1. Department of Forest Science; Faculty of Agriculture; Utsunomiya University; 350, Mine-machi Utsunomiya Tochigi 321-8505 Japan
2. Tama Forest Science Garden; Forestry and Forest Products Research Institute; 1833-81, Todori-machi Hachioji Tokyo 193-0843 Japan
3. The University of Tokyo Hokkaido Forest; The University of Tokyo Forests; Graduate School of Agricultural and Life Sciences; The University of Tokyo; 2-1, Yamabe Furano Hokkaido 079-1561 Japan
4. Education and Research Center; The University of Tokyo Forests; Graduate School of Agricultural and Life Sciences; The University of Tokyo; 1-1-1, Yayoi Bunkyo-ku Tokyo 113-8657 Japan