A tale of elephants, ants, trees and fire shows how complex nature is

Aug 08, 2019

ECOLOGY IS A complicated thing. Given the facts that elephant damage often kills trees and bush fires often kill trees it would be reasonable to deduce that a combination of the two would make things worse. Counter-intuitively, though, as research just published in Biotropica, by Benjamin Wigley of Nelson Mandela University in South Africa shows, if a tree has already been damaged, fire can actually help to make things better.

One common way in which elephants harm trees is by stripping them of their bark. Dr Wigley, who did indeed start from the obvious assumption, set off to find out how much worse bush fires would make the effects of this bark-stripping. To this end he set up a study in the Kruger National Park, a reserve on South Africa’s border with Mozambique.

Since 1954, the Kruger has been the site of experiments in which plots of land have been burned at intervals, to discern the effects of fire on savannah ecology. Dr Wigley tapped into these experiments by looking at trees in three different zones. In one of these the vegetation was burned every year. In the second it was burned every other year. The third zone, by contrast, was actively shielded from fire.

To keep things consistent, he looked at the fate of a single tree species, the marula (pictured), in all three zones. He...

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