1. Kyushu Research Center, Forestry and Forest Products Research Institute, Kumamoto, Japan
2. Okinawa Prefectural Buried Cultural Properties Center, Nakagusuku Okinawa, Japan
3. Kansai Research Center, Forestry and Forest Products Research Institute, Kyoto, Japan
4. Yona Field, Subtropical Field Science Center, Faculty of Agriculture, University of the Ryukyus, Okinawa, Japan
5. Department of Forest Management, Forestry and Forest Products Research Institute, Ibaraki, Japan