摘要:以青藏高原地区高寒草甸常见建群种高山嵩草（Kobresia pygmaea）为研究对象，利用光合测定仪于2018年7-9月测定高山嵩草气体交换参数与环境因子的日变化值，利用土壤水分测量仪及环刀法、透膜法测得0-10 cm土壤水分数据作为模型变量。首先，采用3种气孔导度模型对高山嵩草气孔导度进行拟合和检验，其次，用Jarvis模型、Leuning模型和Gao模型对高山嵩草气孔导度在不同月份（7，8，9月）日变化的模拟结果进行分析，最后，总结并讨论了气孔导度对3个主要环境因子（光合有效辐射（Photosynthetically active radiation，PAR）、气温（T_air）、饱和水汽压差（Vapor pressure deficit，VPD））的响应特征。主要研究结果：（1）3个气孔导度模型都可以较好地模拟高山嵩草的气孔导度变化，Leuning模型表现最好（R²=0.726），Jarvis模型次之（R²=0.659），Gao模型准确度最低（R²=0.624）。（2）高山嵩草叶片气孔导度对3个环境因子的响应敏感度为PAR > VPD > T_air。在5-35℃气温范围内气孔导度呈现"钟形"响应，在T_air为24.83℃时达到最高值；气孔导度随着光合有效辐射强度PAR的增加（300-2100 μmol m^-2 s^-1）而增加，在高PAR时G_s增速变慢，随后出现下降趋势；气孔导度随着VPD增加（0.12-3.48 kPa）而降低。（3）三个模型均可以较好地模拟高山嵩草气孔导度对环境因子的响应特征，其中最敏感的环境因子均是VPD。Leuning模型对T_air和VPD最敏感，而Gao模型对PAR最敏感，对T_air不敏感。以上结果以期为气候变化背景下青藏高原地区植物叶片气孔导度的响应变化以及更大尺度的陆面模式中气孔导度模型的应用提供参考。



Abstract:Kobresia pygmaea, a dominant species of alpine meadows in Qinghai-Tibet Plateau, was selected to measure the diurnal variation of stomatal gas exchange parameters and environmental factors with a portable photosynthesis system from July to September, 2018. The soil water parameters at 0-10 cm layer were measured also with soil moisture meters, ring knife method, and permeable membrane method. Then, the parameters of three stomatal conductance models, Jarvis's model, Leung's model, and Gao's model, were applied to simulate the stomatal conductance of Kobresia pygmaea, after the calibration of their parameters based on the measurements in different months of July, August, and September. It was also analyzed based on the simulation that the response characteristics of stomatal conductance to the main environmental factors such as Photosynthetically Active Radiation (PAR), air temperature (T_air) and Vapor Pressure Deficit (VPD). The main results are as follows: (1) all the three models could well simulate the changes of the stomatal conductance of Kobresia pygmaea, with the performance sequence of Leuning's model (R²=0.726), Jarvis's model (R²=0.659), and Gao's model (R²=0.624). (2) The sensitivity of stomatal conductance of Kobresia pygmaea to the three environmental factors occurred in the order of PAR > VPD > T_air. The stomatal conductance showed a bell-shaped response to T_air ranged of 5-35 ℃, with the maximum value at 24.83 ℃. The stomatal conductance also had a maximum value at PAR of 2100 μmol m^-2 s^-1, but monotonically decreased with VPD ranged of 0.12-3.48 kPa. (3) All the three models could well simulate the response characteristics of the stomatal conductance of Kobresia pygmaea to the environmental factors, with the highest sensitivity to VPD. Among the three models, Leuning's model was most sensitive to T_air and VPD, and Gao's model was most sensitive to PAR, but lest sensitive to T_air. The purpose of this study is to provide a reference for understanding the response of stomatal conductance of plant on Qinghai-Tibet Plateau to climate change, and for the application of stomatal conductance models in larger-scale land surface models.





PDF全文下载地址:

https://www.ecologica.cn/stxb/article/pdf/stxb202001070054