1. Plant Conservation Unit; Department of Biological Sciences; University of Cape Town; Private Bag X3 Rondebosch 7701 South Africa
2. Research Fellow; Centre of African Studies; University of Edinburgh; 4 Carlton Street Edinburgh EH4 1NJ Scotland UK
3. Centre for Statistics in Ecology; Environment and Conservation; Department of Statistical Sciences; University of Cape Town; Private Bag X3 Rondebosch 7701 South Africa
4. African Institute for Mathematical Sciences; 6-8 Melrose Rd Muizenberg 7945 South Africa