How does China combat desertification? | World Day to Combat Desertification and Drought

Produced by: Science Popularization China

Author: Zhao Xueyong (Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences)

Producer: China Science Expo

Desertification is a key and difficult global ecological issue. Since 1995, the United Nations has designated June 17 of each year as "World Day to Combat Desertification and Drought" to raise people's attention to desertification prevention and control and to arouse their sense of responsibility and urgency in desertification prevention and control.

In 1996, China became a signatory to the United Nations Convention to Combat Desertification. Over the past 20 years, China has made unremitting explorations on the path of desertification control and provided a Chinese solution to sand control for the global problem of desertification control.

(Photo source: Veer Gallery)

If you want to “control sand”, you have to “plant trees”!

China has provided a model of "suitable land, suitable trees, and water-based planting" in the prevention and control of sand dunes. For example, in the Horqin Sandy Land, local shrubs such as Caragana microphylla, Artemisia tsabaha, and Salix pumila are mostly used to fix the mobile sand dunes and provide protection. Then, local herbaceous plants will gradually invade naturally under the protection conditions to establish a relatively good sand-fixing vegetation cover.

Shrubs in the desert

(Photo source: Veer Gallery)

In western Inner Mongolia and areas west of it, most of the artificial sand-fixing vegetation is dominated by shrubs such as Haloxylon ammodendron, Elaeagnus cyrtonema, and Calligonum mongolica; on salinized land, shrubs such as Tamarix, Nitraria tangutorum, and Lophatherum hemp, as well as Populus euphratica, are used.

These selections of trees suitable for the land have established a stable vegetation system that can prevent wind and fix sand. At the same time, they have also inspired our relevant scientific researchers: only a truly effective, sustainable and replicable sand prevention and control model is the most suitable model.

Can the "economic crops" we often talk about be used to control sand?

The traditional definition of cash crops is crops that can provide raw materials for industry, especially light industry, and generally include fiber crops, oil crops, sugar crops, seasoning crops, medicinal crops, dye crops, ornamental crops, fruit and vegetable crops, etc.

Before the 1990s, poplar, willow and pine trees were mostly used as building materials. In particular, fast-growing poplars are not only a common building material, but also a good firewood. They can also quickly fix sand in areas with good moisture conditions, and have attracted the attention of the government, researchers and the public.

Later, with the increase of population and climate change, the availability of water resources in the sandy lands of eastern China also generally decreased, and water became increasingly restrictive to plant growth, development and vegetation establishment. Especially at the beginning of this century, my country saw the phenomenon of regional natural vegetation degradation and death of artificial vegetation. There were even sayings that "the vegetation degradation in Ordos was caused by goats" and that the frequent sandstorms in the semi-arid areas of the northwest were caused by poplar trees.

Sand in the desert

(Photo source: Veer Gallery)

If these are the "trouble", then the root cause is our lack of understanding of climate change, changes in water resources carrying capacity in the target area and the adaptability of fast-growing tree species. According to our investigation and research, in the northwest region, fast-growing poplars still play their ecological and economic roles in suitable places, such as "four-side" tree planting - planting various trees in a planned manner beside houses, villages, roadsides and water; but large-scale, high-density afforestation to fix sand should be avoided.

At the same time, we also need to answer a question that everyone is concerned about: Will "sand fixation and afforestation" cause damage to the environment? The answer is no. If it causes "damage" to the environment during afforestation, it is because we have not achieved "moderation", or simply put, we have not done it well.

Scientific sand control requires “new ideas”!

Science and technology play a huge role in sand control. In the process of sand prevention and control, the relevant science and technology have also gone through a long road of learning, development and innovation.

(Photo source: Veer Gallery)

Wind and sand physics is one of the basic disciplines for sand prevention and control. Therefore, as early as the 1930s and 1960s, researchers used the method of building 20-30 cm high wheat straw grid sand barriers on the upwind direction of the railway in the Ningxia Zhongwei section railway sand control system, based on the fact that sand barriers can effectively prevent and control the hazards of wind and sand flows within a height range of 0-60 cm. This technology originated from the Turkmen Desert Research Institute of the Soviet Union and was successfully introduced and transformed by the Shapotou Desert Research and Experimental Station of the Chinese Academy of Sciences and the Sand Control Station of the Ministry of Railways.

If we say that in the late 1970s, China's sand control and sand fixation was still at the stage where mechanical sand fixation was the main method and biological sand fixation was the auxiliary method, then from 1990 to 2010, China entered a development stage where mechanical sand fixation was combined with biological sand fixation .

At the same time, this period was also a period of rapid development in which Chinese researchers, based on their understanding of the relationship between plants, soil, water and climate change, developed and demonstrated sand prevention and control technologies suitable for arid, semi-arid and semi-humid areas in northern China, promoted the development of sand prevention and control theory and applied it to guide practice.

After 2010, based on the above, mechanized sand fixation technology entered a new stage of rapid development, that is, a stage of combining physical sand fixation, chemical sand fixation and biological sand fixation supported by the rapid development of sand fixation machinery.

Although remarkable achievements have been made in sand prevention and control in the above three stages, my country still faces severe challenges of land desertification and its prevention and control.

Specifically, there are pressures from climate change and population growth, pressures from the continued expansion of cultivated land resources and grazing in arid, semi-arid and semi-humid areas driven by development needs, and pressures from industrial transfer... These resource utilization pressures are concentrated and "pressed" on water resources. However, as we all know, water resources are the limiting resource in the northwest region, so China's sand control and sand control work has a long way to go.

(Photo source: Veer Gallery)

Initial results of sand control are evident, but efforts are still needed to move forward

As mentioned above, China has made great progress in desertification control theories, technologies and models, and achieved "world-renowned" results, but the problems it faces remain severe.

In terms of sand control theory, Chinese scientists have gradually built a theoretical system of sand control technology application, model demonstration and engineering implementation based on water resources carrying capacity. The formation of suitable land, suitable trees and adaptive management system is basically based on this eco-geography and eco-hydrology foundation.

In terms of technology, Chinese scientists have developed a series of technologies for establishing vegetation to prevent and fix sand, near-natural restoration of degraded vegetation, and high-yield and water-saving technologies for economic crops, targeting the water, soil, air, and biological characteristics and problems in arid, semi-arid, and semi-humid areas, achieving good ecological, economic, and social benefits.

In terms of engineering sand fixation, whether it is the successful Shapotou Railway Sand Control Project in the 1950s and 1960s, the "Three Norths Shelterbelt Project" implemented in the 1970s, or the Xinjiang Tarim Basin Sand Crossing Highway Project launched in the late 1980s, they have all successfully protected some target projects and areas that are vital to the national economy and people's livelihood under drought or extreme drought conditions, achieved a series of economic, ecological and social benefits, and have been widely recognized by domestic and foreign peers and governments.

Highway through the Taklamakan Desert

(Photo source: Xinhua News Agency)

In terms of sand prevention and control models, in addition to the above-mentioned engineering models, the Babusha model, the Kubuqi model, the Horqin Sandy Land model and other models are all successful models for desertification prevention and control in China's arid, semi-arid and semi-humid areas.

The salient feature of China's land desertification prevention and control is "taking into account people's livelihood and development while preventing and controlling sand". While achieving the above results, we are still faced with problems such as the great harm caused by wind and sand, the large area of ​​control area, the great pressure on resource utilization and the great difficulty caused by regional differences. In particular, the construction of an adaptive management system for preventing and controlling sand based on precise natural and social zoning needs to be further strengthened and explored continuously.

Conclusion

Of course, sand prevention and control is what our scientific researchers have been exploring and practicing unremittingly. As ordinary people, it may be difficult for you to personally participate in the construction projects to prevent and control desertification, but we can start with small things around us - save every drop of water, every kilowatt-hour of electricity, every grain of food... these can all contribute to the prevention and control of desertification.

Editor: Sun Chenyu