Variation of Wood Density and Shrinkage Characters of Pinus oocarpa in Malawi

Wood properties are generally a common and critical feature affecting wood processing and utilization and are essential in tree improvement programs. This study was conducted to assess the wood density and shrinkage (tangential, radial, longitudinal, and volumetric) properties of Pinus oocarpa grown in Malawi. Wood samples from six trees of P. oocarpa at the age of 26 years were used for the study. The estimated mean wood density was 455.4 ± 2.5 kg/m3. There were statistically significant (p<0.001) differences in wood density along the radial direction and stem height. Wood density increased from pith to bark and decreased from the butt upwards. A similar trend was observed for the shrinkage properties. This implies that wood near the bark and at the base of P. oocarpa trees is denser and would be suitable for structural purposes. The results further revealed that wood density had a positive and significant linear relationship with volumetric shrinkage (r =0.236, p<0.001), radial shrinkage (r =0.157, p<0.001), and tangential shrinkage (r =0.191, p<0.001). This warrants simultaneous improvement of wood density and shrinkage properties. Therefore, controlling wood density for the tree improvement program of P. oocarpa in Malawi would have a positive impact on wood shrinkage properties.