Discussion
In this study, we tested the effect of tree-tree interactions and the spatial distribution of microbial biomass and respiration in subtropical forest soils. We did not find any significant tree-tree interaction effects on the aggregated soil samples at the species pair level. However, there were substantial variations in tree-tree interaction effects at the small spatial scale. In fact, effects on both soil microbial properties were spatially distributed, ranging from overyielding near one tree species to underyielding close to the other tree species.