1. Shiiba Research Forest, Kyushu University, 949 Okawachi, Shiiba, Miyazaki 883-0402, Japan
2. Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan
3. The United Graduate School of Agricultural Science, Ehime University, 3– 5–7Tarumi, Matsuyama, Ehime 70-8577, Japan
4. Faculty of Agriculture, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan