ABSTRACT: Invasive alien species represent a major disruption for all biotic systems including terrestrial and aquatic, managed and wild. Invaders can have enormous economic and human health impacts as well as degrading many system properties that society values, including biodiversity. In order to illustrate these negative features of invasive species I briefly summarize our current general knowledge about their past and present status. I then focus specifically on how invasive species can devalue the ecosystem services upon which we all depend in all nations, developed and developing. This information forms the rationale for a new Global Invasive Species Strategy that will be discussed at this meeting.

Five years ago, only a handful of countries had an awareness of the invasive alien species problem that allowed them to address their responsibilities under Article 8h of the Convention on Biological Diversity. In 1996, a Norway/UN Conference on Alien Species brought representatives from over 80 countries together with technical experts on invasive alien species.

At this meeting, a concept for a Global Invasive Species Programme (GISP) was born. This was developed subsequently by three international organizations with specific and complementary expertise on invasive species issues, the Scientific Committee on Problems in the Environment (SCOPE), CAB International (CABI) and the World Conservation Union (IUCN). GISP was established with two objectives:

• to assemble and make available best practices for the prevention and management of invasive alien species
• to stimulate the development of new tools in science, policy, information and education for addressing these problems

GISP has been in operation since 1997 and has completed in 2000 its first phase of activity. It has been supported by voluntary contributions from its three coordinating institutions and from individual participants, and by grants from the Global Environment Facility and a range of private and public sector institutions. GISP works closely with UNEP and is a component of DIVERSITAS, an international programme on biodiversity science.