热带森林土壤微生物残留物对养分添加的响应及其对土壤碳固持的影响

人类活动导致的高氮（N）沉降加剧了热带森林中磷（P）的限制程度，从而显著影响土壤碳循环过程。土壤微生物是土壤有机碳形成与稳定的重要贡献者和调控者，大多数以往的研究关注于微生物的分解作用，而对土壤微生物残留物的关注较少。本项目依托热带次生林的长期N、P添加实验平台（11年），选择土壤氨基糖表征不同微生物来源的残留物，研究土壤微生物残留物对N、P添加在时间尺度上的响应动态；解析微生物残留物在不同粒径团聚体、SOC组分中的分布特征，量化微生物残留物对SOC固持的影响；最终揭示N、P添加背景下微生物残留物影响SOC固持的生态学机制及驱动因素。研究结果不仅有助于从微生物角度阐明土壤有机碳的形成与稳定对养分添加的响应机制，也可为预测热带森林土壤碳循环过程对全球变化的响应提供数据支撑和理论依据。

High nitrogen (N) deposition caused by human activities exacerbate phosphorus (P) deficiency and will further change soil carbon cycle. Soil microorganisms are important contributors and regulators of soil organic carbon (SOC) formation and stability. However, most of previous studies have focused on the degradation of SOC by microorganisms, while less attention has been paid to microbial residues. This project will select a long-term N and P addition (11 years) in tropical secondary forests. Soil amino sugars are used to represent microbial residues to evaluate the response dynamics of microbial residues to N or/and P additions on a time scale. We also explore the effect of microbial residues on SOC retention by analyzing the contribution of microbial residues to different soil aggregates and SOC components. Finally, we will clarify the ecological mechanisms and driving factors of microbial residues and their effects on SOC retention under N and P additions. This research results not only illustrate the microbial mechanism of SOC change under nutrients addition, but also provide data support and theoretical basis for predicting the impact of short-term and long-term environmental changes on SOC retention.