Stochastic and deterministic drivers of seasonal variation of fungal community in tobacco field soil

Background: The soil fungal community plays an important role in global carbon cycling and shows obvious seasonal variations, however, drivers, particularly stochastic drivers, of the seasonal variation in the fungal community have never been addressed in sufficient detail. Methods: We investigated the soil fungal community variation between summer growing (SG) and winter fallow (WF) stage, through high throughput sequencing of internal transcribed spacer (ITS) amplicons. Subsequently, we assessed the contribution of different ecological processes to community assembly using null-model-based statistical framework. Results: The results showed that the fungal community diversity decreased significantly after tobacco cropping in the SG stage and the composition showed a clear turnover between the WF and SG stages. The variation in community composition was largely attributable to the presence of a small portion of Dothideomycetes in the WF stage that dominated the soil fungal community in the SG stage. The organic matter, temperature, and water content were the main deterministic factors that regulated the fungal community; these factors explained 34.02% of the fungal community variation. Together with the result that the fungal community was mainly assembled by the dispersal process, our results suggested that the stochastic factors played important roles in driving the seasonal variation of fungal community. The dispersal limitation dominated the fungal community assembly during the WF stage when homogenizing dispersal was the main assembly process of the fungal community in the SG stage. Thus, we proposed that the dispersal processes are important drivers for seasonal variation of fungal community in tobacco planted soil.