Here’s some info I found on Spekboom’s distribution in South Africa.
Addo Elephant National Park
Spekboom (Portulacaria Afra) grows in abundance in the drier parts of the Eastern Cape, especially on the high plateau Karoo hill slopes or flats (c. 400 to 1,060 meters above sea level) and is particularly prominent in the Addo bush to the south where there is significant summer heat. A vast section of Spekboom grows in the Addo Elephant National Park, situated in the Eastern Cape Province, near Port Elizabeth. The park was created to protect the once numerous Eastern Cape elephants. It consists of 12,126 hectares (30,315 acres) of bushveld, dominated mostly by Spekboom, which covers approximately 80% of the park’s area. Some 500 species of plants are to be found in the park. Elephants eat P. Afra from the top downwards allowing the plant to spread itself vegetatively by spreading