1. Key Laboratory of Agro‐ecological Processes in Subtropical Region, Institute of Subtropical Agriculture Chinese Academy of Sciences Changsha 410125 Hunan China
2. Huanjiang Observation and Research Station for Karst Ecosystems, Institute of Subtropical Agriculture Chinese Academy of Sciences Huangjiang 547100 Guangxi China
3. Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 China
4. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China
5. Department of Earth and Environmental Science University of Pennsylvania Philadelphia Pennsylvania 19104 USA
6. Department of Microbiology and Plant Biology University of Oklahoma Norman Oklahoma 73019 USA