Stage-Associated Plant–Soil–Microbiome Patterns and Rhizosphere Pb–Zn Stabilization in Indocalamus decorus at a Mining Site

Indocalamus decorus is a perennial bamboo with potential for phytomanagement, but its Pb–Zn partitioning and associated microbiome under field co-contamination remain unclear. Parallel plantings were established at a Pb–Zn mining site and the provenance site. Plant nutrients, rhizosphere properties, Pb–Zn concentrations and soil fractions, and bacterial and fungal communities were evaluated across four developmental stages at the mining site; shoot initiation was also evaluated at the provenance site. At shoot initiation, mine-site plants had lower organ P concentrations, whereas root N was maintained. Rhizosphere nutrient availability was relatively high during shooting. Pb accumulated mainly in roots, while Zn was transferred more readily to culms; organ-specific bioconcentration factors for both metals remained below 1. Compared with bulk soil, rhizosphere soil contained lower DTPA-extractable Pb and Zn, smaller acid-soluble/exchangeable fractions, and larger residual fractions. Sample compartment explained 60.8% and 66.9% of bacterial and fungal community variation, respectively. Rhizosphere fungi were associated with a broader range of metal fractions and plant metal-distribution indices than other microbial compartments. These results indicate root-dominated Pb retention, reduced rhizosphere Pb–Zn lability, and compartment-specific microbial associations, supporting further evaluation of I. decorus as a candidate for phytostabilization-oriented management of Pb–Zn-contaminated mine soils.