Interrelations among pressure-volume curve traits across species and water availability gradients

Pressure-volume (P-V) curves for leaves or terminal shoots summarize leaf-level responses to increasing water deficit. P-V curve traits and field-measured shoot xylem pressures were characterized across 62 species from four sites differing in rainfall and soil phosphorus. Within-species variation in the measured traits was small relative to differences among species and between environments. P-V curve traits tended to differ with site rainfall but not with soil phosphorus. Turgor loss points (TLPs) varied widely and averaged more negative in species from lower-rainfall sites. Differences between species in TLP were driven mainly by differences in solute potential, rather than by differences in cell wall elasticity. Among species at individual sites, species seemed to vary in leaf-response strategy reflected in TLP independently from water-uptake strategy reflected in predawn xylem pressures and in xylem pressure drop from predawn to midday.