Short-term response of the soil bacterial community to differing wildfire severity in Pinus tabulaeformis stands

In recent years, the investigation of fire disturbance of microbial communities has gained growing attention. However, how the bacterial community varies in response to different severities of fire at different soil depths is largely unknown. We utilized Illumina MiSeq sequencing to illustrate the changing patterns of the soil bacterial community following low-, moderate- and high-severity wildfire in the topsoil (0-10 cm) and subsoil (10-20 cm), 6 months after the fire. Acidobacteria, Proteobacteria, Actinobacteria, Verrucomicrobia and Chloroflexi were the dominant phyla among all samples. Bacterial alpha diversity (i.e. Shannon and Simpson indices) in the topsoil was significantly higher than that in the subsoil after a high-severity wildfire. Non-metric multidimensional scaling (NMDS) analysis and permutational multivariate analysis of variance (PERMANOVA) revealed significant differences in the bacterial community structure between the two soil layers. Soil pH, ammonium nitrogen (NH4+-N) and total nitrogen were the main factors in shaping the bacterial community structure, of which soil pH was the most robust in both soil layers. Our study reveals that wildfire results in short-term changes in soil bacterial community. However, a long-term monitoring of microbial variation after burning is also essential.