Characteristics of soil carbon emissions and bacterial community composition in peatlands at different stages of vegetation succession

Microorganisms are important components of soil ecosystems and play an important role in material cycles. Northern peatlands are important ecosystems in middle-high latitude regions. In peatlands, different vegetation successions occur with changes in groundwater levels. The overall carbon emission of peat bogs is related to the carbon stability of the surrounding environment. Unraveling the assembly and distribution of bacterial communities at different succession stages in peatland is essential to understanding the soil nutrient cycle. In this study, we investigated the characteristics of soil carbon emissions and the composition of subsurface microorganisms under six different succession stages. The highest carbon emission was observed in mossy peatlands, and their soil enzyme activity was closely related to the aboveground vegetation cover type. The succession pattern of ground vegetation was the main driver of soil microorganisms. The abundance of the dominant Proteobacteria decreased with increasing soil depth, while the opposite trend was observed for Chloroflexi. Furthermore, the community structure of microorganisms became progressively simpler and looser as soil water content decreased. The bacterial alpha diversity was driven by soil dissolved organic carbon and Fe, and the beta diversity was driven mainly by soil water content. The bacteria presented a random distribution in a nutrient-rich soil environment and shifted to deterministic distribution with decreasing water and nutrient contents. The balance between taxonomic diversity and dispersal limitation mediates species coexistence in the soil microbiome. This study provides new insights into the soil environment at different stages of succession in peatlands.