Propagule Pressure——A Mechanism of Explaining Biological Invasion

Propagule pressure is one of the key factors in the process of biological invasion.To explain the relationship between propagule pressure and species invasion,the relationship between propagule pressure and species establishment were discussed.The definitions of propagule pressure were reviewed in three ways:propagule number,the frequency of introduction,the quality of the propagules.It was indicated that the essence of propagule pressure is to signify the invasion potential of alien species.The more propagule pressure,the more invasion potential,and the more easily for the alien species to invade successfully.Considering the characteristics of alien species,it was found that popagule pressure can be affected by alien species' procreation method and ability.Considering the four ways of propagule pressure make it more difficult to value propagule pressure.Propagule pressure is based on explaining alien species establishment so that the relationship between propagule pressure and establishing effect should also be analyzed,the relationship between propagule pressure and environmental factors that could affect the alien species established successfully.Furthermore,considering the complexity of biological invasion,propagule pressure should be combined with the habitat and biological characteristics of invasive species to explain invasion mechanism of alien species.