Community rallies behind Clanwilliam cedar trees

By LUKE FOLB Time of article published May 28, 2019

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Cape Town - Clanwilliam cedar trees were in abundance across the Cederberg, but only a handful of these endemic trees are left and now face extinction.

The Cederberg mountains are the only place in the world where the Clanwilliam cedar grows. It is listed as an endangered species on the International Union for Conservation of Nature (IUCN) Red data list.

Today, between 13000 and 15000 are left in the region. The tree is the only species that survived the last Ice Age period and are meant to grow in snowy and cold conditions.

Cederberg conservation manager Rika du Plessis said climate change conditions had severely affected the tree populations.

“Over 200 years ago you would have found these trees all over the Cederberg, but this number has significantly dropped due to climate change. We’ve been in a climate change since the last Ice Age.

“We used to have long winter rains but now only have these short erratic bursts and there isn’t enough water at a time for them (tree seeds) to germinate,” she said.

Cederberg conservation manager Rika du Plessis with cedar tree saplings. Picture: CapeNature.

Fires have also played a large part in the population reduction and the Clanwilliam cedar doesn’t regrow after a fire - unlike the surrounding fynbos.

“They have very high oil content and because of the oil the tree doesn’t have to even really burn because there is spontaneous combustion. A fire can be 30m away and the tree will just burst into flames,” said Du Plessis.

She said other than climate change, the culling of the Clanwilliam cedar was accelerated when settlers ravaged the region.

A synthesis of long-term monitoring data of trees in four permanent plots recorded a 94% population decline between 1977 and 2003.

“The seeds take a couple of years to reach maturity in the cones. Each cone has four lobes and the cones open up on the seam and seeds drop out with three seeds per lobe making 12 seeds per cone.

“They will lie in the soil until the winter rains and then germinate, but if it doesn’t germinate it can lie dormant for years so we collect these seeds in the soil.

“From 1896, they put in conservation efforts to spread seeds because they realised there would be a problem and actually planted over 17000 seedlings and collected 4.3 tonnes worth of seeds during a two year period.”

She added that today, she and her team struggle to collect 100g of seeds each year, which make up around 1000 trees.

Since 2003, the Heuningvlei community has held annual tree planting events with conservation authority CapeNature and Bushmans Kloof Wilderness Reserve, to ensure the ongoing survival of the species.

Heuningvlei was selected as the location because the Clanwilliam cedar has the best chance of survival in rocky areas around 900m and higher above sea level where the mature trees and seedlings are protected from fire.

The last event was held on May 18.

Du Plessis said the aim was to plant around 2000 trees a year, with the annual event open to the public to participate in the replanting ceremony.

Children are brought along to take part in the event while many older people also make the trip to contribute to conservation.

“We planted 200 trees at the last event and the good news is that the area received good rain a few days after. This will help the trees to settle into their new home.

“While there will be no adverse effects if we lose these trees, it would be a great shame considering they’re nowhere else in the world,” said Du Plessis.

The small trees are planted in a Waterboxx designed by Dutch company Groasis. The Waterboxx is filled with around 2 litres of water, which then drips to the tree’s roots and helps increase its chance of survival.

Once the tree is strong enough to survive without the Waterboxx, it is removed, and another tree is planted.

Weekend Argus

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