Simulating responses of leaf stomatal conductance to environmental factors for Tamarix ramosissma in an extreme arid region of China
极端干旱区多枝柽柳叶片气孔导度的环境响应模拟

Aims Stomata play a key role in plant adaptation to changing environmental conditions and environmental stress because they control both water losses and CO2 uptake. Methods Based on observation of leaf gas exchange parameters of Tamarix ramosissma in an extreme arid region in northwest of China, the relative humidity (hs) (or vapor pressure deficit (Ds)) of the BWB and BBL model were evaluated by introducing diagnosis function f(H). After that, the results were imported into the Ye and Yu mechanism model for simulation of stomatal conductance (gs) of T. ramosissma. Important findings A significant difference was found for hs (or Ds) of the BWB and BBL model with R2 of 0.535 4 and 0.110 3, respectively, and the gs is significantly related to hs and Ds with a Gauss model with R2 of 0.593 and 0.258, respectively. It suggests that the relationship between gs and hs is closer than Ds. Both the simplified model (referred to Simple model) proposed by Ye and Yu and its correction (referred to Gauss-h model) behaved well with R2 of 0.870 7 and 0.828 6 and η of 0.124 5 and 0.017 1 (range from 0 to 1), respectively. The model validation shows that the Gauss-h model clearly underestimated the observations more than the Simple model, and the performance of the Simple model was significantly improved (R2 of 0.960 6) when the observed condition was close to the hypothesis of model infinitely.