Objective The aims were investigate the characteristics of soil microbial community structure and diversity in Chinese fir forest, tea garden and grassland, and to analyze the correlation between soil environmental factors and microbial community structure.

Method Soil samples were collected from Chinese fir forest, tea garden, and grassland. The Illumina Miseq high-throughput sequencing technology was used to analyze the characteristics of soil fungal and bacterial communities in these three vegetation types. The soil chemical factors were also measured to determine their effects on soil fungal and bacterial communities.

Results After conversion of Chinese fir forest to tea garden, the relative abundance of Ascomycota in tea garden soil increased by 33.55%, while the relative abundance of Basidiomycota decreased by 34.93%. After conversion of Chinese fir forest to grassland, the relative abundance of Ascomycota in grassland soil decreased by 33.86%, while the relative abundance of Basidiomycota increased by 19.41%. The relative abundance of Firmicutes decreased by 74.54% and 82.72% in tea garden and grassland soil, respectively, while the relative abundance of Proteobacteria increased by 23.33% and 31.59%, respectively. The relative abundance of Acidobacteria increased by 35.85% and 72.52% in tea garden and grassland soil, respectively. The diversity and richness of soil fungal communities in Chinese fir forests were significantly higher than those in tea gardens and grasslands, while the richness of soil bacteria in Chinese fir forests was significantly higher than those in tea gardens and grasslands. The relative abundance of soil bacteria was significantly higher in Chinese fir forest than in tea garden and grassland. Redundancy analysis showed that the soil bacterial community structure was more influenced by soil environmental factors than the fungal community structure. pH was the most important environmental factor affecting both bacterial and fungal communities, followed by ammonium nitrogen and effective nitrogen.

Conclusion After conversion of Chinese fir forest to tea garden and grassland, the diversity and relative abundance of fungal species decreased, while the diversity of bacterial species increased but their relative abundance decreased. There are significant differences in the structure of bacterial and fungal communities between tea garden and grassland soils derived from Chinese fir forest.