Effects of cadmium pollution on plant-soil feedback between invasive plant Phytolacca americana and native plant Phytolacca acinose

Understanding plant-soil feedback (PSF) between native and invasive plants under heavy metal pollution can inform invasion management strategies. However, the PSF and mechanism between native species Phytolacca acinosa and invasive species Phytolacca americana under heavy metal pollution remain unclear. Here, in a greenhouse experiment, we created soils with varying concentrations of cadmium (Cd) and conditioned them with either the invasive species Phytolacca americana, the native species Phytolacca acinosa, or without any plants. We measured soil chemical, microbial and physical properties. In a subsequent PSF phase, we grew individual plants of P. americana or P. acinosa in these soils. Soil cadmium (Cd) increased the biomass of invasive species while decreasing that of native species. Fungi and bacteria were abundant in soils conditioned by invasive plants, particularly in the absence of Cd. The concentrations of phenols, flavonoids, and tannins, as well as soil pH, increased with the concentration of Cd when plants were present. Phenol and tannin concentrations were higher in the presence of invasive plants, whereas flavonoid concentrations were lower. During the PSF phase, the biomass of invasive species was sensitive to soil microbes. Native plants exhibited reduced growth in soils dominated by invasive species, particularly in soils with higher concentrations of cadmium, indicating their sensitivity to soil chemistry and physical characteristics. This study provides valuable insights into the influence of PSF on plant invasion processes in the context of soil heavy metal pollution.