Combining the [ABA] and net photosynthesis-based model equations of stomatal conductance

Huntingford, Chris; Smith, D. Mark; Davies, William J.; Falk, Richard; Sitch, Stephen; Mercado, Lina. 2015 Combining the [ABA] and net photosynthesis-based model equations of stomatal conductance. Ecological Modelling, 300. 81-88.

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Stomatal conductance gs is variously depicted as being dependent on environmental conditions ( Jarvis, 976), transpiration ( Monteith, 1995), net photosynthesis ( Leuning, 1995) or chemical signalling arriving in the xylem ( Tardieu and Davies, 1993). Accurate descriptions of gs are being increasingly demanded in the large-scale land surface model components of General Circulation Models (GCMs) to predict future land-atmospheric fluxes of water vapour, heat and carbon dioxide. The JULES model, for instance, uses the net photosynthesis description combined with a relatively simple semi-linear dependence on soil moisture content that modulates the photosynthesis dependence ( Cox et al., 1998). Dewar (2002) combines the Leuning (1995) and Tardieu and Davies (1993) models. We revisit that combination, and discuss whether the Vapour Pressure Deficit (VPD) implicit in both components is different or in common. Further, we show a potential re-arrangement of the combined equations reveals that this model for gs can be considered as being dependent on only four variables: evaporative flux JwJw, net photosynthesis an, soil moisture content θ and ambient CO2 concentration ca. Expressed this way, gs is influenced by two relatively slowly varying stores of the hydrological and carbon cycles (soil water content and atmospheric CO2) and two more rapidly fluctuating fluxes from both cycles (evaporation and net photosynthesis). We consider how the modelling structure and its response to both canopy-level and soil environmental controls may make it suitable for inclusion in GCMs, and what this entails in terms of parameterisation.

Item Type: Publication - Article
Digital Object Identifier (DOI):
UKCEH and CEH Sections/Science Areas: Reynard
ISSN: 0304-3800
Additional Information. Not used in RCUK Gateway to Research.: Open Access paper - full text available via Official URL link
Additional Keywords: stomatal conductance, ABA, soil moisture, terrestrial carbon cycle, general circulation models, climate change
NORA Subject Terms: Ecology and Environment
Agriculture and Soil Science
Date made live: 03 Aug 2015 10:18 +0 (UTC)

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