Growth characteristics, stress-wave velocity of stems, and radial variations of wood properties and anatomical characteristics in six-year-old Rubroshorea leprosula and R. macrophylla planted in Central Kalimantan, Indonesia

To switch the origins of wood resources from natural to planted forests, evaluation of wood from planted trees is essential. The objective of this study is to provide the relevant wood properties promoting the utilization of wood from planted trees in the tropics. Growth characteristics (stem diameter at 1.3 m above the ground and tree height) and stress-wave velocity of stems were measured for two six-year-old red meranti species, Rubroshorea leprosula and Rubroshorea macrophylla regenerated by an Indonesian selective cutting system and strip planting in Central Kalimantan, Indonesia. The following radial variations of wood properties and anatomical characteristics were also examined: basic density, compressive strength parallel to the grain at green conditions, vessel diameter, vessel frequency, wood fiber diameter, wood fiber wall thickness, wood fiber length, and vessel element length. Mean values of stem diameter at 1.3 m above the ground, tree height, and stress-wave velocity of stems were 11.6 cm, 13.4 m and 3.80 km/s for R. leprosula and 15.9 cm, 12.0 m, and 3.81 km/s for R. macrophylla, respectively. Although the stress-wave velocity of stems was the same in both species, growth characteristics slightly differed: R. macrophylla showed a significantly larger stem diameter, but tree height was significantly vigorous in R. leprosula. Growth characteristics were not significantly correlated with the stress-wave velocity of stems, suggesting that superior trees with good growth characteristics and high Young’s modulus of wood is possible for tree breeding programs in these two species. With a few exceptions, the mean values of wood properties and anatomical characteristics were statistically the same between the two species. Radial variations in some wood properties and anatomical characteristics still did not show stable values, suggesting that the wood examined in the present study (about 10 cm in half radius at six‐year old) might be wood with unstable quality, such as juvenile wood. © The Author(s) 2025.