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Optimal stomatal conductance in relation to photosynthesis in climatically contrasting Eucalyptus species under drought
Author(s) -
HÉROULT ARNAUD,
LIN YANSHIH,
BOURNE AIMEE,
MEDLYN BELINDA E.,
ELLSWORTH DAVID S.
Publication year - 2013
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2012.02570.x
Subject(s) - stomatal conductance , eucalyptus , transpiration , photosynthesis , biology , plant species , ecology , water use efficiency , environmental science , botany
Models of stomatal conductance ( g s ) are based on coupling between g s and CO 2 assimilation ( A net ), and it is often assumed that the slope of this relationship (‘ g 1 ’) is constant across species. However, if different plant species have adapted to different access costs of water, then there will be differences in g 1 among species. We hypothesized that g 1 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 g 1 than humid‐zone species. In agreement with the theory that g 1 is related to tissue carbon costs for water supply, we found a relationship between wood density and g 1 across Eucalyptus species of contrasting climatic origins. There were significant reductions in the parameter g 1 during drought in humid but not sub‐humid species, with the latter group maintaining g 1 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.