Advances in soil organic carbon sequestration mechanisms on the Chinese Loess Plateau

Soil organic carbon is an important indicator for soil quality, which greatly influence the stability and productivity of soil. China's Loess Plateau is both the largest and deepest loess deposit in the world, and it has long been one of the most severely eroded areas on Earth. With the implementation of the Grain-for-Green Project in 1999, the Loess Plateau has become the most successful ecological restoration zone, and soil organic carbon sequestration has greatly increased. In this case, the Loess Plateau ecosystem has played an important role in carbon sink and will continue to play an important role in the future. However, little is known about the the balance of soil organic carbon sequestration and vegetation restoration, for example, by determining the vegetation carrying capacity and the mechanism of soil organic carbon sequestration for the sustainable development of the Loess Plateau. Currently, under the "double carbon strategy", the soil carbon sequestration effect on the Chinese Loess Plateau will face large changes and challenges. Consequently, this review focused on soil organic carbon sequestration for vegetation restoration on the Loess Plateau. Firstly, the current situations and principal aspects of vegetation restoration processes were reviewed, and the effects of vegetation restoration on soil organic carbon sequestration were summarized. Secondly, based on the new technologies and methods for carbon sequestration, the mechanism of soil microbial carbon sequestration was described, and the fixation of soil organic carbon sequestration during vegetation restoration and its driving factors were reviewed. Finally, we point out the main directions in soil carbon sequestration mechanism for vegetation restoration depending on the basic process of the carbon cycle. Then, the problems and challenges in the later stage of vegetation restoration were outlooked, providing the important reference for soil carbon sink function, ecological benefit improvement on the Chinese Loess Plateau even though in terrestrial ecosystems of China.