1. Department of Forest Vegetation Forestry and Forest Products Research Institute 1 Matsunosato Tsukuba 305‐8687 Japan
2. Fenner School of Environment and Society Australian National University Canberra Australian Capital Territory 2601 Australia
3. Shikoku Research Center Forestry and Forest Products Research Institute 2‐915 Asakuranishi Kochi 780‐8077 Japan
4. Department of Mathematics and Statistics McMaster University Hamilton Hall, Room 218, 1280 Main Street West Hamilton Ontario L8S 4K1 Canada
5. Département de biologie Faculté des sciences Université de Sherbrooke 2500 Boulevard Université Sherbrooke Québec J1K 2R1 Canada
6. Faculty of Science and Technology Kochi University 2‐5‐1 Akebono‐cho Kochi 780‐8520 Japan