氮、水交互对长白山原始阔叶红松林外生菌根的影响

Ectomycorrhizal fungi (EMF) regulate the responses of forest ecosystem carbon (C) cycle to global change. At present, lack of knowledge on the response patterns of temperate forest ectomycorrhizal to increased nitrogen deposition and changed rainfall had become a major problem in predicting the effects of global change on C sequestration of the forest ecosystems. In this project, we will research the effects of nitrogen and water interactions on the spatiotenporal patterns of EMF mycelium production, EMF community structure, fine root functional traits and soil physicochemical properties. The research will use the improved double growth bag method, EMF biomarker method and high-throughput sequencing technology, relying on long-term field control of water and nitrogen two-factor experiment platform in the primitive broad-leaved Korean pine mixed forest in Changbai Mountain. This project is aimed at pinpointing the response patterns of EMF mycelium production and community structure to increased nitrogen deposition and decreased rainfall, and clarifying the relatedness of EMF mycelium production, EMF community structure, fine root functional traits and soil physicochemical properties, and quantifying the contributions of EMF mycelium and fine roots to soil C pool. The results will be significant to accurately assess the rate and potential of forest ecosystem C sequestration in China.

外生菌根真菌（EMF）调节着森林生态系统碳（C）循环对全球变化的响应。目前，对温带森林外生菌根对氮沉降增加及降雨量改变响应模式认识的不足是制约预测分析全球变化对森林生态系统固C功能影响的瓶颈性问题。本项目拟选取长白山原始阔叶红松林为研究对象，依托大型长期野外控水、施氮双因子试验平台，运用改进的双层生长袋法、EMF生物标志物法以及高通量测序技术，研究氮、水交互对EMF菌丝生产力时空格局、EMF群落结构、细根功能性状和土壤理化性质的影响。本项目旨在阐明长白山原始阔叶红松林EMF菌丝生产力时空格局和群落结构对氮沉降增加、降雨量减少及其交互作用的响应模式，明确EMF菌丝生产力与EMF群落结构、细根功能性状和土壤理化性质的关联性，量化EMF菌丝和细根对土壤C库的输入。本研究的结果对于准确评估全球变化背景下我国森林生态系统的固C速率和潜力具有重要意义。

长白山阔叶红松林是我国重要的碳汇功能区之一，在吸收CO2和减缓气候变暖等方面具有重要作用，而外生菌根真菌调节着森林生态系统碳循环对全球变化的响应。本项目主要研究氮、水交互作用下长白山原始阔叶红松林外生菌根真菌菌丝生产力时空格局和菌根真菌群落结构，优势树种细根功能性状的响应，以及细根和菌根真菌菌丝对土壤碳库的输入。结果表明，（1）长白山阔叶红松林菌根真菌菌丝和细根功能性状具有显著的空间变异和时间动态特征；（2）氮、水交互作用显著改变了长白山阔叶红松林群落水平上以及红松、水曲柳物种水平上菌根真菌的群落组成；（3）长白山阔叶红松林水曲柳细根功能性状不但以功能性状的平均值，而且以功能性状的变异和分布方式变化响应土壤养分和水分的改变。（4）本项目提出的双层生长袋法，能够实现对菌丝和细根的同步采样，且简单易行，具有一定的应用价值。利用此方法，本项目估算出长白山阔叶红松林菌根真菌菌丝和细根对土壤碳的贡献分别为3.69 mg cm-2和1.10 mg cm-2。本项目所取得的结果将对准确评估全球气候变化背景下我国温带森林生态系统的固碳速率和潜力具有重要意义。