极端干旱区多枝柽柳叶片气孔导度的环境响应模拟

Simulating responses of leaf stomatal conductance to environmental factors for Tamarix ramosissma in an extreme arid region of China

气孔通过调节植物体水分散失和CO2吸收在植物适应环境变化和环境胁迫中发挥重要作用。该文在对极端干旱区多枝柽柳(Tamarix ramosissma)叶片气体交换参数观测的基础上,引入诊断函数f(H)对BWB模型和BBL模型提出的气孔导度(gs)模型中的空气湿度(hs或Ds)进行了评价,并将评价结果引入叶子飘和于强推导出的gs机理模型。结果表明:(1)BWB和BBL模型对hs(或Ds)的模拟效果存在很大差异:BWB模型拟合效果较好(R2=0.5354),BBL模型的结果显著但效果较差(R2=0.1103)。试验结果显示:随hs(或Ds)的增大,gs呈先增大后减小的趋势,可用Gauss模型进行拟合,R2分别为0.593和0.258,说明gs与hs的关系要比Ds更密切;(2)叶子飘和于强给出的简化模型(Simple模型)和该文给出的指数模型(Gauss-h模型)均具有较好的模拟效果(R2分别为0.8707和0.8286),η值分别为0.1245和0.0171,其值均介于0-1之间;(3)模型验证中Gauss-h模型较Simple模型明显低估了观测值,当观测条件无限趋近于Simple模型的假设时,Simple模型的拟合效果可得到显著提高(R2=0.9606)。

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.