Soil pH and dissolved organic carbon shape microbial communities in wetlands with two different vegetation types in Changdu area, Tibet

Soil microorganisms play pivotal roles in element biogeochemical cycling and ecological functions in wetland ecosystem, which may affect global climate change. Variations in biotic and abiotic factors are known to affect soil microbial diversity, community structure and the corresponding functions. However, the relative importance of these biotic and abiotic factors on wetland soil microbial diversity and community structure on the Qinghai-Tibet Plateau remains poorly understood. In this study, we explored soil bacterial and fungal diversity and composition of five wetlands under two vegetation types (herbs vs Hippophae thibetana) in Changdu area, Tibet, through Illumina high throughput sequencing analysis of 16S rRNA for bacteria and internal transcribed spacer (ITS) for fungi. Results showed that soil bacterial alpha diversity was higher in H. thibetana dominated wetlands and was significantly and positively correlated with soil pH. No difference was detected in the soil fungal alpha diversity among samples and between vegetation types. The dominant soil bacterial phyla were Proteobacteria, Actinobacteria, Acidobacteria, and Firmicutes. While Ascomycota, Basidiomycota and Mucoromycota were the dominant fungal phyla. Soil bacterial and fungal community structures were significantly distinct by vegetation types. In addition, redundancy analysis indicated that soil pH was the key factor shaping soil bacterial community structure. Nevertheless, soil pH showed no effect on fungal community. Instead, soil dissolved organic carbon was the major factor contributing to soil fungal community structure. This study emphasized that wetland soil microbial communities were distinct by vegetation types and the driving factors of microbial beta diversity between bacterial and fungal community were also different in wetlands in Changdu area.