Intermediate disturbance increases bacteria diversity and interaction in tropical lowland rainforest soils of Hainan, China

Tropical rainforests are the most species-rich terrestrial ecosystems in the world and play a crucial role in maintaining biodiversity and regulating climate. It is known that human impact and natural disturbances will change the composition and pattern of plants in these forests, while its influence on bacteria has been less explored. Here, we investigated the influence of different degrees of human disturbance intensity on the bacterial diversity, community structure and interactions by analyzing the tropical lowland rainforest soils in Hainan, China. The results revealed that moderately disturbed tropical rainforests soils harbored higher bacterial diversity (P < 0.05 by one-tailed t-test) than mildly disturbed rainforest soils, while severely disturbed rainforests soils had the lowest diversity. Network analysis showed that moderately disturbed tropical rainforests exhibited the highest network complexity, but had lower network module numbers than mildly and severely disturbed rainforests. Furthermore, the contribution of stochasticity on the prokaryotic community in severely disturbed rainforests was greater than those in moderately and mildly disturbed rainforests. Our findings offer a new insight of how different degrees of human disturbance influences the bacterial community in tropical rainforests, and confirm that intermediate disturbance hypothesis is also applicable to soil microorganisms.