Effects of mowing, grazing and fertilization on soil seed banks in temperate grasslands in Central Europe

Soil seed banks support the recovery of plant species and communities after disturbances. Against the background of increasing disturbance frequencies due to current changes in climate and land use, the importance of seed banks to maintain ecosystem functioning of grasslands is likely to increase. This makes seed bank ecology a highly relevant topic of studies on ecosystem functioning. One of the main drivers of seed bank composition and density in grasslands is the current management. Although highly intensive grassland management can affect soil seed banks negatively, it is still unclear which component of management – fertilization, mowing or grazing – is the most influential. We studied soil seed banks of 73 mesic grasslands, which were arranged along a gradient of land-use intensity, by two seasonally differing surveys. Grasslands generally exhibited rather poor seed banks with low numbers of species and seedlings. Both were even lower in spring compared to autumn sampling. Grassland management turned out to affect soil seed banks in a complex way, via direct and indirect paths. While intensive mowing and fertilization decreased species richness and seedling density, grazing intensity increased species richness in the seed bank. Thus, land-use intensity, an index calculated as a sum of all three components, had highly ambivalent effects on seed banks. We conclude that the positive effect of grazing on soil seed banks makes pastures more resilient towards mechanic disturbances as compared to meadows.