Biomasse, contenu en eau et productivité d'une pessière en Haute-Ardenne. Comparaison avec une hêtraie

Biomass, water content and productivity of a 39 years old spruce stand have been studied during August 1966 at the «Plateau des Tailles» (Ardenne belge, 595 m above sea level) in a spot located close to the beechwood we previously dealed with. Total dry biomass was 166,4 t/ha ; out of this, the underground material is taking a part of 22,98 %. The annual productivity reachs 12,4 t/ha/year with a photosynthetic efficiency of 1,32 % if calculated on the basis of the total radiant energy throughout the year. According to the effective assimilation period only, the photosynthetic efficiency reachs a value of 1,88 %. These results are discussed with special reference to the values obtained in a beechwood.