Counterintuitive: Chopping down water-guzzling gum trees along the Breede River returns millions of litres of water per hectare to the river system. Photo: Peter Chadwick
Removing thousands of water-guzzling eucalyptus trees is the least expensive and most effective way to help avert another “Day Zero” in Cape Town and surrounding areas. The mid-Breede River project is chopping down the alien invasive trees along 25km of the river near Bonnievale. Removing the trees will return seven-million litres of water per hectare to the river system.
With a hint of poetic justice, much of the harvested eucalyptus wood is being sold to global markets that include Australia, where the trees originate, and Vietnam.
The project involves the Western Cape department of agriculture’s LandCare Areawide Planning Initiative, Inhlabathi Environmental Services, farmers and private enterprises. Small, micro and medium-sized businesses will get development advice and training from Avocado Vision, an Inhlabathi affiliate, to ensure sustainability and increase jobs.
Since December, about 4 000 tonnes have been removed, says Inhlabathi director David Gardner, who has spearheaded the project. It is rooted in a “virtuous cycle-based approach” that incorporates 100% clearing of eucalyptus from river areas, ensuring that maximum value is extracted from the felled trees and that a certified aftercare programme is implemented to return the river ecosystem to its original state.
“We’re looking at ways of improving the economic value chains used in getting these trees eradicated,” says Gardner. “It’s about reinventing how invasive alien species are managed. At the moment, [removing invasive trees] has been a fully government-funded programme, and we’re trying to see how we can make it commercially viable.”
Alien invasive trees were brought to South Africa because they had some economic value, Gardner explains. “Wattles were used for matchsticks and tannins. Eucalyptus trees were used for shade and for wood, and various other things. Poplar trees were also used because they had really great wood. They liked our environment so much that they started taking over, specifically in these river areas.”
The potential for high-value commercial use includes decking, furniture, arts and crafts, charcoal, chips for soil reinvigoration and firewood.
In 2019, research by The Nature Conservancy showed how removing invasive alien plants was the most cost-effective intervention to avoid Day Zero, delivering the highest potential water savings.
The cost per 1 000 litres of water saved in six years is R1.20 for alien plant removal in seven sub-catchment areas, resulting in potential water saving in six years of 55.6-billion litres. Desalination per 1 000 litres costs R15.30, with a saving of 55-billion litres in six years. For waste water reuse, the cost per 1 000 litres is R11.40, saving 39.2-billion litres. Tapping into groundwater supplies costs R7.05 per 1 000 litres, saving 36.5-billion litres of water.
The Western Cape agriculture MEC, Ivan Meyer, said in a statement that higher pollution incidents and an increase in invasive alien plants would decrease the availability and quality of water, creating the perfect conditions for soil erosion, land degradation and loss of biodiversity.
Rudolph Röscher, LandCare district manager in the Cape Winelands district, described how the drought helped make farmers aware of how much water invasive alien plants use. “What makes this project unique is that this is a private sector investor who saw the opportunity and made contact with farmers. And then also taking the risk by saying, ‘We’re confident enough with the market, overseas or local, to harvest the wood’, at no cost to the landowner or the government, saving taxpayers money.”