Deciphering the role of biotic factors in community assembly and diversity patterns of soil bacterial communities under different land use

Abstract

Environmental heterogeneities in climate and soil properties have been recognized as key factors structuring the bacterial community at large scale. Although recent evidence has demonstrated the importance of local biotic interactions in driving soil bacterial communities, it is remains unclear how biotic filtering affects bacterial diversity patterns at large scale. Here, we explored the effect of biotic factors on bacterial community assembly and diversity pattern in agricultural and natural ecosystems based on a continental-scale investigation across a 3689 km latitudinal gradient in Eastern China. Despite of the distinct diversity patterns of soil bacterial communities along latitudes in different ecosystems, biotic factors (the fungal and protist communities) were consistently identified as the most important predictor of the latitudinal variations in the bacterial communities, even when considering the influence from climate and soil variables. The bacterial community assembly processes were dominated by homogeneous selection and were primarily affected by soil pH and protist consumers in upland and forest soils but by fungi and protist phototrophs in paddy soils. The bipartite networks between bacteria, fungi and protists provide further evidence that network complexity and specific interdomain interactions may influence the latitudinal distribution of bacteria, in land use-dependent patterns. Our study provides a novel insight into the critical role of biotic factor in shaping geographic patterns of soil bacterial communities, with important implications for maintaining soil large-scale biodiversity and functions.