外来种入侵的过程、机理和预测

生物入侵是指某种生物从原来的分布区域扩展到一个新的（通常也是遥远的）地区，在新的区域里，其后代可以繁殖、扩散并持续维持下去，生物入侵成功的原因，即与入侵者本身的生物学，生态学特征有关，也与群落的脆弱性有关，入侵者可能较本地种的竞争能力强，更适应当地的环境，有的入侵者还可以改变环境，使之对已有利，而不利于本地种。缺乏天敌制约。群落的稳定性低和异常的环境扰动往往导致生物入侵，生物入侵的预测包括哪一种外来种会变成入侵种？哪些生态系统区域会被入侵？影响程度如何？入侵种的扩散态势如何等内容，对有关的理论和模型作了评介。

Biological invasions: process, mechanism and prediction

Biotic invasions can occur when organisms are trans ported to new, often distant, ranges where their descendants proliferate, spread , and persist. Biological invasions have been causing major environmental and ec ological damage, few areas remain sheltered from these immigrations in today's w orld, and they have become a priority concern for conservation biologists and la nd managers. In this paper, we discuss the process of invasions, the mechanism o f alien species displacing native species, and the predicting of biological inva sions. Humans have served as both accidental and deliberate dispersal agents for alie n species immigrations worldwide. The fate of immigrants is decidedly mixed, few survived the hazards of chronic and stochastic forces, and only a small fractio n became naturalized. In turn, some naturalized species do become invasive. The potential reasons why some immigrant species prosper may be related with t he biological and /or ecological characters of nonindigenous species, and the vu lnerability of the communities that they invade. Invasive species usually have h igher competition ability and they fit the environment of invaded ecosystem bett er than native species, many invasive species can even wreck havoc on ecosystems to which key native species are not adapted. Some alien species escape from the constraints of their native predators or parasites, community diversity and sta bility might affect its invasibility, and sudden, radical disturbances in enviro nment may encourage invasions. The predicting of biological invasions include identifying which species will become future invaders, where alien species would invade landscape and what impa ct they bring to native ecosystems, and how the geographic range of the invasive species population expand. Every kind of related models has its advantage and l imitation, their association may heighten our understanding to the expanding mec hanism of invader species.cies p