This work aimed to explore the evolutionary characteristics of soil bacterial community composition and diversity in cold temperate larch forests under snow cover, and investigate its influencing factors and the response mechanism of snow ecology.

The Illumina Miseq high-throughput sequencing technology and redundancy analysis method were used to analyze the changes and influencing factors of soil bacterial community structure and diversity under snow removal (NS), natural snowfall (CK), double snowfall (DS), and extreme snowfall (ES) treatments.

The study found that different thickness of snow cover changed the soil micro-environment of larch forests, soil temperature (Tem) was increased significantly with the increase of snow cover thickness, but OC was decreased significantly, and Tem, pH, OC, TN, AP showed significant differences in the soil of each snow cover treatment. The comparative analysis of bacterial communities showed that a total of 30 bacterial phyla were detected in the four groups of snow-covered environments. The dominant bacterial phyla were Verrucomicrobia and Proteobacteria in the soil of the snow-removed group and other three snow-covered groups, respectively, and the dominant bacterial genera were Candidatus Udaeobacter. In addition, the flora of Planctomycetota, Oxalobacteraceae_Norank and Arenimonas showed significant or extremely significant differences in each snow cover treatment. In terms of community diversity, although different thicknesses of snow cover affected the structure and population distribution of soil bacteria, they did not significantly change the Alpha diversity of bacterial community within the group. However, snow cover significantly changed the Beta diversity of bacterial communities at the OTU level while considering the species differences and abundances among different groups. The correlation analysis of environmental factors showed that pH, OC and TN were environmental factors with low multicollinearity which affect bacterial community structure in the snow cover environment. Among them, pH was significantly correlated with bacterial community at the genus level, which showed an extremely significant correlation at the OTU level. OC showed a significant correlation at the OTU level. Community function prediction and inter-group difference analysis showed that bacteria mainly performed ecological functions such as nitrate and nitrite reduction, nitrogen fixation, methane and aromaticity degradation, cellulose hydrolysis and photochemical energy, and there were significant differences in urea decomposition and iron redox among the groups.

Snow cover affects the composition and diversity of soil bacterial communities in cold temperate larch forests to different degrees, and this effect has important scientific significance for the function of the cold temperate forest ecosystem and its regulation on global climate change in which microorganisms are participated.