Acknowledgements
We sincerely thank Mr. Yingwen Li and Yongxing Li for their helps on the field fertilization and vegetation survey. This work was funded by National Natural Science Foundation of China (31700371, 31670621, 31870463), Guangdong Basic and Applied Basic Research Foundation, China (2019A1515011508), Pearl River Nova Program of Guangzhou (201710010140), Innovation Foundation for Platform Construction of Guangdong Forestry, China (2019KJCX021), R & D program of Guangdong Provincial Department of Science and Technology (2018B030324003), and the Open Funding of Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences (DE2018023).