[Spatial Variation of Soil Organic Carbon and Stable Isotopes in Different Soil Types of a Typical Oasis]

Soil organic carbon (SOC) and its stable isotope composition reflect important information on ecosystem carbon cycle. Under the background of global change, it is of great significance to study carbon dynamics and sustainable development of carbon resources in terrestrial ecosystems. In this study, four soil types in Alar oasis were studied to determine SOC content and δ¹³ C value at different layers, and the differences of δ¹³C_SOC abundance and its relationship with soil environmental factors were also discussed. Three main outcomes were drawn from the results. ①The total organic carbon (TOC) content of the soil was in the order of irrigated desert soil > brown desert soil > saline soil > aeolian sandy soil, and had a higher value in the surface layer (0-20 cm layer); δ¹³C_SOC ranged from -26‰--23‰, the surface layer (0-20 cm) was in the order saline soil > aeolian sandy soil > irrigated desert soil > brown desert soi. ② Both SOC and δ¹³C_SOC were significantly affected by soil type and their interaction, and by soil depth. Furthermore, the effect test of interaction indicated that SOC was significantly impacted by environmental factors, but the impact on δ¹³C_SOCwas relatively weak. ③ The results of redundancy analysis showed that SOC had a significant or extremely significant positive correlation with soil inorganic carbon, total nitrogen, soil water content and bulk density, and had a significant negative correlation with C/N. There was also a significant positive correlation between δ¹³C_SOC and conductivity, and in addition, δ¹³C_SOC was negatively correlated with soil inorganic carbon and soil water content. The analyses showed that SOC and its isotopes changed with soil types, and that the effect of soil type was stronger than that of soil depth, which was mainly determined by soil moisture content.