Effects of enclosure periods on soil active organic carbon and carbon pool management index in Seriphidium transiliense desert grassland

Influences of different enclosure periods on grassland soil active organic carbon and carbon pool management index were studied in Seriphidium transiliense desert grassland in Xinjiang. The results showed that soil carbon density decreased in the following order: Enclosed 9 years> Control> Enclosed 1 year>Enclosed 6 years, and soil active organic carbon and carbon pool management index decreased in the following order: Enclosed 9 years> Control> Enclosed 6 year>Enclosed 1 years. The soil carbon density in grassland enclosing 9 years was significantly higher (P<0.05) than that of enclosing 6 years which increased 36.51%, while soil active organic carbon and carbon pool management index of enclosing 9 years were significantly higher than those of the other treatments in the soil layer of 0-5 cm(P<0.05) which increased 35.81%~84.89% and 35.83%~93.96% respectively. Soil organic matter, total phosphorus, nitrogen and potassium had significant (P<0.05) or extremely significant (P<0.01) correlations with soil active organic carbon, carbon activity and efficiency, while the grey correlative degree of soil carbon pool management index, active organic carbon and biomass of community was higher than that of soil organic matter and carbon density. Soil active organic carbon and carbon pool management index could be more sensitive to indicate the changes of soil carbon and primary productivity in grassland.