Bacterial community dissimilarity over the vertical scale of a few centimeters equal to the horizontal differences over several kilometers in the western Tibetan Plateau

Here we studied depth profiles of bacterial communities in high-elevation soils from Tibet. The relative abundance of Actinobacteria and Alphaproteobacteria was higher in near-surface layers, while Gemmatimonadetes were more prevalent in subsurface layers. The bacterial community structure was distinct between surface and subsurface soil layers, strongly correlating with variation in total carbon (TC) and C/N. The differences in the bacterial community between the layers in a single profile were about the same as the horizontal differences between sites separated by many kilometers. Overall, we found that TC was the best predictor for both surface and subsurface bacterial community distribution. Exploration of the relative contribution of distance and environmental variables to the community composition suggests that the contemporary environment is the primary driver of microbial distribution in this region. Reflecting niche conservatism in evolution, the bacterial communities in each soil site and layer tended to be more phylogenetically clustered than expected by chance, and surface soil layer samples were more likely to be clustered than subsurface samples.