Plant communities regulated by water-level gradient in Caohai aquatic–terrestrial ecotones affect bacterial and fungal structures and co-occurrence networks

Abstract

There is increasing awareness that vegetation dynamics play an important role in ecosystem stability and belowground microbial community diversity in wetlands. Studying plant–microbe dynamics and interactions under various conditions within lakes helps with the effective management of lake ecosystems by restoring ecosystem services. However, our knowledge about the response of microbial interactions to vegetation variation remains limited. We investigated how soil nutrients, enzyme activities, fungal and bacterial community diversity, and their network properties vary along the inundation gradient in aquatic–terrestrial ecotones of Caohai Lake in southwest China. Compared with the arid zone, the organic carbon and ammonia nitrogen contents in the severe inundation zone (SIZ) increased by 28.5% and 16.4%, respectively. Compared with the SIZ, the activities of cellobiohydrolase, β-1, 4-N-acetylglucosaminidase and leucine aminopeptidase in the dry–wet cycling zone increased significantly, increasing by 62.1%, 60.5% and 26.1%, respectively. Moreover, long inundation significantly reduced the abundance of fungi, diversity of bacteria, and size and complexity of their community co-occurrence networks. Microbial networks were smaller (fewer edges) and less stable (higher positive to negative edge ratios) in the SIZ. Aboveground vegetation regulated by water-level gradient can directly or indirectly affect microbial community structure and further interfere with the properties of bacterial and fungal co-occurrence networks. In conclusion, our findings suggested that plant communities regulated by water-level gradient play an important role in maintaining microbial diversity and co-occurrence network stability along the aquatic–terrestrial ecotone in Caohai Lake.