The complex interplay of flooding intensity and land use on soil microbial communities in riparian zones: Insights for ecological restoration

Abstract

The impact of hydrological regimes and land use on soil microorganisms in riparian zones has been well-documented, but their combined effects on the composition and assembly mechanisms of these communities remain unclear. To address this knowledge gap, we conducted a study examining the fungal and bacterial communities in three land use types—artificial mixed forests, natural grasslands, and cornfields—within riparian zones of the China’s Three Gorges Reservoir. We also considered how these communities responded to different flooding intensity gradients. Our results show that natural grasslands fostered increased diversity and network complexity of soil microorganisms with stronger flooding at middle and lower elevations. In contrast, artificial mixed forests enhanced microbial diversity and complexity at higher elevations with lower flooding intensity. Notably, land use had a greater influence on shaping soil microbial community structure, while flooding intensity had a greater impact on assembly processes. Dam-triggered flooding led to a convergence of bacterial community assembly processes across land use types, with deterministic processes playing a dominant role. However, this flooding also magnified the influence of stochastic processes on the structure of soil fungal communities. The assembly processes of these communities were primarily influenced by soil pH, SOC, and TK. These findings underscore the importance of developing vegetation restoration strategies based on riparian zone elevations to maintain soil microbial diversity and stability. This approach offers valuable guidance for ecological restoration efforts in similar regions.