COMPARISON OF 2 METHODS FOR ESTIMATING THE EVAPORATION OF A PINUS-PINASTER (AIT) STAND - SAP FLOW AND ENERGY-BALANCE WITH SENSIBLE HEAT-FLUX MEASUREMENTS BY AN EDDY COVARIANCE METHOD
A method combining sensible heat flux measurement based on temperature and vertical wind speed fluctuations, and energy balance, was used to estimate evaporation above the canopy and the understorey of a Pinus pinaster (Ait.) stand in Les Landes forest. The problems of the horizontal homogeneity of net radiation and sensible heat flux under the canopy, and of estimating heat storage, are reviewed. The differences between above- and below-canopy evaporation are compared with sap flow on five experimental days. Except for one overcast day with little tree transpiration, the method fits sap flow within +/- 15%.