Effects of different vegetation types on functional diversity of soil microbial community in different soil layers of Mollisols

The functional diversity of soil microbial communities plays an important role in evaluating ecosystem stability.The Biolog method was used to compare the effects of long-term vegetation types, including natural restoration of grass (GL), crops (AL), forests (FL) and no vegetation cover (BL), on the functional diversity of soil microbial communities in surface layer (0~15 cm) and subsurface layer (15~35 cm) of Mollisols.The results showed that the average well color development (AWCD) of soil microorganisms in different soil layers under different vegetation types was in the order of GL>AL>FL>BL.The AWCD values were significantly higher in 0~15 cm soil layer than those in 15~35 cm soil layer.Soil microbial Shannon index, McIntoh index and total carbon source utilization capacity under GL, AL and FL were significantly higher than those under BL.The Shannon index and McIntoh index of GL in 0~15 cm soil layer was 3.38 and 6.89, respectively.At 0~15 cm soil layer, more carboxylic acid was utilized in the AL and FL, while the higher capacity to utilize amino acid was observed in GL.At 15~35 cm soil layer, Al and FL were with higher capacity to utilize amino acids, while GL was with higher capacity to utilize carboxylic acids.The principal component analysis showed that the carbon source utilization and metabolic functions were similar in GL, AL and FL at 0~15 cm soil layer, and significantly different from that in BL.The carbon source utilization and metabolic functions of soil microorganisms in 15~35 cm soil layer was similar in GL and AL, significantly different from that in BL and FL.Therefore, the difference in the functional diversity of soil microbial community under different vegetation types was the result of the combined effect of vegetation type and soil depth; the effect of vegetation type on the functional diversity of soil microbial community was greater than that of soil depth.