Plant richness reshuffles the soil microbiome in permafrost ecosystems

Abstract

Empirical and experimental evidence has revealed the strong impacts of plant communities on the soil microbiome. However, the effects of plant richness on the soil microbiome and, subsequently, on soil organic carbon (SOC) storage in permafrost ecosystems remain poorly understood. Here, we investigated the soil microbiome (including bacteria and fungi) and SOC in the top and sub-layer soils across a natural gradient of plant richness in the Greater Khingan Mountains of Northeast China. Our findings revealed that increased plant richness was associated with higher soil bacterial and fungal richness. Additionally, stochastic processes primarily governed soil microbial community assembly, with soil fungal community stochasticity decreasing as plant richness increased but bacterial not, suggesting a potential trade-off between multiple microbial groups in response to plant diversity shifts. Moreover, network complexity was significantly positively correlated with SOC, while network stability showed an inverse relationship. Further analysis revealed that plant richness had both direct and indirect effects (mediated by microbial characteristics) on SOC. Taken together, our results suggest that plant richness fundamentally influenced SOC through its association with microbial characteristics. Our study provides novel empirical insights into the significant role underlying the regulatory effect of plant richness on soil microbiome and SOC in permafrost ecosystems.