Modelling canopy conductance under wet and dry conditions in a subtropical cloud forest

Canopy conductance (gc) in a ridge-top cloud forest in the Garajonay National Park on La Gomera (Canary Islands) was derived by using the Jarvis–Stewart multiplicative algorithm and validated by inverting the Penman–Monteith equation using measured sap-flow data for the two main species, Myrica faya (beech) and Erica arborea (tree-heath). Canopy conductance correlated well with global radiation and vapour pressure deficit, and the multiplicative algorithm reproduced the daytime and seasonal course of gc satisfactorily using only these two factors under moderate and high evaporative conditions. There was no significant relation between soil moisture content in the first 0.3 m and gc, even though topsoil moisture reached very low values in summer, suggesting the roots had access to water at deeper levels.