José C. Rodrigues

Eucalyptus globulus Labill is an important raw material for pulpwood for which low lignin content and high S/G ratios are important parameters. This work shows a highly significant positive and strong correlation between S/G ratio and acid-soluble lignin (ASL) content among E. globulus trees. Although significant, the negative correlation between the S/G ratio and Klason lignin is weak, and there is no correlation with total lignin content. The Klason residue has a lower S/G ratio than that of the original wood. This suggests that the contribution of the S units to the solubilisation of lignin in acidic conditions is not limited to the S units but also to the G units. This effect becomes more pronounced as the percentage of S units increases.