中文摘要：

植物和土壤是陆地生态系统的重要碳库,而碳同位素技术对各碳库中碳元素的迁移具有很好的指示作用,能够为碳转化研究提供有力证据。以往研究土壤碳循环主要是针对有机碳,较少考虑无机碳的作用,但干旱区土壤无机碳在区域碳循环过程中的贡献日益显著,因此干旱区土壤碳循环研究必须同时考虑土壤有机碳和无机碳的行为。基于碳稳定同位素技术的土壤有机碳循环研究和土壤无机碳动态及其碳同位素研究进展,探讨土壤无机碳与有机碳的转化关系,并对干旱区土壤碳循环研究进行展望,期望从稳定同位素生态学的角度探讨干旱区土壤有机碳和无机碳的转化关系,以推动干旱区土壤碳循环研究,揭示干旱区碳循环过程及其在全球碳循环中的作用。

英文摘要：

Vegetation and soil carbon pools is important carbon pool of terrestrial ecosystem , which plays a crucial role in carbon biogeochemical cycle. The stable carbon isotope technique is one of the credible and effective tech- niques in ecological research, which can efficiently trace the dynamics of carbon transfer in ecological systems, and has been extensively applied in many fields of ecology. The previous study is emphasized in soil organic carbon cy- cle, but soil inorganic cycle （pedogenic Carbonate carbnon） is usually neglected. However, soil inorganic carbon storage in arid region is huge and has significant contribution to region carbon cycle process. Therefore, the behav- iors of soil organic carbon and inorganic carbon in the arid region must be considered in the soil carbon cycle study. In this paper, the applications of the stable carbon isotope technique in the researches of reconstruction of paleovege- tation, turnover of soil organic matter, soil inorganic carbon cycle, and interactions between soil organic and inorgan- ic carbon transfer were briefly summarized, and the perspectives of the stable carbon isotope technique in arid region were also discussed, based on the issues existed in current researches. Moreover, some problems to be noted in par- ticular： （ 1 ） the relative proportion of C3 and C4 plants in local biomass can be inferred from the ~ 13C compositions of soil organic matter. The isotopic mass balance equation ware often applied to distinguish the relative proportion of C3 and C4 plants. However, some factors should be considered in the process of using the isotopic mass balance equa- tion, such as the temporal and spatial variability of vegetation succession pattern, the mixed distribution of C3 and C4 plants, changes in atmospheric CO2 concentration, different decay rates of various components in organic matter,iso- topic fractionation during decomposition of litter and vegetation. （2） Due to the 80% of the soil inorganic carbon storage in the soil below lm in arid lan