In many rivers, the excessive growth of trees such as Salix species after river channel excavation has posed negative effects on flood control and the river ecosystem, creating another challenge for river management. In this study, we investigated how Salix species may invade and grow in the Ibi River by conducting flow-regime and vegetation analysis, based on data and information accumulated for ten years after the excavation and research on the current conditions of vegetation in the river channel. This study analyzed the excessive growth mechanism of Salix species and showed their detailed characteristics from the shape of Salix chaenomeloides individuals and the shape of distributions of Salix communities. We proposed a measure to reduce the excessive growth of Salix species in the river channel excavation sites from the each phase of river improvement project.

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