杉木细根周转与根际激发对CO2浓度升高和氮沉降的响应

项目名称： 杉木细根周转与根际激发对CO2浓度升高和氮沉降的响应

项目编号： No.31470625

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 农业科学

项目作者： 王朋

作者单位： 中国科学院沈阳应用生态研究所

项目金额： 81万元

中文摘要： 根际过程在陆地生态系统碳、养分和生物地球化学循环中发挥核心作用，约调控一半的全球陆地生态系统CO2释放量。细根周转和根际激发效应是根际过程、土壤有机质动态和生态系统生产力的关键组分和驱动力，对气候变化因子反应敏感。为了更准确模拟地下碳过程以及预测根系对全球变化的响应，亟需探明细根周转和根际激发效应对气候变化的差异响应机制及其与主控因子间的函数关系。针对该科学问题，本项目拟选取我国亚热带的杉木人工林为研究对象，在OTC平台模拟CO2浓度升高和氮沉降下，借助根窗法监测细根周转、天然13C示踪法研究根际激发效应对CO2浓度升高和氮沉降的差异响应模式与机理，并建立细根周转率和根际激发效应与微生物周转等主要调控因子之间的函数关系，结果将为森林生态系统地下碳氮循环模型提供参数，为未来气候变化背景下准确预测全球气候变化与土壤碳循环间的反馈关系和我国杉木人工林地下碳动态提供新的思路和内核数据支撑。

中文关键词： 森林土壤；细根周转；根际激发效应；土壤微生物群落结构；全球变化

英文摘要： Rhizosphere interactions, such as the crucial components of fine foot turnover and rhizosphere priming effect (RPE), play a central role in terrestrial ecosystem functions, which, at the global scale, may control as much as 50% of the total CO2 released from terrestrial ecosystems, and regulate virtually all aspects of carbon, nutrient and biogeochemical cycling. It is now well accepted that plant-root mediated processes play an important role in regulating SOM dynamics, and understanding of these functions is needed to accurately describe critical processes like fine root turnover and RPE at realized levels. However, limited observations of root dynamics and RPE make it difficult to quantify both the degree to which roots influence SOM dynamics and the mechanisms responsible for such effects. Hence, it is critical to quantify correlationship between fine root turnover with RPE and their relationship with microbial C metabolism in order to develop robust projections of ecosystem C storage and potential forest C cycle-climate feedbacks. In this study, Chinese fir seedlings grown in OTC, effect of elevated CO(2) and nitrogen deposition on fine root turnover will be evaluated by using the root window technique and soil coring methods. Using a natural (13)C tracer method to separately measure SOM-derived CO(2) from root-derived CO(2), this proposed project aims to connect the level of rhizosphere-dependent SOM decomposition with RPE and fine root turnover of the whole plant-soil system, and to mechanistically link the RPE to soil microbial turnover and community composition as well as rhizosphere microbial C metabolism. The results from these innovative experiments will lead to significant advances in our understanding the mechanisms underlying the impact of elevated CO(2) and N deposition on fine root turnover and RPE. By generating empirical functions, the results also will be useful for reducing uncertainty in estimates of root dynamics in response to climate change and soil factors, and for understanding the importance of complex studies on respective regulatory mechanisms in changing climate and sustainable production in Chinese fir forests, thereby impacting other areas of science.

英文关键词： forest soil;fine root turnover;rhizosphere priming;microbial community composition;global change