The balance of trade — the contribution of Africa to biological invasions in South Africa and vice versa

The balance of trade — the contribution of Africa to biological invasions in South Africa and vice versa
Katelyn T. FAULKNER1, 2, Brett P. Hurley3, 4, Mark P. Robertson2, Mathieu Rouget5John R. Wilson1, 6
1Invasive Species Programme, South African National Biodiversity Institute, Kirstenbosch Research Centre, Private Bag X7, Claremont, 7735, South Africa.
2Centre for Invasion Biology, Department of Zoology and Entomology, University of Pretoria, Hatfield, 0028, South Africa
3Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Hatfield, 0028, South Africa
4Department of Zoology and Entomology, University of Pretoria, Hatfield, 0028, South Africa
5Centre for Invasion Biology, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
6Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa

Although alien organisms are often introduced directly from one biogeographical region to another, the spread of species within biogeographical regions also plays an important role in the movement of organisms around the globe. As South Africa shares land borders with six countries, multiple opportunities exist for the transfer of alien species. Here we present scenarios that describe how alien species might have been introduced to the region and spread between South Africa and other parts of Africa. We illustrate these scenarios using case studies and demonstrate that the scenarios are numerous, that their applicability varies across species and that for a species the applicable scenario might change over time. Despite the complex nature of alien species transfer in this region, relatively simple information on introduction and spread are required for management. We believe that by co-ordinating their alien species management responses and sharing information, countries within the region will improve the prevention and management of biological invasions. In an effort to inform such co-operative management, details are provided on the actions that should be taken by invaded countries and their neighbours following the detection of a new invader in the region.