Objective  Clarifying the characteristics of bacterial and fungal communities in Quaternary Red soils under different land-use patterns will provide important biological property data for evaluating the health status of Red soils, and to provide guidance for the rational utilization and scientific management of Quaternary Red soil resources.

  Method  Quaternary Red soils in sparse forest grassland, grassland, woodland, cultivated land and their nearby buried Quaternary Red soils underlying loess from the same stratum were taken as the research objects, and the buried Quaternary Red soil was taken as the control group. The high-throughput sequencing technology was used to determine the abundance, diversity and community composition changes of bacterial and fungal communities in Quaternary Red soils under different land use patterns. Combined with soil physical-chemical properties, the community characteristics of bacteria and fungi in Quaternary Red soils under different land use patterns were systematically addressed.

  Result  There were significant differences between the α-diversity index of microbes in Quaternary Red soils under different land-use patterns. Compared to the buried Quaternary Red soil, the bacterial abundance index, diversity index, and fungal abundance index of Quaternary Red soils of sparse forest grassland, grassland, woodland, and cultivated land increased significantly, while the fungal diversity index of cultivated land decreased significantly. The relative abundance of dominant bacterial and fungal communities in Quaternary Red soils changed significantly under different land-use patterns following the buried Quaternary Red soils eroded to the land surface. Compared to the buried Quaternary Red soil, the relative abundance of Proteobacteria in Quaternary Red soils under other land-use patterns significantly decreased, while the relative abundance of Acidobacteria, Chloroflex and Gemmatimonadetes significantly increased. The relative abundance of Ascomycota decreased significantly in the sparse forest grassland, grassland and woodland, while the relative abundance of Basidiomycota increased significantly in the sparse forest and cultivated land, and the relative abundance of Mortierellomycota increased significantly in the woodland. The principal coordinates and hierarchical clustering analysis showed that the community structure of bacterial and fungal in Quaternary Red soils changed under different land-use patterns, and the community structure of the Quaternary Red soil of sparse forest grassland was the most similar to that of woodland.

  Conclusion  The bacterial and fungal abundance, diversity, and community composition of Quaternary Red soils changed significantly under different land-use patterns following buried ancient red soils exposed to the ground surface. The research results could provide important biological property data for diagnosing the Quaternary Red soil health status, and a foundation for scientific management and utilization of Quaternary Red soil resources.