Moisture is more important than temperature to shape bacterial and archaeal communities in subtropical grassland. Describe the dynamics of bacterial and archaeal communities in a subtropical grassland

It is generally accepted that moisture and temperature play key roles in the assemblage and functioning of microbial communities in soil. However, how seasonal variations regulate the role of niche-based versus neutral processes during the assemblage of these communities has not been examined in the light of the co-existence of active and dormant communities in native subtropical grassland. We carried out an experiment in a well-controlled microcosm system, in which we investigated the individual and combined effects of moisture and temperature mimicking winter and summer in a subtropical grassland. The relative size of the active and dormant populations was assessed using the rRNA:rDNA ratio after direct extraction from soil. Moisture was the most important factor influencing community diversity and structure, with a larger effect on the active, dormant and total community than temperature. The dormant community comprises the larger proportion of microbial diversity in these soils, and mainly reflects on the diversity and structure pattern of the total community. Active and dormant communities were controlled by the same assemblage rules and the relative influence of underlying assembly mechanisms are moisture-dependent, with niche-based mechanisms being more influential in communities under stress at dry conditions. The results of this study provide new information regarding seasonal variations on microbial communities in soil and how the coexisting active and dormant communities are shaped in a native subtropical grassland soil.