1. Institute of Applied Ecology; Chinese Academy of Sciences; Shenyang 110016 PR China
2. CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology; Chinese Academy of Sciences; Shenyang 110016 PR China
3. Department of Earth Sciences; Indiana University-Purdue University Indianapolis (IUPUI); Indianapolis IN 46202 USA
4. State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science; Beijing Normal University; No. 19, XinJieKouWai St., HaiDian District Beijing 100875 PR China
5. Alkali Soil Natural Environmental Science Center; Northeast Forestry University/Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, Ministry of Education; Harbin 150040 PR China