Earth.Org analysed satellite data to assess the changes in vegetation and land cover in the Mu Us desert in North-western China from 1985 to 2018. Images from Google Earth Engine were used to illustrate the changes in this 42 000 sq km area.
China is severely affected by desertification, a process caused by arable land and grassland degradation, and in the context of global warming, the expansion of erosion-induced drylands. More than a quarter of the country is covered in desert, with degraded land spanning 8- 10 million kms of the country and responsible for economic losses amounting to US$ 6.9 billion a year.
As a result of this degradation, the desert area is expanding at a rate of 2100 kms every year, affecting nearly 400 million people in China. Winds blow the sand towards neighbouring land which envelopes the fertile soil, degrading its fertility by shutting off its water and air supply.
A study conducted by Wang et. al in 2017 said that while the key driving forces of desertification in arid Asia (Northeast Asia to Central and West Asia) are poorly misunderstood, the Mu Us desert is an area where human activity is usually considered to be a key driving force of desertification.
The Mu Us desert used to be grazing land; the climate is wetter than most deserts in the world, with annual precipitation of 440mm in the southeast, and 250mm in the west. Therefore, it is an area of interest in China’s curbing of desertification as the desert has suitable conditions for vegetation rehabilitation.
The images below coincide with policies implemented from 1999 to convert farming land back to forest and grazing land back to grassland. Additionally, the Three-North Shelterbelt Forest Project started in 1979 consisted of a series of human-planted windbreaking forest strips in China designed to hold back the expansion of the Gobi Desert.
Afforestation in Yulin
The image above shows the changes of Yulin, a city at the southern edge of the desert, and surroundings in 1985, 2001 and 2018. Urban areas have been expanded, and the neighbouring lands are almost completely covered with vegetation. The grey area is the city of Yulin. Other dark green patches are trees or bushes and the bright yellow is moving sand, while the dimmer yellow is sand covered with herbs. In the 2018 picture, the darkest green on the west and northwest of Yulin are forests.
People living in Yulin, as well as Beijing and Hebei, are reporting less sandstorm weather; Mu Us is a major sand source powering the sandstorms in Beijing.
The featured image illustrates afforestation efforts in the Mu Us desert. Bright yellow areas illustrate sand and dark brownish-green areas are vegetation. The surrounding areas are significantly greener.
China has been working to control this process of degradation, which can be blamed on a combination of environmental and human factors, with several projects working on measures including afforestation, a process involving planting trees in barren lands so as to create forests. According to Wang et. al’s study, high levels of desertification occurred in the 1970s, and from the early 2000s to the present, rehabilitation has occurred in most regions of arid Asia, especially in China.
To optimise these afforestation programmes, a study conducted by Lu et. al in 2015 suggested choosing species of plants with the maximum water-use efficiency that could alleviate the conflict between environmental water needs and human needs. Specifically, project managers should seek to restore the natural grassland vegetation in arid and semiarid areas. However, this may prove difficult in afforestation areas where trees have already lowered the water table to the point where the vegetation will struggle to survive. The study also notes the importance of developing optimised groundwater use schemes to use the resource sustainably.
Another strategy that China has employed in controlling desertification includes the straw checkerboard method, used for fixing sand dunes. Straws of wheat, rice, reeds, and other materials are placed in the shape of a checkerboard. Half is buried in the sand and the other half is exposed. The straw decreases the wind velocity near the ground surface and can prevent wind erosion of the soil. In regions where the annual precipitation is over 200 mm, bushes and herbs can be planted to further improve the windbreak and sand dune fixation qualities. After establishment, the straw gradually rots to become organic soil matter.
China continues to show its commitment to curbing the potentially devastating and far-reaching effects of desertification through various projects that aim to not only rehabilitate degraded land, but empower communities and ensure the long-term economic growth of the territory.