It can be roughly divided into three aspects: threatening the living environment, accelerating environmental deterioration and destroying sandy vegetation. The land area affected by desertification on the earth exceeds 38 million square kilometers. At present, about 6 million hectares of land are desertified every year in the world. The problem of desertification involves a wide range and has attracted worldwide attention. Dryland (defined as an area with low rainfall, usually caused by storms with low rainfall, instability, short duration and high intensity) accounts for 40% of the global land area and feeds 65,438+0/5 of the world population. The desertification of these drylands is land degradation caused by the decrease of vegetation and available water, the decrease of crop yield and soil erosion. It is caused by the overuse of land caused by population growth, increasing human demand or political and economic pressure (such as the need for cash crops to increase foreign exchange), and is usually triggered or aggravated by natural drought. At present, the rate of desertification is 60,000 square kilometers per year or 0. 1% of the total dry land area per year. This is a potential threat to 70% of the dry land (25% of the global land area). Desertification is a great threat to the development of world agriculture. Desertification is a phenomenon of environmental degradation. It reduces the fertility of land, reduces the productivity and biological yield of agriculture and animal husbandry, and reduces the area available for cultivated land and pasture. Soil erosion and barren land caused by desertification have caused many countries to suffer from famine for many years. The land affected by desertification in the world has reached 38 million square kilometers. Every year, the land lost due to desertification is as high as 5~7 square kilometers, and almost every minute 1 1 hectare of land is desertified. If desertification continues without effective control, it is predicted that by the end of this century, the loss of cultivated land will reach 1/3 of the current cultivated land. What a dangerous signal! Therefore, protecting and making good use of land, closing sand and planting grass, building windbreaks, and implementing comprehensive development and management of forest, animal husbandry and water will give full play to the group effect of vegetation and achieve the goal of returning sand to soil. Soil is the mother of plants and the material basis for the prosperity of green homes. Protecting and making good use of land means protecting green homes and protecting human beings themselves. Accelerating environmental degradation The so-called desertification refers to the decline or even loss of productivity of terrestrial organisms. One of the most obvious places of desertification is in Sachl, south of the Sahara Desert. In the northern part of this area, sheep and camels are raised by nomadic or grazing methods, which eats up all the plants in the whole area and creates a bare land. However, in the humid and wide south, due to the over-reproduction of livestock and the lack of cultivated land, the whole area has gradually become barren. Coupled with the shortage of water, people began to dig wells. When people gather together to look for water, there are more livestock, which accelerates the deterioration of the environment and encourages desertification. This vicious circle makes people's lives in this area generally very difficult. There is no rainy season in the Sahara desert, so it won't rain. But as long as there is a little moisture, plants sleeping underground will scramble to sprout new buds, but they will soon be eaten up by overgrazing livestock ... so the desertified soil is still expanding silently ... The answer to this question is extremely simple. In short, the speed of control can't keep up with the speed of destruction, that is, while controlling, it destroys on the surface. This is why the more afforestation, the more desertification control, the larger desertification area and the more serious grassland degradation and desertification. What impressed the city people most was the frequent occurrence of sandstorms. But the specific reasons are really complicated, which can't be explained clearly in one sentence. On the surface, the direct cause of large-scale destruction of vegetation in sandy land is: 1. Urban and rural people, the army of agricultural reclamation, the army of road construction in arid areas → (cutting, chopping wood, digging roots) destroying the vegetation of trees, shrubs and grasses in sandy land → desertification development. 2. Over-reclamation in arid areas: a, partial abandonment due to insufficient water resources; B, excessive water use (flooding) causes salinization and abandonment; C, it also causes the destruction of sandy vegetation and the development of desertification. 3. Sandy grassland unsuitable for farming in semi-arid (grassland) areas → (wide planting and sparse harvest, rotation) land desertification (one acre of desertification and three acres) sandy plants are directly destroyed; 4. (Semi-arid area) grassland (grassland) overgrazing, free grazing, relying on the sky to raise livestock, grassland pot rice → large area (grassland) grassland degradation and desertification, sand vegetation destruction; 5. Unreasonable utilization of water resources (lack of effective management) → excessive water consumption in the upper reaches → the incoming water and water level in the lower reaches have dropped significantly →( 1, large-scale planting and natural vegetation death; 2. Abandoned farmland and renewed sandstorm activities) → Development of desertification. Ejina and Minqin Oasis are the most typical. 6. Profit-driven (1, digging indiscriminately: licorice, cistanche deserticola, Cordyceps sinensis; 2. Chaos: Nostoc flagelliforme → vegetation destruction in sandy land → desertification development. )