The paperbark thorn, formally known as Vachellia sieberiana, previously Acacia sieberiana, is one of the many kinds of shade trees on the grazing land around the Magaliesberg.

These trees have in the late twentieth century been spreading steadily across the land south of the Magaliesberg. This was at least partly caused by the practice of introducing cattle from the north where these trees are more prevalent. Cattle from the colder south are thought by farmers to be less capable of withstanding the parasitic diseases prevalent in this area. So stock is preferably brought in from the north. Livestock from the still warmer north have no problems in coping with the milder infestation of parasites around the Magaliesberg.

Thorn tree pods are eagerly grazed by cattle. On arrival, the dung of  "immigrant animals" offload bushveld plant seeds that duly add to the species diversity in the vegetation.