously assumed to be initiated by endogenous factors (i.e. by the life cycle of the Calluna), it is also clearly interrupted by exogenous factors. The implications of these results for heathland conservation are discussed, and it is suggested that intervention management by cutting and burning, to maintain large areas of Calluna in the building phase, may be the most appropriate long term strategy.This work was funded in part by the Nature Conservancy Council as part of its research programme into nature conservation. I thank Mr D. Malins and Mrs D. Reynolds for assistance in both the field and the laboratory, Ms S. Ide and Mr J. Pattin-gale for preparing the figures, and Professor C. H. Gimigham, Dr J. Miles and Dr I. C. Prentice for helpful comments on earlier drafts of this paper.