Impact of thinning and pruning on tree growth, stress wave velocity, and pilodyn penetration response of clonal teak (Tectona grandis) plantation

Abstract

The objective of this research was to examine the impact of different thinning and pruning intensities on the growth characteristics and wood properties of clonal teak. A 14-year-old clonal teak plantation was used in the study. The first thinning and pruning were established 5 years after planting. Three different levels of thinning (un-thinned, moderate, and heavy) and pruning (low, medium, high) were tested. Growth characteristics, pilodyn penetration, and stress wave velocity were examined. Results showed that different thinning intensities significantly affected the mean annual diameter increment (F = 37.67; p < 0.01). The standing stock estimations of the thinning intensity regimes also significantly differed between different thinning intensities (F = 4.16; p = 0.035). Moreover, pilodyn penetration significantly varied with the thinning treatment (F = 23.53; p < 0.01). The stress wave velocity, however, did not significantly vary with the thinning treatment (F = 2.54; p = 0.11). Meanwhile, the effect of pruning treatment was not observed under all parameters. Heavy thinning treatment promoted all parameters except height and stress wave velocity. A strong positive correlation was observed between pilodyn penetration and DBH. This result suggested that thinning and pruning promoted positive DBH growth and an increase in the economic value of the stand, but it did not affect the wood properties of clonal teak wood.