Highly competitive native aquatic species could suppress the growth of invasive aquatic species with similar traits

Abstract

Multiple invaders usually co-occur in an ecosystem and threaten the ecological safety of ecosystems. Invasive species from the same origin could facilitate each other’s establishment, while some species could suppress invasion from others with similar traits. For the successful management of aquatic ecosystems invaded by multiple invasive species, we need to better understand the interaction between multiple common-origin invasive aquatic plants and native aquatic plants with similar traits in a community. A native species, Ludwigia peploides, and two invasive species from the same origin, Myriophyllum aquaticum and Alternanthera philoxeroides were grown as a monoculture (no competitor) or a mixed culture (with competitor) to determine the interactions between the species. The biomass, morphological and photosynthetic physiological traits were measured. The results showed that the biomass traits, relative growth rate and morphological traits (except specific leaf area) of L. peploides were higher than those of the two invasive species. Additionally, L. peploides had significantly higher photosynthetic physiological traits than those of M. aquaticum (in all treatments) and A. philoxeroides (in monoculture). The mixed-culture treatments had relatively less effect on most of the growth traits of L. peploides. However, most of the mixed-culture treatments prominently reduced the biomass, morphological traits and photosynthetic physiological traits of the two invasive species. In addition, the native species had a greater competitive effect than both invaders. Overall, co-invasion between the two invaders was not observed. Furthermore, these results support that highly competitive native species could reduce the growth and the invasive success of less competitive invasive species with similar traits in communities.