Succulents endemic to South Africa and Namibia are drying up and dying across the increasingly hot northern part of their range. Mongabay contributor Leonie Joubert reports that a combination of climate change and overgrazing are causing desertification that the plants can’t survive.
In September 2024, botanists Wendy Foden and Kayleigh Murray surveyed an area Foden described as a “graveyard” of succulent plants in Namaqualand, an arid region shared by the two Southern African countries. It’s “an avenue of mostly dead Aloidendron ramosissimum,” Foden said. The plant is known as the maiden’s quiver tree in Namaqualand’s Richtersveld National Park.
The botanists surveyed plants in Richtersveld between 2022 and 2024 to understand the effects of an earlier drought. Their survey numbers haven’t been published yet, but Foden said the initial data show a continuing trend of the bushy 60-centimeter (2-foot) trees dying on the northern, hotter edge of their range.
In the cooler southern area of their range, quiver trees, from the same family as aloe vera, are thriving as temperatures become warmer and more favorable. However, the species isn’t shifting into new areas.
“We’d hoped to see them shift further south, and some colonization in newly suitable areas, but sadly, we see no evidence of that. We’re still increasingly losing populations and range up north, and we’re not expanding south,” Foden said.
Foden, who studies climate change impacts on biodiversity loss, has also been monitoring another species of quiver tree, Aloidendron dichotomum, listed as vulnerable on the IUCN Red List, for the last two decades. In fact, researchers have found that at least three species of quiver tree are dying off in an area that today resembles a moonscape but was once so abundant with plant life that it attracted wildlife including gemsbok (Oryx gazella) and springbok (Antidorcas marsupialis).
As the landscape has become hotter and drier, huge sand plumes, so large they can be seen from space, are developing across the region. The sand is released when sheep shear succulents too close to the ground, or when mining vehicles break through the cap that keeps the soil in place. As the sand loses its moorings, Joubert wrote, it’s picked up by strong winds. And while desert-adapted plants are able to survive sandstorms, too much sand exposure pummels the plants like sandpaper, ultimately smothering them.
Foden said “very active conservation approaches” need to be taken to save the species. In addition to reducing threats, some species may need to be cultivated in gardens, as reestablishing populations in the wild isn’t feasible for now.
This is a summary of “Bleak future for Karoo succulents as desert expands in South Africa” by Leonie Joubert.
Banner image of quiver trees by Leonie Joubert for Mongabay.
