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Desert dogma revisited: coupling of stomatal conductance and photosynthesis in the desert shrub, Larrea tridentata
Author(s) -
Ogle K.,
Reynolds J. F.
Publication year - 2002
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 - 10.1046/j.1365-3040.2002.00876.x
Subject(s) - larrea , stomatal conductance , deserts and xeric shrublands , shrub , photosynthesis , vapour pressure deficit , environmental science , atmospheric sciences , arid , botany , ecology , transpiration , biology , physics , habitat
The success of the desert shrub Larrea tridentata (creosotebush) has been largely attributed to temperature acclimation and stomatal control of photosynthesis ( A ) under drought stress. However, there is a paucity of field data on these relationships. To address this void, we conducted a joint field and modelling study that encompassed a diverse set of environmental conditions. At a Larrea ‐dominated site in southern New Mexico we manipulated soil moisture during the growing season over a 2‐year period and measured plant pre‐dawn water potential ( Ψ pd ), stomatal conductance ( g ) and A of individual shrubs. We used these data to develop a semi‐mechanistic photosynthesis model (A–Season) that explicitly couples internal CO 2 ( C i ) and g . Vapour pressure deficit ( VPD ) and Ψ pd affect instantaneous g in a manner that is consistent with a biophysical model of stomatal regulation of leaf water potential. C i is modelled as a function of g , derived from a simplification of a typical A – C i curve. After incorporating the effects of growing temperature on stomatal behaviour, the model was able to capture the large diurnal fluctuations in A , g and C i and the observed hysteresis in g versus C i dynamics. Our field data and application of the A–Season model suggest that dogma attributed to Larrea 's success is supported with regard to stomatal responses to VPD and Ψ pd , but not for mechanisms of temperature acclimation and CO 2 demand.