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Dryad

Vegetation variables and rhizosphere bacterial communities from ten paired sites in southwestern Finland, 2021

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Jan 30, 2024 version files 2.57 MB

Abstract

Plant invasions can have major impacts on ecosystems not only in aboveground but also in belowground through changes in microbiota. Particularly legumes, which often host nitrogen-fixing symbionts (rhizobia), can be expected to modify soil bacterial communities. We examined the effect of the invasive herbaceous legume, Lupinus polyphyllus, on the alpha diversity and community composition of soil bacteria. We also explored whether vegetation cover, the cover of other (non-invasive) legumes or number of vascular plants was associated with soil bacterial communities. We sampled rhizosphere soil and surveyed vegetation from ten paired sites (invaded more than ten years ago and uninvaded locations) in southwestern Finland, and identified bacterial DNA by using 16S rRNA gene amplicon sequencing. The plant invader and the three vegetation variables considered had no effect on soil bacterial alpha diversity in terms of bacterial richness, Shannon and Inverse Simpson diversity indices. The composition of soil bacterial communities differed between invaded and uninvaded soils at four out of the ten sites. However, the differences in the relative abundances of top bacterial families between the two soil origins were inconsistent across sites, including rhizobia in the family of Bradyrhizobiaceae that the study species is hosting. Moreover, vegetation cover, legume cover after excluding the study species, and number of plant species explained a small proportion of the variation in the bacterial community composition. Our findings indicate that L. polyphyllus has the potential to modify the soil bacterial community composition locally, at least at sites where it has been present for more than a decade.