Abstract/Summary

An important ecosystem function of vegetation on riverbanks is the control of soil erosion. Riverbanks also offer potential semi-natural habitats for grassland species. Previous classification of riverbank vegetation in Japan ignored both seasonal changes of dominant species and species composition, offering no information on ecosystem functions. Here we aimed at clarifying the association between dominant species, vegetation composition and species attributes in spring and autumn. We surveyed vegetation in 125 plots on a riverbank in Japan. We identified seven vegetation types on the basis of dominant species in autumn. Imperata cylindrica var. koenigii (Type I) and Pleioblastus chino (Type P) dominated their vegetation year-round. Dominant species changed seasonally in the other five vegetation types, but Lolium multiflorum was dominant in spring. Since the dominance of annuals is linked to fast turnover of root systems and thus poor control of soil erosion, Types P and I are superior in controlling soil erosion. Both the total number of species and the number of grassland species were small, showing species-poor grasslands in all vegetation types. There were no clear differences in numbers of species between species attributes. Nevertheless, this classification was linked to differences in species composition, reflecting several representative species in each vegetation type. Type P has more indigenous representative species and typical grassland species. Since some representative species may be suitable for natural processes (e.g., for pollination), this classification reflects biodiversity functions.