SUPPORTING INFORMATION

Figure S1. Model testing of the observed light-saturated net photosynthesis (An) versus predicted values (Ac) from the model of Farquhar et al. (1980), represented by eq. [1]. Ac values were calculated from estimated gm by the curve-fitting method. Grey symbols represent beech leaves and white ones sessile oak.

Figure S2. Evolution of the quadratic relationships between light-saturated net photosynthesis (An), stomatal conductance to CO2 (gsc), mesophyll conductance to CO2 transfer (gm), maximum carboxylation rate (VCmax) and leaf mass per area (LMA) evaluated at each canopy layer of each species in the three measurements dates. Symbols are described in Fig. 3 and dates are: July (solid line), August (dashed line) and September (dotted line). Note that x and y-scales differ between species.

Figure S3. The relationship between the ratio of maximum rate of electron transport to maximum carboxylation rate (Jmax/VCmax) and leaf predawn water potential (Ψpd). Symbols and regressions are described in Fig. 3.

Figure S4. Leaf photochemistry status evaluated through chlorophyll fluorescence in light acclimated leaves related to predawn water potentials (Ψpd). Fluorescence variables are: quantum yield of PSII (ΦPSII); maximum PSII efficiency in light (Fv´/Fm´); PSII efficiency factor (Fq´/Fv´) and fraction of open centers (qL). Symbols and regressions are described in Fig. 3.

Figure S5. The linear dependency of area-based leaf nitrogen content (Na) on the leaf mass per area (LMA) along the canopy of beech and sessile oak. Triangles represent oak and circles for beech. Closed symbols indicate Lower beech leaves, grey Middle leaves and open symbols Upper leaves. The three dates are represented together.

Figure S6. The close relationship between maximum rate of carboxylation (VCmax) and leaf nitrogen content expressed in area basis (Na). Symbols are the same as Fig. 3. Single linear regression was found for beech and separation of July data from August plus September in sessile oak.

Figure S7. Errors in estimate of Cc at each canopy leaf layer when considering constant maximum gm reached in each species caused by progressive decrease of predawn leaf potential (Ψpd). Symbols are described in Fig. 3. Dashed line represents each quadratic regression line extrapolated to minimum Ψpd reached in Upper beech.

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