1. Botany Department, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa;
2. NERC Centre for Terrestrial Carbon Dynamics and Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK;
3. Climate Change Research Group, National Botanical Institute, P/Bag X7, Claremont 7735, South Africa & Conservation International, Center for Applied Biodiversity Science 1919 M St., NW, Washington, DC 20036, USA