Soil microbiome drives soil multifunctionality across slope positions in a mountain tea plantation ecosystem

Slope position, a key topographic factor, exerts a strong influence on terrestrial ecosystem multifunctionality. However, the contribution of soil microbiomes to driving soil multifunctionality (SMF) along slope positions remains poorly understood. Here, the changes in soil properties, microbial characteristics, and SMF induced by slope position, as well as the relationships between microbial indices and SMF were investigated. The results demonstrated that most soil parameters, such as soil organic carbon, microbial biomass carbon and β-1, 4-glucosidase enzyme activity, were the highest in the middle slope (MS), being 1.77 to 1.90 times that of the top slope (TS). SMF peaked at the MS (0.76), whereas the lowest value (-0.81) was recorded at the TS. Bacterial alpha diversity was greatest at the MS, while fungal diversity was highest at the foot of the slope (FS). Microbial community structure varied significantly among slope positions and showed strong correlations with SMF and multiple soil factors, such as pH and soil organic carbon. Co-occurrence network analysis indicated a decline in bacterial network complexity from 0.53 to 0.25, while fungal network complexity increased from 0.31 to 0.73 with the rising of slope position. Random forest analysis identified fungal and bacterial community compositions as the most important microbial predictors of SMF. Collectively, these findings reveal the slope-microbiome dynamics in sustaining SMF under topographic variation, highlighting microbe-based soil management for enhanced ecosystem functioning in mountainous landscapes.