Received: 2018-03-15 Accepted: 2018-04-18 Foundation: Key Program of the Chinese Academy of Sciences, No.ZDRW-ZS-2016-6; National Key Research and De-velopment Program of China, No.2017YFC0503803 Author: Wang Xiaobo, PhD Candidate, specialized in ecosystem ecology. E-mail: wxbwxb1995@163.com *Corresponding author: Wang Shaoqiang, PhD and Professor, specialized in ecological remote sensing and ecological modelling. E-mail: sqwang@igsnrr.ac.cn