大兴安岭森林作为我国重要的生态屏障，发挥着涵养水源、调节气候及保障国土安全等重要作用。不同演替阶段森林在碳周转及对氮沉降的响应存在较大差异，容易对土壤碳-氮库产生深刻影响，进而作用于气候变化进程。本项目以黑龙江漠河森林生态系统国家定位观测研究站为依托平台，通过对不同演替阶段森林土壤特性、凋落物分解与细根动态、土壤碳-氮储量以及土壤表面二氧化碳和氧化亚氮通量等方面研究，进一步确定土壤理化特征随演替发生而改变，分析森林演替过程中土壤碳-氮周转的变化规律，量化不同演替阶段森林土壤碳-氮通量的动态特征，及森林土壤碳通量对生态系统碳通量的贡献，深入探讨森林土壤碳-氮的耦合机制，为调控和管理大兴安岭林区北方森林生态系统生态过程提供数据支撑与理论依据。

Boreal forest in the Da Hinggan Mountains is the southern expansion of Siberia forest ecosystem and it situates within the cold-temperate climate zone of Northeast China. Different forest succession stages can differ in carbon turnover strategy and also their responses to nitrogen deposition. All these processes may affect carbon and nitrogen pools in forest soil, and hence, it will have profoundly impacts on the global climate change process. The proposal we prepared here aims to compare soil properties, soil carbon-nitrogen storages and soil carbon-nitrogen fluxes in different forest succession stages. These purposes achieved by the methods of spatial series instead of temporal series which are mainly through field measurements of carbon-nitrogen pools and fluxes, combined with respiration and decomposition studies. We hope to understand better why and how soil carbon-nitrogen fluxes differ between different forest succession stages. To explore why soil carbon storage varied among three succession stages, and trying to explain the phenomenon mentioned before by experiments regarding litter quality and quantity, tree growth and decomposition, soil carbon accumulation and mineralization, organic material fluxes and fine root turnover. Having an insight into effects of different tree species on soil carbon and nitrogen fluxes and pools is crucial for quantitatively evaluating regional carbon-nitrogen cycle patterns, and also this can provide data supporting and theoretic basis for better regulating and managing the boreal forest in the Da Hinggan Mountains of China.