Canada goldenrod invasion affect taxonomic and functional diversity of plant communities in heterogeneous landscapes in urban ecosystems in East China

摘要

Invasive pant species (invaders hereafter) have notable effects on the structure and functions of native ecosystems. Plant functional diversity plays a more important role than plant taxonomic diversity in driving ecosystem processes. Moreover, landscape heterogeneity in urban ecosystems may lead to a significant variation in the invasion process. Thus, it is important to evaluate the effects of invaders invasion on the taxonomic and functional diversity of native communities across different types of urban ecosystems to better understand the mechanism underlying successful invasion, especially in heterogeneous landscapes in urban ecosystems. This study aims to determine the effects of an invader Canada goldenrod (Solidago canadensis L.) on the taxonomic and functional diversity of native communities by using a comparative study in nine types of urban ecosystems in East China. Canada goldenrod and coexisting natives tend to functionally converge in all urban ecosystem types. Thus, differences in the functional traits between Canada goldenrod and coexisting natives support the habitat filtering hypothesis. Canada goldenrod invasion did not significantly affect the taxonomic diversity of plant communities. Most of the functional diversity indices of plant communities significantly increased under Canada goldenrod invasion. The increased values of some functional diversity of plant communities under Canada goldenrod invasion may cause an promotion in the utilization of resources at the interspecific degree rely largely on the niche complementarity effects. The relative abundance of Canada goldenrod was positively correlated with various indexes of functional diversity of plant communities (including some of community-weighted means, Rao's quadratic entropy, and Mason alpha functional diversity), rather than taxonomic diversity of plant communities. Thus, the invasibility of plant community may be more closely associated with functional diversity than taxonomic diversity of plant communities. Specifically, the invasibility of plant community from the invaded area reached a maximum in traffic land among the nine types of urban ecosystems because of it's higher plant functional diversity. The higher plant functional diversity is supported by a highly heterogeneous landscape structure and creates a great variety of ecological conditions for plants mainly caused by anthropogenic land use. Overall, landscape heterogeneity in urban ecosystems can obviously increase the invasion degree of invaders via shifts in the functional diversity of plant communities.