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Mi N.,Institute of Atmosphere Environment | Zhang Y.-S.,Institute of Atmosphere Environment | Ji R.-P.,Institute of Atmosphere Environment | Cai F.,Institute of Atmosphere Environment | And 3 more authors.
Chinese Journal of Ecology | Year: 2011

Plant leaf stomatal conductance (g) is an important factor controlling the energy and water exchanges between canopy and atmosphere, while air humidity is a key environmental variable controlling the g. In last decade, the stomatal conductance - humidity relationships in Ball- Woodrow-Berry (BWB) and Leuning models were widely used. In this study, a new diagnostic parameter f(H) was adopted to assess the response of g to air humidity. Based on the leaf-level measurements in a cropland ecosystem, the performance of the BWB, Leuning, and newly developed power-h and power-D models was examined. The results showed that the BWB model which employs a linear relationship between g and relative humidity (hs) led to a larger underestimate of g when the air was wet, while the Leuning model which employs a nonlinear function of water vapor pressure deficit (Ds) decreased this bias but still not adequately captured the significant increase of g under the wet condition. Compared with BWB and Leuning models, the newly developed power-h and power-D models that employ a power function of Ds and a power function of relative humidity deficit (1-hs), respectively, showed better performance. The results also indicated that the models based on Ds generally performed better, compared with those based on hs.

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