Biogeographic Distribution of Soil Bacteria across Precipitation Gradient in Soil Profiles

The biogeographical distribution of soil microbial diversity, driven by climate change, notably precipitation, significantly influences soil functioning in diverse ecosystems. Land-use changes can alter ecosystem services mediated by microbial diversity, particularly in near-surface soil. In this study, we investigated soil bacterial diversity across precipitation gradients in various land uses. We focused on two soil layers (10-20 cm and 40-50 cm) in seven sampling areas along the Northeast China Transect. Utilizing 16S rRNA sequencing, we obtained 897,776,803 optimized sequences. The results reveal a significant shift in bacterial community composition with changing precipitation levels. As precipitation increases, the shifts in dominant bacterial phyla were generally observed. Additionally, soil depth played a role in structuring bacterial communities, with variations observed between surface and subsurface layers. Dominant taxa (Proteobacteria, Acidobacteria, Actinobacteria, Cholloroflexi) exhibited changes in the 10-20 cm layer due to human activity's influence, while the 40-50 cm layer showed more similarity, unaffected by human activities. Notably, parent material significantly affected soil bacterial diversity patterns, underscored by distinct habitats. Such results offer insights into climate change effects and parent material influences on soil bacterial diversity, highlighting the intricate interplay between precipitation, soil depth, and bacterial distribution; enhancing our understanding of ecosystem functioning and responses to environmental changes. This study contributes to the broader comprehension of microbial ecology and underscores the importance of considering multiple factors when studying soil bacterial dynamics.