Water level fluctuation regulated the effect of bacterial community on ecosystem multifunctionality in Poyang Lake wetland.

Soil bacterial communities are critical for maintaining ecosystem functions, yet the impact of water level fluctuations on ecosystem multifunctionality (EMF) and the role of bacterial communities in the lake water-level-fluctuating zone (WLFZ) remain poorly understood. This study investigated how seasonal water level fluctuations influence EMF and their relationships with soil bacterial communities through a two-year field survey. We found that soil bacterial diversity was significantly positively correlated with EMF. Rising water levels decreased soil bacterial diversity and EMF; neutral model analysis showed that the contribution of stochastic processes in bacterial community assembly decreased during the flood period. Structural equation modeling revealed that soil moisture and pH were the primary factors influencing EMF during the dry period, while soil pH, bacterial diversity, and water depth were the main factors affecting EMF during the flood period. Our study highlights that the dry-wet transitions caused by water level fluctuations lead to distinct seasonal driving patterns of EMF. This study provides a data reference for studying the ecological effects of water level fluctuations and wetland management.