Wood Physical and Mechanical Properties of Clonal Teak (Tectona grandis) Stands Under Different Thinning and Pruning Intensity Levels Planted in Java, Indonesia

The objective of this study was to reveal the impact of thinning and pruning regimes on the physical and mechanical properties of clonal teak wood planted in Java. In this study, a 15-year-old clonal teak plantation was carried out and the obtained data were evaluated with analysis of variance (ANOVA). The results showed that different thinning intensities had a significant impact on the alteration of heartwood volume development ( F = 25.63; p < 0.0001). Meanwhile, the impact of different thinning treatments in several physical properties depends on the pruning treatment levels [moisture content ( F = 12.18, p < 0.0001); tangential shrinkage ( F = 15.60, p < 0.0001); T/R ratio ( F = 7.17, p < 0.0001); and volumetric shrinkage ( F = 10.81, p < 0.0001)]. However, different thinning intensities had no significant impact on wood basic density alteration ( F = 0.72, p = 0.486), while pruning intensities affect the differences between radial ( F = 3.52, p = 0.030) and volumetric shrinkage ( F = 3.13, p = 0.044). In mechanical properties, thinning intensity levels did not promote any significant differences [modulus of elasticity ( F = 1.41, p = 0.248); modulus of rupture ( F = 0.94, p = 0.392); compressive strength parallel to grain ( F = 0.21, p = 0.813); and compressive strength perpendicular to the grain ( F = 0.41, p = 0.669)]. Meanwhile, different pruning treatments and combination treatments were not significantly altered all mechanical properties. These results indicated that the thinning and pruning regimes can enhance the mechanical properties without having a serious alteration in the physical properties of clonal teak wood.