1. Huanjiang Observation and Research Station for Karst Ecosystem, Key Laboratory of Agro-ecological Processes in Subtropical Region; Institute of Subtropical Agriculture, Chinese Academy of Sciences, Yuanda 2nd Road 644; Changsha 410125 China
2. Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems; South China Botanical Garden, Chinese Academy of Sciences, Xinke Road 723; Guangzhou 510650 China
3. University of Chinese Academy of Sciences, Yuquan Road 19; Beijing 100039 China
4. Sino-Danish Center for Education and Research, Niels Jensens Vej 2; DK-8000 Aarhus C Denmark
5. Department of Geosciences and Natural Resource Management; University of Copenhagen Rolighedsvej 23; DK-1958 Frederiksberg C Denmark