Focal Area: Threats to biological diversity

Headline Indictor: Invasive Alien Species

Key Indicator Partners:

Associate Indicator Partners:

IUCN Invasive Species Specialist Group (ISSG)

Data Available: Global trend (RLI: 1988-2008, international policy: 1950-2009, national policy: 1965-2009), Global baseline (number of documented IAS: 2009)

Development Status: Ready for global use

Invasive alien species (IAS) are plants, animals or micro-organisms outside of their natural geographic range whose introduction and or spread threatens biodiversity, food security, human health, trade, transport and or economic development. They pose the second biggest threat to biodiversity globally, and in certain ecosystems notably islands, the greatest threat to biodiversity. IAS have reached all corners of the globe and impact biodiversity in many ways. The cost of damage caused by invasive species is estimated as US$ 1.4 trillion per annum – close to 5% of global GDP.

A pressure-state-response model was used in which four indicators were developed and expressed for the purpose of assessing progress towards the 2010 Biodiversity Target for this threat to biodiversity:

PRESSURE

1. Status of alien species invasion is expressed as the number of documented IAS per country.

STATE

2. Red List Index for impacts of invasive alien species shows the overall impact of IAS on the extinction risk of species globally. It is a measure of how fast IAS are driving the world’s biodiversity to extinction (and how effectively we are mitigating this).

RESPONSE

3. Trends in international invasive alien species policy shows the number of international agreements relevant to controlling IAS and how this has changed through time, as well as the change in the number of countries party to these agreements.

4. Trend in national invasive alien species policy shows the percentage of countries with national legislation relevant to IAS concerns and how this has changed through time as countries acknowledge the IAS problem and commit to responding to this threat.

Three of the indicators are measured at a country scale and aggregated up to global scale. As a result they can be disaggregated to examine the status of invasion and trends in international and national policy at regional and national scales. The Red List Index is expressed globally, but may be applied nationally.

Example of IAS impact for birds:

Cumulative percentage of bird species undergoing genuine IUCN Red List category changes driven by impacts of IAS

Adoption of national legislation relevant to the prevention or control of IAS

Source: Global indicators of biological invasion: species numbers, biodiversity impact and policy responses, McGeoch et al., Diversity and Distributions 16, Copyright © , Blackwell Publishing Ltd

Future development for the indicator will include increasing the number of countries and taxa for the invasion pressure indicator (and expression of trends therein) as well as updating the policy and Red List indicators. As more national scale information becomes available, response indicators that directly reflect on-the-ground action against IAS (management effectiveness) should be developed (e.g. control of pathways, operational management plans, extent of invasion) (McGeoch et al. 2010).