Restoration Potential in Seed Banks of Acidic Fen and Dry-Mesophilous Meadows: Can Restoration Be Based on Local Seed Banks?

A crucial question in ecological restoration is whether target species that are missing from aboveground vegetation are represented in the seed bank. We evaluated the role of persistent seed banks in the restoration of species richness, and the relative value of managed and unmanaged grasslands, by studying closely located and floristically similar mown and abandoned stands of fen and dry-mesophilous meadows. We found that a higher proportion of the target species detected in aboveground vegetation possessed persistent seed banks in fen meadows than in dry-mesophilous ones (44 and 29%, respectively). The proportion of target species found exclusively in the seed bank was much lower (11% for both meadow types). Conversely, common rushes (Juncus conglomeratus and J. effusus), mostly missing from the vegetation, dominated the seed banks in all fen meadow plots (50-94% of total seed densities) and were also detected in seed banks of dry-mesophilous meadows. We found that resumed mowing on previously abandoned meadows has promoted species richness and the flowering success of several species in comparison with unmanaged ones in both meadow types. Vegetation type had a stronger influence on seed bank richness and density than management status and we detected much higher seed bank densities in fen meadows (64,000-94,000 seeds/m2) than in dry-mesophilous ones (4,400-6,300 seeds/m2). Therefore, restoration of former richness could not be based exclusively on the local seed banks in the studied meadow types. Further management, such as hay transfer or seeding of target species, is required to increase species richness.