Individual study: Prescribed burning and the role of seed banks in post-fire succession of northern heathlands, Lygra and Lurekalven islands, Hordaland, Norway
Måren I.E. & Vandvik V. (2009) Prescribed burning and the role of seed banks in post-fire succession of northern heathlands, Lygra and Lurekalven islands, Hordaland, Norway. Conservation Evidence, 6, 48-56
Variation in plant species composition, abundance of seeds in the soil seed bank and standing vegetation, over the course of a post-fire succession was investigated in coastal Calluna-heathlands in Western Norway. Vegetation and seed banks were analysed over a 24-year post-fire period. The total diversity of vegetation and seed bank were 60 and 54 vascular plant taxa respectively (39 shared species), resulting in 68% similarity. Over the 24 years the heathland community progressed from open newly-burnt ground via species rich graminoid- and herb-dominated vegetation to mature heather Calluna vulgaris-dominated heath. This post-fire succession was not reflected in the seed bank; the 10 most abundant species constituted 98% of the germinated seeds. The most abundant were Calluna (49%; 12,018 seeds/m2) and cross-leaved heath Erica tetralix (34%; 8,414 seeds/m2). Calluna showed significantly higher germination in the two first years following burning. Vegetation species richness (ranging 23 to 46 species/yr) was highest in the middle years of the post-fire succession period. In contrast, the seed bank species richness (21 to 31 species/yr) showed no trend. This suggests that the seed bank act as a refuge, providing a source of recruits for many species that colonize newly-burnt areas. The traditional management regime has not depleted or destroyed the seed banks, and continuing management is necessary to ensure perpetuation of the heathlands.