Some
grasslands in Namibia are spotted with mysterious lifeless circles that
appear, then disappear after a few decades. What are "fairy circles"
and why do they form?
Writing in the journal PLoS
One,Walter R. Tschinkel, the study’s author and a biologist at Florida
State University, reports that the circles can last 24 to 75 years.
The
circles, which range from about 6 to 30 feet in diameter, begin as bare
spots on an otherwise continuous grass carpet; after a few years,
taller grass starts to grow around the circle’s perimeter. [...]
So
while the reasons for the circles are still unknown, Dr. Tschinkel says
his study has raised several crucial questions: “Why are they regularly
distributed, rather than random or clumped; why do they appear with the
grass dying suddenly; why is there taller grass at the perimeter; and
why is there a difference in diameters?”
Until then, he continued, “the mystery of the fairy circles, or at least what causes them, remains a mystery.”
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