Bankrupt bush encroachment on the increase

South Africa’s grasslands are threatened by the encroachment of bankrupt bush (Seriphium plumosum), according to Dan’sile Cindi, deputy director: Ecological Infrastructure at the South African National Biodiversity Institute (SANBI).

Bankrupt bush is listed as an indicator of bush encroachment in the North West and Free State in terms of Regulation 16 of CARA (the Conservation of Agricultural Resources Act, Act 43 of 1983).

However, the occurrence of bankrupt bush had markedly increased since 1983. “The bush has spread to most of the country and resulted in a decrease in grazing, which in turn has affected food security,” she said.

Bankrupt bush belongs to the plant family Asteraceae, Cindi explained. It was also known as slangbos or vaalbos, and was indigenous to South Africa. Seriphium comprises a total of nine species, of which five occur in South Africa.

Seriphum plumosum was regarded as the most aggressive encroacher. Bankrupt bush was extremely difficult to control once established, said Cindi. The reasons for the uncontrolled occurrence and densification of the plant, especially over the past five to 10 years, had not been determined yet.

Researchers suspected that elevated carbon dioxide levels might have played a role in the increased colonisation by bankrupt bush.

According to a SAPIA (Southern African Plant Invader Atlas) newsletter, South Africa had a total surface area of 122 million ha, of which 71% consisted of veld. This was mostly used for livestock and game ranching.

It was estimated that about 10 million ha in South Africa had been infested by bankrupt bush. It could potentially turn a profitable fodder source into a degraded piece of land on which sustainable livestock production was no longer possible.