Background Clarifying the impact of slope aspect on the short-term soil carbon recovery of slopes, and analyzing the main influencing factors may provide scientific basis for the improvement of carbon sink recovery technology of artificial slope.

Methods This study focuses on the artificial slopes on the Guanglian Expressway, which have been restored for one year. The vegetation restoration, soil organic carbon content, soil physicochemical properties, soil bacterial community characteristics, and enzyme activity of slopes were compared and analyzed with different slope aspects. Partial least squares regression (PLSR) was used to explore the main driving factors of short-term soil organic carbon changes on slopes.

Results 1) The density of the Cajanus cajan community on the shady slope is much higher than that on the sunny and semi-sunny slopes, which also results in a significant increase in the total biomass of the vegetation community on the shady slope compared to other slopes. The soil organic carbon content on shady slopes is 4.3 and 4.7 times higher than that on sunny and semi-sunny slopes, respectively, while there is no significant difference between sunny and semi-sunny slopes. 2) The soil moisture content and available nutrient content of the shady slope are significantly higher than those of other slope aspects, and there are also significant differences in soil bacterial community structure and enzyme activity among different slope aspects. 3) In addition to soil moisture and nutrient content, the relative abundance of Actinobacteria is also the main factor affecting short-term changes in soil organic carbon.

Conclusions The differences in hydrothermal conditions between different slope aspects have an impact on the short-term soil organic carbon recovery of slopes by changing soil moisture, nutrient content, and bacterial community composition. Changing the composition of soil bacterial communities through microbial agents may affect the short-term accumulation process of soil organic carbon on slopes.