Effects of mixed plantations on soil microbial diversity and ecosystem multifunctionality across China: a meta-analysis

Mixed plantations have emerged as a key afforestation strategy for enhancing the stability and sustainability of forest ecosystems. However, their effects on soil microbial diversity and ecosystem multifunctionality (EMF) remain inconsistent. Here, we compiled a dataset from 121 peer-reviewed publications and conducted a meta-analysis to evaluate the effects of different mixed plantation strategies on soil microbial diversity and EMF. The results showed that mixed plantations significantly increased bacterial and fungal Shannon indices by 1.43 and 7.4%, respectively, compared to monocultures. In addition, mixed plantations enhanced key ecosystem functions, including increased soil organic carbon, nutrient availability, and moisture retention, while reducing soil bulk density. Collectively, these improvements resulted in a 19.25% increase in the EMF index. Further analysis revealed significant positive correlations between both bacterial and fungal diversity and EMF, as well as significant associations between EMF and key soil physical properties. Moreover, the effects of mixed plantations on microbial diversity and ecosystem functions varied depending on the mixing strategy. Overall, our findings highlight the ecological benefits of mixed plantations for soil microbial diversity and EMF, supporting more effective and sustainable afforestation practices.