[Liao, Liuwen] Changsha Univ, Coll Econ & Management, Changsha 410022, Peoples R China.
[Ma, Enpu] Hunan Normal Univ, Sch Geog Sci, Changsha 410081, Peoples R China.
[Long, Hualou] Guangxi Univ, Sch Publ Adm, Nanning 530004, Peoples R China.
[Long, Hualou] Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China.
[Peng, Xiaojun] Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.