Invasive trees hold key to Cape Town's chronic water supply problems - Experts

The slogan has been planting trees to save the environment. In Cape Town, South Africa - the opposite is happening.

Faced with debilitating water supply problems, environmental workers are cutting down invasive trees growing on the outskirts of Cape Town.

They work for The Nature Conservancy, a global non-profit environmental organization.

The invasive trees - mostly pines - have deep root systems and take up more water than native species.

The removal of invasive trees also benefits native plants, as the pine trees compete with them for space.

"These trees are aliens," says tree cutter Onalenna Matsididi.

"They're the ones that absorb more water from Cape Town, like not only from Cape Town, wherever you find those trees, they're the ones that drink all the water and then you end up not having enough water."

Local resident Matsididi joined the training program last year when she saw an advertisement on Facebook and is now a full-time employee.

She knew she was cut out for the job as she has no fear of heights - the job requires reaching highly remote areas.

The work doesn't come without risks and extensive high-altitude training is required.

The tree cutters must hike, abseil and climb rough terrains.

The area they cover is 54,000 hectares. 350 people are needed to cut the invasive trees in this area.

A hundred of those are the so-called "high-angle operators", highly specialized teams that access the remote areas.

"Some, they think that I'm risking my life, some they think; 'How am I supposed to do this kind of job while there are other jobs outside?' They don't even understand that this is the job that I chose for myself, this is what I love," says Matsididi.

The project started after Cape Town almost hit 'Day Zero' more than two years ago, when the city was hit by severe drought and nearly ran out of water.

It's thought the invasive trees soak up about 55 billion liters of water from rainfall every year, enough to provide the entire city of Cape Town with water for about two months.

"We cut the down for mainly three reasons. Firstly, to save water, secondly to protect native plants because the pines outcompete native species for space, and then to avoid damaging wildfires," explains Louise Stafford, director of source water protection South Africa at The Nature Conservancy.

"We can save up to 55 billion liters of water every year if we clear invasive trees in the catchments of the greater Cape Town region. And to put that in context, it's two months water supply for Cape Town that we can save by removing the invasive trees from the water shelf."