Invasive Alien Plants With Broader Niches Possess Higher Invasive Potential in China as a Result of Niche Conservatism and Effective Niche Filling

ABSTRACT Aim Niche conservatism and niche shift, as two opposing ecological processes influencing invasive species spread, pose challenges for developing management strategies in China. However, how these mechanisms interact during invasion remains unclear. We propose that this uncertainty stems from species traits and invasion histories. Specifically, compared to weak invasive and non‐invasive alien plants, we hypothesize that vigorous invasive plants in China are more likely to exhibit niche shifts. Location China. Methods We quantified the niche dynamics of three categories of alien plant species in China using PCA and their driving factors, while simultaneously predicting their potential distributions with the MaxEnt model. Results Annual mean temperature (Bio1), maximum temperature of the warmest month (Bio5), and precipitation of the driest month (Bio14) were identified as key environmental variables. Most alien plant species exhibited strong niche conservatism. Vigorous and weak invaders showed higher niche stability, lower unfilling, and lower pioneering, whereas non‐invaders displayed higher niche expansion, unfilling, and pioneering. The niche centroids of most species shifted toward warmer, drier, and lower‐elevation areas with more intensive human activity. Longer residence time was associated with lower niche unfilling across all three species categories. Propagule pressure promoted niche filling in vigorous and weak invaders. Species with broader native ranges exhibited higher niche stability. MaxEnt models indicated that vigorous and weak invaders had extensive potential distributions, while non‐invaders were more restricted. Main Conclusion The invasion success of alien plants in China mainly depends on niche conservatism and effective niche filling rather than extensive niche expansion. Long‐term residence and strong propagule pressure promote the occupation of potential habitats. Native niche breadth has a positive effect on niche conservatism. These findings provide a scientific basis for the monitoring, risk assessment, and management of alien plants.