Northern China's agro-pastoral ecotone is a typical ecologically fragile semi-arid zone that has undergone severe desertification. However, even though the region remains highly ecologically fragile, it has high potential as a carbon sink. Therefore, it has become a region of interest for evaluating the effects of desertification control and the carbon sequestration potential of degraded ecosystems through strategies such as grazing exclusion and afforestation. 

However, no research has quantified the long-term soil organic carbon (SOC) changes for the whole region. Besides, there is little knowledge about the region’s SOC changes and dynamics for the whole research region and how climatic and anthropogenic factors affected the long-term SOC changes is not clear. 

To better understand the current SOC reservoir and detect its changes over time in northern China's agro-pastoral ecotone, scientists from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences (CAS) conducted a field survey in 2018 and updated the regional SOC information obtained during China's National Soil Inventory in the 1980s. 

In this study, the scientists evaluated the current total SOC stock in northern China’s agro-pastoral ecotone, detected changes in the total SOC stock between the 1980s and 2018 in the study area at site and regional scales, and analyzed the effects of climatic and anthropogenic factors on SOC changes during the last 30-40 years. 

In northern China's agro-pastoral ecotone,they compared SOC data derived from 238 sampling sites during China's National Soil Inventory in the 1980s and 2018. They found that the mean SOC stock to a depth of 30 cm decreased significantly, from 4.48 kg C m^-2 in the 1980s to 3.60 kg C m ^-2 in 2018, and the total SOC stock decreased from 2,793.17 Tg to 2,248.34 Tg. 

In addition, the study shows that the human influences on SOC change in northern China's agro-pastoral ecotone have been stronger than the climatic factors. The problem of grassland degradation is still serious. In the future, grassland protection and restoration should be strengthened in northern China's agro-pastoral ecotone to prevent further decreases in SOC. 

This study has been published in the CATENA in an article entitled "Changes of soil organic carbon stocks from the 1980s to 2018 in northern China’s agro-pastoral ecotone".