Radial variations in wood mineral element concentrations: a comparison of beech and pedunculate oak from the Belgian Ardennes Valérie Penninckx, Suzanne Glineur, Wolf Gruber, Jacques Herbauts and Pierre MeertsAnn. For. Sci., 58 3 (2001) 253-260DOI: https://doi.org/10.1051/forest:2001124