Fig. 3: Linkages among the root economics space, chemical defence, and decomposition for arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) tree species.

Root trait biplots of phylogenetic principal component analyses (pPCAs) for AM (a, purple circle) and EcM (e, green circle) tree species. For more details on pPCA scores, see Supplementary Table 3. Within the root economics space, the ‘lifespan gradient’ the first principal component (PC1) for EcM species and the second principal component (PC2) for AM species, ranges from short-lived roots with high specific root length (SRL) to long-lived roots with high root tissue density (RTD); while the ‘symbiosis gradient’ for AM (PC1) and EcM (PC2) species, representing the reliance of roots on fungi ranges from weak to strong. The strong reliance on fungi is represented by high branching intensity (BI) for EcM species and represented by high root diameter (RD) or cortex thickness (CT) for AM species. RN root nitrogen concentration. The regressions are fitted among scores of the RD/CT-BI axis within the root economics space, chemical defence gradient, and decomposition rate (b, c, d, f, g, h). Except for the transition of dominant traits from BI to RD/CT on ‘symbiosis gradient’, the gradients of the other variables (e.g., the concentrations of condensed tannins, decomposition rate) ranging from low to high are denoted in colour from grey to blue on the corresponding axis. Solid lines indicate regression lines, shaded areas around each line are 95% confidence intervals (F-test). Source data are provided as a Source Data file.