1. State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
2. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
3. Department of Soil Science, University of Wisconsin-Madison, Madison, WI, USA
4. Department of Geography, University of Wisconsin-Madison, Madison, WI, USA
5. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China