关键词: 碳稳定同位素, C₃和C₄植被, δ¹³C富集, 发生性碳酸盐, 土壤CO₂

Abstract: 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 techniques 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 cycle，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 behaviors 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 paleovegetation，turnover of soil organic matter，soil inorganic carbon cycle，and interactions between soil organic and inorganic 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 particular：（1） the relative proportion of C₃ and C₄ plants in local biomass can be inferred from the δ13C 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 equation，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，isotopic fractionation during decomposition of litter and vegetation. （2） Due to the 80% of the soil inorganic carbon storage in the soil below 1m in arid land，so sampling depth should be up to 3 m for estimation the soil inorganic carbon pool. Otherwise，it will cause the soil carbon pool estimation is low. Furthermore，soil CO₂ flux can significant change the δ13C value of soil inorganic carbon （pedogenic Carbonate）. So the research of soil inorganic carbon cycle should more emphasis the role of soil CO₂ flux. （3） Although soil organic carbon can transfer to inorganic carbon by soil physical，chemical and microbial action and soil parent materials weathering，but the actual number of sequestration atmospheric CO₂ in the process of formation pedogenic carbonates was hard to assess it. So the study on soil carbon transfer should be strengthened in the future. The arid region is the ideal area for the research of soil organic carbon and inorganic carbon transfer. The following three questions will be the focus of future research：the effects of soil total carbon source/sink，soil pedogenic carbonate formation and soil carbon origin and turnover base on the stable carbon isotope method in arid region.

Key words: the stable carbon isotope, C₃ and C₄ vegetation, δ¹³C enrichment, pedogenic carbonate, soil CO₂