[Soil Degradation-Associated Microbial Community Structure Changes in an Alpine Meadow Under Tibetan Pig Herding]

Anthropic activities lead to a high risk of peatland degradation in the alpine regions. Along with the declined plant productivity and the impaired functioning of the soil carbon sink, the diversity and structure of soil microbial communities are also affected in a degraded peatland ecosystem. Tibetan pig herding is a unique peatland management strategy, which can significantly affect the peatland ecosystem, but it has been rarely studied. The changes in the microbial community structure and its responses to disturbances were studied using a 16S rRNA high throughput sequencing technique in an alpine meadow peatland under Tibetan pig herding disturbance and under control (without Tibetan pig herding) in the Northwestern Yunnan province. The results showed that Tibetan pig herding significantly reduced the α diversity of soil microbes, and the soil microbial community structures were significantly changed by pig herding. The soil microbial communities in the peatland soils were dominated by Proteobacteria, Acidobacteria, and Chloroflexi. Compared with those at the phylum level, the changes at the genus level under pig disturbance were more obvious. It was seen that the relative abundances of Sphingomonas and Hymenobacter significantly increased, while the abundances of Nitrospira and Rhodoplanes significantly decreased under pig herding. Venn diagram analysis revealed that there were 71 and 136 core OTUs in the soil under pig herding and in the control group soil, respectively. Burkholderiales, Pseudomonadales, and Sphingomonadales were the main taxa exclusively found under Tibetan pig herding, and could serve as indicators of soil disturbance. CCA ordination further showed that the distribution of Nitrospira and Rhodoplanes were mainly controlled by soil moisture, available phosphorus, and organic matter contents. Our findings provide an insight into the linkages between the soil microbial communities and the degradation of peatlands in alpine regions.