Objective  The soils with different vegetation types in karst peak-cluster depression in northwest Guangxi were selected as the research object to study the characteristics of soil physical and chemical properties, microbial carbon (MBC), nitrogen (MBN) and phosphorus (MBP) contents and their relationship under different vegetation types.

  Method  Ecological stoichiometry and Pearson correlation analysis were used to study the effects of different vegetation types and soil depth on soil MBC, MBN, MBP and nutrient contents.

  Result  (1) Soil nutrients, MBC, MBN and MBP contents in different vegetation types were in the order of secondary forest > shrub > shrubby > grassland > cropland. The vertical distribution of soil nutrients showed a decrease with the depth of soil layer, and the contents of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) differed significantly among different soil layers. And the MBC, MBN and MBP contents differed significantly among different vegetation types and different soil layers, with the order of MBC > MBN > MBP. (2) The values of soil MBC/SOC and MBP/TP were smaller for different vegetation types, and the differences of MBN/TN were larger. The differences in soil MBC/MBN of different vegetation types were significant, and the range of MBC/MBP variation was large, with MBN/MBP showing secondary forest > scrub > shrub > grassland > cropland. (3) Soil MBC and MBN were significantly correlated with SOC, TN, TP, available nitrogen and available potassium, and showed negative correlations with soil bulk density and pH, indicating that soil MBC and MBN could be used as sensitive indicators of soil nutrients.

  Conclusion  There is a significant epistatic effect of carbon, nitrogen, phosphorus, nutrient content and stoichiometric characteristics of soil microbial biomass in different vegetation types, and soil structure, nutrients and microbial community functions are significantly improved with the positive vegetation succession.