Previous authors have suggested that cyclical succession takes place in Calluna-dominated heathland, and is determined by the different growth phases of the dominant. Characteristic species are said to invade at different stages of the life cycle of Calluna, particularly in the initial and pioneer phases and in the degenerate phase. In the last phase, gaps are formed due to separation and dying of the oldest frame branches.
This paper aims to analyze in which microhabitat and in which phase of the Calluna life cycle seedling emergence and establishment is possible.
More seedlings appear in pioneer Calluna than in mature Calluna stands in experimentally manipulated micro-sites. In pioneer Calluna establishment is affected only by application of litter, in mature Calluna by increased illumination. The differences between treatments disappeared after three years, but not the difference in establishment between stands.
Seedling emergence from species sown experimentally was different in the successive phases of Calluna. Highest emergence was in the pioneer stand.
In a seedling survey also most seedlings appeared and established in the pioneer phase. The number of recently germinated seeds was high in all phases. However, seedling survival was very low, except in the pioneer stands. This study does not of itself show evidence for cyclical succession in Calluna-dominated heath vegetation. Colonization of gaps by seedlings of Calluna in mature or degenerate phases is possible, but must be an infrequent occurrence.