Development of a Coupled Leaf and Canopy Model for the Simulation of Plant-Atmosphere Interaction

A numerical scheme was developed to couple a multilayer canopy radiation model, a photosynthesis model for C3 species, and a leaf stomatal conductance model with a single-leaf energy balance equation. This coupled leaf and canopy model was used to simulate the responses of a horizontally uniform forest canopy to its ambient microenvironment, using micrometeorological data collected from field measurements in a forest canopy. Emphasis was placed on issues associated with modeling the transient responses of plant leaves. For example, thermal storage was found to be important in modeling transience of leaf temperature, which in turn influenced the transient heating or cooling of the atmosphere by plant leaves. In addition, modification of the Ball-Berry leaf stomatal conductance model, using an exponential formula with an empirical time lag, yielded more realistic transient leaf stomatal conductances, which were important for estimating evaporation and CO2 assimilation.