Shifts in Rhizosphere Bacterial Community Composition and Predicted Functional Potential Associated with Impatiens parviflora Invasion in Temperate Forest.

Impatiens parviflora is a widespread invasive plant in temperate European forests, yet its influence on rhizosphere microbial communities remains poorly understood. This study provides initial metagenomic insights into taxonomic shifts and predicted functional potential of bacterial communities associated with this invader. Rhizosphere soils were collected from eight I. parviflora-invaded and eight non-invaded control plots in a mixed coniferous forest in northern Poland and analysed using Oxford Nanopore shotgun sequencing, with functional inference performed using the taxonomy-dependent FAPROTAX database. Bacterial richness was significantly higher in invaded soils, whereas Shannon and Simpson diversity indices did not differ between treatments, indicating an expansion of rare taxa without changes in overall diversity structure. The invaded rhizosphere was characterised by a uniform depletion of dominant bacterial orders, with no significantly enriched taxa detected, contrasting with the selective enrichment of microbial groups often reported for other invasive plant species. FAPROTAX-based predictions indicated consistently lower inferred abundances of 37 metabolic processes in invaded plots, including those related to nitrogen cycling and degradation of complex plant polymers. Because these functional predictions are derived from taxonomic composition, they represent inferred ecological potential rather than measured activity. Overall, these results generate testable hypotheses regarding plant-soil feedbacks and highlight the utility of long-read metagenomics for exploring microbial dynamics potentially contributing to the ecological success of I. parviflora in temperate forests.