Synergistic effects of hydrology and microtopography on plant community assembly in a modified lakeshore zone: a case study of lake Chaohu

Interactions between hydrology and microtopography are a key factor shaping habitat heterogeneity in lakeshore zones, yet their synergistic effects on the Chaohu lakeshore plant communities remain unclear. Here, we addressed this issue by delineating four flooding zones along an elevation gradient and selecting four microtopographic types: Estuarine Zone, Sheltered Cove, Windward Upland, and Terraced Wave-Breaker to explore how their combined effects shape community structure and diversity. We conducted systematic field vegetation surveys and soil physicochemical measurements, and employed non-metric multidimensional scaling, two-way permutational multivariate analysis of variance, and redundancy analysis to quantify the individual and interactive effects of hydrology and microtopography on plant community composition and species diversity. Results showed that: (1) Hydrology predominantly shaped plant community differentiation along the elevation gradient, with composition transitioning from hygrophytes and hydrophytes to meso-xerophytes as flooding decreased; (2) The ecological effect of microtopography varied with hydrological conditions—masked by strong hydrological filtering in long-term flooded areas, it drove further differentiation by regulating local conditions as flooding stress weakened; (3) Species diversity was jointly regulated by both factors, with richness peaking in the short-term flooding zone and the Estuarine Zone hosting the highest species diversity. This study clarifies plant community assembly under anthropogenic disturbance, highlighting the synergy between hydrology and microtopography as key to understanding regional biodiversity patterns, and offering a basis for lakeshore restoration through integrated hydrological and microtopographic management.