The recent situation of desertification in our country and what are the hazards of desertification

The reasonable population density in the valley of the Tibetan Plateau is no more than 20 people per square kilometer, but today it is 90 people in the region, which is much more than the carrying capacity of the land. Over-cultivation and overgrazing caused wind and sand to rage. In southwest China, the mountains are high and the slopes are steep, the soil is barren, and the rocky desertification is serious after the destruction of vegetation.

Rocky desertification permanently renders land unproductive and therefore more serious and difficult to control than desertification.

On the first floor, it is copied from the encyclopedia entry ---desertification.

Land desertification is a sign of environmental degradation and a positive feedback process of environmental instability. If fundamental measures are not taken, the process of land erosion and desertification will not stop automatically, but will intensify development. For example:

The area of desertification in the central region of Ningxia has reached 10,000 hectares. Its pace of development is fast. In the past 22 years, the area of desertification has increased from 20% to 50-60% of the area.

The problem is serious.

Land DesertificationDeserts are a product of an arid climate, and there were deserts on Earth long before the advent of humans. But there is no insurmountable line between a desolate desert and a fertile steppe. With water, lush plants can grow on the desert and become an oasis full of life; Without water and plants, green spaces can quickly degenerate into gravel.

In order to get more food, people will open up wasteland for farming and overgraze regardless of climate and land conditions; In order to solve the fuel problem, regardless of the consequences, trees and grass are cut and cut indiscriminately. The arid and semi-arid regions, which were already dry and windy, are now ravaged and the vegetation destroyed, with less precipitation and stronger winds, strong winds eroding the topsoil, increasing the amount of sand and slowly developing sand dunes. This turns arable land into desertified land that is not suitable for grazing and farming.

1. The production potential of the land is declining, and the biological production potential of the land is gradually decayed and disappeared due to desertification.

2. Land productivity has declined, since the 90s of the 20th century, the output of farmland seriously affected by land desertification has generally dropped by 70% 80%, and the annual loss in this area in the world is as high as 26 billion US dollars.

3. The decline in grassland quality and the loss of land desertification to animal husbandry are very serious in most grasslands in the world, especially in the arid steppe areas of developing countries. Due to the harm of desertification, the development of animal husbandry has been hindered for a long time, and many areas have shown a downward trend.

Desertification control:

Desert plant management refers to the sowing of psammophytes in desert areas to stop desert expansion and improve desert land. Psammophytes have the characteristics of less water transpiration and well-developed mechanical and transport tissues, which can resist the attack of strong winds and deliver water and nutrients to the organs that need it as soon as possible.

Its cells often maintain a high osmotic pressure, and have a strong ability to continuously absorb water, so that the plant is not easy to lose water and can adapt to the arid and rainy environment. The method of its management: the planned cultivation of psammophytes in desert areas to create sand forests.

Windbreaks are created on the edge of the desert to weaken the winds in the desert area and stop the desert from expanding.

Desertification is particularly harmful to agriculture. In desertified areas, seeds and fertilizers are blown away, seedlings are uprooted, soil water is lost, and seedlings are dried to death or buried. In some places, it is necessary to remedy it repeatedly, and even miss the agricultural time.

The degradation of grasslands caused by desertification has led to a gradual reduction or even a complete loss of dominant grass species suitable for livestock consumption. The pasture has become low and sparse, the yield has been significantly reduced, and the carrying capacity of the pasture has been greatly reduced.

Desertification causes blockages of rivers, reservoirs and canals. The Yellow River transports an average of 1.6 billion tons of sediment every year, of which 1.2 billion tons come from desertified areas. Every year, more than 50,000 kilometers of irrigation canals across the country are affected by wind and sand.

Desertification has caused damage to railway embankments, bridges and culverts in some areas, caused sand to cover highway embankments and roads, forced the suspension of highway traffic, and even abandoned highways. The sand and dust weather caused by desertification affects the normal take-off and landing of aircraft.

Windswept sand activities damage communications, power transmission lines and facilities, and the resulting disasters threaten the safety of residents.

1. Global status of desertification.

1. Global status of desertification.

According to the United Nations Environment Programme's assessment of desertification in the world (1992), about 1 billion people in the world are affected by desertification, 2 3 countries and regions in the world are affected by desertification, and 1 4 of the world's land area (70% of the world's arid and semi-arid regions), that is, 100 million hectares of land are threatened by desert dispersion.

2) Trends in global desertification.

According to the United Nations Environment Programme's assessment of desertification worldwide, the global desertification area is still expanding, from 100 million hectares in 1984 to 100 million hectares in 1991. Every year, 50,000-70,000 square kilometres of the world's land is converted to desertification, and 6 million hectares of arable land are lost every year due to desertification.

2. The current situation of desertification in China.

China's arid, semi-arid and sub-humid arid areas cover an area of 10,000 square meters, accounting for 10,000 percent of the total land area. Desertification in China is mainly divided into four types: wind erosion desertification, water erosion desertification, freeze-thaw desertification and soil salinization. According to the results of the second national monitoring of desert Ponzi in 1999, China's desertified land area is 10,000 square kilometers, accounting for the area where desertification may occur and the land area of the country.

3. The causes of desertification in China.

1) Extensive land use, leading to desertification.

In the desertification areas of China, dry farming is the mainstay, and the area of irrigated land only accounts for the total area of cultivated land. The irrigated land in the sandy area of Inner Mongolia only accounts for the total cultivated area, the northern part of Shanxi, and the northern part of Shaanxi.

One-third of the Earth's land mass is desert. Deserts formed by climatic factors are concentrated in the north and south latitudes between 15° and 35°.

It is concentrated in the central part of Asia and the western part of the United States.

Genesis. Desertification, that is, the process in which the ground loses its cover after the destruction of vegetation, and the green fields gradually turn into desert-like landscapes under the action of arid climate and high winds. Land desertification mainly occurs in arid and semi-arid areas, and the key factor in the formation of deserts is climate, but in the marginal areas of the desert, native vegetation may be grasslands, which are desertified due to human reasons, and these people are aware of the main factors as follows:

1) Unreasonable agricultural reclamation. Whether in desert areas or native grassland areas, once reclaimed, the land will be desertified. The phenomenon of indiscriminate reclamation of pastures in pastoral areas has led to the rapid development of desertification of pastures.

b) Overgrazing. Due to the overabundance of livestock, the grassland grass production is insufficient, so that many high-quality grass seeds can not grow or the seeds are ripe and eaten. In addition, like goats, which account for more than half of the total number of livestock, they are very fast, good at stripping the stems and bark of sandy shrubs, gouging grass roots, and trampling, so that the grassland produces less and less grass, forming desertified land, causing a vicious circle.

3) Unreasonable timber mining. Historically, firewood mining is one of the important factors causing the formation of quicksand in Bixu irrigation oases and dryland agricultural areas in China. According to statistics, China's Yikezhao League has only one piece of woodmining and the area of desertification in Bala grassland has reached 200,000 hectares.

Climatic factors: Desert areas, dry climate, scarce rainfall, annual precipitation of less than 250 mm, some desert areas with less than 10 mm of annual precipitation (such as the Taklamakan Desert in Xinyi, China), but occasionally sudden heavy rain. Steaming in desert areas.

The amount of hair is very large, far exceeding the local precipitation; The humidity of the air is on the low side, and the relative humidity can be as low as 5%.

Climate change is significant, with average annual temperature differences generally exceeding 30 degrees Celsius. The difference in absolute temperature is more often above 50 degrees; The daily temperature difference is extremely significant, with near-surface temperatures reaching 60 to 80 degrees Celsius in summer and autumn at noon, and dropping below 10 degrees Celsius at night.

Desert areas often have clear skies and cloudless skies, and the wind is burning strongly, with maximum winds reaching hurricane levels. Causes of tropical deserts: Mainly shrouded by the subtropical high pressure, the air sinks and warms more, inhibits surface convection, and is difficult to cause rain.

If it is isolated by high mountains, located inland, or on the west coast of the tropics, deserts can be formed. For example, the desert in the interior of the Australian continent was formed because the sea breeze had lost all its water when it arrived. Sometimes, deserts also form on the leeward side of mountains.

1) The increase in sandstorms affects the growth of life and agricultural products.

2) Loss of arable land, resulting in less food**.

3) The ecological balance is affected.

4) Reduced living space available to humans.

5) The sparrow becomes hot and hot, making life hard.

Reduce fart, human deforestation accelerates desertification, human causes, desertification is the main cause, 2010-10-19 21:11:55 Added:

1) Sandstorms increase the size of the crop, affecting the growth of life and agricultural products 2) The reduction of arable land leads to the reduction of food**.

3) The ecological balance is affected.

4) Reduced living space available to humans.

5) As the weather gets hotter and harder, the question should be reverted to the question of the impact of human beings on desertification

Human deforestation accelerates desertification, the formation of the main cause of the trap, the human cause, the desertification is the effect, your problem is the cause of the inverted effect, understand,

Causes of desertification:

1. The population is growing, but the area of land is getting smaller, which leads to overuse of land.

2. Overgrazing, over-reclamation, and over-cutting have led to land desertification or aggravation of land desertification.

3. The irrational use of water resources and unreasonable mining also have a great impact on land desertification.

4. Arid and semi-arid areas are deep in the hinterland of the continent, with the least precipitation and the largest evaporation, and these places are prone to land desertification.

5. Climate also affects desertification. When the climate becomes drier, desertification develops, and when the climate becomes wetter, desertification reverses.

Desertification mainly occurs in the period of human history, especially in the past 100 years, but under the scale of 100 years, the changes in natural conditions, that is, mainly the fluctuations in climate, are small after all, which is not enough to cause major changes in the natural environment. In the same period, the rapid increase of population pressure and the strong interference of economic activities on the environment can cause the deterioration of the ecological environment and the rapid occurrence and development of desertification in a large area.

A large number of historical archaeological data and field investigation results have proved that when nomads occupy the semi-arid areas of the north, there is less pressure on the ecological environment; However, after agricultural production activities were replaced, the ecological environment was greatly damaged.

As for the anthropogenic causes of desertification, the current consensus is that under the adverse environmental background, due to the continuous growth of population pressure and the widespread use of extensive and predatory ecological management methods such as indiscriminate reclamation, indiscriminate grazing, indiscriminate woodlogging, and over-exploitation of groundwater, the destruction of land cover has led to the rapid development of desertification.

According to the study, due to the artificial destruction of land surface cover, it will be difficult to conserve water, which is not conducive to the uplift and auxiliary of surface airflow cracking. At the same time, the rate of surface reflection source socks will increase dramatically, and the downdraft will prevail, which will eventually lead to a more arid climate.

Therefore, the harm of desertification caused by human causes is more rapid, direct and serious than that of desertification caused by natural causes through the influence of biological and geophysical feedback mechanisms.

According to the analysis of field surveys and aerial satellites**, from the perspective of land use, we found that the land degradation caused by over-agricultural reclamation accounts for 9% of the desertified land area in northern China, the proportion due to overgrazing, the proportion caused by over-mining, the improper use of water resources and the destruction of vegetation by industrial and mining construction, while the desertified land formed by the forward movement of sand dunes solely due to the action of wind only accounts for 9%. From the above, it can be seen that the human factor should be the most active and dominant factor in the process of desertification.

The speed of governance cannot keep up with the speed of destruction, that is, the point is being governed at the same time, and the surface is being destroyed. This is the reason why the more afforestation is planted, the more desertification is controlled, the larger the desertification area, and the more serious the degradation and desertification of grassland. What makes the people in the city feel the most is the frequent occurrence of sandstorms.

But the specific reasons are indeed complex, and it is not clear in one sentence.

On the surface, the direct causes of the large-scale destruction of sandy vegetation are:

1 Urban and rural people, agricultural reclamation armies, and road construction armies in arid areas have destroyed the development of desertification of sandy trees, shrubs, and grass vegetation due to fuel demand (logging, woodcutting, and digging by roots).

2. Excessive reclamation in arid areas: a. Insufficient water resources and rapid abandonment of farmland; b. Excessive water use (flood irrigation) causes salinization and abandonment of farming; c. It also causes the destruction of sandy vegetation and the development of desertification.

3. Sandy grasslands that are not suitable for farming in semi-arid (grassland areas) (extensive planting, thin harvesting, rotational planting), desertification (one acre of desertification, three acres) of sandy land plants are directly destroyed;

4 (Semi-arid areas) grassland (grassland) overgrazing, free grazing, relying on the sky to raise livestock, grassland big pot rice Large areas (grassland) grassland degradation and desertification, sandy land vegetation and poor destruction;

5 Lack of water resources utilization (lack of effective management) Excessive water use in the upstream Significant reduction in downstream water and significant drop in water level (1. Death of large areas of planted forests and natural vegetation; 2. Cultivated land is abandoned, and sand activities are revived) Desertification development. Ejina and Minqin Oasis are the most typical.

6. Profit-driven (1. Indiscriminate digging: licorice, cistanche, cordyceps; 2. Messy hugging: hair cabbage destroys sandy vegetation and desertification develops. ）

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