Agriculture expert Bai Yonglei shows crabs raised in desert rice fields in Yulin City, northwest China's Shaanxi Province, Aug. 4, 2018. The administrative region of Yulin City is located to the south of the Maowusu Desert. Environment protection measures have curbed the expansion of the desert and then witnessed the retreat of the desert as a result of the increase in planted forests and grasslands after reducing and stopping farming and animal husbandry. (Xinhua/Tao Ming)