1. School of Economics, Tianjin University of Commerce, Tianjin 300134, China
2. Department of Food and Resource Economics, Københavns Universitet, Rolighedsvej 23, 1953 Frederiksberg C, Denmark
3. Research and Impact Assessment Division, International Fund for Agricultural Development, 00142 Rome, Italy
4. International Union Laboratory of Landscape Architecture, College of Landscape Architecture and Art, Henan Agricultural University, Zhengzhou 450002, China