Soil organic matter availability and climate drive latitudinal patterns in bacterial diversity from tropical to cold-temperate forests

Jing Tiana, Nianpeng He, Lauren Hale, Shuli Niu, Guirui Yua, Yuan Liu, Evgenia Blagodatskaya, Yakov Kuzyakov, Qun Gao and Jizhong Zhou

Patterns of variation in plant diversity at local, regional and global scales have been extensively studied. But despite the crucial role of bacteria for terrestrial ecosystem functioning, our understanding of their large-scale biogeography patterns in different forests lags significantly behind that of larger organisms. We also lack complete understanding of the primary drivers of microbial biogeography patterns at large spatial scales varying in environmental gradients.

The north-south transect of eastern China (NSTEC) used in this study includes a range of forest types from cold temperate to tropical, and therefore provides an ideal set of experimental plots to explore the responses of bacterial diversity and community structure to different environmental gradients at a large spatial scale. We collected soil samples from 9 typical forests along the NSTEC, determined bacterial diversity and community structures and quantitatively assessed the relative importance of multiple environmental variables in shaping bacterial diversity and community structure.

Significantly higher bacterial taxonomic richness and phylogenetic diversity (a measure of biodiversity that incorporates evolutionary differences between species) were observed for temperate forests compared with subtropical or tropical forests. Soil organic matter (SOM) availability is the most important factor influencing bacterial taxonomic richness from tropical to cold-temperate forests. Climate features (mean annual temperature and mean annual precipitation) exhibited the highest positive correlations with bacterial β diversity (variations in community structure between different environments). In addition, SOM availability and soil pH played equally important and positive roles in shaping bacterial β diversity.

These results provided new evidence of bacterial biogeography patterns from tropical to cold-temperate forests. They indicated a close linkage among soil bacterial diversity, climate and SOM decomposition, which is critical for predicting continental-scale responses under future climate change scenarios and promoting sustainable forest ecosystem services.

Read the article in full here.