1. School of Geographical Sciences, Northeast Normal University , Changchun 130024 , China
2. College of Tourism and Geographic Science, Jilin Normal University , Siping 136000 , China
3. College of Economics, Management and Law, Jilin Normal University , Siping 136000 , China
4. College of Ecology, Taiyuan University of Technology , Taiyuan 030024 , China