Thursday, 15 November, 2018

Namibia’s giant baobab trees are dying, climate change blamed

0611-Tree2 Namibia’s giant baobab trees are dying, climate change blamed
Melissa Porter | 13 June, 2018, 22:13

Some of the largest are more than 20m wide - one specimen in South Africa known as the Platland housed a bar until it began to rot and split apart in 2016.

It is also said that the intertwined baobab trees in Madagascar symbolise a couple from different villages who fell in love against the wishes of their elders. While using radio carbon dating to investigate the age and structure of trees in Zimbabwe, Namibia, South Africa, Botswana, and Zambia, the team discovered that many baobabs had stems that had died completely, or had partially collapsed.

For centuries - millennia even - they've towered over the savannah like giants from another world, but their long, nearly immortal watch is at last beginning to fade.

To conduct the study, researchers combed books, articles, and the internet and asked local Africans in order to locate the biggest baobabs.

Patruts co-authors hail from institutions in South Africa and the United States, and the work was published in Nature Plants on Monday. The common theory, Baum said, is that as the tree slowly grows around these scars, they can become large hollows. However, as it grows older, the roots give rise to several more stems in a ring. This leads to a odd feature in which, moving outward from the cavity center, the wood can actually get older for a time, rather than younger as might normally be expected.

A lot of scientists are increasingly getting concerned over the health of African baobab trees in Africa.

None of the trees showed obvious signs of infection, the researchers found, and the pattern of deaths did not fit what would be expected had the die-off been caused by a contagious disease. "Such fix growth would lead to an inverted age sequence where wood initially gets older as you move towards the outside of the tree from the hollow".

"Each of these trees was unique and special", he wrote. “They have seen more history than we can imagine.”.

Between 2005 and 2017, researchers documented and monitored 60 of the largest baobabs in southern Africa, including a handful believed to be more than 2,000 years old. And baobab specialist Sarah Venter of the University of Witwatersrand says if drought was the problem, it would affect all baobabs, not just the largest and oldest.

The researchers don't know for sure, but they describe the spate of high-profile deaths - the end of trees so grand they each had their own names - is an event of "unprecedented magnitude" that likely points to climate change.

In Zimbabwe, baobab deaths are reportedly being accompanied by what appears to be some type of fungus that turns the trees black before they die. After studying data on girth‚ height‚ wood volume and age‚ they noted the "unexpected and intriguing fact" that most of the oldest and biggest trees died during the study period.

The deaths are “an important modification in the ecosystem and the integrity of the biodiversity, ” Patrut said.