Speaker
Description
Grazing is a dominant land use in alpine grasslands, yet it remains unclear whether different livestock assemblages can enhance soil multifunctionality through shifts in soil microbial diversity and network organization. We tested this question in a long-term, moderate-intensity grazing experiment on the Qinghai–Tibetan Plateau, comparing yak-only grazing, Tibetan sheep-only grazing, three yak–sheep mixed-grazing ratios (1:2, 1:4 and 1:6) and grazing exclusion. We quantified soil multifunctionality using standardized indicators of carbon, nitrogen and phosphorus availability, soil moisture, pH and bulk density, and characterized bacterial and fungal communities using Illumina MiSeq sequencing, co-occurrence networks and random forest models. Grazing effects were strongly assemblage-dependent. Yak-only grazing reduced soil multifunctionality relative to the fenced control, whereas all other grazing treatments increased it, with the highest values under Tibetan sheep grazing and yak–sheep mixed grazing at 1:6. Bacterial and fungal richness, but not Shannon diversity, was positively associated with soil multifunctionality. Mixed grazing at 1:4 and 1:6 also shifted microbial community composition, reducing oligotrophic Acidobacteria and increasing copiotrophic or saprotrophic fungal groups, including Mortierellomycota and Mucoromycota. Random forest analysis identified total nitrogen, available nitrogen, available phosphorus, bulk density and soil moisture as the main predictors of soil multifunctionality; bacterial communities were chiefly associated with bulk density, available phosphorus, available nitrogen and moisture, whereas fungal communities were linked to total organic carbon, available nitrogen, bulk density and available phosphorus. Network analysis further showed contrasting microbial mechanisms: bacterial module hubs were negatively related to soil multifunctionality, while fungal keystone taxa were consistently positive predictors. These findings demonstrate that livestock assemblage composition, not grazing presence alone, regulates belowground multifunctionality in alpine grasslands. Moderate yak–sheep mixed grazing, particularly at 1:6, may provide a practical management option for sustaining soil functions while maintaining productive use of fragile alpine rangelands.
| Status Group | Doctoral Researcher |
|---|---|
| FOR TALKS: Poster Presentation Option | Yes, I’m willing to present as a poster. |