Tibetan herdsmen carry baskets filled with highland willows in Ruo'ergai county, Sichuan province. Photos by Jiang Hongjing

April to May is the most precious time for sand control, because highland willow and grass have higher chance of survival.

In May, everything comes to life on the Ruo'ergai prairie in Sichuan province. Tibetan herdsmen transport organic fertilizer and grass protective screens, sowing grass seeds to prevent desertification. Soon, the bare sand dunes are covered with patchworks. Desertification is caused by multiple factors - climate warming, rainfall reduction, rodents and excessive grazing. Early April to the end of May is the most precious time for sand control, because highland willow and grass have higher chance of survival. The Ruo'ergai county has a total of 128 sand control spots, where people set up tents and live during the two months. According to the county's environmental protection and forestry bureau, from 2007 to date, 23,619.79 hectares of sandy grassland has been harnessed for sand control, accounting for 29 percent of the total desert in the region. By 2020 the county is expected to harness 42,984.5 hectares.