Modelling surface conductance and transpiration of an oak forest in The Netherlands

The surface conductance of an oak forest was modelled as a non-linear function of solar radiation, temperature, specific humidity deficit, soil moisture deficit and leaf area index. Two Jarvis-Stewart type models were used, differing only in the formulation of the specific humidity function. Both yielded good predictions of average hourly surface conductance and transpiration. Simulation with parameter values obtained in pine forests in England and France gave poorer results, indicating the empiricism of the model. In comparing parameter values obtained from different data sets, it is essential that exactly the same algebraic formulation should be used.