Long-term weathering difference in soil-like indicators of bauxite residue mediates the multifunctionality driven by microbial communities

Long-term weathering enhances the stability of ecosystem services and alters the microbiome, however, its influences on the relationship between microbial diversity and multifunctionality are still poorly understood. Hereby, 156 samples (0–20 cm) from five artificially divided functional zones including central bauxite residue zone (BR), the zone near residential area (RA), the zone near dry farming area (DR), the zone near natural forest area (NF), and the zone near grassland and forest area (GF) were collected in a typical disposal area to determine the heterogeneity and development of biotic and abiotic properties of bauxite residue. Residues in BR and RA exhibited higher values of pH, EC, heavy metals, and exchangeable sodium percentage compared to those in NF and GF. Our results showed a positive correlation between multifunctionality and soil-like quality during long-term weathering. Microbial diversity and microbial network complexity responded positively to multifunctionality within the microbial community, which was parallel with ecosystem functioning. Long-term weathering promoted oligotrophs-dominated bacterial assemblages (mostly Acidobacteria and Chloroflexi) and suppressed copiotrophs (including Proteobacteria and Bacteroidota), while the response of fungal communities was lower. Rare taxa from bacterial oligotrophs were particularly important at the current stage for maintaining ecosystem services and ensuring microbial network complexity. Our results underscore the significance of microbial ecophysiological strategies in response to changes in multifunctionality during long-term weathering, and highlight the necessity of conserving and augmenting the abundance of rare taxa to ensure the stable provision of ecosystem functions in bauxite residue disposal areas.