1. Department of Geography, Geoinformatics and MeteorologyUniversity of Pretoria Private Bag X20, Hatfield, 0028 South Africa
2. Geosciences DepartmentNelson Mandela University PO Box 77000, Port Elizabeth, 6031 South Africa
3. Department of Plant and Soil SciencesUniversity of Pretoria Private Bag X20, Hatfield, 0028 South Africa