Fig. 4

Linear regressions between clonal extension and clonal average sap flux (F_H2O, L day⁻¹) (a), [CO₂] dissolved at stem base ([CO₂ ^*]_base, mmol CO₂ L⁻¹) (b), and CO₂ flux through the xylem (F _T, mmol CO₂ day⁻¹) (c) in two large and two small Quercus pyrenaica clones measured during the growing season of 2012. Soil CO₂ efflux on surface basis (F _S16, μmol m⁻² s⁻¹) (d) and root-respired CO₂ diffused through soil to the atmosphere per stem (F _S16-root, mmol CO₂ day⁻¹) (e) in 20 Q. pyrenaica clones measured during the growing season of 2014. [CO₂ ^*]_base, F _T, F _S16, and F _S16-root were log transformed to satisfy Shapiro-Wilk normality tests. Statistics (R ² and p values) apply to transformed regressions. Back-transformed values were used to display (geometric) means, SE intervals, and regression lines. Only significant (p < 0.1) regression lines are depicted