Relationship between plant diversity and soil microbial under quantity different soil layer-depths in karst area

Soil samples were collected in different soil layer-depths developed from limestone and dolomite， and the plant situation was investigated. The microbial incubation methods were used，and the correlation between plant diversity and microbial quantity was analyzed. The results showed that，besides the thin soil developed from limestone，the species richness，Simpson index and Shannon-Wiener index of vegetation in the ground and the microbial quantity declined gradually with the decrease of soil layer-depth，performing the thick soil>the middle soil>the thin soil. The trends in herb and shrub layer were obvious. The species richness（S） of forest decreased from 5 to 0. There was no forest in the thin soil. Under the same soil layer，the biodiversity and microbial quantity in the ground soil developed from limestone was higher than this index of dolomite. There were significant or extremely significant correlation among the species richness（S），Simpson index（ D） and Shannon-Wiener index（ H） of vegetation and the microbial quantity of underground.