毛竹根际沉积碳降解对氮沉降响应的微生物机制

日益增强的大气氮沉降增加了毛竹林土壤有机碳的降解，但其内在机理仍不清楚。本项目基于野外毛竹林模拟氮沉降长期实验平台，采用野外13CO2原位脉冲标记，探索毛竹根际沉积碳在土壤活性有机碳库中的分配对氮沉降的响应；采用稳定性同位素核酸探针结合高通量测序及荧光定量PCR技术探索降解毛竹根际沉积碳的关键微生物功能类群对氮沉降的响应；采用非靶标代谢和靶标代谢组学方法，探究氮沉降对毛竹根际土壤溶解性有机碳代谢图谱及根际沉积碳代谢关键产物的影响，筛选差异代谢物；在此基础上，构建根际沉积碳关键差异代谢物与根际沉积碳降解微生物功能类群的共现网络，剖析两者之间的互作关系，揭示氮沉降影响毛竹根际沉积碳代谢的微生物机制。本研究将从微生物组学和代谢组学角度，为氮沉降增强背景下降低毛竹林土壤碳降解提供新的应对思路。研究成果将为森林土壤有机碳库平衡的维持、森林土壤碳汇的辨识等奠定相关科学基础。

The increasing atmospheric nitrogen deposition increased the decomposition of soil organic carbon in Moso bamboo forest, however, its internal mechanism was still unclear. Based on long-term simulated experimental platform for nitrogen deposition, we will use in situ 13CO2 isotope pulse-labelling to explore the effects of atmospheric nitrogen deposition on rhizodeposition carbon distribution in soil active organic carbon pool. In addition, DNA-based stable isotope probing (DNA-SIP), high-throughput sequencing and qPCR will be combined to seek key functional microbial populations involved in rhizodeposition carbon decomposition under nitrogen deposition. Furthermore, the untargeted and targeted metabolomics will be used to investigate the the metabolic profile of dissolved organic carbon in rhizosphere soil and the key differential metabolites of rhizodeposition carbon in Moso bamboo forest. Based on above results, the co-occurrence network between key differential metabolites of rhizodeposition carbon and functional microbial populations involved in rhizodeposition carbon decomposition will be constructed. The interaction between them will be further analyzed to reveal underlying microbial mechanism of nitrogen deposition on rhizodeposition carbon metabolism in Moso bamboo forest. This study will provide new solutions for how to reduce soil organic carbon decomposition in Moso bamboo forest under global increasing nitrogen deposition and lay a scientific foundation for maintaining the balance of soil organic carbon pool and identifying soil carbon sink in forest.