1. Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany; Chinese Academy of Sciences; Kunming 650201 Yunnan PR China
2. East and Central Asia; World Agroforestry Centre; Kunming 650201 Yunnan PR China
3. Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science; University of Göttingen; Göttingen 37707 Germany
4. National Engineering Laboratory for Improving Quality of Arable Land; Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences; Beijing 100081 PR China
5. Institute of Environmental Sciences; Kazan Federal University; Kazan 420049 Russia
6. Soil Science Consulting; Göttingen 37077 Germany