Micro-food web complexity and stability drive differences in soil multifunctionality of subtropical karst plantations in southwest China
Afforestation is vital for combating land degradation and restoring ecosystem multifunctions in karst desertification regions. However, the connections between multiple characteristics of microbial communities and soil multifunctionality (SMF) remain poorly understood in the different plantations within subtropical karst regions. Here, using the single function, and averaging method, we calculated the SMF of the two typical types of plantation (i.e., Pinus armandii Franch. PAF, and Alnus nepalensis, ANP) based on 20 variables associated with soil nutrient provisioning and cycling, soil water retention, microbial growth efficiency, and soil organic matter decomposition. The results showed that the carbon and nitrogen cycling indexes, soil water regulation capacity, and SMF were all significantly greater in the PAF compared to the ANP. The fungal and protistan communities, along with multitrophic microbial β-diversity, positively influenced SMF, while the complexity and stability of bacterial-fungal-protistan networks have a negative impact. Remarkably, changes in the abundance of sensitive taxa within Module 3 adversely impacted the SMF, with sensitive taxa of fungi (e.g., Trichocladium) and protists (e.g., Spongospora, Hartmannellidae_X and Trinematidae_X), as opposed to bacteria, playing a crucial role in driving the SMF. Furthermore, carbon and nitrogen sources, exchangeable Mg, and soil water content were determined to be pivotal forcing factors of SMF. Overall, these findings offer a framework for predicting ecosystem functions in subtropical karst forests and valuable insights for managing and conserving fragile ecosystems globally.