SEEDLING RECRUITMENT IN DECIDUOUS FOREST HERBS - THE EFFECTS OF LITTER, SOIL CHEMISTRY AND SEED BANK

A litter removal experiment, in combination with analyses of soil chemistry and seed bank, were performed to investigate the role of these factors for seedling recruitment of herbs and grasses in a deciduous forest fragment in Sweden. An additional experiment was used to investigate effects of seed availability and seed predation on germination of one selected species, Anemone nemorosa. Removal of litter increased both seedling number and species diversity among seedlings. No species was directly favoured by litter but a few species, most notably A. nemorosa, were capable of germination under litter. No relationships were found between recruitment and soil chemistry. Only 26% of the species in the established vegetation were found in the seed bank. Recruitment in the field, after litter removal, was positively correlated to size and diversity of the seed bank. Seedling recruitment of A. nemorosa was partly limited by seed availability and seed predation. As a generalization, it is suggested that an increase in seed size among deciduous forest herbs implies (1) that litter effects of recruitment decrease, (2) that species become less likely to have a persistent seed bank, (3) that effects of seed predation increase, and (4) that recruitment limitation by seed availability becomes increasingly important.