Guanyi Yin1, Liming Liu2,3, Chengcheng Yuan1. 1. Department of Land Resources Management, College of Resource and Environmental Sciences, China Agricultural University, Beijing, 100193, China. 2. Department of Land Resources Management, College of Resource and Environmental Sciences, China Agricultural University, Beijing, 100193, China. liulm@cau.edu.cn. 3. Department of Land Resources Management, China Agricultural University, No.2 Yuanmingyuan West Road, Haidian District, Beijing, 100193, China. liulm@cau.edu.cn.