Differential response of abundant and rare bacterial subcommunities to abiotic and biotic gradients across temperate deserts.

The biogeography of soil bacterial communities has been well documented, yet the associated difference in spatial distribution and drivers between abundant and rare bacteria still remains unclear. Here, we compared the species richness, composition, and their drivers of rare and abundant bacteria along a 2500-km regional transect in Chinese deserts. Our results demonstrated that abundant and rare bacterial diversities were determined by plant community together with climatic, soil and spatial factors, but the shifts in bacterial richness and composition caused by abiotic and biotic variations varied between abundant and rare subcommunities. Rare bacterial richness significantly decreased with increasing temperature, drought and nutrient limitation, while abundant bacterial richness showed an increasing trend. Plant richness was negatively associated with abundant bacterial richness, but positively related to rare bacterial richness. Abiotic and biotic differences caused greater variations in rare species composition than that in abundant species composition. Furthermore, our results also confirmed that the spatial patterns of abundant and rare bacterial distribution differed remarkably. Our findings collectively suggest that similar abiotic and biotic drivers but distinct influences lead to distinct spatial distribution patterns of abundant and rare bacteria in harsh deserts. Therefore, taking more ecological traits such as stress tolerance and abundance into account will strengthen our understanding of soil bacterial assembly mechanisms.