1. Authors Zhou, Fan, and Pei are with the State Key Laboratory of Tree Genetics and Breeding, Research Inst. of Forestry; Chinese Academy of Forestry; Haidian District Beijing 10091 P. R. China
2. Authors Chu and Wang are with the Inst. of Chemical Industry of Forest Products; Chinese Academy of Forestry; Xuanwu District Nanjing 210042 P. R. China