From disturbance to stability: Ten‐year dynamics of riparian arthropod communities in the Three Gorges Reservoir

River damming profoundly modifies natural riparian zones, yet the successional trajectories of biological communities in the novel riparian ecosystems created by dam operation remain poorly understood.

From 2015 to 2024, we conducted six field surveys of arthropod communities along elevational gradients in the riparian zone of the Three Gorges Reservoir. We examined temporal dynamics in biodiversity, spatial distribution patterns and the mechanisms governing community assembly under the influence of reservoir operations.

In response to flooding stress, the riparian arthropod community developed a distinct spatial zonation along the elevational gradient, characterized by a unimodal pattern with abundance and taxonomic richness peaking at 170 m. The relative abundance of predators and herbivores decreased with elevation, whereas that of detritivores and omnivores increased.

Interannual dynamics revealed that both the composition and structure of riparian arthropod communities stabilized after 2018, with no significant differences observed among subsequent years. This trajectory was further supported by β ‐diversity across elevations, which remained stable after 2021.

Community stabilization is driven by a two‐stage assembly mechanism. Initial inundation stress acted as a stringent environmental filter, eliminating submergence‐intolerant species and restructuring community composition. Subsequently, dispersal processes, rather than niche differentiation, became the dominant force maintaining community dynamics. This was evidenced by a significantly negative values of the Dispersal‐Niche Continuum Index, reflecting directed migration and rapid recolonization along the elevational gradient.

Our study demonstrates the importance of migration and colonization processes in shaping successional trajectories of riparian arthropod communities in regulated rivers. This process relies fundamentally on connectivity with adjacent terrestrial areas, which serve as critical refugia and source populations during inundation. Conserving riparian biodiversity in dam‐regulated rivers therefore requires extending management to these adjacent terrestrial habitats.