Seasonal dynamics of bacterial communities in aBetula albosinensisforest

Abstract

Soil bacteria play a key role in nutrient cycling, but the mechanisms behind seasonal variation of bacterial communities in different types of soil remain unclear. In this study, the bacterial composition during four seasons and at four soil depths (0–10, 10–20, 20–40 and 40–60 cm) in aBetula albosinensisforest of the Qinling Mountains (southern Shaanxi Province, China) was investigated. Illumina 16S rRNA gene sequencing was used to analyse soil bacterial diversity and communities. The soil properties, including temperature, pH, water content, organic carbon and total nitrogen content, were determined. Soil bacterial diversity did not decrease with increasing depth, indicating that the bacterial communities in the top‐ and sub‐soil had adapted to the availability of different substrates at different depths. The Chao1 richness and Shannon diversity indices at the four depths typically decreased by 54.43–86.87% and 13.31–33.91%, respectively, from warm summer to cold winter, which was probably a result of the decrease in soil temperature. Moreover, the abundance ofAcidobacteriaincreased with soil temperature, whereas the abundance ofBacteroidetesdecreased with increasing temperature. Soil temperature accounted for 49% of the total variation among the bacterial taxa. Overall, the results suggested that changes in the bacterial communities were attributable to physiological adaptation, which was controlled by soil temperature.HighlightsWe assessed the effects of soil depth and season on soil bacterial community structure.We used Illumina 16S rRNA sequencing to study bacterial diversity and community composition.Changes in bacterial Shannon index with soil depth were influenced by carbon type, not quantity.Soil temperature had important effects on bacterial communities and abundance.