The evergreen perennial herb, Asarum tamaense (Aristolochiaceae), is an endangered species distributed across the Tama Hills in the Kanto region of Japan. In abandoned secondary forests, Pleioblastus chino can grow unregulated and suppress the growth of the herbaceous layer. This study investigated how cutting P. chino affects the growth and flowering of A. tamaense in an abandoned secondary forest. Two study areas (cutting and non-cutting) were defined in an area of the Tama Hills secondary forests that had been untouched for approximately 40 years. P. chino was cut with a sickle in only the cutting area during the summers of 2010 - 2018. Each April from 2015 to 2018, in both areas, the number of patches, leaves and flowers were counted in 30 quadrats, 5m × 5m at each quadrat, and the photosynthetically active radiation (PAR) and soil moisture content were checked. The cutting area had less the number of patches than the non-cutting area, and there were no differences in the patches increase rate over time between the areas. The number of leaves and flowers and the increase rate in the cutting area were higher; as the number of leaves increased, the number of flowers increased. PAR was also higher in the cutting area. These results suggest that cutting P. chino contributes the conservation of A. tamaense.
