Present address: Department of Earth and Ecosystem Analysis, Division of Physical Geography and Ecosystem Analysis, Lund University, Sölvegatan 12, S-223 62, Lund, Sweden.
Optimal stomatal conductance in relation to photosynthesis in climatically contrasting Eucalyptus species under drought
Article first published online: 7 AUG 2012
© 2012 Blackwell Publishing Ltd
Plant, Cell & Environment
Volume 36, Issue 2, pages 262–274, February 2013
How to Cite
HÉROULT, A., LIN, Y.-S., BOURNE, A., MEDLYN, B. E. and ELLSWORTH, D. S. (2013), Optimal stomatal conductance in relation to photosynthesis in climatically contrasting Eucalyptus species under drought. Plant, Cell & Environment, 36: 262–274. doi: 10.1111/j.1365-3040.2012.02570.x
- Issue published online: 3 JAN 2013
- Article first published online: 7 AUG 2012
- Accepted manuscript online: 4 JUL 2012 01:04PM EST
- Received 18 April 2012; received in revised form 27 June 2012; accepted for publication 28 June 2012
- leaf gas exchange models;
- net photosynthesis;
- plant hydraulic conductance;
- stomatal optimization theory
Models of stomatal conductance (gs) are based on coupling between gs and CO2 assimilation (Anet), and it is often assumed that the slope of this relationship (‘g1’) is constant across species. However, if different plant species have adapted to different access costs of water, then there will be differences in g1 among species. We hypothesized that g1 should vary among species adapted to different climates, and tested the theory and its linkage to plant hydraulics using four Eucalyptus species from different climatic origins in a common garden.
Optimal stomatal theory predicts that species from sub-humid zones have a lower marginal water cost of C gain, hence lower g1 than humid-zone species. In agreement with the theory that g1 is related to tissue carbon costs for water supply, we found a relationship between wood density and g1 across Eucalyptus species of contrasting climatic origins. There were significant reductions in the parameter g1 during drought in humid but not sub-humid species, with the latter group maintaining g1 in drought. There are strong differences in stomatal behaviour among related tree species in agreement with optimal stomatal theory, and these differences are consistent with the economics involved in water uptake and transport for carbon gain.