Spatial Distribution and Correlation of Plant Species and Functional Diversity in the Floodplain of West Dongting Lake

Dongting Lake is located in the middle of the Yangtze River flood plain and connects with the Yangtze River, exhibiting crucial ecological roles like flood regulation, preservation of adjacent wetland ecosystems, and fostering biodiversity. The study delves into the characteristics and interconnections among species diversity and functional variety within plant communities existing in diverse environmental settings. Grasping these dynamics proves pivotal in unraveling plant community distribution patterns and safeguarding the ecosystem's structure and functionality. Focusing on the flood-affected shores, this research scrutinizes plant communities influenced by these river surges. It encompasses on-site surveys, gathering dominant species, and scrutinizing eight functional attributes of roots and leaves' carbon, nitrogen, phosphorus concentrations, leaf area ratio, and root length ratio, etc.. The study endeavours to decipher species diversity variations, functional diversity shifts along flood trajectories, associations between species and functional diversity, and correlations within diversity indices. Key findings reveal: (1) Noticeable species diversity disparity aligning with distinct water flow positions. Species richness diminishes notably at the Yuan River and Li River confluence points with the lake. Notably, midstream Yuan River shores display heightened species richness and Shannon's index, while the lake outlet records the lowest species diversity. (2) The midstream Li River plant community exhibits the lowest Community Weighted Mean (CWM) values and Rao's Quadratic Entropy across all traits. Conversely, upstream Li River shores manifest higher CWM values for carbon, nitrogen, and phosphorus concentrations. Additionally, the upstream Yuan River community showcases elevated leaf trait values, possibly attributed to rapid-growth strategies of dominant annual herbaceous plants. (3) A significant correlation emerges between species diversity and CWM of functional diversity parameters among West Dongting Lake's shore plant communities. Root carbon concentration's community-weighted mean shows a negative correlation with species richness and Shannon's index. Nevertheless, no correlation materializes between species diversity and Rao's Quadratic Entropy along different plant community positions along the water flow. The research findings shed light on how the differences in hydro-geomorphic characteristics among the Yuan and Li Rivers, as well as within various surveyed areas along the water flow, impact both the species and functional diversity of wetland plant communities. Interestingly, plant communities with higher species diversity, including dominant species composition and richness, don't necessarily demonstrate greater adaptability. Furthermore, there's a noticeable divergence in species diversity and functional variety along the floodwater's trajectory within the lake shore plant communities. Hence, when undertaking conservation and restoration efforts for the shore plant communities of West Dongting Lake, a comprehensive consideration of multiple factors (such as soil quality, topography, etc.) becomes pivotal for a holistic understanding and management of its intricate and distinctive ecosystem.