根际效应对滨海盐沼甲烷代谢微生物的影响及其地理格局研究

The rhizosphere is one of the most active soil spaces for biological processes because of the significant difference of microorganisms in and out of the rhizosphere. This rhizosphere effects have been widely studied in terrestrial ecosystems, but their significances in hydrosphere wetlands remain to be explored. By using a PVC ring mesh method, the applicant successfully divided the soil under the vegetations into rhizosphere soils and non-rhizosphere soils in a coastal saltmarsh of the Yangtze River estuary and found that the rhizosphere effects promoted methane emission, but the related microbiological mechanisms need to be further explored. Across different latitudes of China's east coastal saltmarshes, this project is aimed to investigate the rhizosphere effects on microbial habitat, and microbial functional communities and their interactions through linking microbial processes, geochemistry, and environmental factors. We will attempt to generalize the geographical patterns of these rhizosphere effects in different regions on Chinese coasts, and explore the underlying mechanisms that generate those patterns. Through the comparative study of the rhizosphere effects across latitudes, this project can not only promote understanding of microbe-induced biogeochemical cycling but also provide important scientific basis on carbon emission reduction in China’s coastal zones. Moreover, it is hoped that the outcomes of this proposed project can make contributions to solve a core scientific question “macro-mechanisms and ecological effects of hydrosphere microbial functioning” in this research plan.

根系的存在使根际内外微生物有显著的差异，因而使根际成为生物过程最为活跃的土壤空间之一。这一根际效应在陆地生态系统得到了广泛研究，但对其在水圈湿地中的意义作用还有待探究。通过PVC环网孔法，申请人前期在长江口滨海盐沼成功将植被下土壤分成根际土与非根际土，发现根际效应促进了滨海盐沼甲烷排放，但相关微生物学机制有待进一步探究。本项目拟以我国东海岸跨不同纬度的滨海盐沼为研究区，以甲烷代谢相关微生物为研究对象，着眼于从微生物、地球化学过程与环境因子三者的联系，研究根际效应对微生物生境、微生物群落及其相互作用、甲烷排放等的影响，探讨影响的地理变异格局与成因。本项目通过对根际效应影响的跨纬度比较，不仅能提升认识滨海盐沼关键生源要素循环的微生物学机制，而且也将为我国海岸带生态系统的固碳减排提供重要科学依据，对于解答“水圈微生物作用的宏观机制与生态效应”这一重大研究计划中的核心科学问题将有积极的推动作用。

本项目以我国东海岸跨不同纬度的芦苇与互花米草滨海盐沼为研究区，以甲烷代谢相关微生物为研究对象，着眼于从微生物、地球化学过程与环境因子三者的联系，研究根际效应对微生物生境、微生物群落及其相互作用、甲烷排放等的影响，探讨影响的地理变异格局与成因。我们通过了3年野外与室内的研究取得了以下主要进展：1）阐明了中国主要滨海盐沼植物地上与地下性状以及土壤环境因子的地理变异，并揭示了植物与土壤环境对微生物的影响；2）从地理上阐明了滨海盐沼氮素、水位、温度对甲烷代谢相关微生物及其活性的影响与机制；3）揭示了底物变化对产甲烷菌和硫酸盐还原菌相互作用以及甲烷排放的影响。本项目探讨了根际效应对滨海盐沼甲烷代谢相关微生物的影响及其空间分异规律，进一步揭示了我国东海岸盐沼生态系统中关键微生物对于碳循环特征、碳汇/源形成的贡献。本项目对于解答“水圈微生物作用的宏观机制与生态效应”这一核心科学问题将有积极的推动作用。项目按照计划任务书执行，共发表了 17 篇学术论文，其中在Nature Climate Change、Nature Communications、Ecology Letters 等国际主流期刊上发表SCI 论文 15 篇；申请国家发表专利一项。