CONCLUSION
Overall, our results demonstrate that high AMF diversity enhanced ecosystem multifunctionality. However, under multiple GCFs, the competition among AMF likely intensified, leading to no significant differences in ecosystem multifunctionality between high and low fungal diversity treatments. These multiple GCFs also may have enabled plants to select more efficient mycorrhizal partners, ensuring that high AMF diversity consistently benefited plant photosynthesis and growth. Our findings suggest that BEF studies should integrate both aboveground and belowground multi-trophic levels biodiversity within a unified framework. Additionally, our research emphasizes the importance of preserving AMF diversity for plant growth, particularly in agricultural ecosystems that are suffering from multiple global changes.