Seasonality and vertical structure of microbial communities in the alpine wetland

Abstract The soil microbial community plays an important role in wetland ecosystem material transformation and energy flow. The temporal dynamics and spatial distribution of soil microbial communities have always been central questions in ecology. Numerous studies on wetland microbial community structure have focused on low altitudes, while patterns of microbial diversity across seasons and depths and their environmental determinants remain poorly studied. Here, we collected soil samples across four seasons at 0–5, 5–10, and 10–30 cm in the NamCo wetland on the Tibetan Plateau to study the seasonality and vertical patterns of soil microbial communities and their main drivers. We found clear seasonal variation in bacterial community composition, most pronounced in winter, but nonsignificant seasonal variation in archaea. In particular, Proteobacteria decreased by 11.5% in winter compared with other seasons (P < 0.05). The alpha diversity, indicated by the Chao1 index, showed hump-shaped seasonal patterns with a lower diversity in winter for bacteria but nonsignificant patterns in archaea across depths. PERMANOVA showed that the bacterial community structure had significant differences between winter and the other three seasons (P < 0.05). In addition, bacterial and archaeal community structures differed between surface (0–5 cm) and deeper (5–30 cm) soils (P < 0.01). Redundancy analysis demonstrated that soil total nitrogen, soil total phosphorus, and total soil organic carbon had significant effects on bacteria and archaea (P < 0.05). Furthermore, the bacterial community structure was strongly affected by soil moisture content and temperature (P < 0.001). Our findings highlighted the seasonal variation in the microbial community and the profound influence of soil moisture and temperature on microbial structure in alpine wetlands on the Tibetan Plateau.