The
bizarre circles dotting the dry landscapes of southwestern Africa have
long posed a mystery, and there's still no accepted explanation for
them. Now Norbert Juergens (University of Hamburg) has put forward a new
explanation: the architects of these circles are termites, and they're
making water traps.
The circles (known as fairy circles) are barren patches of sandy earth situated amid grassy terrain,
each circle surrounded by a ring of taller grass. They grow and shrink
over 30-60 year periods. Local stories say the circles have supernatural
causes, and while scientists have offered a host of natural
explanations (toxic gases, poisonous plants, ants etc) none are well
supported by the evidence.
While working on conservation
projects, Jeurgens found that only one creature was present at all fairy
circle sites - the sand termite Psammotermes allocerus. These termites
don't build huge mounds like others do, living mostly under the surface
and "swimming" through fine tunnels in the sand.
According to
Juergens, the termites make the traps by eating plant roots, increasing
the size of the circle as they push out from the centre. When rain falls
it stays in the soil instead of being sucked up by plants, giving the
termites access to water even when there hasn't been rainfall for a long
time. Analysis has confirmed that fairy circle soil has a much higher
water content than the surrounding soil.
Not everyone agrees
with Jeurgens' conclusions. He's been accused of confusing correlation
with causation - just because the termites are in the circles doesn't
mean they make them. Others propose the circles are the result of
natural vegetation patterns. For now, there's still no definite answer
on what's causing fairy circles.
Photo credit: Norbert Juergens.
http://
http://www.bbc.co.uk/news/
http://www.wired.com/
http://news.sciencemag.org/
The
bizarre circles dotting the dry landscapes of southwestern Africa have
long posed a mystery, and there's still no accepted explanation for
them. Now Norbert Juergens (University of Hamburg) has put forward a new
explanation: the architects of these circles are termites, and they're
making water traps.
The circles (known as fairy circles) are barren patches of sandy earth situated amid grassy terrain, each circle surrounded by a ring of taller grass. They grow and shrink over 30-60 year periods. Local stories say the circles have supernatural causes, and while scientists have offered a host of natural explanations (toxic gases, poisonous plants, ants etc) none are well supported by the evidence.
While working on conservation projects, Jeurgens found that only one creature was present at all fairy circle sites - the sand termite Psammotermes allocerus. These termites don't build huge mounds like others do, living mostly under the surface and "swimming" through fine tunnels in the sand.
According to Juergens, the termites make the traps by eating plant roots, increasing the size of the circle as they push out from the centre. When rain falls it stays in the soil instead of being sucked up by plants, giving the termites access to water even when there hasn't been rainfall for a long time. Analysis has confirmed that fairy circle soil has a much higher water content than the surrounding soil.
Not everyone agrees with Jeurgens' conclusions. He's been accused of confusing correlation with causation - just because the termites are in the circles doesn't mean they make them. Others propose the circles are the result of natural vegetation patterns. For now, there's still no definite answer on what's causing fairy circles.
Photo credit: Norbert Juergens.
http://
http://www.bbc.co.uk/news/
http://www.wired.com/
http://news.sciencemag.org/
The circles (known as fairy circles) are barren patches of sandy earth situated amid grassy terrain, each circle surrounded by a ring of taller grass. They grow and shrink over 30-60 year periods. Local stories say the circles have supernatural causes, and while scientists have offered a host of natural explanations (toxic gases, poisonous plants, ants etc) none are well supported by the evidence.
While working on conservation projects, Jeurgens found that only one creature was present at all fairy circle sites - the sand termite Psammotermes allocerus. These termites don't build huge mounds like others do, living mostly under the surface and "swimming" through fine tunnels in the sand.
According to Juergens, the termites make the traps by eating plant roots, increasing the size of the circle as they push out from the centre. When rain falls it stays in the soil instead of being sucked up by plants, giving the termites access to water even when there hasn't been rainfall for a long time. Analysis has confirmed that fairy circle soil has a much higher water content than the surrounding soil.
Not everyone agrees with Jeurgens' conclusions. He's been accused of confusing correlation with causation - just because the termites are in the circles doesn't mean they make them. Others propose the circles are the result of natural vegetation patterns. For now, there's still no definite answer on what's causing fairy circles.
Photo credit: Norbert Juergens.
http://
http://www.bbc.co.uk/news/
http://www.wired.com/
http://news.sciencemag.org/
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