Abstract
Control of the invasive alien species Robinia pseudoacacia L. is an important issue in river ecosystem management in Japan. The removal of alien plants by cutting is one option for vegetation management. This study assessed the effect of different annual cutting schedules (one to three times per year) on the sprout production of R. pseudoacacia, and estimated the number of years of management required to convert R. pseudoacacia forest into riparian grassland. Ten management plots (10 × 10 m) were established in a R. pseudoacacia forest along the Arakawa River. The trunks and sprouts of the species had been cut one to three times per year for 5 years (2007-2011) . The results showed that the sprout production decreased gradually in the plots managed two or three times a year, while no obvious reductions were observed in the plots managed once a year. Annual cutting performed at least twice a year would change R. pseudoacacia forest into riparian grassland within 6-8 years. These results suggest that annual repetitive cutting management for 6-8 consecutive years might be effective for controlling R. pseudoacacia forest along rivers.
