Conclusion
In the present study, we were able to show in a subtropical tree diversity experiment (BEF-China) that soil microbial biomass and respiration show a fine spatial pattern in the tree-tree interaction zone, both vertically and horizontally. Whereas aggregated soil samples were not affected by tree-tree interactions, tree-tree interactions ranged from overyielding close to Liquidambar formosana to underyielding close to Sapindus saponaria . Our findings suggest that tree-tree interactions are driving soil functioning when zooming to the appropriate spatial scale. Therefore, in order to understand relationships between trees and soil processes, future research should focus on fine-scale spatial variability (Eisenhauer et al. 2023).