An enemy is turned back - with plants as weapons

Locals join the fight to bring back fertility to their region with the help of nature and technology

For several decades, people who live along the Hexi Corridor in northern China have fought to halt the desert as it spreads, and they have notched up significant victories.

To the eye, the barren landscapes of loess plateau in the city of Lanzhou, Gansu province, are at once grand and heart-rending, with an endless string of yellow mountains that Mother Nature seems to have given up on. Long scars formed by water erosion run from the top of the mountains down through the surface, adding to the picture of desolation.

In Yuzhong county of Lanzhou, the 300 millimeters of rain that fall each year wash loose earth down the mountains and into the Yellow River in torrents that run through Lanzhou.

Yet locals have managed to grow 253 square kilometers of caragana on the sunny and semi-sunny slopes of the loess mountains. The plants survive easily in the dry soil, with a lifespan of decades and some even projected to live for more than 100 years. Cargana's roots run deep into the soil, as much as three meters, and help to fix soil, preserve 34 percent of rainfall and reduce surface erosion by more than two-thirds.

The contrast between these mountains - those covered with flourishing plants and those covered with unsightly scars - is as clear as the difference between life and death.

Gongjing Tree Farm in Yuzhong is located on a tributary 37 kilometers from the Yellow River. It is one of the major sources of sediment in the river, whose tattered surrounding landform, loose soil and sparse vegetation cause severe water and soil loss.

Since 2013, local people have planted more than 3 million trees and dug 6 million holes to grow plant seeds. More than 75 percent of the seeds and their offspring have survived. Apart from shrubs such as caragana, they also grow Chinese thuja, Siberian apricot, Scots pine and elm - plants that can endure drought.

Over the same period, average annual rainfall in the region has risen from 280 mm to 330 mm.

Efforts by the locals have not only helped improve the natural environment, but have helped many make a living, for example by raising chickens in the areas where the trees they planted grow. From 2014 to 2017, 60 percent of a 20 million yuan ($3 million; 2.5 million euros; ￡2.3 million) government land care fund was paid in wages to locals.

Sunlight and water

The city of Zhangye, 500 kilometers northwest of Lanzhou, is famous for its natural environment, and through it runs the second-largest inland waterway in China, the Heihe River. Flat land, fertile soil, adequate water and copious sunlight have helped Zhangye become an important food production center for the country. In ancient times, it was an important military base on the Silk Road.

Yet, as fortunate as Zhangye seems to be, it has not totally escaped the misfortunes of nature. Two-thirds of one of its counties, Linze, on the southern edge of Badain Jaran Desert, consist of desert or semidesert, and it faces a severe threat from desertification.

Song Entai, 54, chief engineer of the Linze Forestry Bureau, says that when he was a boy, severe sandstorms were a frequent occurrence.

"From March to May in the 1970s and the '80s, when sandstorms came, you couldn't see your hand in front of your face. We had this little verse: 'When the wind blows, sand takes wing/Burying fields, houses and everything.' If farmers managed a harvest of 200 kilograms a mu (0.067 hectare) that was a good year, but in the bad years they lost everything.

"We still have sandstorms, but there's much less sand."

In 1978, Linze county was listed as a key county for combating desertification as the Three-North Forest Shelterbelt Development Program took effect. Since then, locals have set up sand defenses that consist of checkbox barriers, growing trees and shrubs inside them. Planting trees and shrubs is a top priority for the local government every April.

From south to north, trees such as poplar have been planted, and mixed forest zones have been planted, using sacsaoul and rose willows, and in the desert, shrubs that can better endure drought have been planted.

In the county's southern and central areas, plants have been put down to keep sand in check, and in the north, forest zones have been created that push seven kilometers into the Badain Jaran Desert.

The frost-free season, which was an average of 152 days a year in the 1950s and 1960s, is 170 to 180 days a year now.

"That gives crops more time to grow, resulting in improved output," Song says.

Farmers join battle

Linze is noted for its quality maize seeds and organic red dates, and planting in the name of fighting desertification has increased locals' incomes.

Other farmers in Gansu who have joined battle against the spreading desert include those of Minqin county, in the city of Wuwei, who are also earning money by growing Chinese medicine based on sacsaoul. Nearly 89.8 percent of Minqin's 15,900 sq km of land is desertified, compared with 94.5 percent in 2009. The county has a population of 270,000.

Had desertification gone unchecked, much more of the county would lie under sand, because at one stage the Tengger Desert and Badain Jaran Desert looked destined to meet, sandstorms laying siege to many villages between March and May. In 2007, locals officially joined the battle against desertification, and there is evidence to suggest that this work has paid off in reducing the severity of sand-wind events.

"People used to move the sand with carts," says Cai Chengcheng, 31, deputy head of the county in charge of desertification control. "There was so much sand in the wind that after a sandstorm, donkeys could climb onto the roofs of houses. The population kept falling as more people moved away. Now they can sweep sand away much more easily."

To make sand-fighting efforts more efficient, New Energy Technology Co of Gansu Construction and Investment Group Corp in Wuwei has developed sand-stabilizing machines to replace human labor, said to be the first of their kind in the world.

Researchers first use drones to learn about a desert's landform in an effort to work out the optimal point for measuring wind speed and direction, to determine the required size, height and direction of checkbox barriers.

Then the sand-stabilizing machines build barriers according to the requirements. The machines are large converted trucks. Woven straw is kept in the box of the truck.

Eventually, wind-breaking seedlings are planted in the checkboxes.

In the traditional way, three or four people can build more than 600 sq m of woven straw checkbox barriers in a day, but a machine operated by three people can build 40,000 sq m.

"This will help overcome the problem of labor shortages and rising labor costs," says Wang Chunfeng, deputy director of the International Department of the State Forestry Administration. "I hope this experience can be used in desertification control in other countries."

yangyang_1@chinadaily.com.cn

(China Daily European Weekly 08/04/2017 page16)