1. Centre for Invasion Biology; Department of Botany and Zoology; Stellenbosch University; Private Bag X1 Matieland 7602 South Africa
2. Environmental Resource Management Department (ERMD); Westlake Conservation Office; City of Cape Town Ou Kaapse Weg Tokai 7966 Cape Town South Africa
3. Stockholm Resilience Centre; Stockholm University; SE 106 91 Stockholm Sweden
4. Stellenbosch Institute for Advanced Study (STIAS); Wallenberg Research Centre at Stellenbosch University; Marais Street Stellenbosch 7600 South Africa
5. Centre for Studies in Complexity; Stellenbosch University; Private Bag X1 Matieland 7602 South Africa
6. Department of Ecology and Environmental Science; Umeå University; SE 901 87 Umeå Sweden
7. Department of Conservation Ecology and Entomology and Centre for Invasion Biology; Department of Botany and Zoology; Stellenbosch University; Private Bag X1 Matieland 7602 South Africa
8. Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University; Matieland 7602, South Africa; African Institute for Mathematical Sciences; Muizenberg 7945 VT South Africa
9. Department of Plant Biology; University of Vermont; Burlington VT 05405 USA