Contrasting contributions of plant and soil biodiversity to multifunctionality in a subtropical forest decades after restoration

Subtropical forests are global biodiversity hotspots where plant and soil biodiversity play crucial roles in supporting multiple ecosystem functions (i.e., multifunctionality). However, the relative contribution of plant and soil biodiversity in explaining multifunctionality in subtropical forests, particularly decades after subtropical forest restoration, remains largely unclear. Here, we conducted a standardized field survey to explore how plant (i.e., woody plants) and soil biodiversity (i.e., bacteria, arbuscular mycorrhizal (AM) fungi, ectomycorrhizal (EM) fungi, and saprotrophic fungi) contribute to multifunctionality including plant biomass, plant-soil mutualism, soil carbon cycling, pathogen control, water regulation, soil macronutrients and micronutrients in a subtropical forest decades after restoration. We found that both plant and soil biodiversity were significantly correlated with multifunctionality, though each contributed to different dimensions of ecosystem functioning. Specifically, plant diversity was closely linked to the multifunctionality dimension related to plant–soil mutualism and soil carbon, whereas soil biodiversity was primarily associated with the multifunctionality dimension related to soil macronutrients and micronutrients. Our work highlights the divergent roles of both plant and soil biodiversity in regulating different dimensions of ecosystem functioning, which is critical for restoration and conservation efforts in subtropical forests under global change.