Dung-soil microbial community coalescence can exert dual effects on alpine grasslands through changing soil microbiomes

PurposeLivestock dung deposition significantly impacts the greenhouse gas emissions, soil nutrient dynamics, soil microbial biomass, and enzyme activities of grasslands. As a typical process of microbial community coalescence, dung deposition may also affect grassland ecosystems by changing soil microbiomes. However, its effects on alpine grassland soil microbial abundance, diversity, and community profiles remain largely unexplored. Therefore, this study aimed at evaluating the influences of dung deposition-mediated community coalescence on alpine grassland soil microbiomes.MethodsSoils were collected from 40 pairs of yak dung-covered patches and their adjacent grasslands along a transect on the Tibetan Plateau. Quantitative PCR and amplicon high-throughput sequencing were employed to determine the abundance, diversity, and community composition of soil microbes.ResultsDung deposition-mediated community coalescence significantly altered multiple soil properties and the composition of soil microbial communities. Specifically, the relative abundance of diazotrophs, photoautotrophs, nitrifiers, pathogens, and lichens significantly decreased due to dung-soil microbial community coalescence, while the proportions of methanogens, denitrifiers, saprotrophs, cellulolytic microbes, and chemoheterotrophs showed opposite change trends. Soil microbial community structures were closely correlated with multiple soil and plant properties (e.g., nutrient contents and plant aboveground biomass) in both control and dung-covered soils. Additionally, dung deposition-mediated community coalescence dramatically decreased the complexity of soil microbial co-occurrence patterns but exerted negligible effects on network stability.ConclusionsThese findings suggest that yak dung deposition has the potential to increase greenhouse gas emissions, but it can also improve soil nutrient contents and decrease plant disease risks. This study highlights the dual effects of dung deposition on grassland ecosystems and provides critical information for guiding alpine grassland management.