Global indicators of biological invasion: species numbers, biodiversity impact and policy responses
Article first published online: 18 JAN 2010
© 2010 Blackwell Publishing Ltd
Diversity and Distributions
Volume 16, Issue 1, pages 95–108, January 2010
How to Cite
McGeoch, M. A., Butchart, S. H. M., Spear, D., Marais, E., Kleynhans, E. J., Symes, A., Chanson, J. and Hoffmann, M. (2010), Global indicators of biological invasion: species numbers, biodiversity impact and policy responses. Diversity and Distributions, 16: 95–108. doi: 10.1111/j.1472-4642.2009.00633.x
- Issue published online: 18 JAN 2010
- Article first published online: 18 JAN 2010
- Biological invasions;
- Convention on Biological Diversity 2010 Biodiversity Target;
- environmental legislation;
- invasive alien species;
- Red List Index;
- species richness
Aim Invasive alien species (IAS) pose a significant threat to biodiversity. The Convention on Biological Diversity’s 2010 Biodiversity Target, and the associated indicator for IAS, has stimulated globally coordinated efforts to quantify patterns in the extent of biological invasion, its impact on biodiversity and policy responses. Here, we report on the outcome of indicators of alien invasion at a global scale.
Methods We developed four indicators in a pressure-state-response framework, i.e. number of documented IAS (pressure), trends in the impact of IAS on biodiversity (state) and trends in international agreements and national policy adoption relevant to reducing IAS threats to biodiversity (response). These measures were considered best suited to providing globally representative, standardized and sustainable indicators by 2010.
Results We show that the number of documented IAS is a significant underestimate, because its value is negatively affected by country development status and positively by research effort and information availability. The Red List Index demonstrates that IAS pressure is driving declines in species diversity, with the overall impact apparently increasing. The policy response trend has nonetheless been positive for the last several decades, although only half of countries that are signatory to the Convention on Biological Diversity (CBD) have IAS-relevant national legislation. Although IAS pressure has apparently driven the policy response, this has clearly not been sufficient and/or adequately implemented to reduce biodiversity impact.
Main conclusions For this indicator of threat to biodiversity, the 2010 Biodiversity Target has thus not been achieved. The results nonetheless provide clear direction for bridging the current divide between information available on IAS and that needed for policy and management for the prevention and control of IAS. It further highlights the need for measures to ensure that policy is effectively implemented, such that it translates into reduced IAS pressure and impact on biodiversity beyond 2010.