Stress wave velocity, basic density, and compressive strength in 34-year-old Pinus merkusii planted in Indonesia

The relationship between the growth speed and wood properties of Pinus merkusii was investigated using 34-year-old trees planted in Indonesia in an attempt to promote the establishment of plantation of this species. The trees in the test plot were categorized as fast, middle, or slow growing according to the mean stem diameter and standard deviation in the plot. Five trees were selected from each category to investigate the effects of the growth rate on the wood properties [basic density (BD) and compressive strength parallel to the grain in a 5-mm-diameter core sample (CS)]. No significant correlation was recognized between the stem diameter and the stress wave velocity of trees. Clearly lower values of BD and CS were found in slow-growing trees than in fast- and middle-growing trees. The BD of xylem near the pith was reduced by extraction with organic solvent. BD after extraction and CS gradually increased from pith to bark. The results obtained in this study clarified that an early selection of trees with high BD is possible by using the BD after extraction at 4 cm from the pith.