Simple models for stomatal conductance derived from a process model: cross-validation against sap flux data

Area of Science:

• Plant physiology
• Ecology
• Biophysics

Background:

• Accurate modeling of plant-atmosphere gas exchange is crucial for understanding water use.
• Current process-based models of stomatal physiology are limited by complex parameter estimation.

Purpose of the Study:

• To derive and validate simple, parameter-efficient models of stomatal conductance.
• To improve the prediction of plant water use by relating model parameters to biophysical properties.

Main Methods:

• Derived simplified stomatal conductance models from a process-based model.
• Cross-validated models against sap flux measurements in Eucalyptus trees across various sites and ages.
• Models were driven by irradiance and evaporative demand, with 2-4 parameters.

Main Results:

• Derived models reproduced a median of 83-89% of observed variance in sap flux.
• Model performance was consistent whether fitted with extensive data or shorter seasonal periods.
• Parameters in the simple models are transparently linked to underlying biophysical parameters.

Conclusions:

• Developed simple yet effective models for predicting plant water use.
• These models offer an advance over complex models due to easier parameterization and interpretability.
• The models facilitate the integration of new knowledge on parameter responses to environmental changes and species differences.