PLANT INVASIONS: THEIR THREATS IN ANIRISH CONTEXT

摘要

Although there are some notable exceptions, introduced plant species tend not to receive the public and media attention that their animal counterparts do; however, the impacts they have on the environments they invade can be equally, and sometimes more, dramatic. This article presents a short overview of the main ecological and economic impacts that alien plants can have on invaded regions, with particular reference to Ireland. In terms of biological impacts, invasive alien plants may affect the ecology of native species, the composition of biological communities and, in turn, ecosystem processes. In addition, because human-mediated introduction of new species can remove geographic barriers, gene flow between formerly separated species can occur. This can potentially lead to the loss of native genotypes through hybridisation and introgression. However, the impacts of invasive alien plants on native biodiversity and ecosystems are difficult to assess, and are often species- and context-specific, making it almost impossible to make general statements. Economically, invasive alien plants can have impacts on the delivery of ecological goods and services, and can be costly in terms of management and control. Conservative estimates of the cost of invasive alien plants at the European scale run to several billion euro per year, but no assessment has been made specifically for Ireland. Although some invasive alien plants may be directly hazardous to human health, it is their indirect effect on native biodiversity and local economies that are likely to cause most harm to humans. Finally, this paper provides a summary of current and potential Irish invaders and discusses the problems associated with predicting which species will be the next invasive aliens.