In order to evaluate the physical and mechanical properties of plantation Japanese larch wood, various physical and mechanical indicators were measured with reference to Chinese national standards. The characteristics of the growth ring on the end face of wood samples were captured, with the mean latewood percentage being 21.4% and the mean ring width being 3.24 mm. Relationships between growth ring characteristics, latewood percentages, and the physical and mechanical properties of the plantation Japanese larch wood were investigated. The results revealed that it is most appropriate to use growth ring width to evaluate MOE and MOR, and to use latewood percentage to evaluate air-dry density, radial air-dry shrinkage, IBS and UTS. Regression analysis confirmed that air-dry density (R2 = 0.99), radial shrinkage (R2 = 0.97) and UTS (R2 = 0.96) had significant positive correlations with latewood percentage, while MOE (R2 = 0.88) and MOR (R2 = 0.90) had significant negative correlations with RW. IBS was not significantly related to either characteristic. RW can be used to define juvenile wood and mature wood, with the dividing ring width being 4.85 mm. There is a large difference in MOE and MOR between the two wood types.

The purpose of this paper is to investigate the influence of kiln temperature, relative humidity and wood moisture content on the content of acid and alcohol released in the drying process of high temperature kiln by studying the radiated pine sawn timber of 40mm thickness. The drying temperature was between 101°C and 115°C, the relative humidity in the drying kiln was reduced from 86.1% to 39.6%, the moisture content of the lumber was reduced from 106.16% to 11.98%, and gas extraction was executed nine times with an extraction speed of 1.0 L•min-1 and a sampling time of 30 min. The concentrations of acids and alcohols were analyzed by HPLC. The results showed that the concentrations of formic acid, acetic acid, and methanol emitted in the kiln during drying were 215.6-748.2, 4148.8-16803.2, and 6381.9-15648.9 mg•m-3, respectively, and these concentrations were significantly higher than the relevant standards. The concentrations of the emitted formic acid and acetic acid were proportional to the drying temperature, the concentrations of the emitted formic acid and acetic acid were inversely proportional to the relative humidity in the kiln and the moisture content of the lumber. The concentration of the emitted methanol was independent of the drying temperature, relative humidity in the kiln, and moisture content of the lumber. It is therefore suggested that formic acid, acetic acid, and methanol be separately recovered during the high-temperature drying of Pinus radiata lumber.