1. Laboratory of Silviculture, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
2. Silviculture and Forest Ecological Studies, Hokkaido University, Sapporo, Japan
3. Institute of Conservation Ecology, Vytautas Magnus University Agriculture Academy, Kaunas, Lithuania
4. Laboratory of Forest Resource Biology, Hokkaido University, Sapporo, Japan
5. Hokkaido University Forests, Sapporo, Japan