Abstract: In this article, some concepts about biological invasion were presented and the process of alien species change to invasive species was summarized and primary types of biological invasion were concluded. Furthermore, the mechanism of invasion was elaborated, some hypotheses that relate to alien species and the ecological environment of the invaded habits were analyzed, and the damage of invasive species to the human was described. With the study on urban vegetation of Shanghai, the present situation of alie...

Key words: native species, alien species, biological invasion, mechanisms of invasion, ecological method