Invasion by Fallopia japonica increases topsoil mineral nutrient concentrations

ABSTRACT Fallopia japonica is one of the most troublesome alien invasive plants across temperate regions, with large negative impacts on plant species diversity. We examined its impacts on topsoil chemistry and nutrient stocks in standing biomass at 6 sites with contrasting resident plant communities in Belgium. Topsoil and biomass were sampled in invaded and closely adjacent uninvaded plots. Standing biomass and mineral nutrient concentrations in soil (ammonium acetate exchangeable cations and P, total C, and N) and plants were determined. Soil under F. japonica generally had higher exchangeable nutrient concentrations (Cu: +45%, K: +34%, Mg: +49%, Mn: +61%, P: +44%, Zn: +75%). Standing biomass was 3- to 13-fold higher depending on site. Despite lower nutrient concentrations in aboveground biomass, invaded stands had 3.2- to 5.4-fold larger nutrient stocks in aboveground biomass compared to the resident vegetation. We conclude that F. japonica enhances nutrient cycling rates and topsoil fertility, probab...