Preliminary study on spatial heterogeneity of soil mineral composition and organic carbon content at different micro-habitats that under different vegetation types in karst region

The spatial heterogeneity of soil mineral composition and soil organic carbon (SOC) are determined through sampling at 7 kinds of micro-habitats, including soil surface, rocky surface, stone crevice, stone gully, stone cavern and stone groove as well as stone pit, under different vegetation cover, arbor and shrub and grass as well, in karst region. The results prove that, (1) The composition of soil mineral is diversity under different vegetation types. Quartz and kaolinite in the soil do not change under grass and shrub as well as arbor vegetation cover, dolomite in the soil in grass land disappears, and chlorite gradually appears in the shrub and arbor forest. (2) With the vegetation succession, the content of SOC significantly increases, and the content of micro-habitats SOC shows evident heterogeneity as follows: grassland ＞　arbor forest ＞ shrub land. Moreover, taking the content of SOC and the coefficient of variation at micro-habitats as evaluation factors, cluster analysis to the SOC under arbor forest and shrub as well as glass covers is done. The results show that the micro-topography is very important factor affecting the content of SOC and its spatial heterogeneity. To protect the SOC, the major work is improving vegetation covered ratio in grass and shrub vegetation cover areas, and keeping the good conditions of vegetation and decreasing human interference in the arbor vegetation cover areas.