1. Chinese Academy of Sciences, Institute of Mountain Hazards and Environment, #9, Block 4, Renminnan Road, Chengdu 610041, People's Republic of China
2. Sichuan Center for Rural Development Research, College of Management of Sichuan Agricultural University, # 211, Huimin Road, Wenjiag District, Chengdu 611130, People's Republic of China
3. College of Land and Resource, China West Normal University, No. 1 Shi Da Road, Nanchong 637000, People's Republic of China