Tuesday, June 12, 2018

                 THE ANTHROPOCENE:  BAD FOR BAOBABS ?


NATURE NEWS  12 JUNE 2018

Africa’s majestic baobab trees are mysteriously dying
 LES BAOBABS MAJESTIQUES EXTRA-TERRESTRES
Between 2005 & 2017,[a team from] Babeş-Bolyai University in Romania.
dated more than 60 trees across Africa and its islands — nearly all of the continent’s largest, and potentially longest living, known baobabs. To compare ages of different parts of the trees, the researchers collected samples of wood from the inner cavities and exteriors of the trunks and from deep incisions in the stems, which were then sealed to prevent infection.
Patrut and his colleagues say that their measurements suggest the trees live so long because they periodically produce new stems, similarly to how other trees produce new branches. The team says that over time, these stems fuse into a ring-shaped structure, creating a false cavity in the middle.
BAOBABS IN A BAD MOOD
But, surprisingly, the scientists also found that most of the oldest and largest baobabs died during the study, often suddenly between measurements. Nine of the 13 oldest, and 5 of the 6 largest, baobabs measured died in the 12-year period — “an event of unprecedented magnitude”, says the study. The researchers found no signs of an epidemic or disease, leading them to suggest that changing climates in southern Africa could be to blame — but they stress that more research is needed to confirm this idea.
In one instance, the researchers observed that in 2010 and 2011, all the stems of Panke, a giant, sacred baobab tree in Zimbabwe, fell over and died. The team estimates that the tree was 2,450 years old, making it the oldest known accurately dated African baobab and angiosperm. Other trees across southern Africa also died completely, or had partial stem collapse.