[Temporal and Spatial Changes and Driving Forces of Soil Organic Carbon Density in Anhui Province over Past 40 Years]

The spatiotemporal variation in soil organic carbon density （SOCD） is of great significance for improving global carbon cycle management and the local ecological environment, so it is necessary to study the spatiotemporal distribution and influencing factors of regional SOCD. This study collected a total of 614 soil profiles from 1980 to 2021 in Anhui Province, analyzed the temporal and spatial changes of SOCD in different geographical regions and land use in Anhui Province, and used the structural equation model （SEM） to explore the influencing factors of SOCD. The results showed that： ① In 1980 and 2021, the spatial distribution of SOCD in Anhui Province was as follows： south Anhui hilly region>west Anhui mountain region>riverine plain>Jianghuai hilly downland>Huaibei plain. From 1980 to 2021, SOCD increased in Huaibei plain and Jianghuai hilly downland but decreased in the riverine plain, west Anhui mountain region, and south Anhui hilly region. The highest SOCD content among land use types in 1980 and 2021 was grass land. Compared with that in 1980, the SOCD content in uplands will increase the most in 2021, while the SOCD content in grass lands will decrease the most. ② The results of structural equation model analysis showed that SOCD was positively correlated with average annual precipitation, land use, fertilizer application, NDVI, and terrain and negatively correlated with average annual temperature. In 1980, the terrain in the 0-30 cm soil layer in Anhui Province was the main factor affecting the spatial distribution of SOCD, and the land use in the 30-100 cm soil layer was the main factor affecting the spatial distribution of SOCD, while the average annual temperature in the 0-100 cm soil layer in Anhui Province in 2021 was the main factor affecting the spatial distribution of SOCD. The results provide scientific basis for the development of soil carbon sink management measures in Anhui Province.