1. Agricultural Economics and Rural Policy Group; Wageningen University; Wageningen The Netherlands
2. China Center for Agricultural Policy, School of Advanced Agricultural Sciences; Peking University; Beijing PR China
3. Environmental Economics and Natural Resources Group; Wageningen University; Wageningen The Netherlands
4. College of Pastoral Agricultural Science and Technology; Lanzhou University; Lanzhou PR China
5. Department of Economics and Management; Northwest Agricultural & Forest University; Xianyang PR China