Defense Responses of Native Plant Communities to Alien Plant Invasion.

Understanding the mechanisms that facilitate the successful invasion of invasive plant species is essential for improving invasive species management and ensuring biosecurity. Traditional invasion ecology has primarily focused on the traits of invasive plants or the static characteristics of invaded communities, while comparatively overlooking the potential active responses of native plant communities during the invasion process. Drawing inspiration from the concept of "herd immunity" in medicine, this study proposes that native plant communities may develop a "community defense" response mechanism through a series of ecological defense processes. This article begins by reviewing the two principal pathways that trigger plant defense: pathogens and environmental changes, along with the mechanisms behind them. We then discuss the impact of plant defense responses on the invasiveness of alien species and the invasibility of native plant communities. Building on this, we explore four key mechanisms through which invasive plants may induce defense responses in native species: pathogens and herbivores, allelopathic substances, interspecific competition, and environmental conditions. Based on these insights, we propose "Plant community defense hypothesis," which posits that plant invasions can trigger defense responses in native plant communities that, in turn, influence community invasibility. Finally, the article provides an experimental design to test this hypothesis. This review highlights the understanding of dynamic responses in plant communities and introduces a novel theoretical pathway to explain invasion heterogeneity at the community level. It enriches invasion ecology and offers theoretical support for more targeted management of alien plants.