This study aimed to evaluate the environmental effect on the wood chemical composition of Eucalyptus grandis x Eucalyptus urophylla clones for pulp production. Seven clones of 6.5 years old were evaluated. The clones were planted in two growing sites, Nova Almeida – Espírito Santo and Posto da Mata – Bahia, established in 3 x 3 m spacing. Five trees were selected from each clone and discs were removed from fi ve different positions equidistant from the trunk and at diameter at breast height (DBH) height. Two wedge from opposite sides were obtained from the discs. A chemical analysis was performed with a sample composed of all the wedges of each tree in order to determine extractive contents, lignin, holocellulose, carbohydrates and the ratio among syringyl (S) and guaiacyl (G) lignin substructures (S/G) per tree. The S/G ratio was considered to be the most stable characteristic to environmental change, followed by the holloceluloose content, which was considered the second least characteristic infl uenced by the growth site. Most of the studied clones presented a statistical difference between the growing site for the wood extractive content, in contrast to the total carbohydrates content that was highlighted by presenting values which were little infl uenced by the genetic material and the growth site.
