Abstract
We conducted a survey on vegetation and a sampling of topsoils on the riverbed of growing sites of 5 species (Sicyos angulatus L., Ambrosia trifida L., Coreopsis lanceolate L., Rudbeckia laciniata L. and Eragrostis curvula (Schrad.) Nees) in nationwide six rivers. After that, we performed a germination experiment using the sampled topsoils. We also analyzed Veronica anagallis-aquatica L. that germinated in the experiment. As a result, germination was obserbed in the second year of the experiment, with five species except Rudbeckia laciniata L., suggesting the formation of persistent soil seed banks.
