Vegetation succession accelerated the accumulation of soil organic carbon on road-cut slopes by changing the structure of the bacterial community

More emphasis on the soil carbon sequestration of restored rock-cut slopes will be beneficial for reducing carbon emissions from the transportation sector. However, the changes in soil carbon storage with vegetation succession are unclear. We selected two different highways where the cut slopes had been restored for 3 and 10-20 years in Guangdong Province, China, as the study plots. By examining the two restored slopes at different recovery times, we analyzed the differences in soil organic carbon, soil physicochemical properties and the diversity of the soil microbial communities of road-cut slopes with vegetation succession. The soil organic carbon of restored slopes increased significantly with vegetation succession. Moreover, vegetation diversity increased soil organic carbon storage by reducing the microbial activity of Proteobacteria. Additionally, the results indicated that pH remained a key factor in controlling microbial activity and that the effect of soil moisture was site specific. Additionally, our study highlights the importance of investigating the microbial community, pH, and vegetation diversity for a more complete understanding of the mechanisms that regulate soil organic carbon dynamics in restored slope ecosystems. Understanding the multivariate processes controlling soil organic carbon dynamics should be an important goal of future soil organic carbon research for restoring ecosystems on bare slopes.