The functional diversity of native ecosystems increases during the major invasion by the invasive alien species, Conyza canadensis

Invasive alien species can exhibit different degrees of invasion and colonize multiple districts due to their strong adaptability [e.g., the notorious invasive alien species Conyza canadensis (L.) Cronq. (originated from North America)]. We verified that the degree of C. canadensis invasion (based on its relative abundance in colonized communities) was critical to the functional similarity and dissimilarity between invasive alien species and coexisting native plant species and studied their impacts on plant taxonomic diversity, plant functional diversity, and ecosystem stability along with the Yangtze River areas in China. C. canadensis and coexisting native plant species tend to exhibit functional convergence and divergence under low and high degree of invasion, respectively. Low degree of invasion increased plant taxonomic diversity (diversity, dominance, and evenness) and ecosystem stability and high degree of invasion reduced plant taxonomic diversity (diversity, dominance, evenness, and richness) and ecosystem stability. However, high degree of invasion improved plant functional diversity. Thus, the relative abundance of C. canadensis was significant for the shifts of the functional similarity and dissimilarity between C. canadensis and native plant species, plant taxonomic diversity, plant functional diversity, and ecosystem stability.