Scaling-Up Gas Exchange and Energy Balance from the Leaf to the Canopy Level
Having discussed the gas exchange and energy balance of individual leaves in previous chapters, we are now in a position to “scale up” to the canopy level. In moving between scales, it is important to determine which interactions should be considered and which can either be ignored or taken as independent variables. The water relations of plant canopies are distinctly different than would be predicted from the study of individual leaves because each leaf modifies the environment of adjacent leaves through reduced irradiance, wind speed, and vapor pressure deficit. These changes within the canopy reduce transpiration from each leaf more than would be predicted from an individual leaf model, using the atmospheric conditions above the canopy. For example, irradiance declines exponentially with leaf area index within the canopy (Box 7), reducing the energy that each leaf dissipates.
KeywordsStomatal Conductance Leaf Area Index Vapor Pressure Deficit Individual Leaf Leaf Area Ratio
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References and Further Reading
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