[Soil Microbial Community Characteristics in Alpine Meadows of Typical Yellow River Source Watershed and Their...

Microorganisms are key factors involved in soil aggregate formation； however， research analyzing soil aggregate stability from the perspective of microbial functional prediction remains limited. Therefore， this study selected alpine meadows along the upper， middle， and lower reaches of a typical watershed in the Yellow River source region as the research subject. By analyzing soil physicochemical properties and microbial community composition and combining Fungal FUNGuild prediction with Bacterial BugBase phenotype prediction， it aims to reveal the spatial variations in soil aggregate stability within the watershed unit and identify their driving factors. ① The stability of soil aggregates was upstream>downstream>midstream. ② There were significant differences in the community structure of soil bacteria and fungi upstream， midstream， and downstream （P<0.05）， and the dominant bacterial species were Actinobacteriota， Proteobacteria， Acidobacteriota， Ascomycota， and Basidiomycota， and there was no significant difference in the relative abundance of Mortierellomycota in the upstream， midstream， and downstream （P<0.05）. ③ The aerobic and gram positive phenotypes were the two most predominant bacterial groups in the soil. The average relative abundance of aerobic bacterial communities was higher in upstream regions compared to that in the midstream and downstream areas， while the relative abundance of anaerobic communities was lower in upstream regions than that in the midstream and downstream. Bacterial phenotypic functions showed no significant impact on soil aggregate stability（P>0.05）. Saprotrophs constituted the dominant functional group of soil fungi， with the relative abundance of wood saprotrophic fungi in upstream soils being significantly higher than that in midstream and downstream soils. ④ In the watershed unit， the soil fungal community regulated the stability of soil aggregates by affecting the composition of fungal functional groups.