Abstract:

Based on achievement of multi-purpose regional geochemical survey (1∶250 000) in Fujian pro-vince, reserve estimation and average density of soil organic carbon were calculated in seven different focus using unit soil carbon calculation method. Comparison was made by the computation result above, the second soil census result of Fujian, result of other regions in China, and the result of the typical areas of China. The results showed that the reserve and average density of topsoil(0-0.2 m) organic carbon were 427.5 Mt and 3 446.8 t/km², respectively. The middle soil (0-1.0 m) was 1 495.0 Mt and 12 052.9 t/km², respectively. The deep soil (0-1.5 m) was 1 986.8 Mt and 16 017.5 t/km², respectively. It was higher than the average level in the typical areas of China and had higher organic carbon reserves and carbon density. Furthermore, the average density of soil organic carbon increased with the increase of altitude, and was higher in inland areas than in coastal areas. In recent 30 years, the organic carbon storage of topsoil was decreased. The main influencing factors of topsoil organic carbon density distribution can be consider as geomorphic landscape, climate, vegetation, soil texture, physical and chemical properties of soil, ecosystem stability, human activities, etc.

Key words: soil organic carbon, reserves estimation, spatiotemporal distribution characteristics, influencing factors, Fujian Province