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Climate warming will shift the seasonal variation of the soil microbial community and thereby regulate the soil process dynamics of forest ecosystems. To evaluate the effects of warming on soil microbial community seasonal dynamics, an in situ experiment was conducted in a natural forest and a dragon spruce plantation in the subalpine region of the eastern Tibetan Plateau. Open‐top chambers (OTCs) were used to increase the mean soil temperature by 0.54 and 0.58°C for the natural forest and plantation, respectively. Our results showed that the initial levels of soil carbon and nitrogen were much higher in the natural forest than in the plantation. Compared to no‐warming, the annual average soil carbon and nitrogen contents increased by 14% and 16% in the natural forest, but decreased by 7 and 6% in the plantation after 4 years of OTC warming, respectively. Conversely, warming caused a significant reduction in the annual average microbial biomass by approximately 50% in the natural forest but enhanced this parameter by approximately 30% in the plantation. Warming further enlarged the differences in seasonal variation in microbial community composition between the two forests. The seasonal variation in microbial community‐level substrate utilization also responded differently to warming in the two forest types. These opposite responses of the soil microbial community and soil properties to warming will further magnify the differences in soil conditions between the two forest types under future climate warming. Highlights: Soil microbial biomass is reduced by warming in the natural forest but increased in the plantation.Seasonal shifts of microbial community respond differently to warming in the two forests.Soil initial properties likely affect responses of microbial community to warming.Warming will enlarge the differences between the two forests. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the relationships among changes in the soil microstructure, soil physicochemical traits and microbial communities during desertification. Soil samples were collected from grasslands at different stages of desertification, from an area of the Tibetan Plateau. Soil aggregate fractionation and soil physicochemical properties were analysed using standard methods, and the abundance and diversity of bacteria associated with different aggregate fractions were estimated by quantitative PCR and Illumina Miseq amplicon sequencing. Sequential changes in response to desertification stages were detected in the analysed features. For instance, soil nutrients, microbial biomass C and N, water content and pH initially changed during the light desertification stage; then, the soil aggregation decreased during the intermediate stages; and finally, bacterial abundance and diversity decreased during heavy and severe desertification stages. During grassland desertification, vegetation coverage positively influenced soil aggregation by affecting soil properties (e.g., pH and SOC), whereas bacterial communities in FMi (free microaggregates) and FSC (free silt and clay) were negatively related to soil aggregation. This study reports novel information concerning the desertification process and the sequential modification of soil traits and interactions among soil physical properties (aggregate composition), soil nutrients and the soil microbial community in the grasslands of the Tibetan Plateau. Highlights: Bacterial community was more sensitive in macroaggregates than in microaggregates.Composition of small macroaggregates and associated bacteria changed during desertification.Bacterial community in microaggregates, silt and clay negatively affected aggregation.Vegetation coverage affected aggregation by changing soil traits and bacterial community. [ABSTRACT FROM AUTHOR]