Portugal with a Mediterranean type climate is the world first producer of cork. Experimental measurements of the sensible and latent heat fluxes by eddy covariance were made in a cork oak stand at Rio Frio, long. 9.1ºW e lat. 38.8ºN. The main micrometeorological parameters were also measured. The measurements covered the periods of Spring and Summer of three years. The mean daily value of the latent heat flux was 124.06W/m2.

The canopy resistance data, obtained by inversion of the Penman Monteith equation, increased during the afternoon with the water vapor deficit. The total mean daily ratio between the latent heat flux and equilibrium evapotranspiration was 0.44, typical of a dry canopy. The mean daily value of the coupling coefficient was 0.18, representative of an imposed evaporation regime, with dependence to vapor pressure deficit. The analyses of the mean daily values of the Bowen ratio revealed an indirect relationship between latent heat flux and net radiation, typical of forest canopies.