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Seed banks and fire; A study of west Norwegian heathlands Måren, I. E. & Vandvik, V. Ecological and Environmental Change Research Group (EECRG), Department of Biology, University of Bergen, Allégaten 41, N-5007 Bergen, Norway. Poster-session: Management ABSTRACT - Dormant seeds in the soil serve a dual function in plant populations. They are “memories of populations and communities past”, and at the same time a potential for future persistence and survival. Hence, the longevity of seeds in the soil affects the resilience of plant communities. Heathlands are influenced by many factors leading to vegetational change. Burning and grazing has been the most commonly employed management practices of the west Norwegian heathlands. Propagule input is an important and integral part of the successional process where the successful recruitment may be limited either by the availability of seeds, or by the availability of safe sites where the seedlings may germinate and establish. A proper understanding of how heathlands respond to disturbance must take account of seed production-, dispersal-, seed bank- and germinability dynamics. In cyclic vegetation types such as heathlands, seed banks are particularly important so that the species can survive locally with time. Few studies have focused on the temporal changes in seed banks during cyclic heathland succession. Very few studies deal with the role of the seed bank in post-fire recovery, and particularly in heathlands. In this study we investigated the relationship between vegetational composition and seed bank in burnt heath of varying age. A total of 50 species were found to germinate from the seed bank, while 65 species occurred in the vegetation analysis. 15 species only occurred in the seed bank, while 32 species occurred only in the vegetation. The main component of the seed bank was Calluna vulgaris, constituting 48 %. Erica tetralix was the second largest contributor; constituting 34 %. The 10 most commonly occurring species of the seed bank constituted 98 % of the germinated seeds. Calluna vulgaris showed a higher germination rate in the two first years following fire. This might be caused by changed chemical properties of the soil following a heath fire; charcoal particles deposited on the surface might absorb germination inhibitors and allelophathic chemicals, and may contribute to explain why we see an increased germination rate in Calluna immediately following a fire. Thus, the size and the quality of the viable seed bank may both determinants of successful heathland management and restoration on successional sites. These findings emphasize the need for continued management measures in order to maintain heathlands. |