Land desertification and desertification is a gradual process, but its harm and disaster are lasting and far-reaching. It will not only have an impact on contemporary people, but also cause harm to future generations. According to experts' calculation, the direct economic loss caused by land desertification in China is as high as 54 billion yuan every year, which directly or indirectly affects the survival, production and life of nearly 400 million people. Land desertification and desertification not only worsen the ecological environment, reduce land productivity, threaten river safety, but also aggravate poverty in sandy areas. In 2003, the per capita net income of farmers in China's heavy sand areas was only two thirds of the national average, and the gap with developed areas was even greater. The hazards of land desertification and desertification mainly include the following:

First, the available land resources are reduced.

Since 1950s, 670,000 hectares of cultivated land, 2.35 million hectares of grassland and 6.39 million hectares of forest land have been turned into sandy land in China. The desertification area in Houshan area of Wulanchabu League in Inner Mongolia, Alashan area, lower reaches of Tarim River in Xinjiang Uygur Autonomous Region, Qaidam Basin in Qinghai Province, Bashang area in Hebei Province and Naqu area in Xizang Autonomous Region increased by more than 4% on average. Due to the sandstorm, thousands of herders were forced to move to other places and become "ecological refugees".

According to the data provided by the State Forestry Administration of China, at the end of the 20th century, desertification expanded at an annual rate of 3,436 square kilometers. Every five years, a land area the size of a Beijing administrative division loses its use value due to desertification, and the population affected by desertification reaches1.700 million.

Second, the land productivity has seriously declined.

Soil wind erosion is the main component of desertification and the primary link. Wind erosion will cause the loss of organic matter and fine matter in soil, which will lead to soil coarsening and fertility decline. According to sampling analysis, in Mu Us sandy land, 5? 7 cm, 7,700 kg of organic matter, 387 kg of nitrogen, 549 kg of phosphorus and 39,000 kg of physical clay particles less than 0.0 1 mm were lost per hectare. China Academy of Sciences estimates that desertification causes 55.9 million tons of soil organic matter, nitrogen, phosphorus and potassium loss every year, equivalent to 270 million tons of chemical fertilizer, equivalent to 9.5 times the national agricultural chemical fertilizer output 1996.

Third, natural disasters have intensified.

There is also a kind of harm that can be directly felt by human beings, that is, it leads to the intensification of natural disasters and frequent sandstorms.