A Study on wood Physical and mechanical properties of thirteen Poplar varieties
Wang Guiyan ,Wang Yan, Li Shanwen Qiao Yuling Wang Weidong (Shandong Forestry Research Institute, Jinan 250014)
Nine-year wood samples of 10 varieties of black poplar(Populus nigra), and Thirteen-year wood samples of 3 varieties of white poplar P.tomentosa were collected. Their physical and mechanical properties, the variation of heartwood and sapwood in different heights and trees were measured and analyzed. The results indicate: the heartwood ratio of entire tree wood of 13 poplar varieties is between 14.6% and 34.1%, moisture content in green condition is between 86.2 and 148.5%. Shrinkage rate from green condition to air-dry condition (a wood moisture content of 12 percent) is between 8.66% and 11.96%. Proof- density, strength, hardness, and shock resistance are light or very light, low, soft or very soft, and medium respectively. Black poplar varieties have dark color heartwood, and large difference of properties between heartwood and sapwood. White poplar varieties have bright color heartwood, and less difference of properties between heartwood and sapwood. The physical and mechanical properties among different varieties are significant. The thirteen varieties can be divided into 4 classes based on the main characteristics.