Figure captions
Figure 1: Sampling Design. Overview of the BEF-China experimental Site A (panel A) with the two sampled plots (green) representing two-species mixture plots. Plot tree planting grid pattern with a marked tree pair, here only a small section of the 20x20 trees plot was drawn. Positions of the five soil cores between the tree pair with the in-core division of the depths. Tree species combinations are shown in panel B.
Figure 2: Distance to tree and depth effects on microbial biomass (top) and respiration (bottom) in monospecific tree pairs.Effects are predicted from the model (soil properties ~ depth * distance to tree ) with plot as random effect. Distance to tree reports the distance to the closest tree from monospecific tree pairs. Microbial biomass coloured blue (low) to red (high), microbial respiration coloured purple (low) to orange (high). The significance levels were standardised across the panels (p<0.05: *, p<0.01: **, p<0.001: *** ).
Figure 3: Distance to tree and depth effects on microbial biomass (top) and respiration (bottom) overyielding in heterospecific tree pairs. The mean value (grey square) of overyielding for microbial biomass (A) and respiration (D) across all depths and positions, for each depth (microbial biomass: B, yellow circle for 0-5 cm; brown triangle for 5-10 cm, and microbial respiration: E, light blue circle for 0-5 cm; dark blue triangle for 5-10 cm), and for each sampling point by depth (microbial biomass: C and respiration: F). Confidence intervals were predicted from models using the “ggpredict” function of the R package ggeffects . The significance levels were standardised across the panels (p<0.05: *, p<0.01: **, p<0.001: *** ).