Comprehensive knowledge of bacterial ecology mainly in supraglacial habitats is pivotal particularly at the frontier of accelerated glacier retreat. In this study, bacterial diversity and community composition in glacial soil and meltwater runoff at the frontier of Baishui Glacier No.1 were evaluated using high throughput sequencing. Significant variations in the physiochemical parameters formed an ecological gradient between soil and meltwater runoff. Based on the richness and evenness indexes, the bacterial diversity was relatively higher in soil compared with meltwater runoff. Hierarchical clustering and bi-plot ordination revealed that the taxonomic composition of soil samples was highly similar and significantly influenced by the ecological parameters than the meltwater runoff. The overall relative abundance trend of bacterial phyla and genera were greatly varied in soil and water samples. The relative abundance of Proteobacteria was higher in water runoff samples (40.5-87%) compared with soil samples (32-52.7%). Proteobacteria, Firmicutes, and a little part of Cyanobacteria occupied a major portion of water runoff while the soil was dominated by Acidobacteria (6-16.2%), Actinobacteria (5-16%), Bacteroidetes (0.5-8.8%), and Cyanobacteria (0.1-8.3%) besides Proteobacteria and Firmicutes. Higher numbers of biomarkers were found in soil group compared with the water group. The study area is diverse in terms of richness, while community structures are not evenly distributed. This study provides a preliminary understanding of the bacterial diversity and shifts in community structure in soil and meltwater runoff at the frontier of the glacial. The findings revealed that the environmental factors are a significantly strong determinant of bacterial community structures in such a closely linked ecosystem.

Global climate change is accompanied by changes in the amounts of ice and snow. These changes have both a direct effect on the plant community structure, primary productivity and carbon cycle and an indirect influence on the belowground ecosystem. However, the effects of changes in snowpack on the soil environment and belowground ecological processes, particularly in soil microbial communities are still poorly understood in alpine meadows. We conducted a field study of controlled snowpack in the eastern margin of the Tibetan Plateau, where five treatments were set up, named as S0, S1, S2, S3, and S4 (S1: the amount of a natural snowpack; S2, S3, and S4 were twofold, threefold, and fourfold of Sl, respectively; and SO: completely removed snow). Soil physicochemical properties, soil community structure and diversity measured by 16S rRNA gene amplicons were studied. The results indicated that 1) as snowpack increased, the average soil temperature decreased, but soil moisture and soil compaction increased; 2) soil chemical properties (pH, available nitrogen, available potassium, available phosphorus, total nitrogen, total potassium, total phosphorus and total soil organic carbon) all changed as snowpack changed; and 3) increasing snowpack led to a decrease in the relative abundance of Acidobacteria, but Bacteroidetes and Actinobacteria did not decline in response to increasing snowpack. In summary, these results showed that soil bacterial communities are sensitive to changes in snowpack in alpine meadows.