ANATOMICAL, CHEMICAL AND MECHANICAL PROPERTIES OF FAST-GROWING POPULUS x EURAMERICANA CV. '74/76'

摘要

The anatomical characteristics, chemical composition, and physical and mechanical properties of fast-growing Populus x euramericana cv. '74/76'juvenile wood were investigated. Four- to five-year-old clonal plantation trees were harvested from two different experimental sites in the suburbs of Beijing. The Shunyi site had black alkali soil with a planting density of 4 x 6 m and the Miyun site had sandy loam soil with a planting density of 3 x 5 m. The test results showed that the poplar trees from thetwo sites were both fast growing, with poplar at Shunyi growing faster than at Miyun. There were no significant differences in wood properties between trees grown at the two sites. Fiber length at breast height varied from 872 to 1300 um between growthrings, average fiber width varied from 21.0 to 25.5 mum and double wall thickness varied from 5.0 to 6.6 um. Average cellulose, lignin and hemicellulose contents in the samples were 48.9%, 25.4%, and 18.8%, respectively. MFA was higher in the first two growth rings (20-25°), and then decreased rapidly to 12° close to the bark. The average air-dry density at breast height was 401 kg/m3 while the average MOE at breast height was 9.3 GPa. The trees showed large growth rates in both height and stem diameter during the growing season. However, wood properties of the juvenile poplar appeared to be similar to those of poplars with a slower growth rate.