Variations in Soil Microbial Community Structure and Respiration Intensity in Different Typical Herbaceous Marsh Wetlands in Northeastern China

ABSTRACT Herbaceous marsh wetlands are widely distributed in northeast China, with huge soil organic carbon storage, playing an important role in the carbon cycle. The microbial communities in their soils are highly sensitive to environmental changes, and their respiration is a major component of wetland carbon cycling. However, there are few studies on the characteristics of soil bacteria in large‐scale herbaceous marsh wetlands. This study employed 16S rRNA sequencing technology to analyse soil bacterial communities in Carex marshes, Phragmites australis marshes and Carex‐Deyeuxia angustifolia mixed marshes in Heilongjiang Province, and determined soil microbial respiration (SMR) through laboratory incubation methods. The characteristics and driving factors of soil bacterial communities and SMR were explored using one‐way analysis of variance (ANOVA) and correlation analysis. Our results showed that Proteobacteria and Acidobacteria were dominant in the soils of herbaceous marsh wetlands. The Carex marshes exhibited the highest soil bacterial diversity and soil microbial respiration (SMR), while Phragmites australis marshes showed the lowest. Investigations into driving factors revealed that soil moisture content (MC), pH, and bulk density (BD) significantly influenced bacterial communities, whereas MC and underground biomass (UB) significantly affected SMR. Structural equation modelling (SEM) demonstrated that vegetation types indirectly impact bacterial communities and diversity by regulating soil MC, thereby influencing SMR. In conclusion, Carex spp.‐dominated herbaceous marsh wetlands serve as hotspots for microbially mediated carbon fluxes and play a crucial role in the global carbon cycle. The findings provide empirical support for prioritising such wetlands in climate change mitigation strategies and offer insights into targeted wetland conservation and restoration.