外来种入侵的不确定性动态模拟

外来种的入侵性和生境的可入侵性是研究生物入侵机制的两个关键因素。总结多数学者的研究成果,认为外来种的拓殖率(迁移率或繁殖率)、死亡率及在新生境中的竞争力是衡量外来种能否入侵成功的内在实质。从全新的角度出发,将引入的外来种看作是对原有生态系统的一种干扰,并在此基础上结合Tilman的多物种共存模型提出了外来种干扰模型。模拟发现外来种在入侵时具有明显的不确定性。拓殖率小的外来种在新的生态系统中由于不能适应环境无法成功定殖,被排斥在系统之外;相反,拓殖率足够大的话,外来种由于自身优势具有很强的入侵性,在几年或几十年的时间内就会成功地在新的环境中建立种群并拓殖入侵,影响了当地物种的生存及原有生态系统的稳定。研究还发现,物种入侵也存在一定的不确定性,入侵不一定会一直持续下去,或许在百年或几百年的时间内入侵种会突然灭绝,原生态系统又恢复到原来的水平。

Dynamical simulation on the uncertainty of exotic invasion

Exotic invasiveness and community invisibility are two key factors to study the mechanism of biotic invasion. Referring to related researches, we consider that the colonization (migration or propagation), mortality and competition are the inherent essence determining successful exotic invasion. In the paper, from a new angle of considering alien species invasion as a disturbance to native community, we propose a disturbance model on biology invasion, which is based on Tilman's multispecies coexistence model. The numerical simulation discloses obvious uncertainties of species invasion. Alien species with weak colonization couldn't adapt to new habitat and is excluded out of indigenous community. On the contrary, strong alien species succeed in colonizing new habitat and develops new populations in several or decades of years, threatening indigenous populations. However, it is noticeable that exotic species maybe extinct suddenly after a successful invasion, which is another perplexing uncertainty. Besides above conclusions, the numerical simulation also provides some references to the evolution of alien-species.