Impact of Land Use/Cover Changes on Regional Soil Organic Carbon Storage in the Main Stream of the Tarim River from 1990 to 2020

Land use/cover (LULC) type change is one of the important causes of global change and the imbalance of the carbon cycle. Investigating the temporal variation in regional soil organic carbon storage (Rsoc) driven by LULC change is of great significance for scientifically guiding sustainable regional land management and facilitating the realization of China’s “dual carbon” objectives. Focusing on the main stream of the Tarim River, based on the LULC data of 1990, 2000, 2010, and 2020, combined with the data of soil organic carbon (SOC) content and soil bulk density, the temporal variation in the LULC and its impact on the Rsoc in the main stream of the Tarim River were analyzed. The results indicate that the LULC exhibited a pattern of “slow change—sharp change—slow change” across the three periods 1990–2000, 2000–2010, and 2010–2020. Grassland (GL) area consistently declined, while other types of LULC fluctuated during the period 1990–2020. The type and area of LULC conversion varied across the three periods: 1990–2000, 2000–2010, and 2010–2020. The area of the GL and bare land (BL) conversion was greater than that of conversion between other LULC in all three periods. The total amount of soil organic carbon (Tsoc) associated with different LULC types in the main stream of the Tarim River varied in 1990, 2000, 2010, and 2020, with the GL contributing the highest SOC levels, and conversion from the BL to GL had the largest increase in the Tsoc for the BL among the three periods, which was 0.20 × 1010~0.31 × 1010 kg, 0.97 × 1010~1.48 × 1010 kg, and 0.04 × 1010~0.06 × 1010 kg during1990–2000, 2000–2010, and 2010–2020 periods, respectively. Overall, the Rsoc in the 0–100 cm soil layer decreased from 2.18 × 1010 to 2.18 × 1010 kg during the period 1990–2020 in the main stream of the Tarim River.