The mystery of the Namib Desert􀆳s circles沙漠中神秘的圆圈

在非洲南部的纳米布沙漠，雨季时地上会出现很多圆圈，圈外长草，圈内不长草。科学家一直在研究这些圆圈是怎么形成的。

For over 50 years， ecologists havestudied and debated the mystery of theNamib Desert’s“ fairy circles”. These cir⁃cular patches （小块土地）， mostly barren（不长草的） of grasses， have spread across1，100 kilometers in the arid grasslands ofSouthern Africa.

What makes the fairy circles distinc⁃tive are the barren patches within them，but the growth of grasses around them isnotable as well—they have found a way tothrive in what is considered one of thedriest places in the world. In previousresearch， Stephan Getzin， an ecologist atthe University of Göttingen in Germanyand lead author of the study， and his teamthought that plants in the circles outerrings had evolved to maximize their limi⁃ted water in the desert.

For the past three years， Getzin hasspent time in Namibia tracking the growthof the grasses to find more evidence forthis theory. During the drought season of2020， the researchers installed sensorsthat could record the moisture （ 水汽） ofthe soil at around 20 centimeters deep tomonitor the grasses’water uptake.

Analyzing data from the 2021 and2022 rainfall seasons， Getzin’s team foundwater within the circles was drying up fast，despite not having any grass to use it，while the grasses on the outside were asstrong as ever. Under the strong heat in thedesert， these well⁃established grasses hadevolved to create a vacuum （真空） systemaround their roots that drew any watertoward them. Meanwhile， the grasseswithin the circles， which attempt to growright after rainfall， were unable to receiveenough water to live.

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How did the mysterious circle of the Namib Desert form according to the text？

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