Legacy effects of invasive plants on subsequent plant growth under nitrogen deposition independent of management measures

The ecological impacts of biological invasions are persistent and complex. Even after invasive plants are removed, their legacy effects can continue to influence subsequent plant growth. However, few studies have integrated invasion legacy effects, nitrogen deposition, and management measures into a unified framework to evaluate the risk of secondary invasion. In this study, a two-year controlled pot experiment was conducted to simulate soil legacy effects generated by single-species and mixed invasions, and to examine their influences on subsequent plant productivity under nitrogen deposition and management treatments. The results showed that both invasion legacy and nitrogen deposition significantly increased the biomass of subsequent plants, while no significant difference was found between single-species and mixed-species invasion legacies. However, this facilitative effect was mainly driven by invasive plants, and the legacy effect was stronger for heterospecific invasive plants. In contrast, the promotive effects of invasion legacy and nitrogen deposition on native plants were limited, and no significant differences were observed between native monocultures and native communities. In addition, no significant differences were detected among the three conventional management treatments. Interaction analyses further indicated that nitrogen deposition weakened the promotive effect of invasion legacy on the height of subsequent plants. This study revealed that nitrogen deposition can partially attenuate the strength of invasion legacy effects, but cannot eliminate the secondary invasion risk associated with these legacy effects. These findings provide new insights into the ecological consequences of invasion legacy effects in the context of global change.