A letter to the editor of go! magazine (July 2016) alleged that “many of the halfmens succulents” in the |Ai-|Ais/Richtersveld Transfrontier Park have been damaged and that “it’s definitely vandalism”. But is this true? By Roxanne Reid

The halfmens (Pachypodium namaquanum) is a small, hardy plant that’s endemic to the lower Orange River Valley, across a range of some 15,000 square kilometers of Namibia and South Africa. You’ll find it on steep slopes of this area’s craggy mountains, where it grows very slowly but may live 300 years or more. It’s protected under both the Convention on the International Trade in Endangered Species of Wild Fauna and Flora (CITES) and domestic legislation in Namibia and South Africa.

Given that its restricted range makes the halfmens more vulnerable to extinction, it would certainly be worrying if vandalism was taking place. But is it?

On a visit to the Richtersveld at the end of July, I asked park manager Brent Whittington about it. He told me that their Richtersveld plant specialist and nursery assistant Pieter van Wyk had investigated the allegation and found it to be untrue. What he found was much more interesting.

Vandalism ruled out

After examining the sites mentioned in the letter, as well as other random populations, Pieter reported that they had self-amputated – something both the halfmens and kokerboom (Aloe dichotoma) are known to do when under threat.

The photo below is of one of these amputated halfmens limbs cut longitudinally. “I noticed a larva inside that caused the limb to rot,” said Pieter. So an insect laying an egg inside the plant is the root cause of the problem.

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Picture supplied by Brent Whittington

The white line, circled in red, is where the plant created a protective layer to prevent further contamination and then sealed it off and amputated from that point. “This suggests no sign of human interaction but rather a natural phenomenon,” he said.

“We’re concerned about the rate at which this is happening and have brought it to the attention of the responsible departments,” said Brent. Pieter has also contacted scientists to find out more about the larvae so they can identify the insect, discover whether it’s indigenous or alien, and find a way forward.

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We took this picture of a halfmens on Halfmens Pass in June 2004.

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We took this picture in July 2016. Although the viewpoint isn’t exactly the same as in the one above from June 2004, you can see from background features that it appears to be the same plant, now with fewer limbs.

New research project kicks off

“In addition, a three-year research project into the halfmens and kokerboom in the |Ai-|Ais/Richtersveld Transfrontier Park is kicking off in September,” Brent told me. It will look into whether these populations are in decline, and weigh up the role played by climate change, illegal wild collection, seed parasitism by insects, mining activities in Namibia, and grazing by domestic livestock in South Africa.

The field research, conducted by a conservation scientist in Namibia’s Ministry of Environment and Tourism in collaboration with the University of Cape Town, will study sites in both Namibia and South Africa. The results should allow environmentalists to figure out a strategy to conserve both species in the long term.

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Where it grows, the halfmens is often the tallest plant, with a bottle-shaped trunk and a crown of wavy leaves.

“There is illegal collection of the plants as well as their seeds,” Brent admitted, “but we can only combat this through stricter gate control and improved law enforcement.” A senior section ranger is being appointed to help with law enforcement and patrolling in the park. “This should be approved by the beginning of September. Then we can tackle the concerns about succulents as well as other illegal activities like gill netting along the Orange River.”

For more about parks and nature, see Roxanne’s weekly blog.