我国人工用材林较低的生产力严重影响了国家木材战略安全，其根本原因是土壤有机质的含量和质量不高。因此，提高土壤有机质是人工林地力培育的重要基础。然而，目前人工林土壤有机质形成与转化的生物学机制尚不清楚，制约了我们对土壤有机质的培育与调控。鉴于此，本项目以杉木人工林为研究对象，依托DIRT、施肥、间伐等长期控制试验，结合野外调查和模拟试验，以凋落物-微生物-土壤有机质为核心，采用13C示踪、PLFA、团聚体分级、GS-MS等技术与方法，通过研究凋落物碳的分配与稳定、微生物残留物续埋效应、凋落物同化与激发的动态平衡等过程，探讨凋落物和微生物所驱动的土壤有机质的形成与转化过程，解析它们对养分管理、树种组成、采伐等经营活动的响应，最终阐明土壤有机质形成与转化的生物学机制及其调控。本项目的研究将为人工林土壤有机质和林地地力的培育与管理提供理论和实践支持，促进我国人工林高效、稳定、可持续发展与经营。

In China, the low productivity of timber plantations has seriously affected the national timber strategic security. The fundamental reason of the low productivity is the low content and quality of soil organic matter. Therefore, improving soil organic matter is an important basis for soil fertility cultivation. However, the biological mechanism of soil organic matter accumulation is not clear, which restricts the cultivation and regulation of soil organic matter in plantations. Therefore, based on DIRT, fertilization, and thinning long-term control experiments, combined with field investigation and simulated incubation, this proposed project will address this key issue using the methods and techniques of 13C tracer, PLFA, aggregate fractionation, and GS-MS in the subtropical Chinese fir plantation. We aimed at evaluating the dynamic balance between litter assimilation into new soil organic matter and priming of old soil organic matter, distribution and stability of litter-derived carbon in soil different aggregates, and entombing effect of soil microbial residues. We also investigated the responses of these processes to nutrient management, tree species composition and harvesting in plantation ecosystems. Finally, we will clarify the biological mechanism and regulation of the formation and transformation of soil organic matter driven by litter and microorganisms. The results of this study will provide the theoretical and practical supports for the cultivation and management of soil organic matter and soil fertility in plantation ecosystems, and promote the efficient and sustainable development of plantation forests in China.