EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Coordination of plant hydraulic and photosynthetic traits: confronting optimality theory with field measurements

Huiying Xu1, Han Wang1, I. Colin Prentice1,2,5, Sandy Harrison1,3, and Ian Wright4,5
Huiying Xu et al.
  • 1Department of Earth System Science, Tsinghua Univeristy, Beijing, China
  • 2Department of Life Sciences, Imperial College London, London, UK
  • 3School of Archaeology, University of Reading, Reading, UK
  • 4Hawkesbury Institute for the Environment, Western Sydney University, New South Wales, Australia
  • 5Department of Biological Sciences, Macquarie University, New South Wales, Australia

Close coupling between water loss and carbon dioxide uptake requires coordination of plant hydraulics and photosynthesis. However, there is still limited information on the quanti- tative relationships between hydraulic and photosynthetic traits. We propose a basis for these relationships based on optimality theory, and test its predic- tions by analysis of measurements on 107 species from 11 sites, distributed along a nearly 3000-m elevation gradient. Hydraulic and leaf economic traits were less plastic, and more closely associated with phy- logeny, than photosynthetic traits. The two sets of traits were linked by the sapwood to leaf area ratio (Huber value, vH). The observed coordination between vH and sapwood hydraulic conductivity (KS) and photosynthetic capacity (Vcmax) conformed to the proposed quantitative theory. Substantial hydraulic diversity was related to the trade-off between KS and vH. Leaf drought tolerance (inferred from turgor loss point, –Ψtlp) increased with wood density, but the trade-off between hydraulic efficiency (KS) and –Ψtlp was weak. Plant trait effects on vH were dominated by variation in KS, while effects of environment were dominated by variation in temperature. This research unifies hydraulics, photosynthesis and the leaf economics spectrum in a com- mon theoretical framework, and suggests a route towards the integration of photosynthesis and hydraulics in land-surface models.

How to cite: Xu, H., Wang, H., Prentice, I. C., Harrison, S., and Wright, I.: Coordination of plant hydraulic and photosynthetic traits: confronting optimality theory with field measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-949,, 2022.


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