At present, the area of desertification land in the world has reached 36 million square kilometers, accounting for 1/4 of the total land area, becoming the "number one killer" of global ecology, and it is still expanding at a rate of 50,000 to 70,000 square kilometers per year; More than 1 10 countries in the world are endangered by desertification, and 10 billion people are directly threatened. This means that14 of the land on the earth has basically lost the conditions for human survival.
The sharp decline of forests has directly led to six global ecological crises.
First, the oasis became a desert.
At present, the area of desertification land in the world has reached 36 million square kilometers, accounting for 1/4 of the total land area, becoming the "number one killer" of global ecology, and it is still expanding at a rate of 50,000 to 70,000 square kilometers per year; More than 1 10 countries in the world are endangered by desertification, and 10 billion people are directly threatened. This means that14 of the land on the earth has basically lost the conditions for human survival.
Second, a lot of soil erosion.
Soil erosion is one of the most direct and serious consequences caused by forest destruction. As long as there is a litter layer with a thickness of 1 cm on the surface, the surface runoff can be reduced to less than 1/4 of the bare land, and the sediment can be reduced to less than 7% of the bare land. The soil permeability of forest land is stronger, generally 250 mm per hour, which exceeds the intensity of general precipitation. A rainstorm can generally be completely absorbed by the forest. Due to the serious destruction of forests, the global soil erosion is increasing. At present, the global13 land is seriously eroded, and more than 60 billion tons of fertile topsoil are lost every year, of which more than 25 billion tons are cultivated land. The arable land with declining fertility and nutrient deficiency in the world has reached 2.99 billion hectares, accounting for 23% of the total land area.
Third, drought and water shortage are serious.
Forests are called "green oceans" and "invisible green reservoirs". It is estimated that each hectare of forest can store about 1000 cubic meters of precipitation, and the storage capacity of 1 10,000 hectares of forest is equivalent to a reservoir with a storage capacity of1000 cubic meters. Due to the sharp decline of forests and water pollution, the world is seriously short of water. At present, 60% of the mainland is short of fresh water resources, and 100 countries are seriously short of water, among which more than 40 countries are seriously short of water and more than 2 billion people lack drinking water. It is estimated that in the next 30 years, about two-thirds of the world population will be short of water.
Fourth, frequent floods.
Flood and drought are twins. Deforestation will inevitably lead to no rain and drought, with rain and waterlogging. A large number of facts show that forests have powerful functions of intercepting precipitation, regulating runoff and reducing waterlogging disasters. With its huge canopy, deep litter layer and developed roots, forest can play a good role in regulating precipitation. The flood control function of forest is mainly manifested in two aspects: one is to intercept and store rainwater; The second is to prevent siltation in rivers, lakes and reservoirs. After these two functions are weakened, a rainstorm will inevitably flood.
5. The species has become extinct.
Scientists have analyzed that if the area of a forest is reduced by 10%, the species that can survive in the forest will be reduced by half. There are 5 million to 50 million species of living things on the earth, more than half of which inhabit and multiply in forests. Due to the massive destruction of global forests, the extinction rate of existing species is 1000 times that of natural extinction. The United Nations predicts that 1990-2000 may lose 15000 to 50000 species every year. At present, 25% of species on the earth have disappeared, and 20%-30% are in danger of extinction.
Sixth, the greenhouse effect has intensified.
Modern humans use a lot of fossil fuels, such as oil, coal and natural gas. In the past 1 10 years, the concentration of carbon dioxide in the atmosphere increased from 270 ml/m3 to 350 ml/m3, and will reach 600 ml/m3 in the middle of the 20th century. Forests absorb carbon dioxide and release oxygen. Every hectare of forest produces 10 ton of dry matter, absorbs 16 ton of carbon dioxide and releases 12 ton of oxygen.
It can be seen from these six ecological crises that the consequences of destroying forests are extremely serious. Scientists assert that if forests disappear from the earth, 90% of life on land will be extinct; 90% of the fresh water in the world will flow into the sea in vain; Biological nitrogen fixation will be reduced by 90%; Biological oxygen release will be reduced by 60%; The wind speed in many areas will increase by 60% to 80%; At the same time, there will be many ecological problems and production problems, and human beings will not be able to survive. At present, a series of ecological crises caused by the sharp decline of forests have posed a serious threat to mankind.
Land resource is one of the three major geological resources (mineral resources, water resources and land resources), and it is the most basic resource and labor object of human production activities. The use of land by human beings reflects the development of human civilization, but it also causes direct damage to land resources, mainly manifested in soil erosion, land desertification, secondary salinization of land and soil pollution caused by unreasonable farming, among which soil erosion is particularly serious, which is another serious crisis facing the world today. It is estimated that the global surface soil loss of cultivated land is about 23 billion. Soil erosion refers to the whole process of soil erosion, migration and precipitation under the action of water flow. In the natural state, the process of surface erosion caused by natural factors is very slow, and it is often in a relatively balanced state with the process of soil formation. Therefore, the slope can remain intact. This kind of erosion is called natural erosion, also known as geological erosion. Under the influence of human activities, especially after human beings have seriously damaged the vegetation on sloping land, the process of surface soil destruction and land material movement caused by natural factors is accelerated, that is, soil erosion occurs.
Soil erosion is the most common geological disaster that destroys land resources in China, especially in the Loess Plateau. At present, the overall situation of soil erosion in China is that it is controlled in point and expanded in surface, and the control can't keep up with the destruction. The area of soil erosion in China was 65.438+0.74 billion mu at the beginning of liberation, and about 600 million mu was controlled by 654.38+0.980. Due to the failure of control, the area of soil erosion has expanded to 2.25 billion mu, accounting for about 1/6 of the total land area, involving nearly 1,000 counties. There are about 400 million mu of sloping farmland in mountainous and hilly areas of China, including 654.38 billion mu of terraced fields, and another 300 million mu of sloping farmland is suffering from soil erosion. Tons/year. When soil fertility declines, soil erosion will cause a lot of fertile topsoil to lose. According to statistics, China loses about 5 billion tons of soil and about 40 million tons of nitrogen, phosphorus and potassium every year.
Reservoir siltation, river bed elevation, navigation capacity reduction, flood disaster.
Threaten the safety of industrial and mining traffic facilities. In high mountains and deep valleys, soil erosion often leads to debris flow disasters, endangering the safety of industrial and mining traffic facilities.
Deteriorate the ecological environment. In 1930s-1960s, people's understanding of soil and water loss disasters remained on the direct economic loss of land, but after 1960s, it began to involve the impact on the whole human environment, including sediment pollution and ecological environment deterioration.
Soil erosion is caused by the movement of slope surface runoff. The basic principles of various prevention and control measures are: reducing slope runoff, slowing down runoff speed, improving soil water absorption capacity and slope erosion resistance, and raising erosion datum as much as possible. When taking prevention measures, we should start from the area where surface runoff forms, follow the runoff movement route, adjust measures to local conditions, strengthen and control step by step, combine prevention with prevention, and give priority to prevention; Slope control is combined with gully control, mainly slope control; Engineering measures are combined with biological measures, mainly biological measures. Only by taking various measures for comprehensive management, centralized management and continuous management can it be effective. Pollution is the abbreviation of environmental pollution, which refers to the phenomenon that the environmental quality deteriorates due to the intermediary of some substance or energy. Legally speaking, environmental pollution refers to the phenomenon that the environmental quality of a specific area is inferior to the applicable environmental quality standards in that area because of the intermediary of a certain substance or energy. Substances that can cause environmental pollution are called pollutants, such as harmful gases such as SO2 emitted in the production process and various heavy metals. The phenomenon that energy intervention worsens environmental quality is usually called pollution, such as thermal pollution. Environmental pollution can be caused by human activities (such as pollution caused by pollutants from human production and living activities) and natural causes (such as pollution caused by dust and harmful gases released by volcanic eruption). The environmental pollution to be prevented by the environmental protection law is mainly caused by human activities. Environmental pollution can be divided into biological pollution, chemical pollution and physical contamination according to the nature of pollutants; According to the environmental factors of pollution, it can be divided into air pollution, water pollution, soil pollution and marine pollution. According to the source of pollution, it can be divided into industrial pollution, agricultural pollution, traffic pollution and domestic pollution. Prevention and control of environmental pollution is the basis of environmental management and scientific research, and it is also an important content of environmental protection, and it is also one of the most important tasks of China's environmental protection law. First, if human beings want to conquer the terrible nature, they must respect it. We should not only be cautious about transforming nature, but also boldly practice and improve it, so as to control nature and make our own interests develop harmoniously with nature. We must never repeat the mistake of "polluting first, then managing" in western developed countries.
Second, starting from me, first choose a lifestyle that is conducive to protecting the environment. Be kind to our home and the earth and create a beautiful living environment.
1。 Save resources and reduce pollution
(1) Be proud of saving water. Turn off the tap at any time to prevent dripping.
(2) Use detergent carefully and use soap as much as possible to reduce the pollution of chemicals in detergent to water quality.
2。 Green consumption and environmental protection choice
(1) Use unleaded gasoline, cadmium-free lead batteries and phosphorus-free detergents to reduce water and air pollution.
(2) Buy low-priced household refrigeration appliances and mousse that doesn't hurt hair, so as to reduce the pollution to the ozone layer.
3。 Multiplexing and reuse
Try to use disposable goods less and use durable goods more. If disposable plastics and lunch boxes are not used, white pollution will be reduced; Do not use disposable chopsticks; Bring your own shopping bag or basket.
4。 Classified recovery and recycling
Do not throw waste batteries, waste plastics and other garbage and waste; Classify garbage, turn waste into treasure, recycle resources and benefit mankind.
5。 Protect everything in nature.
Do not hunt and use rare animals and protect animals, and cherish and protect wild animals and plants; Afforestation, care for every inch of green space, every flower and every tree around you.
6。 Pay attention to hygiene and protect the environment.
No spitting, no littering, no smoking and no noise in public places.
As a primary school student in the new era, I advocate students to improve their awareness of environmental protection, and also suggest that uncles and aunts join our team to contribute to environmental protection and benefit future generations. Because: protecting the environment is urgent!