Among-site differences in wood properties and decay resistance of wood in Pinus sylvestris naturally growing in Mongolia

Abstract The wood properties (basic density and compressive strength parallel to the grain under green conditions), chemical components (lignin content, total polyphenol [as equivalent with tannic acid], monosaccharides [as equivalent with glucose], and ethanol-toluene extracts), and decay resistance were investigated in the heartwood of 50 naturally growing Pinus sylvestris L. trees from five different sites (Sites 1 to 5) in Ulaanbaatar, Mongolia. A mixed-effects model was developed to evaluate the among-site differences in measured properties. In addition, principal component analysis was applied to characterize the wood properties of sample trees in each site. The mean values of lignin content, polyphenol content, monosaccharide content, and mass loss caused by Trametes versicolor and Fomitopsis palustris were 30.3%, 95.3 mg/g, 38.9%, 34.4%, and 4.2%, respectively. Mass loss caused by T. versicolor was negatively correlated with lignin content but not with monosaccharide content. In contrast, mass loss caused by F. palustris showed a significant negative correlation with monosaccharide content but not with lignin content. Among-site differences were observed in polyphenol content, mass loss by T. versicolor , and physical and mechanical properties of wood. The principal component analysis results showed that trees from Site 4 showed higher mechanical properties and excellent decay resistance compared to other Sites. Based on these results, it is concluded that site selection is important to control the quality of the final products. In addition, improvement of wood quality can be achieved by selecting mother trees in the appropriate tree breeding program for establishing plantations.