Invasion debt – quantifying future biological invasions

We acknowledge funding from the National Research Foundation (grants 76912, 81825 and 89967 to CH; grant 85417 to DMR) and the DST-NRF Centre of Excellence for Invasion Biology. JRUW and JLR were supported by the South African National Department of Environment Affairs through its funding of the South African National Biodiversity Institute Invasive Species Programme. FE received funding from the Austrian Science Foundation (FWF grant I2096-B16). We acknowledge support from the South African Research Chairs Initiative of the Department of Science and Technology and the National Research Foundation of South Africa.