What
causes fairy circles, those circular barren patches of land found in the
grasslands of Southern Africa? German scientist Norbert Juergens found
the answer: termites.
These so-called fairy circles have variously been pinned on the presence
of other, poisonous plants, on ants, and even toxic gases rising from
below.
But Norbert
Juergens says the one ever-present factor is sand termites.
The creatures have engineered the rings to maintain a supply of water
in their environment, he
tells Science magazine. [...] He reports how the invertebrates (Psammotermes
allocerus) first clear a patch of ground by eating the roots of short-lived,
annual grasses.
This bare, sandy earth then becomes an effective rain trap - with no
vegetation, water cannot be lost through transpiration (the evaporation
of water from plants).
Instead, it collects, oasis-like, just below the surface where it can
sustain the termites and a supply of perennial grasses at the margins
of the circles. These are available to eat even in the driest seasons.
Jonathan Amos of the BBC News' Science & Environment has the story:
Here.
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