Figure 2.

Evaporative enrichment of leaf water. Comparison between the diel course of oxygen isotopic enrichment (Δ¹⁸O) for beech (Fagus sylvatica) (a), oak (Quercus petraea) (b), pine (Pinus sylvestris) (c) and Alpine ash (Eucalyptus delegatensis) (d) as observed in the lamina leaf water (Δ¹⁸O_L) and the values estimated from models for isotopic enrichment at the site of evaporation (Craig and Gordon model, Δ¹⁸O_es) and for mean lamina leaf water: Δ¹⁸O_Ls and Δ¹⁸O_Ln, Péclet-based steady-state and nonsteady-state models, respectively. Vertical error bars indicate the standard error of the mean of three plants. White/shadowed areas denote light/dark periods. The observed values are means from three replicates (i.e. three individual trees) ± SD.