1. Jiangsu Key Laboratory of Soil and Water Conservation and Ecological Restoration, Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Forestry College of Nanjing Forestry University, Nanjing 210037, China
2. College of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36839, USA
3. The Institute of Water Resources for Pastoral Areas, Hohhot 010020, China
4. College of Geographical Science, Inner Mongolia Normal University, Hohhot 010022, China