The formation of small macro‐aggregates induces soil organic carbon stocks in the restoration process used on cut slopes in alpine regions of China

Abstract

AbstractRoad construction in mountainous areas of China has formed bare slopes on a large scale, which has aggravated soil erosion and carbon loss, and the restoration processes have changed soil structure and fertility. However, there are few reports regarding the differences of soil aggregate dynamics and SOC sequestration under different restoration process for cut slopes. In this study, three types of cut slopes [cut slope restored naturally (CSN); cut slope restored with three‐dimensional mesh (CST); cut slope restored with galvanized wire mesh (CSG)] and natural slope (NS) in alpine regions were selected as the research objects. SOC stocks and their key driving factors were then analyzed. The results showed that CSG was more beneficial to the formation of macro‐aggregates than CSN and CST. There were significant differences in wet‐sieved aggregate stability under different restoration process, where the sort by strength of stability was NS > CSG > CST > CSN. Aggregate size was a more important factor for SOC stocks than restoration process. The increase of SOC stocks was mainly due to that within small macro‐aggregates. RandomForest analysis revealed that the mass proportion of micro‐aggregates was the most important factor affected SOC stocks, while SOC stocks within large macro‐aggregates and small macro‐aggregates and porosity significantly affected SOC stocks. Partial least squares path modelling analysis found the particle size and stability of aggregates had negative total effects on SOC stocks, and SOC content had positive total effect on that. Overall, for the ecological restoration of cut slope in alpine regions, CSG was most beneficial to increase soil aggregate stability and SOC stocks.