Native plants play crucial role in buffering against severity of exotic plant invasions in freshwater ecosystems

Few studies have evaluated the relative importance of various factors in the invasion of exotic plants in freshwater ecosystems due to the difficulty of observing numerous factors simultaneously. In this study, we surveyed 236 exotic aquatic plant communities using 2267 quadrats in China's freshwater ecosystems to explore the roles and relative importance of various biotic and abiotic factors in the invasion of exotic aquatic plants. We found that competition from native plants was the most important factor determining the mean biomass of all exotic plants in communities, as well as the biomass of the submerged plant Cabomba caroliniana and the free-floating plant Eichhornia crassipes. Whereas competition from co-occurring exotic plants was the most important for the biomass of the emergent plant Alternanthera philoxeroides. Elevated water nutrient status accelerated the invasion of exotic plants by directly favoring them and indirectly weakening the resistance of native plants. Exotic plants responded differently to climate. Moreover, water depth, habitat area, herbivory, and anthropogenic disturbance had relatively weak impacts on the biomass of exotic plants. Our study highlights the necessity and priority of biodiversity conservation and vegetation restoration in controlling invasive aquatic plants. It also emphasizes the significance of considering interactions between invaders in the research and management of invasive species.