Grassroots Vol 20 No 4 | Page 30

NEWS

It ’ s not magic : Mysterious ‘ fairy circles ’ are built by grasses

Fairy circles might finally make sense . These regular barren patches that pop up in grasslands in Australia and Namibia have long created controversy , with some researchers arguing that they might be the result of underground termite activity . But now , the most detailed monitoring effort ever shows that fairy circles are engineered by the grasses themselves .

Stephanie Pappas

Current Address : Live Science Contributor Reprinted From : https :// bit . ly / 33Ve9pS
The research , published Sept . 21 in the Journal of Ecology , reveals how harsh , dry conditions in Australia , punctuated by occasional heavy rainstorms , create a hostile crust of clay that makes up the barren part of the fairy circles . But water runs off this crust , creating a relative oasis at its edges where grasses can make a home . It ' s a self-fulfilling cycle : Where there are no plants , weathering from rain and sun makes the soil ever more inhospitable , while areas where grass has managed to grow become a safe haven , where the vegetation cover lowers the soil temperature by up to 77 degrees Fahrenheit ( 25 degrees Celsius ), traps water and allows new seedlings to take root .
Figure 1 : The active formation of nearly circular grassland gaps ( fairy circles ), as seen from a helicopter . © S Getzin , University of Göttingen
" This is the positive feedback , where plants do ' self-organized patch formation :' They do ecosystem engineering to benefit as much as possible from the limited water in this harsh environment ," study lead author Stephan Getzin , an ecologist at the University of Göttingen and the Helmholtz Centre for Environmental Research in Germany , wrote in an email to Live Science .
Self-organizing patterns
Getzin and his colleagues had previously theorized that fairy circles are an example of what ' s called a Turing mechanism . This is a type of pattern formation first identified by English mathematician Alan Turing , in which spotted or striped patterns arise naturally from the interaction of two substances .
But to clinch this explanation for the
Figure 2 : A drone image of the weather station and a fairy circle from above . All cables of temperature and soil-moisture sensors have been buried underground . © S Getzin , University of Göttingen
29 Grassroots Vol 20 No 4 December 2020