1. b Shikoku Research Center , Forestry and Forest Products Research Institute , 2–915 Asakura-Nishi, Kohshi 780-8077, Japan
2. a Tohoku Research Center , Forestry and Forest Products Research Institute , 92–25 Nabeyashiki, Shimo-Kuriyagawa, Morioka 020-0123, Japan
3. c Institute of Geographical Sciences and Natural Resources Research , Chinese Academy of Sciences, Building 917, Datun Road, Anwai, Beijing 100101, PR China
4. d The Institute of Forestry Science and Technology Information Research , Chinese Academy of Forestry , Summer Palace, Beijing 100091, PR China