Effect of season and vegetation change on microbial diversity and community assembly

Soil microbiomes constitute a large proportion of biodiversity, playing a crucial role in ecosystem functionality, contributing to the health of other organisms. However, the impacts of season and vegetation change on microbial diversity and community assembly remain largely unclear. To bridge the knowledge gaps, we investigated the diversity, community structure, network complexity and assembly processes of bacteria, fungi and protists in summer and winter from a subtropical coastal wetland following S. alternilflora invasion and subsequent Cyperus malaccensis or Kandelia obovata restorations. We tested the following hypotheses: (i) Microbial diversity would be higher in summer than in winter, since higher plant photosynthetic activity and temperature in summer would favor more microbial taxa; (ii) Microbial community assembly would be more influenced by stochastic processes in summer than in winter, since higher temperature would accelerate the random birth, death and speciation, and favored stochastic processes; and (iii) Vegetation succession, including S. alternilflora invasion, C. malaccensis and K. obovata restorations, would significantly alter bacterial, fungal and protistan diversity and community structure, due to the strong environmental disturbance. Our findings demonstrate that seasonality is definitely a critical factor regulating microbial communities, and a higher microbial diversity, network complexity and determinism in community assembly in winter than in summer from a subtropical coastal wetland.