Difference Analysis of Different Land Use Types on Soil Organic Carbon in Loess Gullied-Hilly Region of China

The cycles of carbon in terrestrial ecosystems has received increasing attention worldwide. Because the balance between inputs and outputs of carbon to the soil has an important influences on the atmospheric CO2 and global climate. With the increasing deforestation and overgrazing, the impact of human disturbances on carbon storage and fluxes have exceeded the rate and extent of effects from natural variability, this could significantly raise the CO2 concentration in the atmosphere. Thus, accurate estimations of land use and land cover in soil ecosystem have become increasingly important for estimating the carbon balance of regions. One of the greatest uncertainties concerning the influence of human activities is changes in soil carbon stock. In this study, soil samples were collected form farmland, orchard, woodland, grassland, wasteland five different land use types. Each soil sample core was separated into 0-10, 10-20, 20-40 and 40-60 cm depth. The study revealed the difference of soil carbon pool storage and mass effect in different land use styles by the contrast analysis of total organic carbon, labile organic carbon and carbon management index in number, distribution and changes. The results showed that there were big differences for the density of Total Organic Carbon (TOC) among different land use types, which means soil organic carbon storages were different. The extent of variation of the mass fraction of TOC and LOC was increase with the increase of soil depth and 0-20 cm layer was significantly greater than 20-60 cm layer. Relative to wasteland, the density of LOC and NLOC, total organic carbon storage and carbon management index for other four land use types were higher, especial for woodland and grassland. The woodland use type and grassland use type were significantly increased the carbon management index and improved the quality of soil carbon pool. The change of soil organic carbon reserve is huge influenced by human land use.