Organic carbon pool of forest soil and its relationship to environment factors in Xingguo county of Jiangxi province

Soil organic carbon is the main part of terrestrial carbon pool. It plays an important role in terrestrial carbon cycle and is one of the important components in the research of global change, so it is important for soil carbon cycle to ascertain soil organic carbon reserves and spatial distribution in soil carbon cycle research. This paper adopted the soil distribution areas, sampling data and soil organic contents from 84 samples and 50 profiles to estimate soil carbon pool in Xingguo county of Jiangxi province. The calculation results show that parent material has influence on contents of soil organic carbon, soil derived from lime rock has higher levels of organic carbon (17.92 g/kg) in surface layer(0-20 cm),soil derived from red sandstone has lower levels of organic carbon (6.11 g/kg); and contents of soil organic carbon increased in turn from red clay,red sandstone, granitic, phyllite to lime rock. The contents of soil organic carbon vary greatly under different vegetation types.Soil under pin (Pinus massonniana) has lower levels of organic carbon, but soil under fir(Cunninghamia lanceolata) or broad-leaved forest has higher levels of organic carbon. The total amount of soil organic carbon is about 559.38×10 4t and organic carbon density is about 2.47 kgC/m 2 in depth of 20cm, the total amount of soil organic carbon is about 1437.19 10 4t and organic carbon density is about 6.36 kgC/m2 in depth of 100cm. The distribution of soil organic carbon density is high in the northwest and northeast but low in the middle and southwest in Xingguo county. Soil organic carbon and topographic variables have correlations. In topsoil(0-20cm), the correlations of aspect and the content of soil organic carbon is positively significant while that of elevation and the content of soil organic carbon is highly significant. In profile(0-100cm), the correlation of elevation and the content of soil organic carbon is significant while the content of soil organic carbon and aspect and slope grade have no obvious correlations.