Weak tradeoff between xylem safety and xylem‐specific hydraulic efficiency across the world's woody plant species

The evolution of lignified xylem allowed for the efficient transport of water under tension, but also exposed the vascular network to the risk of gas emboli and the spread of gas between xylem conduits, thus impeding sap transport to the leaves. A well-known hypothesis proposes that the safety of xylem (its ability to resist embolism formation and spread) should trade off against xylem efficiency (its capacity to transport water). We tested this safety-efficiency hypothesis in branch xylem across 335 angiosperm and 89 gymnosperm species. Safety was considered at three levels: the xylem water potentials where 12%, 50% and 88% of maximal conductivity are lost. Although correlations between safety and efficiency…

• SR
  Sight Research UK

  Award: NE/I011749/1
• NE
  Natural Environment Research Council

  Award: NE/I011749/1
• AR
  Australian Research Council