麻豆影院

Barren circles of red sand, 30 to 100 feet wide, form a Swiss-cheese pattern across hundreds of miles of arid grasslands in the Namib Desert of southwest Africa. No one knows why. Local legends call them footprints of the gods.

Scientists have proposed various causes for these 鈥渇airy circles,鈥� as they鈥檙e also known, including hungry termites and underground gases wafting up and killing patches of grass. Now a CU 麻豆影院 team is going back to basics as it tries to solve this enduring ecological mystery.

鈥淲e just went to the principles of how ecosystems work and didn't let how cool these were distract us,鈥� said Nichole Barger, professor of ecology and evolutionary biology, who鈥檚 closing in on answers after years of research.

It鈥檚 no wonder it鈥檚 taken a while: Just getting to the fairy circles, which can last for up to 60 years, is a challenge.

In April, Barger and her team traveled six hours southeast from Windhoek, Namibia鈥檚 capital, into the NamibRand Nature Reserve, far from gas and groceries. They continued in an all-wheel-drive truck over sandy roads and dunes to follow up on an ongoing experiment.

Two years earlier, Barger had added water, fertilizer and insecticide to some circles to see if she could 鈥渒ill鈥� them by changing the conditions they form in. The hypothesis: Plants organize into the striking pattern simply due to competition.

Sure enough, in fairy circles where water and nutrients were both added, the grasses grew back 鈥� the circles started to 鈥渄ie.鈥� Adding resources had decreased competition among plants, which otherwise fight for them in the low-nutrient, dry environment.

The findings suggest fairy circles form when starved plants die, freeing resources for their neighbors, which grow tall around the dead patch and form the characteristic ring.

The promising results are still only 鈥減ieces of the puzzle,鈥� Barger said: The initial cause and what perpetuates the circles might be different. She noticed, for instance, that in fenced circles, inaccessible to zebra and oryx, the grasses also grew back, indicating grazers might play a role in maintaining fairy circles.

On her last day in Namibia, a local guide asked Barger, 鈥淲hat鈥檚 causing the circles in the hills?鈥�

She鈥檇 never heard of those circles 鈥� a new mystery for her next trip.
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Photo by Nichole Barger听