Identifying the most noxious invasive plants in China: role of geographical origin, life form and means of introduction

In a heterogenous world, invasive plants often differ in noxiousness and nature of impacts, and there is a difference between strong and weak invaders. That knowing which invaders are most noxious and their nature of impacts is of great value to invasive ecology and management. Here we show that in China the most notorious invasive plants are with a perennial life cycle, clonal growth ability and from the American continent. They often form monocultural populations in land and water, replacing almost all other plants, and are mainly distributed in Central and South China. Following are some accidentally introduced annuals. Annuals from the American continent are often common, dominant or in monocultural populations in ruderal and agricultural habitats whereas those from Eurasia are highly noxious only in agricultural habitats. Annuals are not restricted in distribution and could spread fast to all of the country. There are also two perennial grasses from Europe and Mediterranean area and four intentionally introduced annuals from South America that were identified in this study. Factors that may account for these patterns include relatedness between invasives and natives, vegetative propagation, and plant strategies. The invasive plants identified in this study have caused significant negative impacts to native biodiversity, environment, economics and agriculture, with different groups being different in their extent and nature of impacts.