Impact of the bambooPhyllostachys bambusoides on the light environment and plant communities on riverbanks

The bambooPhyllostachys bambusoides has been widely planted on riverbanks in Japan to protect against erosion. Recently, unmanagedP. bambusoides stands with high culm density are spreading along the banks of rivers. In order to study the impact of the bamboo stands on riparian ecosystems, the relations between bamboo stand structure, light conditions and plant communities under the canopy were examined. The study sites were set in bamboo stands with various culm densities in the middle of the Yahagi River in Toyota, Aichi Prefecture. There was a close relationship between canopy coverage and relative photon flux density (RPFD) in the bamboo stands. RPFD showed a highly negative relationship with total culm density, whereas no significant relation was observed between the basal area of bamboo and RPFD. The total number of plant species in the bamboo stands increased with decreasing culm density. Only a small number of tree saplings were observed in the stands with the highest culm densities, while several species of forest floor herbs were found in the stands with lower culm densities. A number of invasive and annual plants colonized the thinned stand. We suggest that moderate thinning and clearing of dead culms are needed to maintain biological diversity in the bamboo stands on riverbanks.