Fig. 1.

An overview of observed relationships among stomatal density (D), pore size at maximal stomatal opening (a_max), and the resulting maximal stomatal conductance (g_smax) and leaf surface area allocated to stomatal pores at a_max (A_%). (A) Power law relationship between D and a_max are plotted together with lines of equal g_smax (solid lines) and A_% (dashed lines). See Eq. 1 and Table S1 for calculations of g_smax. Note that logarithmic axes are used. (B) Cumulative probability of A_% for woody angiosperm and conifer species fitted to a lognormal distribution. The value of 0.6 indicates the estimated lower bound (5% probability) on A_% defined here as A_%low. Note that a logarithmic x axis is used. (C) Species-specific strategies to adapt g_smax linearly with A_%. The dashed line denotes A_%low. Lines of linear least squares regressions are indicated per species and used to determine the intersect with A_%low to predict the lowest attainable g_smax for each species, defined as g_low. The r² values are: 0. 97 (Ar), 0.96 (Ic), 0.86 (Mc), 0.96 (Ql), 0.91 (Qn), 0.85 (Pe), 0.98 (Pt), and 0.94 (Td) with P < 0.001 for all. Data FB09 are from ref. 23, others from ref. 8. Species names and their abbreviations are defined in the legend.