Simple SummaryIn a river system where material flow is dynamic, the expansion of exotic plants through seed dispersion is affected by physical and biological factors, such as water, wind, and animal activities. In this study, the relationship between the life forms of plants and terrestrial birds that carry plant seeds in the establishment of exotic plants in exposed areas that were originally submerged and exposed to a drop in water level was analyzed. As a result, the development of exotic plants was promoted in proportion to the area of vine plants and the population of small terrestrial birds. This provides insight not only about the life forms of existing plants, but also the landscape of potential bird habitats, including vegetation patches; these should be considered for the effective management of exotic plants along rivers.AbstractFor the study on the relationships between the seed dispersal of exotic plants and bird population, flora, avifauna, vegetation patches, and the dynamics of seed banks were investigated in and around the exposed floodplains of the large rivers, and the causes of exotic vegetation development were determined with respect to plant life form, bird population characteristics, and landscape using multivariate analysis. The number of dominant exotic plant species observed in exposed areas was higher than that observed in an abandoned field and paddy field undergoing secondary succession. Additionally, the area occupied by exotic vegetation in exposed areas increased with the increase in number of vine plants and small terrestrial birds, whereas the relationship between vine and runner plants was inversely proportional. Therefore, to control exotic plants in exposed floodplains surrounding large rivers, it is necessary to remove vines and shrubs along the waterfront where small resident birds carrying plant seeds live and to maintain and manage runner plant populations. Furthermore, implementing an ecological landscape management strategy, such as afforestation through the planting of trees, may also be effective.