外来种对生物多样性的影响及其控制

外来种是那些借助自身力量或其它外界力量传播到其未曾分布过的地域 ,并且能进行繁殖传播的生物。外来种入侵已成为一种引人关注的现象。外来种通过竞争、捕食、牧食、改变生境和传播疾病等方式对本地生物产生威胁 ,影响本地生物多样性。外来种入侵成了生物多样性丧失的两个主要影响之一 (另一影响是生境的破坏 )。因此 ,探寻阻止或减少外来种入侵的方法很有必要。目前 ,人们运用机械法、化学法和生物控制法来控制外来种。在外来种入侵的初始阶段或外来种数量不多时 ,运用机械法较好。化学法有带来新环境污染的危险。生物控制法是应用天敌来防治或消灭有害生物。在外来种的控制上 ,生物控制法有一些成功的案例 ,但它并不是万能的。有些生物控制剂可能对非目标种产生影响 ,这要求在释放前对生物控制剂作更严格的检测。

The impacts of non-native species on biodiversity and its control

Non-native species is a species or race that does not occur naturally in an area,i.e. it has not previously occurred there,or its dispersal into the area has been mediated by humans. Today,the phenomenon of non-native species which have established and dominated in seminatural and urbanized habitats is general in many parts of the world. The invasion of non-native species have been getting concern globally. This has devastating effects on native diversity,and introductions of non-native species is one of the two major threats to native biodiversity(behind habitat destruction). Detrimental impacts of invasion of non-native on native biota have occurred through competition,predation,herbivore,habitat alteration and disease et al. Thus,the practical and effective ways and means of stopping or reducing invasions are in an urgent need. Mechanical methods, chemical means and biological control technologies are used in control and elimination of non-native species. Mechanical methods are only used at the starting of invasion or small number of non-native species appearing. Chemical means can cause new environmental problem which can bring new pollution and threats to other native species. Biological control is the science and technology of controlling pests and other dangerous species by using natural enemies. There has been many successful cases in the field of using biocontrol. However,biocontrol is not a panacea. Without careful use,it can produce threats to non-target species. This indicates that a more thorough screening biocontrol agents for non-native species should have preceded the release of these agents.