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


Gleason, SM and Westoby, M and Jansen, S and Choat, B and Hacke, UG and Pratt, RB and Bhaskar, R and Brodribb, TJ and Bucci, SJ and Cao, KF and Cochard, H and Delzon, S and Domec, JC and Fan, ZX and Feild, TS and Jacobsen, AL and Johnson, DM and Lens, F and Maherali, H and Martinez-Vilalta, J and Mayr, S and Mcculloh, KA and Mencuccini, M and Mitchell, PJ and Morris, H and Nardini, A and Pittermann, J and Plavcova, L and Schreiber, SG and Sperry, JS and Wright, IJ and Zanne, AE, Weak tradeoff between xylem safety and xylem-specific hydraulic efficiency across the world's woody plant species, New Phytologist, 209, (1) pp. 123-136. ISSN 0028-646X (2016) [Refereed Article]

Copyright Statement

Copyright 2015 New Phytologist Trust

DOI: doi:10.1111/nph.13646


  • 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 were weak (r2 < 0.086), no species had high efficiency and high safety, supporting the idea for a safety–efficiency tradeoff. However, many species had low efficiency and low safety. Species with low efficiency and low safety were weakly associated (r2 < 0.02 in most cases) with higher wood density, lower leaf- to sapwood-area and shorter stature.
  • There appears to be no persuasive explanation for the considerable number of species with both low efficiency and low safety. These species represent a real challenge for understanding the evolution of xylem.

Item Details

Item Type:Refereed Article
Keywords:cavitation, embolism, hydraulic conductivity, mean annual precipitation, mean annual temperature, xylem
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the environmental sciences
UTAS Author:Brodribb, TJ (Professor Tim Brodribb)
ID Code:110869
Year Published:2016
Funding Support:Australian Research Council (DP120101686)
Web of Science® Times Cited:333
Deposited By:Plant Science
Deposited On:2016-08-19
Last Modified:2017-11-13

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