Canopy conductance, commonly denoted g c {\displaystyle g_{c}} , is a dimensionless quantity characterizing radiation distribution in tree canopy. By definition, it is calculated as a ratio of daily water use to daily mean vapor pressure deficit (VPD). Canopy conductance can be also experimentally obtained by measuring sap flow and environmental variables. Stomatal conductance may be used as a reference value to validate the data, by summing the total stomatal conductance g s {\displaystyle g_{s}} of all leaf classes within the canopy.
g c = ∑ l a y e r 1 l a y e r N ( g s , s u n i ⋅ l s u n i ) + ( g s , s h a d e ⋅ l s h a d e ) {\displaystyle g_{c}=\sum _{layer_{1}}^{layer_{N}}(g_{s,sun}^{i}\cdot l_{sun}^{i})+(g_{s,shade}\cdot l_{shade})}
See also Ecohydrology Stomatal conductance Transpiration
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