Box 7: Key facts
  • Invasive alien species threaten all sub-regions in Africa.
  • Invasive alien species occur in all major taxonomic groups. They include viruses, fungi, algae, plants, fish, amphibians, reptiles, birds and mammals.
  • Numerous species – including as high as 10 per cent of the world’s 300 000 vascular plants – have the potential to invade other ecosystems.
  • IAS affect wetlands, forests, drylands, marine and coastal and other ecosystems, contributing to biodiversity loss and ecosystem degradation.
  • IUCN has estimated that, worldwide, the total economic cost of invasives is US$400 000 million annually.
  • The CBD estimated that Africa spends as much as US$60 000 million annually to control IAS.
  • Invasive alien species flourish in areas disturbed by human activities.

Sources: IUCN/SSG/ISSG 2004, Howard and Matindi 2003, McNeely and others 2001, MA 2006

Although Africa has recognized the problems associated with IAS for several decades, a comprehensive approach to IAS is still to be developed. However, as discussed in Box 8, considerable progress has been made towards this with the adoption of the New Partnership for Africa's Development (NEPAD) Environmental Action Plan (NEPAD-EAP).

Understanding the factors driving the spread of IAS and their impacts is essential to developing effective responses. Where species have become invasive they are an important factor in environmental change, contributing to or exacerbating human vulnerability, and in some cases foreclosing livelihood and development options (UNEP 2004). Globalization – with its expanding trade and increased human movement – is likely to increase the risk of IAS. The inadvertent ending of millions of years of biological isolation has created major ongoing problems that affect both developed and developing countries (IUCN/SSC/ISSG 2004). Given that the threat posed by IAS stems from transnational processes, responses need to be based on collaborative measures. Further, the potential severity of IAS needs to be acknowledged; this includes its impacts on socioeconomic systems as well as the costs of eradication. On the basis of a global assessment, the MA found that climate change and the introduction of IAS are the two drivers of environmental change that are the most difficult to reverse (MA 2006).

Box 8: NEPAD makes IAS a priority

The NEPAD-EAP has prioritized IAS. The reasons are simple:

  • Alien species are second only to habitat loss as a cause in endangering species and their extinction (IUCN/SSC/ISSG 2004).
  • IAS affect Africa’s forestry, horticulture, trade and tourism industries, as well as other sectors of the economy.
  • IAS affect human well-being by indirectly contributing to poverty, food insecurity and ill-health.

The control of IAS is an important aspect of biodiversity conservation. A NEPAD thematic workshop on prevention, control and management of IAS which was held in Pretoria in January 2003, identified 14 project proposals for the implementation of this programme area. The sub-programme areas include: prevention of IAS; awareness-raising and provision of information; training and capacity-building; aquatic IAS; terrestrial IAS; ballast water; and African islands.

Sources: NEPAD 2003

The threats of IAS cannot be treated in isolation. They are part of a complex set of pressures and drivers of biodiversity loss and environmental change. As discussed in Chapter 1: The Human Dimension, social, political and economic drivers are growing in both scale and scope. The underlying causes are a complex tangle, rooted both in our expanding demands on the planet and the unfair ways that we share our resources (BirdLife International 2004). Rising individual consumption and material expectations, especially in rich nations, are driving agricultural intensification, habitat destruction and overexploitation elsewhere (BirdLife International 2004). Poverty, along with inequity, particularly in trade, access to technology, and the distribution of benefits from the use of biodiversity, make sustainable use and development particularly challenging for developing countries (WRI and others 2005). Therefore, responses need to go beyond short-term crisis-focused approaches. They need to be at multiple levels, and in many incidences an interlinkages approach – which takes into account the horizontal linkages between environmental sectors as well as the links between development and social objectives – will need to be adopted. Policies across different sectors as well as at different scales, including the national and regional, will need to be harmonized. Chapter 8: Interlinkages: The Environment and Policy Web considers this approach to decision making and responses more fully.

Traditionally, environmental law has focused on protected areas and species protection, and it has failed to take into account the multiple drivers affecting the environment, and consequently environmental protection has been insufficient. Developing an effective legal framework demands adopting appropriate measures at multiple scales: in the case of IAS this may include, among others, having more effective customs controls, appropriate trade measures, and sanitary and phytosanitary provisions for imports and transportation vessels. Legal and policy approaches to IAS need to be at multiple levels, from the local, to national, to regional, to global, and law at these different levels needs to be harmonized. Policies and laws across different sectors, such as trade and environment, need to reinforce overall social priorities and not pull in different directions.

IAS are a constant and potential threat, and thus require strategic policy responses and action.