Soil carbon pools have a great impact on global climate change, and land degradation caused by natural conditions or human activities is one of the important causes of soil carbon sequestration changes. In order to explore the impact of different types of land degradation on soil carbon sequestration and its mechanisms, this paper reviews the effects of different types of land degradation on soil carbon sequestration, such as desertification, soil erosion, soil salinization, nutrient loss and soil impoverishment. It is pointed out that various types of land degradation will increase the rate of CO2 release from soil to the atmosphere to varying degrees, which will increase the function of soil carbon source and weaken the function of carbon sink.

However, the impact of land degradation on soil carbon stocks is likely to be reversed. In the future, the dynamic changes of soil carbon sequestration and deep soil carbon pools in different types of land degradation processes should be strengthened in order to further study the effects of soil carbon cycling in land degradation. And lay a foundation for enhancing the function of soil carbon sources.

Impact of desertification on soil carbon sequestration Some studies suggest that land desertification caused by increased human disturbance intensity is the main reason for the accelerated release of soil organic carbon into the atmosphere. Particularly for fragile ecosystems in arid and semi-arid regions, non-sustainable land use patterns will accelerate carbon emissions from the soil.

The direct cause of desertification leading to increased soil carbon emissions and reduced soil carbon pools is exacerbated by erosion of the topsoil layer, resulting in the exposure of carbonate materials or calcium deposits in the soil to the topsoil, and promotion of soil organic carbon (SOC) and inorganic carbon (SIC). Mineralization, in turn, led to acidification and CO2 release [15]. The indirect reason is that the vegetation coverage is reduced, and the amount of plant debris returned to the soil is rapidly reduced, which leads to a decrease in soil respiration and a decrease in secondary carbonate formation in the soil

Impact of soil salinization on soil carbon sequestration The salinization of the land caused by high groundwater level, arid climate and poor drainage will result in too high salt content in soil, too strong soil alkalinity, a decline in yield of large areas of good farmland, even abandonment of cultivation, and a decrease in grassland forage yield. Reduction of stocking capacity in pastureland and other hazards