Soil Organic Carbon Distribution of Different Vegetation Types in the Ili River Valley

Based on data from field investigations and laboratory research work in 2008 and 2009, this paper, by variance analysis, studies the distribution and storage of soil organic carbon contents of typical types of vegetation in the Ili river valley including alp meadow, meadow grassland, typical steppe, desert steppe, temperate coniferous forest and so on. The results show that soil organic carbon contents varied with the changes of plant types. At 0-50 cm soil layer, soil organic carbon contents of alp meadow and meadow grassland are the highest, followed by temperate coniferous forest, typical steppe, and desert steppe. Deciduous broad-leaved forest and secondary forest almost have the same content of organic carbon, which is higher than that of typical steppe, the soil organic carbon content is the lowest in intrazonal vegetation and desert vegetation. Soil organic carbon contents of different types of vegetation, with the exception of intrazonal vegetation, have a descending trend with the decrease of soil depth. There are differences in soil organic carbon density of different types of vegetation. A higher density of soil organic carbon occurs in alp meadow, meadow grassland and temperate coniferous forest, while the lowest density is observed in desert vegetation. In the Ili river valley, soil organic carbon contents of grassland at surface soil layer are higher, so it is very important to protect surface soil of grassland and to prevent soil organic carbon change in surface layer, which is very useful to keep stability of soil carbon pool.