Biodeterioration of wood from two fast-growing eucalypts exposed to field test

• Chemical structure of eucalypt wood changed after one year in a field test.
• Effect of exposure time on mechanical strength was evaluated.
• Deterioration of wood in the forest canopy or in the outdoor was similar.
• Brazilian fast-growing eucalypts showed lower decay resistance when compared with Australian native eucalypts.

This study aimed to evaluate changes in the chemical composition and mechanical properties of static bending of wood from two fast-growing eucalypt species (blue gum and lemon-scented gum) after exposure for one year in a field test. To achieve this, decayed untreated wood (after 1 yr of exposure in the field test) was characterised by chemical analysis, thermogravimetric analysis, and infrared spectroscopy, and was compared with control samples. Mass loss and modulus of elasticity (MOE) and modulus of rupture (MOR) as a function of the exposure time were evaluated. The main findings showed that lignin and carbohydrate content of the two decayed woods decreased after exposure in the field test. Mass loss increased with increasing time of exposure, while MOE and MOR decreased for both woods. Nevertheless, blue gum wood was more susceptible to decay.