1. Department of Environment Conservation, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3– 5–8Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
2. Department of Forest Policy and Economics, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
3. Department of Environmental Systems Engineering, College of Science and Engineering, Ritsumeikan University, 1– 1–1Nojihigashi, Kusatsu, Shiga 525-8577, Japan
4. Environment and Energy Division 1, Mizuho Information and Research Institute, Inc., 2–3 Kandanishiki-cho, Chiyoda, Tokyo 101-8443, Japan