Fig. 2: Linkages among the root economics space, chemical defence and decomposition as well as the integrative strategies of species based on the ‘acquisition-defence-decomposition’ loop.

Root trait biplots of phylogenetic principal component analysis (pPCA) for 90 angiosperm tree species (a). The purple and green circles represent arbuscular mycorrhizal (n = 65) and ectomycorrhizal (n = 25) tree species, respectively. For more details on pPCA scores, see Supplementary Table 3. Within the root economics space, the ‘symbiosis gradient’ (the first principal component, PC1) representing the reliance of roots on fungi ranges from the high reliance on EcM fungi with high branching intensity (BI) to the strong reliance on AM fungi with high root diameter (RD) and cortex thickness (CT); and the ‘lifespan gradient’ (the second principal component, PC2) ranges from the short-lived roots with high specific root length (SRL) to the long-lived roots with high root tissue density (RTD). RN root nitrogen concentration. The linear regressions are fitted among scores of the SRL-RTD axis or RD/CT-BI axis within the root economics space, condensed tannins concentrations, and decomposition rate (b, c, d). The chemical defence gradient refers to the concentrations of condensed tannins from low to high, and the decomposition rate indicates the root mass loss from low to high. The colour from grey to blue represents the gradients of the variables ranging from low to high on the corresponding axis, except that represent the transition of dominant traits (from BI to RD/CT) on the ‘symbiosis gradient’. Solid lines indicate regression lines, shaded areas around each line are 95% confidence intervals (F-test). The linear regressions are also fitted between the score of RD/CT-BI axis (PC1) and the divergence time in evolutionary history (MYA, million years ago), of major taxonomic groups (n = 15) at the family level (only families with at least three species were retained) (e). The cubes represent a multidimensional strategy along the ‘acquisition-defence-decomposition’ continuum driven by the ‘symbiosis gradient’. Source data are provided as a Source Data file.