Effects of Phyllostachys nigra var. henonis bloom for the first time in 120 years on the dynamics of organic matter and nitrogen in forest: Differences in decomposition processes between leaf and flower

Bamboo flowering occurs over a long cycle, yet the precise mechanisms and consequences of this phenomenon remain unknown. Although several studies have investigated the dynamics of forest communities post-flowering, the effects of flowering on the material cycle remain unclear. Recent reports have documented the first flowering of Phyllostachys nigra var. henonis in 120 years across several regions of Japan. P. nigra var. henonis flowers exhibit higher nitrogen concentrations compared to their leaves, suggesting potentially different decomposition patterns upon reaching the forest floor and subsequent contributions to the nitrogen cycle. Based on this observation, we conducted decomposition experiments using litter bags to investigate the dynamics of organic matter and nitrogen. After 1 year, litter bags containing both leaves and flowers were retrieved. The remaining mass of flower and leaf litter was 38% and 60%, respectively. On the other hand, the nitrogen remaining in flower and leaf litter was 54.9% and 98.2%, respectively. Net nitrogen release from the flower litter was estimated to be 36 kg/ha/year in the study site. The potential maximum nitrogen released from flower litter decomposition in a high-density ramet stand was estimated to be 221 kg/ha/year. The results of this study suggest that the nitrogen addition through mass flowering of P. nigra var. henonis would have a significant impact on the nitrogen cycle of the ecosystem.