Seasonal variation modifies the composition and co-occurrence network of the abundant and rare fungal groups in a seasonally frozen ground

Soil freeze-thaw is a common phenomenon at high latitude regions, and it can alter soil physical properties and microbial diversity. However, how the abundant and rare fungal groups respond to environmental temperature changes (i.e., seasonal variations), particularly freeze-thaw events, are still not well understood.

In this study, we investigated the dynamics of soil properties, fungal community diversity, structure, and co-occurrence network in a typical seasonally frozen ecosystem. We sampled three times during the non-freeze-thaw, freeze-thaw, and freezing periods, respectively.

Our findings revealed that significant variations in the fungal community diversity were detected among different sampling periods. Notably, compared to the non-freeze-thaw and freeze-thaw periods, soil freezing significantly increased the alpha diversity of abundant and rare fungal taxa. We also found that the abundance of rare taxa was important to promote the stability of fungal co-occurrence network. Soil moisture, organic carbon, total nitrogen, and total phosphorus content were the primary factors affecting fungal community composition and structure. Although soil pH had no significant impact on fungal community structure, it exhibited significant correlations with some rare taxa.

Overall, the study results provide the useful information on the prediction of soil fungal community in response to environmental temperature changes in seasonally frozen ground.