Species identity outweighs the extent of abundance change in driving soil bacterial community divergence

Here, we conducted an abundance manipulation experiment using natural soil bacterial communities, where the abundance of five bacterial species was artificially increased to three distinct levels within separate microcosms. The microcosms were then incubated in laboratory while the community dynamics were monitored over time. We found that increasing species abundance induced immediate, species- and abundance-specific changes in community composition. Over the subsequent ten weeks, abundance of the manipulated species consistently declined, and a general trend of convergence among all experimental communities was observed. Notably, no significant differences were detected between communities subjected to different abundance treatments since the second week. By contrast, the species-specific community divergence persisted throughout the experiment.