Soil and litter microbiomes jointly drive the ecosystem multifunctionality of a 60-year-old plantation

Afforestation is considered an effective strategy to mitigate a changing climate. However, it is unclear how ecosystem multifunctionality (EMF) changes under long-term afforestation and which are influencing factors. To address this knowledge gap, we studied a well-characterised 60-year-old plantation and analysed soil and litter samples from different stand ages to investigate the interactions between microbial communities and EMF. We found that EMF significantly increased annually, and soil and litter microbial communities underwent succession, with microbial networks evolving towards greater complexity and stability. There were significant differences in soil and litter microbial communities and functions, with soil bacteria and litter fungi in older stands having a higher metabolic potential. Structural equation modelling revealed that biological factors, including soil microbial community composition, network stability, litter microbial community composition, and network stability, coupled with abiotic factors such as soil and litter physicochemical properties, jointly explained 98% of the variation in EMF. This demonstrates that soil and litter microbiomes jointly drive the increase in plantation EMF.