The Influence Mechanism of Vegetation Type on the Characteristics of nirS-Type Denitrifying Microbial Communities in Qinghai Lake Wetlands.

Soil denitrification is an important process in the emission of N2O, an atmospheric greenhouse gas. Environmental factors of different vegetation types are largely heterogeneous, which may directly or indirectly affect N2O fluxes. Through high-throughput sequencing of the nitrite reductase gene nirS, this study investigated the influence of vegetation type on the structure and diversity of denitrifying microbial communities in Qinghai Lake wetlands, China. The results showed that among the four vegetation types in the Qinghai Lake wetlands, Carex rigescens (CR) had the highest species richness index, and Leymus secalinus (LS) had the lowest species richness index. Species evenness followed the opposite trend. Proteobacteria were the main denitrifying bacterial phylum in the wetland soil of Qinghai Lake. There were 40 differential bacterial flora at different levels in the four vegetation types, most of which belonged to Proteobacteria. Magnetospirillum is a bacterium that differed significantly across the four vegetation types, and it was one of the main denitrifying taxa based on relative abundance in the LS vegetation type. Soil pH was the most important regulating factor of nirS-type denitrifying microbial community in Qinghai Lake wetland. In summary, the succession of vegetation types in the Qinghai Lake Wetlands changes the soil microenvironment and significantly affects the community structure and diversity of the denitrifying microbial communities. The large-area growth of CR might even increase the emission of nitrous oxide. This study can serve as a reference for further exploration of the N2O emission mechanism in the unique habitats of alpine wetlands.