Relationship Between Alternanthera Philoxeroides Invasion And Plant Community Characteristics

Habitat and diversity loss driven by invasive alien species pose a major threat to wetland communities.Plant communities differ markedly in their susceptibility to plant invaders due to numerous aspects.Alternanthera philoxeroides has become a wide-spread invasive species in China,to understand the mechanisms underlying invasion,we addressed this study incorporating species distribution model,field survey and controlled experiments to investigate potential distribution of A.philoxeroides in China;correlation between latitude,community diversity and A.philoxeroides invasion;effects of species richness and phylogenetic diversity on A.philoxeroides invasion;and impact of A.philoxeroides invasion level and phylogenetic evenness on both the invader and resident plant community.Results showed that the southeast coastal areas of China may suffer more A.philoxeroides invasion than the other areas probably due to suitable climate,developed economy,active infrastructure construction and other anthropogenic disruptions.Alternanthera philoxeroides growth traits went better along latitudinal gradient to the north and became more competent and more invasive in high-latitude areas.Species richness,Shannon-wiener diversity index,phylogenetic diversity and phylogenetic species richness were all negatively correlated with A.philoxeroides growth traits and relative dominance index.One possible inference is that strengthened complementarity of the resident community promoted its resistance to A.philoxeroides invasion.Alternative explanation is that A.philoxeroides became more dominant in the community and consequently impaired biodiversity and damaged community health.As compared to species richness,phylogenetic diversity performed better in predicting low-diversity wetland community resistance to A.philoxeroides invasion.When invasion level increased,A.philoxeroides occupied more spaces,promoted intraspecific competition and lowered resident plant proportion,thus reduced interspecific competition.Alternanthera philoxeroides grew better in aquatic habitat with stronger intraspecific competition,the increase of invasion level further promoted intraspecific competition and suppressed A.philoxeroides individual growth,resulting in stronger negative correlation between A.philoxeroides growth traits and invasion level in aquatic habitat.Overall,phylogenetic evenness had no significant effect on both the invader and the resident community.This study evaluated A.philoxeroides invasion situation in China,provided important evidence and approach for A.philoxeroides prevention and ecosystem monitoring and protection,and offered advice to restoration of damaged wetland plant communities.