Recovery, Biomass Allocation, and Leaf Traits of Invasive Coreopsis lanceolata Following Natural Flooding

Flooding acts as a major physical disturbance in riverine ecosystems, influencing species composition through differences in recovery capacity. We investigated the post‐flood recovery and biomass allocation of the invasive species Coreopsis lanceolata relative to co‐occurring species. Vegetation was monitored in 60 permanent quadrats from May to September 2023, a period that included a natural flood in July. We analyzed (i) the relationship between C. lanceolata cover and species richness, (ii) the post‐flood cover trajectories of the focal species, and (iii) their biomass allocation. Before flooding, C. lanceolata cover showed a significant but weak negative relationship with species richness (generalized additive model, p = 0.029). Flooding significantly reduced C. lanceolata cover, with mean cover falling from 43% to 6% before partially recovering to 15% within 2 months after the flood (aligned rank transform mixed model, p < 0.05). This species was the only one to show a decline‐and‐recovery trajectory, and its recovery‐phase cover was comparable to that of the co‐occurring species. Coreopsis lanceolata had the highest root mass fraction (0.24 g g −1 ) and leaf mass fraction (0.76 g g −1 ) among the studied species, indicating substantial allocation to both roots and leaves. This trait combination may support post‐flood regeneration in sandy riparian habitats and could promote displacement of native vegetation under more frequent flood regimes. Because C. lanceolata flowers before the summer floods and regrows from belowground organs afterward, management is likely to be most effective during the pre‐flood, pre‐flowering period rather than after disturbance.