Response pattern of soil prokaryotic community under an artificial moisture gradient. Moisture gradient

Moisture is recognized as a key factor shaping the structure of soil microbial community and function. However, the temporal response patterns of soil microbes under various moisture regimes remain poorly understood. To investigate the temporal response of a soil microbial community to moisture, we monitored soil samples incubated under an artificial moisture gradient for three months. Robust effects were observed of both moisture gradient and incubation time on increased greenhouse gas emissions (methane, carbon dioxide and nitrous oxide). Furthermore, the moisture gradient as well as the incubation time exerted significant effects on species turnover of the soil prokaryotic community. In contrast, the artificial moisture gradient did not show any significant effects on prokaryotic alpha diversity. Alpha diversity of the soil prokaryotic community decreased significantly with incubation time. Different community assembly patterns were observed (based on both the mean nearest relatedness index (NRI) and nearest taxon index (NTI)). The mean NRI exhibited the dominance of stochastic factors, while the NTI indicated the dominance of deterministic factors. The prokaryotic community in soils with less moisture tend to be controlled by stochastic factors, while prokaryotes in soils with higher moisture (60%) were controlled by deterministic factors. Both the mean NRI and its null model percentile differed along the artificial moisture gradient. In contrast, the mean NTI changed with incubation time; however, the null model percentile did not indicate any changes among incubation times. Relative abundances of oligotrophs and copiotrophs did not change significantly along an artificial moisture gradient, while the relative abundance of prokaryotic taxa did vary significantly along an artificial moisture gradient.