We studied the seed bank of a calcareous grassland in four sites with different management history: original old grassland, which has been described as one of the richest plant communities in Europe, long-term restored grassland, which has been overgrown in the seventies, recently overgrown (ca. 20 years ago) and long-term overgrown grasslands. The seed banks in grassland sites at Laelatu were small both in size and number of species. The number of species and seeds in the seed bank declined significantly from managed grasslands to closed overgrown community. The highest species richness of the soil seed bank (number of species per soil volume) was found in the managed grassland sites, the seed density in the bank was the highest in the long-term restored grassland site. About one third of ail the grassland species were found in the seed bank. The proportion of species in the established vegetation - represented also in the bank - was higher in overgrown sites. However, ordination (Correspondence Analysis), which also took into account species frequencies, showed that the similarity between established vegetation on plots and seed bank samples decreased from original grassland to closed overgrown grassland. The persistence of the seeds of only 8-10 typical grassland species in the seed bank of overgrown grassland sites makes the significance of the seed bank for community restoration quite small. (C) Elsevier, Paris. [References: 28]
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