Driving force of soil microbial community structure in a burned area of Daxing'anling, China

Fires are an important factor impacting forest ecosystems of Daxing'anling and have a significant effect on soil microbial community structure. In this study, high-throughput sequencing for 16S rDNA and ITS rDNA were applied to analyze the changing characteristics and driving factors of bacterial and fungal community structures in burned areas with different fire severity. PICRUSt2 software was used to predict the functional characteristics of burned areas with different fire severity. The purpose was to unveil the responsive relationships among the structure and function of bacterial and fungal communities, fire severity, and post-disturbance restoration times. After high severity fires, the destruction of surface vegetation and loss of soil nutrients reduced the diversity and abundance of soil bacteria and fungi. The soil bacteria community structure, which was dominated byAcidobacteria,Proteobacteria, andActinobacteria,changed to be dominated byProteobacteriaandChloroflexi. As well, soil fungal community changed from domination byHelotiales,EurotialesandRussulalesto domination byArchaeorhizomycetalesandHelotiales. Over time, soil bacterial community was gradually restored to pre-fire levels 30 years after the fire. Soil fungal community changed and failed to restore to pre-fire levels after 30 years. After low/intermediate severity fires, environmental factors were relatively unchanged so that soil bacteria diversity and abundance increased, optimizing community composition. The diversity and abundance of soil fungi decreased and the community structure changed slightly. Over time, both bacterial and fungal communities were gradually restored to pre-fire levels 30 years after the fire. After fire disturbance, with increasing severity, soil carbon fixation, lignin degradation, mineralization of organic nitrogen and hydrolysis of organic phosphorus are enhanced. Denitrification is weakened. Therefore, forest fires have certain positive effects on carbon, nitrogen and phosphorus cycles where soil bacteria and fungi are involved.

Automated summary

Fires have a significant impact on forest ecosystems in Daxing'anling, affecting the soil microbial community structure. Different fire severities lead to changes in bacterial and fungal community structures. The recovery process and responsive relationships of soil bacterial and fungal communities vary under different fire severity levels.