Inferring Relative Heat, Water Vapor and Carbon Exchange From Digital Images of Vegetative Canopies.

Vegetative canopies mediate water, energy and carbon atmospheric exchange processes. Canopy reflectance of visible, near-infrared and thermal radiation can provide information about these exchange processes, which can support multiple applications to crop improvement and environmental management.  Our objective was to develop a procedure for rapid quantification of vegetative canopy characteristics which are useful for scaling heat, water vapor and carbon exchange processes. A digital vegetative index camera (Tetracam ADC) quantified vegetative index from reflected red, green and near-infrared bands. A digital thermal camera (ICI 7320) quantified the corresponding vegetative radiative temperature. Both cameras were mounted on a portable platform suitable for field use. Using energy balance and stomatal conductance models, relative heat, water vapor and carbon exchange rates were calculated for canopy elements. Sample results for corn demonstrate the feasibility of this field procedure.