Driving factors of soil bacterial biogeographical distribution in three alpine grassland types

The biogeographic distribution of plants and animals on the Qinghai-Tibetan Plateau (QTP) has been extensively studied; however, the biogeographic patterns and factors affecting bacterial communities in alpine grassland ecosystems over large scales were not fully understood. In this paper, we explored the biogeographic patterns of soil bacterial communities in wet meadow, meadow, and steppe. The results showed that bacterial & alpha;-diversity was similar in the three grassland types, while bacterial & beta;-diversity differed significantly. The dominant bacteria were Proteobacteria (29.86%), Acidobacteriota (17.76%), and Actinobacteriota (16.42%), which were caused by the changes in soil pH, C/N, and soil moisture. In addition, the significant distance-decay of bacterial communities was found across environmental and geographical distances. Partial Mantel test showed that the differences of bacterial community in wet meadow and meadow were influenced by environmental and geographical factors, while the difference of bacterial community in steppe was only affected by geographical distance. The MRM accounted for 38.7%, 37.2%, and 11.8% of the variability in wet meadow, meadow, and steppe, respectively. In wet meadow and meadow, geographic distance was the most powerful factor in explaining the similarity of bacterial communities, while soil moisture was the most critical factor in steppe. It was obvious that environmental and geographical factors played different roles in shaping structures of bacterial community in wet meadow, meadow, and steppe, which provided new insights for the effective management of alpine grassland.