Novel plant-soil feedbacks drive adaption of invasive plants to soil legacies of native plants under nitrogen deposition

Soil legacies mediate interactions between native and introduced plants, contributing to both invasion and biotic resistance to invasion. Given that nitrogen deposition can promote allelochemical release, reduce the benefits of soil microbes, and affect trait plasticity, nitrogen deposition likely alters soil legacies as well. However, it is not clear how mechanisms that facilitate adaptation to soil legacies are altered by nitrogen deposition. In a greenhouse setting, we investigated how an invasive and a native plant in northern China (Rhus typhina and Ailanthus altissima, respectively) acclimate to soil legacies and how these dynamics change with nitrogen availability. We measured plant functional traits, soil microbial abundance, microbial enzyme activities, and soil allelopathic effects to characterize plant responses to soil legacies from plants of the same and of the other species. Rhus typhina had a stronger growth response to soil legacies than did A. altissima. Rhus typhina established a novel plant-soil feedback by increasing fungi and bacteria, changing the composition of the microbial community, and effectively transforming negative effects of soil allelopathy to positive effects. Nitrogen deposition promoted the growth of R. typhina and alleviated the negative effects of heterospecific soil legacies on the performance of R. typhina. Invasive plants can acclimate to the soil legacies of native species through a combination of high trait plasticity, manipulating soil microbes, and establishing novel plant-soil feedbacks. Nitrogen deposition can facilitate invasive species acclimating to soil legacies by monopolizing nitrogen absorption, though this may diminish the benefit of soil microbes.