Invasive Alien Species in Kruger National Park: The 1950s and increasing trends in invasion
As indicated in Part B, the invasion of alien species into the KNP could not be prevented. Unfortunately, little was done to combat the problem of IAPs until the 1950s, and even then, at an insufficient intensity to prevent or curtail the invasions. This was not a problem unique to the KNP, in fact, the book that is widely considered to have been the first influential book in establishing the field of ‘invasion ecology’ was only written in 1958 titled “The ecology of invasions by animals and plants” by Charles S. Elton.
The introduction and invasion of IAPs continued. The sour prickly pear (Opuntia stricta) was reportedly used as an ornamental plant species in Skukuza in the 1950s and would become one of the parks worst invasive alien plant species a few decades later. The alien species list has been periodically updated thanks to general botanical surveys and specific IAP surveys that targeted areas of high potential for introduction, as well as an increased awareness of the problem. It is estimated that there are now about 400 alien species in the KNP, of which about 350 are plants. Certainly, not all of the species are invasive and are unlikely to cause problems, however, it is not always possible to know which species are going to become problematic until too late.
Opuntia Stricta flowering
O.Stricta Fruit, eaten by birds
O.Stricta treated with cochineal
Graph of Increase of Invasions over time
