Composition of Aquatic Plant Communities Emerging in a Newly Constructed Flood-control Reservoir

抄録

The composition, diversity, and early dynamics of aquatic plant communities were investigated in a newly constructed flood-control reservoir in Tochigi Prefecture, central Japan. Field surveys conducted from 2022 to 2025 recorded a total of 148 taxa across the reservoir and surrounding habitats, including rice fields, rivers, and water channels. Species composition and vegetation similarity among quadrats were analyzed using non-metric multidimensional scaling (NMDS) based on Bray–Curtis dissimilarity of species cover data. The reservoir supported high species diversity, including numerous taxa not observed in nearby environments and several Red-listed species. NMDS ordination showed that community composition in the reservoir was intermediate between those of rice fields and lotic habitats, incorporating elements from both. This pattern suggests that vegetation establishment was primarily driven by soil seed banks and remnant propagules derived from pre-construction environments. Despite species turnover during the study period, no clear directional temporal trend in community composition was detected. Differences in water depth were associated with variation in life-form composition and likely contributed to the high overall diversity by creating heterogeneous habitats. These findings indicate that newly constructed flood-control reservoirs can support diverse and unique plant communities and may contribute to the restoration and conservation of aquatic plants.