Abstract
We examined the species composition of soil seed banks (to 5 cm depth), using germination tests, for the Ooyamazawa riparian forest in the Chichibu Mountains. The canopy of this forest is dominated by Fraxinus platypoda. The dominant species in the soil seed bank were Hydrangea macrophylla var. acuminata, Euptelea polyandra and Betula grossa, which existed in the above-ground vegetation, and Buddleja japonica, which was not present in the above-ground vegetation. Of the buried viable seeds, there were few Fraxinus platypoda and a few zoochorous seed plants, such as Actinidia arguta and Rubus phoenicolasius. However, there were many species found in both the buried viable seeds and the current above-ground vegetation. In riparian forests, there are frequent disturbances such as flushing. It is assumed that old seed banks which included zoochorous seeds were lost in the riparian forest, while anemochorous and/or barochorous seeds were provided by parent plants near the riparian forest.
