a, c, Drought coupling is expressed as the percentage of explained variation (R2). b, d, Drought sensitivity is shown as the summed absolute values of standardized coefficients for drought variables that are regressed against latent energy (LE) exchange. Regression: LE ≈ VPD + SM + VPD × SM. a, b, Panels are identical to Fig. 2 but with site identifications shown. Hydraulic variation is expressed as the community-weighted standard deviation in the hydraulic safety margin of species. c, d, The hydraulic safety margin was calculated from the 50% loss of hydraulic conductivity in gymnosperms and 88% loss of hydraulic conductivity in angiosperms. Colours indicate biomes of deciduous broadleaf (green) and needleleaf (red) forests. The size of the dot indicates the number of days included for each flux site. The solid black line is the best fit of the ordinary least-squares linear regression (c, P = 0.008; d, P = 0.01) and dashed lines are the 95% confidence interval of the regression fit.