The effects of hybridization on the small-scale variation in seed-bank composition of a rare plant species, Erica ciliaris L.

The size and composition of the seed bank of a rare species (Erica ciliaris L.) was analysed. E ciliaris hybridizes with a common relative in southern England (Erica tetralix). The seed banks of these co-occurring species were measured at a number of sites with a range of vegetation types and different management histories. Additional sets of samples were taken from forestry plantations on former heathland sites, where these species were known to occur. Relatively few hybrid seedlings were found in any of the seed-bank samples, even though their vegetative abundance within the sampling areas was equal to that of the pure plants. However, the abundance in the vegetation of the two pure species was reflected in the seed-bank size on each of the vegetation types, both with and without burning management. The seed banks from the forestry plantations show that the numbers of seeds of both E tetralix and the hybrid were depleted, but that the seed bank of E. ciliaris was not significantly different from that of open heathland seed banks. The long-lived nature of the seed bank indicates that there are opportunities for habitat restoration on former heathland sites.