1. Research Faculty of Agriculture Hokkaido University Sapporo 060‐8589 Japan
2. Graduate School of Agriculture Hokkaido University Sapporo 060‐8589 Japan
3. Forestry and Forest Products Research Institute Tsukuba 305‐8687 Japan
4. Forest Bio‐Research Center Forestry and Forest Products Research Institute Hitachi 319‐1301 Japan
5. Faculty of Agriculture University of Miyazaki Miyazaki 889‐2192 Japan
6. Institute for Mountain Science Shinshu University Minami‐minowa 399‐4598 Japan
7. Forest Research Institute Hokkaido Research Organization Bibai 079‑0198 Japan