Vegetation patterns influence on soil microbial biomass and functional diversity in a hilly area of the Loess Plateau, China

Purpose Shifts of microbial biomass and functional diversity under different vegetation patterns can impact the soil processes, and the specific knowledge about this can be used to develop sound vegetation restoration strategies. This study was devoted to examine the effects of different vegetation patterns on microbial biomass and functional diversity and explore the relationship between soil erosion and soil microbial properties under typical erosion conditions of the semiarid hilly area of the Loess Plateau, China. Materials and methods Soil samples were collected from the Yangjuangou catchment near Yan’an City, northern Shaanxi province, China. Four types of slopes, each with different vegetation pattern, were sampled, including F (forest planted by human), G (grass), G–F–G (grass on the upper and lower slopes and forest on the middle slope), and F–G–F (forest on the upper and lower slopes and grass on the middle slope). Top soil samples (0–10 cm) from each of the four slopes were analyzed for their physicochemical properties, microbial biomass, and functional diversity. The microbial biomass was analyzed using the fumigation– extraction method and microbial functional diversity using the community-level physiological profile method. Results and discussion The analysis of variance revealed a trend of increasing nutrient concentrations and soil microbial biomass nitrogen in the G–F–G soil samples. However, the F–G–F slope had the highest microbial biomass carbon, with an average of 289 mg kg and had the highest average well color development values (up to 120 h of incubation), which is used as an indicator of microbial activity. Mean values of Shannon diversity (H′), which are indicative of soil microbial functional diversity, ranged from only 2.75 for F to 2.82 for F–G–F. Principal component analysis showed that the four vegetation patterns had differences that are consistent with different carbon substrate utilization patterns. The greatest differences in single-carbon substrate utilization were between F–G–F and F and between F–G–F and G–F–G. Conclusions The F–G–F vegetation pattern was the best pattern for restoring soils on sloping land in terms of improving soil microbial biomass carbon, soil microbial functional diversity, and activity. Soil erosion processes might have an indirect effect on soil microbial biomass through its influence on soil physicochemical properties in the typical erosion-prone region of the Loess Plateau, China.