Wetland types and soil properties shape microbial communities in permafrost-degraded swamps

Global warming has accelerated permafrost degradation, destabilizing soil organic carbon (SOC) in wetlands. Soil microorganisms play a crucial role in SOC decomposition. Despite increasing studies on soil microorganisms and their associated impacts on SOC decomposition in wetlands, few studies have simultaneously investigated the impacts of soil physical properties and nutrient stoichiometry on soil microbial communities across diverse swamp wetlands. By selecting three types of swamp wetlands in the Xiaoxing'an Mountains, China, this study explored the relationships between soil physical properties, nutrient stoichiometry and microbial communities across different soil profiles. Our results showed that there were significant differences on soil physical properties and soil pH across the three types of swamp wetlands, leading to divergent patterns on soil carbon, nitrogen and phosphorus content, as well as on microbial diversity. Soil depths also significantly affected carbon, nitrogen, phosphorus content and bacterial diversity. Particulate organic carbon (POC) strongly correlates with microbial community composition and diversity, making it a key indicator. Dominant bacteria included Proteobacteria, Acidobacteriota and Actinomycetes, while over 80% of fungi were Ascomycetes, Basidiomycetes and Mortierellomycota. These findings will enhance the understanding of the relationship between microbial community distribution patterns and carbon components in different swamp wetlands, providing both theoretical and empirical insights into the role of soil microorganisms in the carbon cycle.