Functional trait differences between alien and native plants under hydrological variability in the riparian zone of the Three Gorges Reservoir

Riparian zones play a vital role in maintaining biodiversity and ecological functions, yet they are increasingly affected by hydrological disturbances in large-scale engineered systems. This study aimed to investigate how varying flooding intensities influence both taxonomic diversity and functional trait composition of invasive and native plant species in the riparian zone of the Three Gorges Reservoir (TGR), a globally significant hydrological project. Field surveys were conducted between 2021 and 2022 across 127 sites in 22 districts along the Yangtze River. Plant community composition and functional traits were assessed across three elevation bands (145–175 m), representing distinct flooding regimes. Results revealed a non-linear, N-shaped relationship between species diversity and flooding intensity, with species richness and diversity indices negatively correlated with prolonged inundation. While overall functional differentiation did not significantly vary with flooding intensity, convergence in plant height traits was observed under moderate flooding, whereas stronger flooding led to increased trait divergence. Invasive species, predominantly annuals with fibrous root systems, exhibited trait plasticity that supported persistence under hydrological stress. In contrast, native species demonstrated a broader range of life history strategies and stronger adaptations to variable flood conditions. This research advances our understanding of how flood regimes structure riparian plant communities and identifies key functional differences between native and invasive species. The findings provide valuable insights for biodiversity conservation and invasive species management under future hydrological change, offering a novel perspective on trait-based responses to flooding in large, human-modified river systems.

Abstract licence: CC BY-NC

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