Multiple floods interactions shape riparian plant communities and diversity.

Disturbances are pivotal ecological events that influence the formation of biological communities. Although disturbances have been studied in isolation, studies recently have highlighted the interaction among multiple disturbances. Riparian plant communities are primarily shaped by flooding disturbances, where periodic seasonal floods, and rare large-scale floods also play a role. Therefore, the interaction between these floods can markedly impact the formation of riverine plant communities. Such disturbance interactions, caused by the same type of representation, have been overlooked. In this study, we examined a riparian area impacted by Typhoon Hagibis in October 2019, situated along the Akigawa River in Tokyo. Through a comparison of land covers before and after the typhoon, we determined the effects of large-scale flood, and assessed the influence of periodic floods one and two years post-typhoon. Plant community surveys were conducted in both post-typhoon periods, investigating the relationship between community structure using both α- and β-diversity and disturbance interaction regimes. One year postdisturbance, the plant communities strongly reflected the varying intensities of the large-scale flood disturbance. However, two years postdisturbance, community structures exhibited changes, likely influenced by interactions with periodic disturbances. The results of this study suggest that interactions with the same type of disturbance may enhance community diversity.