Both habitats and seasons can determine the dynamics of microbial communities, but the relative importance of different habitats and seasonal changes in shaping the soil bacterial community structures on a small spatial scale in permafrost areas remains controversial. In this study, we explored the relative effect of four typical alpine meadow habitats (swamp wetland, swamp meadow, meadow and mature meadow) versus seasons on soil bacterial communities based on samples from the Qinghai-Tibetan Plateau in four months (March, May, July and September). The results showed that habitats, rather than seasons explained more variation of soil bacterial composition and structure. Environmental cofactors explained the greatest proportion of bacterial variation observed and can help elucidate the driving force of seasonal changes and habitats on bacterial communities. Soil temperature played the most important role in shaping bacterial beta diversities, followed by soil total nitrogen and pH. A group of microbial biomarkers, used as indicators of different months, were identified using random forest modeling, and for which relative abundance was shaped by different environmental factors. Furthermore, seasonality in bacterial co-occurrence patterns was observed. The data showed that co-occurrence relationships changed over months. The inter-taxa connections in May and July were more pronounced than that in March and September. Bryobacter, a genus of subgroup_22 affiliated to Acidobacteria, and Pseudonocardia belonging to Actinobacteria were observed as the keystone taxa in different months in the network. These results demonstrate that the bacterial community was clustered according to the seasonal mechanism, whereas the co-occurrence relationships changed over months, which indicated complex bacterial dynamics in a permafrost grassland on the eastern edge of Qinghai-Tibetan.

Soil microbes are key drivers of ecosystem processes promoting nutrient cycling, system productivity, and resilience. While much is known about the roles of microbes in established systems, their impact on soil development and the successional transformation over time remains poorly understood. Here, we provide 67 diverse, rhizosphere-associated Pseudomonas draft genomes from an undisturbed salt march primary succession spanning >100 years of soil development. Pseudomonas are cosmopolitan bacteria with a significant role in plant establishment and growth. We obtained isolates associated with Limonium vulgare and Artemisia maritima , two typical salt marsh perennial plants with roles in soil stabilization, salinity regulation, and biodiversity support. We anticipate that our data, in combination with the provided physiochemical measurements, will help identify genomic signatures associated with the different selective regimes along the successional stages, such as varying soil complexity, texture, and nutrient availability. Such findings would not only advance our understanding of Pseudomonas’ role in natural soil ecosystems but also provide the basis for a better understanding of the roles of microbes throughout ecosystem transformations.