in the role played sandstorms.Quicksand of Oasis external frontier of sandstorms invaded farmland and was further deteriorating,the very poor and fragile ecological environment.

• 绿洲外围风沙前沿地带在起风沙的作用下，流沙侵入农田，进一步恶化了本已很贫瘠而又脆弱的农业生态环境。