What is the main reason for the continuous expansion of desertified land in China in the past decade

Choose C. The causes of land desertification can be divided into two categories, namely natural causes and anthropogenic causes. The mechanism of desertification of natural causes can be summarized into two points:

First, the global climate change is abnormal, especially in the mid-latitude region, the climate is developing in a warm and dry direction, so that the large ecological background is conducive to the occurrence of desertification; Second, there are some unfavorable natural factors, such as arid climate, high precipitation variability, high soil sand content, loose and easy to move, etc., especially strong and frequent sand winds provide a strong driving force for the occurrence of desertification. The phenomenon of desertification has developed particularly rapidly since the beginning of the 20th century. In the last 100 years, changes in natural conditions have been small enough to cause major environmental changes.

Therefore, the surge in population pressure and a large number of environmentally damaging economic activities during the same period are the main causes of large-scale land desertification. At present, there is a relatively unified understanding of the anthropogenic causes of desertification, that is, due to the continuous growth of population pressure and the widespread existence of such phenomena as indiscriminate reclamation, indiscriminate grazing, and indiscriminate woodlogging, vegetation destruction and rapid development of desertification. Since the middle of the 20th century, China has begun to pay attention to the problem of land desertification, but the rate of desertification has not slowed down but accelerated in the 90s, and at the same time, the phenomenon of sandstorms directly related to land desertification is relatively more active than before, which is a symptom of environmental degradation.

In fact, it is nature's revenge for man's previous wanton destruction of the environment.

Definitely c, I'm doing it too. a is simply not enough to desertify the land; b is clearly incorrect; d Not really.

c. Human industrial and agricultural production and other production activities.

Shameless! Grass! You should answer it yourself! If you don't have the ability, don't report it! Indecent.

Are you all from Sichuan???

China's "Three Norths" region (Northwest, North China, Northeast China) has a total area of about 10,000 square kilometers. Among them, there are 10,000 square kilometers that have been formed in history, and 10,000 square kilometers that have been formed in the past 100 years. In addition, there is a risk of desertification for 10,000 square kilometers.

According to preliminary statistics, from the 50s to the end of the 70s of the 20th century, the desertified land expanded by an average of about 1,500 square kilometers per year. Desertification affects 11 cities (prefectures, prefectures) and 212 counties (cities and districts), with a population of 35 million, 4 million hectares of cultivated land and 5 million hectares of grassland. In recent years, desertification has also occurred in the humid areas of southern China, such as the Poyang Lake Plain.

Our country is facing a serious problem of land desertification. In recent years, China's desertified land area has increased from 10,000 square kilometers to 10,000 square kilometers. Among the desertified land in China, the land that has been desertified is 10,000 square kilometers, the land that is potentially desertified is 10,000 square kilometers, and the land that is wind-blown desertification in the humid zone is 10,000 square kilometers.

More than 5 million people are affected by desertification, with nearly 4 million hectares of dry farmland and 5 million hectares of pasture affected. Therefore, the situation of continuous erosion of China's land resources is very serious. The main reason for this situation is that the general trend is that desertification and desertification are still developing and intensifying.

The main reason for the formation of these new desertified lands is the irrational exploitation and utilization of land by human beings, resulting in the destruction of vegetation.

In recent years, excessive land reclamation, over-ridge grazing, indiscriminate deforestation and irrational use of water resources have seriously degraded land, destroyed forests, and gradually dried out the climate, resulting in serious land desertification. Therefore, the new increase in desertified land is mainly due to irrational production activities.

Land desertification refers to arid and semi-arid areas, due to the influence of natural factors and human activities caused by the destruction of the ecosystem, so that the original non-desert areas have a similar desert environment changes. Due to the irrational economic activities of human beings, the environmental degradation process similar to the desert landscape has occurred in the areas of the original non-sandy desert, which are mainly marked by wind-blown sand activities and undulating sand dunes.

Measures to combat desertification of land

1. Rational use of water resources.

The rational use of water resources is extremely important in the process of desertification prevention, but the most important thing is to maintain the balance of water and soil. To solve the problem of water resources, we should mainly consider water drawing, water transportation, and water-saving irrigation. Among them, there are two main methods of water drawing: underground well water extraction project and qanats, water transmission mainly includes channel water diversion and pipeline water transportation, and water-saving irrigation mainly includes sprinkler irrigation and micro irrigation.

2. Use biological measures and engineering measures to build a protection system.

Integrate economic, social and ecological benefits, and apply biological measures according to local conditions, such as the construction of ecological and natural restoration projects, the implementation of forest and grassland agricultural land restoration projects, etc., or take engineering measures, such as planting windbreak and sand-fixing plants, building protective walls, etc., in an effort to dilute the negative impact of man-made damage or severe weather on the land. The most common methods, such as afforestation, returning farmland to forest, and returning farmland to grassland, can increase the coverage of surface vegetation, prevent soil erosion, and slow down the rate of land desertification.

1. Population growth. The population is growing while the land area is shrinking, leading to overuse of land.

2. Overgrazing, over-reclamation, and over-logging. These actions have led to desertification of the land or the aggravation of the desertification of the land.

3. Unreasonable use of water resources and unreasonable mining. This has also had a significant impact on the desertification of the land.

4. There is also the influence of geographical environment factors. Arid and semi-arid regions are deep in the hinterland of the continent and have the least precipitation and the largest evaporation in the same latitude in the world, and these places are prone to desertification.

5. Finally, there is the influence of climate. When the climate becomes drier, desertification develops, and when the climate becomes wetter, desertification reverses.

What are the hazards of land desertification?

1. Reduction of available land resources.

Desertification means land degradation, and the continuous decline in the productive capacity of desertified land will lead to a reduction in agricultural and animal husbandry production land, and farmers and herders will be forced to "ecological migration". At the same time, desertification will also affect the land for residential production by severe sandstorms and resource shortages, resulting in the reduction or even disappearance of land population.

2. Threatening traffic safety.

Shifting sand dunes can bury roads and railways; Sandstorms can reduce atmospheric visibility and force airports and roads to shut down.

3. Natural disasters are intensifying.

The most obvious aspect of desertification is the intensification of natural disasters. Sandstorms, sandstorms, and fog will ruthlessly disrupt the order of our production and life, and even endanger people's health.

4. Land productivity is in serious decline.

Soil wind erosion is not only a major component of desertification, but also a primary link. Wind erosion causes the loss of organic matter and fine-grained matter in the soil, resulting in soil coarsening and reduced fertility.

Climatic factors of desertification of the land.

The updraft in the equatorial region flows in the direction of the poles at high altitude, due to the influence of the earth's rotational deflection force, near 30 degrees north and south latitudes, the air in the large wide collapse no longer advances, but accumulates at high altitude, and radiates to cool and sink, and the near-surface atmosphere maintains high pressure all year round, which is called the "subtropical high pressure belt" in meteorology. Except for the monsoon climate zone on the east coast of Eurasia, this area has a dry climate and few clouds and rains, and has become the main desert distribution area.

Desertification in the narrow sense (i.e., desertification) refers to the process of environmental change similar to desert landscape in areas that resemble desert landscapes in fragile ecosystems due to excessive economic activities by humans and the destruction of their balance. That is, to cut down trees indiscriminately, so that the balance of the land is destroyed and turned into sand!

Land desertification: Land degradation in arid, semi-arid and dry sub-humid areas due to a variety of factors, including climate variability and human activities. Desertification in the narrow sense (i.e

Desertification refers to the process of environmental change similar to desert landscapes in areas that resemble desert landscapes due to excessive economic activities by humans in fragile ecosystems.

Land desertification: refers to arid and semi-arid areas, due to the influence of natural factors and human activities caused by the destruction of ecosystems, so that the original non-desert areas have a desert-like environment changes. In arid and sub-arid areas, under the conditions of arid and windy and loose sandy surface, due to the irrational economic activities of human beings, the environmental degradation process similar to desert landscape has occurred in the areas of the original non-sandy desert, which are mainly marked by aeolian sand activities and undulating sand dunes.

There is not much difference between land desertification and land desertification, but the severity of desertification is higher.

Status:

On August 16, the United Nations officially launched the "United Nations Decade for Deserts and Combating Desertification (2010-2020)" in Brazil to further raise awareness of the threat of desertification, land degradation and drought to sustainable development and poverty alleviation.

UN Secretary-General Ban Ki-moon said in a statement: "Both climate change and poor water management have contributed to the deterioration of the land situation. The continued degradation of land not only poses a threat to food security, causing famine in the most affected areas, but is also stealing other rich and fertile lands from the world.

The 10-year plan was officially launched on the occasion of the Second International Conference on "Climate, Sustainability and Development in Semi-Arid Regions", held in Fortaleza, Ceará, Brazil.

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Natural causes: arid climate, loose sandy sediments on flat land, windy days and concentrated in the dry season in winter and spring.

Anthropogenic causes: over-mining, over-reclamation, overgrazing, improper use of water resources, etc.