Modeling stomatal and nonstomatal effects of water deficits on CO2 fixation in a semiarid grassland

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dc.contributor.authorGrant, Robert F.
dc.contributor.authorFlanagan, Larry B.
dc.date.accessioned2019-08-26T22:38:10Z
dc.date.available2019-08-26T22:38:10Z
dc.date.issued2007
dc.descriptionSherpa Romeo green journal. Permission to archive final published versionen_US
dc.description.abstractThe confidence with which we can model water deficit effects on grassland productivity is limited by uncertainty about the mechanisms, stomatal and nonstomatal, by which soil water deficits reduce CO2 uptake. We propose that these reductions can accurately be modeled from a combination of stomatal effects on gaseous CO2 diffusion and nonstomatal effects on biochemical CO2 fixation. These effects can be combined through a solution for the intercellular CO2 concentration (Ci) at which rates of diffusion and fixation are equal for each leaf surface in the canopy. In this model, both stomatal and nonstomatal effects are driven by a common indicator of plant water status calculated in a hydraulically-driven scheme of soil-plant-atmosphere water transfer. As part of the ecosystem model ecosys, this combined model simulated concurrent declines in latent heat effluxes and CO2 influxes measured by eddy covariance during soil drying in a drought-affected semiarid grassland. At the same time, the model simulated the declines in Ci at which CO2 fixation occurred during soil drying as calculated from seasonal measurements of phytomass d13C. Alternative model formulations based on stomatal or nonstomatal effects alone simulated these declines in CO2 influxes and in Ci less accurately than did the formulation in which these effects were combined. We conclude that modeling water deficit effects on CO2 fixation requires the concurrent simulation of stomatal and nonstomatal effects. As part of a larger ecosystem model, this combined model can be used to assess climate effects on grassland productivity.en_US
dc.description.peer-reviewYesen_US
dc.identifier.citationGrant, R. F., & Flanagan, L. B. (2007). Modeling stomatal and nonstomatal effects of water deficits on CO2 fixation in a semiarid grassland. Journal of Geophysical Research (Biogeosciences), 112, G03011.doi:10.1029/2006JG000302en_US
dc.identifier.urihttps://hdl.handle.net/10133/5518
dc.language.isoen_USen_US
dc.publisherAmerican Geophysical Unionen_US
dc.publisher.departmentDepartment of Biological Sciencesen_US
dc.publisher.facultyArts and Scienceen_US
dc.publisher.institutionUniversity of Albertaen_US
dc.publisher.institutionUniversity of Lethbridgeen_US
dc.publisher.urlhttps://dx.doi.org/10.1029/2006JG000302
dc.subjectEcosystemen_US
dc.subjectCO2 fixationen_US
dc.subjectWater deficitsen_US
dc.subjectStomatal effectsen_US
dc.subjectNonstomatal effectsen_US
dc.subject.lcshGrassland ecology
dc.titleModeling stomatal and nonstomatal effects of water deficits on CO2 fixation in a semiarid grasslanden_US
dc.typeArticleen_US
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