Cape Town ploughs millions into clearing of invasive plants

Thirsty alien plants such as pine and eucalyptus trees are being cleared from mountain catchment areas across Cape Town. These plants drain billions of litres of water.

The City of Cape Town partnered with The Nature Conservancy (TNC) in July 2021 and committed to a two-year contract for R50-million to clear invasive species around important catchment areas such as Wemmershoek, Steenbras, Berg River, and Theewaterskloof. So far 4,617 hectares have been cleared. Another 7,000 hectares will be cleared over the next year. About 1,088 jobs have been created through the project.

The City, in a recent statement, said clearing invasive plants will, in a few years, result in savings of billions of litres of water per year.

Research from 2018 by the Greater Cape Town Water Fund (GCTWF) found that invasive species around these catchment areas contribute to significant water losses. It recommended that they be cleared as a sustainable and cost-effective way to reduce Cape Town’s water losses. According to its study, without intervention, the 55-billion litres of water sucked up by invasive trees could more than double in the next 30 years.

It noted that initial control operations would cost up to R40,000 per hectare “in very dense invasions in rugged terrain and riparian areas”. After this, the cost should decline as plant density and size decreases.

Jasper Slingsby, of the Department of Biological Science at UCT, wrote in 2018 that invasive alien species were a greater threat to Cape Town’s water supply than climate change.