Sapwood capacitance is greater in evergreen sclerophyll species growing in high compared to low rainfall environments

1. The capacitative release of water from sapwood allows photosynthesis to continue for longer into dry periods, both diurnally and seasonally. However, costs of high capacitance include increased vulnerability to xylem cavitation. The degree of reliance on stored water is predicted to differ among environments as a result of this trade off 2. Xylem water potential and sapwood capacitance were measured on 32 evergreen sclerophyll shrub and tree species in eastern Australia, sampled from four sites contrasting in soil nutrients and rainfall. 3. Capacitance calculated over species’ typical shoot water potential operating range was 3-fold higher for species from high compared to low rainfall sites, and 1.5-fold higher for species from high compared to low nutrient sites. 4. To determine whether these site differences were related to extrinsic (e.g. water availability) or intrinsic (e.g. species anatomical construction) factors, we calculated capacitance at two common operating ranges; i.e....