Fig. 4

Percentage loss of xylem conductivity as a function of stem water potential for petioles (red) and stems (blue) of four angiosperm tree species, (a) Populus tremula, (b) Betula pendula, (c) Liriodendron tulipifera, (d) Olea europaea. Solid lines are fitted curves computed using Weibull function with confidence interval. Red and blue solid and dashed lines indicate water potential induced 50% loss of conductivity and corresponding upper and lower bound bootstrap confidence interval, respectively