Leaf Temperature Fluctuations of Typical Psammophytic Plants and Their Application to Stomatal Conductance Estimation

Monitoring of stomatal conductance to water vapor in psammophytes is important in studies of vegetation transpiration in sandy areas. Leaf temperature monitoring has the advantages of convenience, reduced damage to the plant without contact, and a larger measurement area. Stomatal conductance to water vapor estimation models, based on leaf temperature, have been proposed in agricultural studies in recent years. However, observations for verification of these models are still lacking, which has limited the application of these models. We performed a drought stress experiment on three typical psammophytes: Artemisia ordosica, Salix psammophila, and Caragana korshinskii. We monitored their leaf temperature and built two leaf temperature-based models to test whether the models could accurately estimate stomatal conductance. Results verified that neither of the two models accurately quantified psammophytes' stomatal conductance in field operations. We further tested the differences among plants and identified that the differences in stomatal mechanism and physical morphology of the leaves drives leaf temperature differences, which affects the accuracy of stomatal conductance estimation using the models. We concluded that more precise measurements of leaf temperature-related parameters, such as wind speed and leaf physical morphology, are needed to improve the models' estimation accuracy. Our study offers references for developing a practical application of stomatal conductance estimation models in field operations.