1. Graduate School of Environment, Hokkaido University, Sapporo, Japan
2. Nayoro Station, Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Japan
3. Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
4. Nakagawa Experimental Forest, Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Japan
5. Arid Land Research Center, Tottori University, Tottori, Japan
6. Faculty of Agriculture, Iwate University, Morioka, Japan