Pyrosequencing-Based Assessment of Bacterial Community Structure in Forest Soils From Changbai Mountain, China.

Changbai Mountain is one of the largest biosphere reserves in China and the forests inside this site represent the typical types of forest vegetation in Northeast Asia. However, the bacterial diversity and community structure in forest soils from Changbai Mountain and their ecological meanings have rarely been documented. In this work, bar-coded pyrosequencing technique was used to characterize bacterial communities in 137 soils collecting from four types of forest (Broad-leaved Korean pine mixed forest, Poplar-birch forest, Spruce-fir forest, and Larch forest) with an elevation ranging from 740m to 1500m in Changbai Nature Reserve. Results showed that the bacterial diversity (H’) was higher in the mixed conifer-broadleaf forests than in the coniferous forests. In addition, the H’ was positively correlated with the total nitrogen content, silt/clay fraction, and soil pH, which decreased with soil C-to-N ratio. However, the richness indices (ACE and Chao 1) were very similar (P>0.05) across forest types. The bacterial communities of mixed conifer-broadleaf forests clustered separately from those in coniferous forest on an ordination, suggesting that structurally distinct microbial communities develop under different plant species. Broad-leaved Korean pine mixed forest and Poplar-birch forest were associated with higher relative abundance of Acidobacteria and Verrucomicrobia, while Alphaproteobacteria and Gammaproteobacteria were more abundant in Spruce-fir forest and Larch forest. We found that the relative abundance of Alphaproteobacteria (with >60% sequences were Rhizobiales) was positively correlated with soil C-to-N ratio, but was negatively correlated with silt/clay fraction and soil pH. In contrast, the relative abundance of Acidobacteria and Verrucomicrobia demonstrated the opposite trends, which partially supports the copiotrophic/oligotrophic model of soil heterotrophic microbes suggested by Fierer et al. (2007). This work increases our current understanding on the bacterial diversity in soils of natural forest from Changbai Nature Reserve. Such understanding may prove to be useful in both temperate forestry and conservation.