Effects of radial growth rate on juvenile wood properties of Pinus sylvestris planted in Mongolia
The establishment of forest plantations in boreal zones in Mongolia is important for wood production as well as carbon dioxide fixation. The present study aims to elucidate the juvenile wood properties (basic density, modulus of elasticity [MOE], modulus of rupture [MOR], and compressive strength parallel to grain) of plantation-grown Pinus sylvestris to promote the establishment of plantations. In addition, the effect of the radial growth rate on wood properties was also evaluated using a linear mixed-effects model. In the juvenile wood phase, wood properties were increased from the pith to bark side based on the results of model selections. Up to the 20th annual ring from the pith, the estimated mean values of basic density, MOE, MOR, and compressive strength were 0.40 g/cm3, 5.35 GPa, 65.1 MPa, and 28.4 MPa, respectively. Variance component ratios of growth categories were low in wood properties, with the exception of basic density, suggesting that the radial growth rate did not affect wood properties in the juvenile wood phase in this species growing in Mongolia. Based on the results obtained in the present study, we have concluded that although basic density in the faster growth category yielded relatively lower values, appropriate radial growth promotion during the initial stage of growth in P. sylvestris trees planted in Mongolia exerted no negative impact on juvenile wood properties.
Keywords: annual ring width, basic density, compressive strength, modulus of elasticity, modulus of rupture