Erigeron canadensis affects the taxonomic and functional diversity of plant communities in two climate zones in the North of China

Plant communities across multiple climate zones are at risk of invasive species. Understanding the effects of invasive alien species on both the taxonomic and functional diversities of plant communities in different climate zones enables insight into the mechanisms underlying successful invasions. This study investigated the effects of Erigeron canadensis at different degrees of invasion on both the plant taxonomic and functional diversities in the Chinese zones of Jinan (warm temperate climate) and Zhenjiang (north subtropical climate). A high degree of E. canadensis invasion resulted in a stronger decrease of plant diversity compared to a light degree of E. canadensis invasion. This may be because E. canadensis invasion can lead to a decrease in the number of native species via competition and subsequent local extinction. A high degree of E. canadensis invasion increased the Rao's quadratic entropy of plant height and ground cover. This may be because both the plant height and ground cover of E. canadensis and natives increased with increasing degree of E. canadensis invasion. The number of plant species in plant communities was lower in Jinan than in Zhenjiang. This is presumably because E. canadensis grows better in Jinan than in Zhenjiang and therefore, rare species are more likely to go extinct there. A small number of functional diversity indices of Jinan plant communities were higher than those of Zhenjiang. This may be due to the higher value of functional traits of E. canadensis in Jinan.