biodiversity
Leucospermum tottum, the elegant pincushion protea. Photo Jay Caboz.
  • Cape Town has the most animal and plant species in the world, according to the City Nature Challenge.
  • The Mother City has at least 1,500 species more than its nearest competitor, La Paz in Bolivia.
  • But the region’s diversity is under threat: a recent study found that the Cape has the second highest plant extinction rate after Hawaii.

In its first year in the City Nature Challenge, Cape Town has hammered its competition and leads the world rankings as the most biologically diverse city on Earth.

The challenge, which began in the United States in 2016, is an international effort to get citizens to record plant and animal species, and to see which city can make the most observations and record the most creatures. It started out as a battle between San Francisco and Los Angeles, but went global in 2018.

In 2019, Cape Town won by a long margin. “We did not just win the challenge,” says Tony Rebelo, a senior scientist at the South African National Biodiversity Institute (Sanbi). “We totally outperformed all other cities when it came to species.”

The city had 53,763 observations by 1,141 people and recorded 4,588 different species. Its closest competition, La Paz in Bolivia, saw 46,931 observations and 3,006 species recorded - even though it had more people trying to observe species at 1,500. San Diego County in the United States came in third place, with 38,241 observations of 3,019 species.

The Cape is home to the smallest of the planet’s six floral kingdoms, and the Cape Floral Kingdom has a high number of unique species found nowhere else on Earth.

But at the same time, the Cape’s natural beauty is under threat. A new study published in scientific journal Nature Ecology and Evolution found that the Cape had suffered the second highest plant species extinction rate since 1900 at 37, after Hawaii which has lost 79.

“And again, Cape Town is outperforming all other cities on earth,” says Rebelo. “If the Cape Flora is the second worse place on earth for species threatened with extinction, the Mother City is the city with the largest problem.”

He estimates that 13 plant species are already extinct in the city, and this is having a knock-on effect on insects, amphibians, and other animals. “Cape Town has a huge responsibility for conservation of our biodiversity,” he says.

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