三峡库区消落区水文变化和植被恢复对土壤氮循环的关键微生物过程的影响与机制

Effects of hydrologic changes and revegetation on the soil nitrogen cycling in the water level fluctuation zone (WLFZ) has been considered as the focus problem in the current global change research. How to relate the soil nitrogen cycling to soil microbal communities is still a difficult problem to be solved. In the present project, we will simulate three different hydrologic changes including non-flooded, permanently flooded and periodically flooded in situ to investigate the key processes of nitrogen cycling (i.e., nitrification, denitrification and anammox) and related microbial communities (dominant species, diversity, and abundance) following the hydrologic changes and revegetaion in the WLFZ of the Three Gorges Reservoir (TGR). Multiple techniques will be uesd in this study, such as isotope pairing, cosmically sequence, quantitative real-time PCR and so on. We identify mechanisms by vegetation and environmental factors under hydrologic changes and revegetation affect soil nitrogen cycling and microbial communities. Meanwhile, we will explore the relationships between the key processes and dominant species, diversity, and abundance of microbial communities related nitrogen cycling and identify the microbial mechanism for the effects of hydrologic changes and revegetation on the soil nitrogen cycling. This project will provide the scientific theory for wetland ecosystem nitrogen cycling related to global environment change.

消落区水文变化和植被恢复对土壤氮循环过程影响是当前全球变化研究的焦点问题，如何将土壤氮循环过程与其功能微生物群落结构相关联仍是一个亟待解决的难题。本项目以三峡库区消落区忠县植被恢复区和自然植被区为研究对象，在前期的研究基础上，通过原位模拟水文变化（连续水淹、周期性水淹-干旱和正常水位）的控制实验，运用氮同位素配对、高通量测序和实时荧光定量PCR 等方法，研究消落区水文变化和植被恢复背景下土壤氮循环关键过程（包括硝化、反硝化和厌氧氨氧化作用）及其对应功能微生物群落结构（优势种群、多样性和丰度）的动态变化，揭示植被与环境因素对氮循环和微生物群落结构的影响机制；通过定量土壤氮循环关键过程与其对应功能微生物群落结构之间的相关性，揭示消落区水文变化和植被恢复对土壤氮循环关键过程影响的微生物学机理。本项目的实施将为揭示湿地生态系统氮循环对全球变化的响应提供科学依据。

消落区水文变化和植被恢复对土壤氮循环过程影响是当前全球变化研究的焦点问题，如何将土壤氮循环过程与其功能微生物群落结构相关联仍是一个亟待解决的难题。本项目以三峡库区消落区忠县植被恢复区和自然植被区为研究对象，在前期的研究基础上，通过原位模拟水文变化（连续水淹、周期性水淹-干旱和正常水位）的控制实验，运用氮同位素配对、高通量测序和实时荧光定量PCR 等方法，研究消落区水文变化和植被恢复背景下土壤氮循环关键过程及其对应功能微生物群落结构（优势种群、多样性和丰度）的动态变化，揭示植被与环境因素对氮循环和微生物群落结构的影响机制；通过定量土壤氮循环关键过程与其对应功能微生物群落结构之间的相关性，揭示消落区水文变化和植被恢复对土壤氮循环关键过程影响的微生物学机理。研究结果表明水文变化主要通过改变土壤硝态氮含量进而对土壤反硝化速率产生影响，其中乔木区土壤再淹没阶段反硝化速率高于饱和和落干状态。水文变化对土壤反硝化菌群落结构的影响主要通过改变土壤温度、湿度和铵态氮的含量。植被类型对土壤反硝化细菌群落结构产生影响，其中草本区拥有较高的nirS基因丰富度和nirS及nirK基因的多样性。然后土壤反硝化作用和反硝化细菌群落结构之间没有显著的相关关系。本研究将为三峡库区消落区植被恢复以及库区生态环境建设提供理论基础，同时为揭示湿地生态系统氮循环对全球变化的响应提供科学依据。