Study on the Importance Value of Exotic Plants Community in Changsha of Hunan Province

The quantitative method,which importance value was synthesized from three characteristic indexes,was applied to the determination of the status and function of exotic plants.The result showed that the habitat form of exotic plants displayed diversify.With the interference increasing of human,the species of exotic plants increased at first and then declined,but the influence of exotic plants on structure,function and biodiversity of local ecosystem increased.Base on the dominate species of community and importance value of exotic plants,the most harmful exotic plants in Changsha were Alternanthera philoxeroide,Hyptis rhomboidea,Paspalum conjugatum and Veronica polita.