中文摘要：

区分草原土壤呼吸的主要目的在于准确估算草原生态系统土壤碳蓄积和碳源、汇潜力,为预测气候变化提供科学依据。论文主要论述了稳定同位素13C在草原土壤呼吸区分方面的应用。主要在以下几个方面进行了阐述：①碳同位素区分土壤呼吸的两种主要标记方法——脉冲标记法和持续标记法,其中脉冲标记法包括单次脉冲标记法和重复脉冲标记法,持续标记法包括FACE实验标记法和13C自然丰度标记法,也介绍了利用核爆产生的14C标记;②应用碳稳定同位素区分土壤呼吸的理论依据和计算方法;③土壤呼吸稳定同位素组成的取样方法和测定,包括静态箱-Keeling Plot法、静态箱平衡状态法和动态箱连接红外分析仪法等;④指出了减小静态箱-Keeling Plot法测定土壤呼吸碳同位素值的误差需采取的措施。

英文摘要：

The main purpose of partitioning soil respiration lies in accurately estimating the source and sink of carbon and soil carbon accumulation in grassland ecosystem and providing data for forecasting global climate change.The application of the stable Isotope 13C in the partitioning of grassland soil respiration was introduced in this paper.The applications are as follows： 1） Continuous labeling methods and pulse labeling methods of plants in grassland by 13CO2.Continuous labeling methods include bomb-14C labeling,13C natural abundance labeling and FACE labeling,and pulse labeling methods include single pulse labeling and repeated pulse labeling.2） The theory and method of calculation of separating soil respiration by stable isotope 13C.3） Sampling and measuring of 13CO2 for soil respiration in grassland.They include a method of static closed chamber-Keeling Plot,a method of static closed chamber at equilibrium and a dynamic closed system with infrared gas analyzer（IRGA）.4） Means of improving Keeling-Plot accuracy for measuring carbon-isotopic composition of soil-respired carbon dioxide in static closed chambers.