Habitat change and interspecific associations mediate the response of riparian ground-dwelling arthropod assemblages to flooding in the Three Gorges Reservoir

Seasonal water level fluctuation is a typical characteristic of reservoirs created by dams on rivers. Due to their important roles in connecting ecological processes between riparian zones and adjacent uplands or waterbodies, ground-dwelling arthropods are essential components for maintaining riparian ecosystem health. However, the dynamic characteristics and response mechanisms of ground-dwelling arthropod assemblages to seasonal water level fluctuations have not been clearly established. We investigated ground-dwelling arthropods before and after summer floods (along with the influence of planned winter impoundment) in the drawdown zone of the Three Gorges Reservoir. Redundancy analysis and examination of interspecific associations were conducted to explore driving mechanisms for variations in these arthropod assemblages. Our results demonstrated that: i. floods are dominant mediating factors for variations in ground-dwelling arthropod assemblages in riparian zones; ii. species composition and abundances of ground-dwelling arthropod assemblages were in a state of dynamic change under the influence of floods; iii. Interplay of habitat modifications and interspecific associations influenced the composition as well as the distribution of ground-dwelling arthropods. We suggest that grounddwelling arthropods are sensitive indicators for riparian ecosystem health and are valuable for evaluating work on the conservation and management of riparian zones.