Impact of yak excreta on soil bacterial community in alpine marsh under warming conditions

Livestock excreta and climate warming are two main disturbances of wetlands embedded in grazing lands, resulting in long-lasting changes in soil microorganisms. However, the impact of livestock excreta on the soil bacteria community in wetlands with climate warming has not been elucidated. In the current study, a laboratory culture experiment was designed to investigate how yak excreta, temperature, and their interaction regulate the soil bacterial community in an alpine marsh. The results show that yak dung increased soil moisture, pH, total organic carbon (TOC), and available phosphorus (AP), but decreased NO₃^--N (P < 0.05). Yak urine increased soil moisture, NH₄⁺-N, and NO₃^--N (P < 0.05). Warming decreased soil moisture and pH of marsh soil (P < 0.05). Warming increased the alpha-diversity of the bacterial community in marsh soil; yak dung had an opposite effect, while yak urine exerted almost a negligible effect. In comparison with warming, yak excreta was the main cause of changing the bacterial community in marsh soil. Yak dung altered more bacterial genera of marsh soil than yak urine. Moreover, yak dung obviously strengthened the bacterial association interaction in marsh soil, while yak urine had the opposite trend. Yak excreta and temperature altered the bacterial community by regulating NO₃^--N, AP, pH, TOC, and moisture of marsh soil. This study confirms the different influences of yak dung and urine on the bacterial community of marsh soil under warming conditions and highlights that the impacts of yak excreta on the bacterial community are sensitive to climate warming.IMPORTANCEInvestigating the response of the bacterial community in marsh soil to external disturbances is an important but poorly elucidated topic in microbial ecology. In this study, we evaluated the impacts of yak excreta, temperature, and their interaction on the bacterial community in alpine marsh soil. Our results showed that yak excreta exhibited a stronger influence on the bacterial community of marsh soil than temperature. The response of the bacterial community of marsh soil to yak dung is more sensitive than to yak urine. Yak excreta and temperature significantly altered the bacterial community by regulating NO₃^--N, AP, pH, TOC, and moisture of marsh soil. Understanding the impact of yak excreta on soil bacterial community under warming conditions is extremely significant for managing grazing and maintaining a healthy alpine marsh ecosystem.