This study aimed to determine the response of soil bacterial and fungal community structures to seasonal and forest type variations, verify ecological processes, and elucidate the relationship between soil physicochemical factors and microbial community changes. Soil samples were collected from coniferous, broadleaf, and mixed forests on the Chinese Loess Plateau over four seasons. Bacterial and fungal communities were characterized via amplicon sequencing (16s and ITs). Seasonality significantly (P \(<\) 0.001) affected the Chao1 and Shannon indices of soil bacterial and fungal communities and was strongly associated in soil microbial species (e.g., Firmicutes, Verrucomicrobiota, Ascomycota). Forest type did not significantly affect the soil microbial community (P \(>\) 0.05). While forest type and season did not alter the dispersal limitation or drift process in microbial community assembly, they did impact the relative importance of ecological processes. Forest type and season significantly affected soil physicochemical properties. Soil microbial β-diversity among forest types in different seasons was correlated with different physicochemical factors, and soil nitrogen and phosphorus were significantly correlated with the seasonal changes in soil microbial community structure. Seasonal changes, rather than forest types, significantly impact soil microbial communities. The fluctuation in the relative importance of ecological processes may be a fundamental factor driving changes in soil microbial community structure. Soil N and P are crucial for seasonal variations in the soil microbial community. Seasonal factors should be considered when assessing the effects of forest type on soil microbial communities.
