Figure captions

Fig. 1 Comparison of fine-root attributes in plant mixtures and monocultures at the community level. Values (estimated β 0 in Equation (5)) are mean ± 95% confidence intervals of the percentage effects between plant mixtures and monocultures. The number of observations is shown beside each attribute without parentheses, with the number of studies in parentheses.
Fig. 2. Plant mixture effects on fine-root attributes in relation to species richness in the mixtures, stand age, and soil depth at the community level. Plant mixture effects on (A) fine-root biomass (root biomass), (B) root length density (RLD) and (C) specific root length (SRL) in relation to the species richness in mixtures, stand age, and soil depth. The blue lines for each attribute were estimatedβ 1, β 2, and β 3 in Equation (5), respectively, with bootstrapped 95% confidence intervals shaded in gray. The sizes of red circles represent the relative weights of corresponding observations
Fig. 3 Temporal and spatial trends of root biomass (root biomass) and specific root length (SRL) associated with plant species richness (SR) in mixtures. Temporal trends of the effect size of root biomass and SRL corresponding to SR in mixtures (a, b) and spatial trends of the effect size of root biomass and SRL corresponding to SR in mixtures (c, d). Coloured and black lines refer to the specific age or soil depth responses and their average responses, respectively, with their bootstrapped 95% confidence intervals shaded in gray. Pvalues are the interactive terms tested.
Fig. 4 Plant mixture effects on root length density (RLD) and root biomass (RB) in relation to MAT and MAP, respectively. The effect sizes of (a) RLD between species mixtures and monocultures in relation to mean annual temperature (MAT). The effect sizes of plant mixtures on (b) root biomass with MAP in relation to species richness. In Fig. 4a, the sizes of the red circles represent the relative weights of corresponding observations, whereas the blue lines are the estimated coefficient, with bootstrapped 95% confidence intervals shaded in gray. In Fig. 4b, the coloured and black lines represent specific species richness and their average responses, respectively, with their bootstrapped 95% confidence intervals shaded in gray
Fig. 5 Plant mixture effects on ecosystem types with (a) root biomass, (b) root/shoot ratio, (c) community-weighted mean rooting depth, (d) root length density, (e) specific root length, (f) mean root diameter, (g) root nitrogen between ecosystem types. Values are mean ± 95% confidence intervals of the percentage effects between the plant mixtures and monocultures. The numbers of observations are shown beside each attribute without parentheses, with the number of studies in parentheses

Fig. 1