Are Sclerophylls and Malacophylls Hydraulically Different?

This work tests the hypothesis that sclerophylls (i.e. hard-leaved species) would be less efficient than malacophylls (i.e. soft-leaved species) in terms of water transport through the stem as well as within the leaf blade. Mean leaf surface area (A_L), leaf specific mass (LSM) as well as shoot (K_WL), stem (K_SL) and leaf (K_LL) hydraulic conductances were measured in eight Mediterranean evergreen sclerophylls and eight temperate deciduous malacophylls. No difference was observed between the two groups in terms of K_LL and of the contribution of leaves to the overall shoot hydraulic resistance. Leaves represented in all cases 48 to 90 % of the shoot hydraulic resistance, suggesting that the sclerophyllous habitus does not per se lead to low efficiency in water transport within the leaf blade. A weak negative relationship (r² = 0.252) appeared to exist between K_SL and LSM. This might provide an explanation for the lower growth rates of sclerophylls with respect to malacophylls.