Figure 8.

Synthetic conceptual hypothesis for trait associations and impacts of leaf shrinkage and structural traits on leaf hydraulic vulnerability. Leaf hydraulic vulnerability is influenced independently by major VLA acting on the xylem pathways and leaf shrinkage in thickness acting on the outside-xylem pathways of water movement through the leaf. Thickness shrinkage is determined by cell properties (i.e. the pressure-volume curves parameter ε, π_o, and π_TLP). The dotted lines signify that the ε and osmotic pressures are not directly linked but strongly associated; saltier cells need a higher ε to maintain RWC at TLP above lethal levels (Bartlett et al., 2012b). The ε, being related to cell wall thickness, is correlated with leaf density and LMA, which are also related to cell wall thickness; thus, all these variables influence thickness shrinkage. The ε also influences PLA_dry. PLA_dry and not ε acts directly on g_min, possibly through enhanced leaky stomata (see Supplemental Discussion S2). Red arrows indicate significant negative correlations between traits, while black arrows indicate significant positive correlations between traits. Double-headed arrows indicate traits that are too intrinsically linked to tease apart. [See online article for color version of this figure.]