本文由国家自然科学基金项目41501282、森林与土壤生态国家重点实验室开放基金课题项目LFSE2015-15和中国科学院战略性先导科技专项项目XDB15010303资助 This work was supported by the National Natural Science Foundation of China 41501282,the State Key Laboratory of Forest and Soil Ecology LFSE2015-15,and the Strategic Priority Research Program of the Chinese Academy of Sciences XDB15010303.