Bacterial diversity in the mountains of South-West China: climate dominates over soil parameters.

Certain patterns in soil bacterial diversity and community composition have become evident from metagenomics studies on a range of scales, from various parts of the world. For example, soil pH has generally been seen as dominating variation in bacterial diversity, above all other soil and climate parameters. It is important however to test the generality of these relationships by studying previously un-sampled areas. We compared soil bacterial diversity and community composition under a wide range of climatic and edaphic conditions in mountainous Yunnan Province, SW China. Soil samples were taken from a range of primary forest types and altitudes, reflecting the great variation of forest environments in this region. From each soil sample, DNA was extracted and pyrosequenced for bacterial 16S rRNA gene identification. In contrast to other recent studies from other parts of the world, pH was a weaker predictor of bacterial community composition and diversity than exchangeable Ca(2+) concentration, and also the more poorly defined environmental parameter of elevation. Samples from within each forest type clustered strongly, showing the distinctive pattern of their microbial communities on a regional scale. It is clear that on a regional scale in a very heterogeneous environment, additional factors beyond pH can emerge as more important in determining bacterial diversity.