In recent decades, the frequency of exotic plants invasions has reached to an unprecedented level. It is very important to investigate the mechanism for exotic plant invasion. There are several hypotheses to explain the plant invasion. The previous researches were reviewed in this paper, and the explaintation of exotic plant invasion from the allelopathic perspective was further addressed. Compared to exotic plants, native species are more sensitive to the chemical compounds released by exotic plants, exotic plants may use "chemical weapon" to interfere with native plants, avoid predation by herbivores and prevent infection from pathogenic microbe so that they hold advantage relative to native species, extend distribution area, and finally achieve successful invasion. Furthermore, the theoretic and applied implications from the chemical mechanism were discussed, and some suggestions were also proposed.
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