Mysterious “fairy circles” may arise from plants competing for water

Atlantic : Circular areas of bare soil freckling low-lying patches of vegetation in Australia and Namibia, known as fairy circles, have perplexed scientists for almost a century. Proposed causes have included sand termites, grazing ants, poisonous plants, and even radioactive gas leaks. Because of the circles’ regular, hexagonal spacing, Stephan Getzin of the University of Goettingen in Germany ruled out insect activity. While in Australia, Getzin and colleagues found that lack of rain probably drives the fairy circles’ formation. Bigger plants have deeper roots and draw more water than their smaller neighbors. The smaller plants die, leaving empty circles of soil that act as rain collectors and nourish the remaining plants. That proposal has been backed up by computer simulations. To add support to their theory, Getzin and colleagues are searching for more examples of fairy circles through the use of satellite imaging.