Fig. 2
a Time course of the daily relative sap flux density (SFD%) and the potential evapotranspiration (PET; Penman formula) for the studied tree species studied in 2006. Symbols correspond to species: Bp, B. pendula; Cb, C. betulus; Fs, F. sylvatica; Qr, Q. robur; Sc, S. capreae. b Predawn leaf water potential (black symbols, Ψwp; left vertical axis), midday leaf water potential (grey symbols, Ψwm; left vertical axis) and relative extractable soil water (grey line, REW; right vertical axis) in summer 2006. Vertical bars indicate standard error