1. JSPS research fellow, Forestry and Forest Products Research Institute, Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
2. Graduate School of Agriculture and Life Science, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
3. Forestry and Forest Products Research Institute, Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
4. Mikura Island Tourist Information Center, Mikura-shima village, Tokyo 100-1301, Japan