Affiliation: | 1. Graduate School of Agriculture , Hokkaido University , Sapporo , 060-8589 , Japan guomeng@env.agr.hokudai.ac.jp;3. Research Faculty of Agriculture , Hokkaido University , Sapporo , 060-8589 , Japan;4. Northeast Institute of Geography and Agroecology , Chinese Academy of Sciences , Changchun , 130012 , China;5. Institute of Public Administration , South China Agricultural University , Guangzhou , 510642 , China |