鄱阳湖洲滩湿地土壤微生物呼吸的热适应性

土壤微生物呼吸的热适应性能显著影响陆地生态系统对全球变暖的反馈过程，进而改变未来气候变化的趋势。然而，湿地作为一个独特而重要的碳库，其土壤微生物呼吸的热适应性研究成果至今未见报道。此外，水分梯度如何影响微生物呼吸热适应和土壤微生物群落结构在热适应中的作用机理等重要问题依然没有解答。本项目拟利用鄱阳湖洲滩湿地不同水分含量的土壤样本，通过实验室长期培养方法，分析洲滩湿地土壤微生物呼吸的热适应特征及其受土壤水分的影响，揭示其中的微生物群落结构变化机理。研究内容包括：1）验证洲滩湿地土壤微生物呼吸的热适应性，分析其热适应类型；2）明确土壤水分梯度对洲滩湿地土壤微生物呼吸热适应的影响；3）探索微生物群落结构调控土壤微生物呼吸热适应性的机理。本项目将为模拟鄱阳湖未来的碳循环规律和生态系统服务功能提供数据支撑，还将为预测长江中下游平原对全球变暖的反馈作用和制定该区域的减排政策提供理论依据。

Understanding thermal acclimation of soil microbial respiration (Rm) has become one of the most urgent scientific challenges for ecologists as a small change in global soil Rm could dramatically impact the atmospheric CO2 concentration and thus profoundly alter future climate processes. To our knowledge, however, there has no paper studied thermal acclimation of soil Rm in wetland ecosystem which is a unique and important carbon pool. Meanwhile, many vital scientific questions are also far from being settled, such as, how would soil moisture impact on thermal acclimation of soil Rm, and what are the roles of the shifts of soil microbial community structures in thermal acclimation processes. In this project, we will conduct a long-term incubation experiment so as to investigate thermal acclimation processes and their impacts by soil moisture in the typical littoral wetland in Poyang Lake, China. A temperature gradient (10, 20, 30℃) and a soil moisture gradient (20%, 60%, 90% and 150% of the water holding capacity) are included in this incubation experiment. The mass-specific respiration (Rmass) is used to indicate thermal acclimation of soil Rm. Moreover, we also will analysis the functions of the changes of soil microbial community structures in thermal acclimation of soil Rm by conducting the phospholipid fatty acid assay and a DNA-based assay. Our results are crucial to determining the future carbon cycling and the ecosystem service values in Poyang Lake, and also important for simulating the feedbacks of terrestrial ecosystem to global warming in the middle and lower reaches of the Yangtze River and making the emission reduction polices in this region.