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Where did China change from an oasis to a desert?
2. Causes of desertification
The factors that cause land desertification in some parts of western China include natural factors and human factors, among which natural factors are the objective internal causes of the occurrence and development of desertification, and human factors are the social inducing factors of the occurrence and development of land desertification.
2. 1 Natural factors of desertification
Natural factors are mainly the degraded land, inferior soil and desert left over from history caused by natural conditions such as less precipitation, water shortage and uneven distribution, strong sunshine evaporation, windy weather at high altitude, drought, sparse vegetation, soil erosion and wind erosion in the western part of China, especially in the inland areas of northwest China.
China is a country with serious water shortage, and its per capita fresh water resources are about 1/5 of the world's, and the drought is unevenly distributed in the north and south, especially in the northwest, and the per capita water resources decrease obviously with the population growth. With the warming and drying of the climate, the precipitation in the west of China at the beginning of 2 1 century is obviously lower than that in the 1970s. Since 1990s, the Yellow River has been cut off frequently, and the water volume of Yili River, Tarim River, Shule River and Heihe River has been decreasing year by year, which has aggravated the water crisis in the basin. Most parts of western China, especially the northwest provinces, live in the inland far from the ocean, with high altitude and many mountains, which reduces the ways and quantities of water vapor entering this area with the wind and increases the difficulty, so the precipitation is less (mostly below 400mm, even below 200mm in many places, and the least is only15.4 mm); ); In addition, the intense evaporation of sunlight (from east to west, the evaporation increased from 800mm to 3,000 mm) made the natural water supply of land in most parts of the west unable to make ends meet, and the drought intensified, resulting in a continental dry climate, which seriously affected the development and reproduction of local forest and grass vegetation, led to the scarcity of ground vegetation, made the land vulnerable to external damage, and even degraded and desertification due to lack of protection.
The dry soil formed by the arid and windy climate in the northwest plateau of China is eroded by strong winds, and the organic matter and minerals are blown away and lost by the wind. In the past, the land gradually became barren, degraded and even desertification, and many desert lands gradually formed, migrated and expanded under the conditions of drought and windy.
2.2 Human factors of desertification
The human factors that cause land desertification mainly include the following aspects:
2.2. 1 Deforestation, excessive excavation of forest and grass vegetation resources, resulting in vegetation destruction and extinction, bare land degradation and even desertification. For example, in the tropical rain forest area of the Hani River basin in Brazil, 450 plants were wiped out, 204 species of birds were completely extinct, the inland river was blocked by quicksand, and the ecosystem was unbalanced, which made people want to cry. In 1980s, when the rural economic system in China was reformed, many collective trees were distributed to individual farmers, but they were cut down and destroyed at will because of neglecting the protection of trees. Most provinces in northern China, especially the northwest provinces, belong to arid and semi-arid areas, with backward social economy and large population. For the basic survival and development, people here have relaxed the management and protection of forest and grass vegetation resources in the already fragile ecosystem, allowing them to cut down trees and dig grass vegetation at will to meet the needs of production and life consumption, resulting in serious damage to the ecological environment and the gradual disappearance of vegetation from point to area and from near to far. For example, in Hotan area of Xinjiang, due to the neglect of the management of firewood cutting and burning, Populus euphratica, Populus euphratica and other natural desert forests were destroyed by 57 thousand mu in five years; In many places in northwest China, natural Chinese herbal medicines and economic plants such as Lycium barbarum, licorice, ephedra and Nostoc flagelliforme are also dug and scraped down at will, which destroys vegetation, even reduces or even loses the functions of forest and grass vegetation in preventing wind and fixing sand, maintaining water and soil and conserving water resources, and worsens the land ecological environment.
2.2.2 Blind reclamation and overgrazing cause soil erosion, farmland and grassland degradation and desertification. China has a large population and is chronically short of food. In this case, in order to survive, people develop the land without restriction, and increase the grain output through land reclamation, which seriously destroys the original vegetation and makes the land degenerate and desertification. In the grassland pastoral areas in the arid areas of northern China, the carrying capacity of grassland is limited, and only limited grazing is allowed, but in fact, almost all pastoral areas exceed the reasonable carrying capacity allowed by ecological security (according to the survey, the overloading rate of grassland in sandy areas in China is above 50%, and even as high as 100% in some areas). In many areas, grasslands are seriously degraded due to excessive stocking and overgrazing. In some places, cattle and sheep even eat grass roots. Therefore, ecologists believe that grazing cattle and sheep is the "first killer" of grassland plants, and overgrazing is the main reason for grassland degradation.
2.2.3 Excessive and unreasonable development and utilization of water resources, resulting in land drought, desertification and salinization. Due to the shortage of water resources in the northwest inland, it is mined underground when there is no water on the ground. Long-term over-exploitation has led to a sharp drop in groundwater level and the drying up of rivers and lakes. The vegetation that had been growing well died in a large area because of the lack of shallow groundwater support, which inevitably turned the once prosperous place where cattle and sheep could be seen into a sand source where the wind blew bare land and raised dust. However, in some places, irrigated land was developed in the upper reaches of the water source, but only irrigated but not drained, which made saline-alkali land accumulate continuously in low-lying areas, causing serious secondary salinization of land. Vegetation in low-lying areas died due to saline-alkali harm, and farmland was forced to abandon farming, forming an abandoned saline-alkali desert and becoming a pair of "twin brothers" with the desert with poor ecological environment.
2.2.4 Excessive use of pesticides, indiscriminate hunting, poisoning beneficial insects and wild animals, making pests and rats parasitic on forest and grass vegetation rampant, and endangering forest and grass due to the loss of natural enemies. The indiscriminate use of toxic and harmful pesticides and the indiscriminate hunting of wild protected animals have seriously endangered the natural enemies of harmful pika in the ecological food chain, leading to the rampant occurrence of harmful pika and seriously endangering forest and grass vegetation. In the grassland, forest and farmland ecosystem in arid and semi-arid areas of northern China, the harmful pest pika and its predatory natural enemies, insects and animals, are interdependent in the food chain and are in a state of dynamic balance and mutual restriction. However, due to the indiscriminate application of pesticides and the killing of natural enemies insects and wild animals, the natural enemy population of the pest pika has dropped sharply, breaking the natural ecological balance, and the harmful pest pika is rampant, seriously endangering grassland trees. The forest and grass vegetation resources in the grassland of Inner Mongolia and the source region of the Three Rivers in Qinghai Province are particularly seriously harmed by pikas, which not only reduces the functions of forest and grass vegetation in preventing wind and fixing sand and maintaining national security, but also significantly reduces the livestock carrying capacity. In order to change this situation, the state takes corresponding preventive and protective measures and has to invest a lot of manpower, financial resources and material resources for prevention and protection.
2.2.5 Industrial traffic construction and production contributed to desertification. Modern industry, traffic production, living construction, the development and utilization of land resources and the emission of waste gas all have greenhouse effects, which have caused soil erosion, land waste, high temperature and drought, and contributed to the abuse of land desertification. The modern industrial revolution has greatly promoted the development and progress of human society. It not only brings immediate benefits to mankind, but also makes modern people suffer greatly. In the process of construction of industrial and mining enterprises, traffic road construction, production and life, not only the original landscape vegetation is destroyed, but also a large number of toxic and harmful solid waste pollutants and high-temperature gaseous CO2 are produced and discharged, which leads to the collapse and subsidence of landslides and the desertification of the destroyed land after long-term soil erosion, drought and exposed wind erosion. The land polluted by waste has thus become barren wasteland; In the process of production and life, a large number of hot flue gases such as CO2 are emitted, which makes the global climate warm and the greenhouse effect increasingly prominent, and the resulting drought is becoming increasingly obvious, resulting in hundreds of billions of dollars lost worldwide every year. Especially today, individual countries refuse to sign the Kyoto Protocol for their own economic interests, which directly affects the control of industrial waste gas emissions, which is disturbing.
2.2.6 Insufficient understanding, imperfect legal system, lax law enforcement, poor management, rampant bureaucratic corruption, disputes and wars, and man-made fires are also important factors leading to land desertification. In the forestry industry, there are all kinds of corruption phenomena, which have caused great losses to forestry, but they have not attracted enough attention. We know that the fourth phase of the "Three North" shelterbelt project has been implemented. Who can know how much of the project construction cost and the "huge" construction achievements of the project are caused by false reports and fraud by some local governments and project implementation units? What is particularly abhorrent is that many bureaucrats find excuses to put national debt into their own pockets, thus making ecological construction such as desertification control an illusory thing, thus undermining the impact and weakening and delaying the efforts and progress of land desertification control.
3. Countermeasures for desertification control
Desertification control can hardly be achieved by one method of one place, one department or even several people. It must be the action of the whole society, and comprehensive measures such as law, administration, economy and technology should be taken in forestry, agriculture and animal husbandry, water conservancy, environmental protection, economy, science and technology, justice, publicity and education. Specifically, the following measures should be taken:
3. 1 Vigorously plant trees and grass, reduce population pressure, improve energy utilization rate, organize protection by legislation, strengthen law enforcement, and reduce, curb and prohibit all acts that damage the natural ecological environment. The CPC Central Committee and the State Council made the strategic decision of "developing the western region and giving priority to ecology", and began to implement a series of ecological environment protection and construction projects, such as returning farmland to forests, grazing and grassland, and protecting natural forests, which created good opportunities for people to retreat from desertification, created a new situation of national defense and desertification control, safeguarded national security and effectively curbed the development trend of land desertification. Attach importance to ecological construction and protection in the north, and carry out ecological migration in a planned and step-by-step manner in ecologically fragile areas; In areas where conditions permit, promote the application of biogas, wind energy and solar energy technologies and resources to reduce the damage of wood burning energy consumption to forest vegetation; At the same time, we should establish a legal system for the construction and protection of the ecological environment in the western region, implement a one-vote veto system for ecological damage, strengthen law enforcement in combating desertification and protecting the ecological environment, and severely crack down on all kinds of illegal and criminal acts such as deforestation that damage natural ecological environment resources and bureaucratic officials who are irresponsible for desertification control.
3.2 Implement a legal reclamation system, develop eco-intensive agriculture, and reasonably limit grazing. Formulate plans for preventing and controlling desertification, delimit areas where agriculture, grazing and firewood are prohibited, take protective measures of fence signs, establish a fence grazing prohibition system, implement the project of returning grazing to grassland, vigorously cultivate artificial high-yield grassland, reduce the livestock carrying capacity of natural grassland, shorten the grazing time of natural grassland and relieve the grazing pressure of natural grassland. The Institute of Botany, Chinese Academy of Sciences uses small-area high-efficiency land to plant high-efficiency Hong Ying corn to provide feed for a large number of captive livestock, which solves the contradiction between developing animal husbandry and protecting the environment in arid and semi-arid grassland areas, and is of typical representative significance and worth demonstrating and popularizing.
3.3 Management, scientific allocation and rational development and utilization of water resources according to law to ensure ecological water demand. First, establish the idea and mechanism that water resources are limited, water should be saved and recycled for governance, and change the view that water is inexhaustible. In both urban and rural areas, water conservation and rational use are advocated. Focus on building large sewage treatment plants in urban industrial and mining areas to solve the problem of sewage reuse and alleviate the shortage of water resources; Agricultural production should change backward irrigation methods and advocate water-saving irrigation. The second is to establish and improve the water resource fee collection system, raise the price of non-ecological water and water exceeding the standard, and restrict urban industrial water use by economic means. Third, establish a unified dispatching compensation system for the whole basin, and take measures to discharge water from upstream reservoirs during the peak water consumption period in summer, especially in dry years, so as to ensure the ecological water supply for the whole basin; At the same time, according to the principle of market economy, a cross-regional compensation mechanism should be established in the whole basin, that is, the downstream directly benefited areas should pay a certain amount of resource compensation fees through taxes or other means, and support the upstream areas to plant trees for water conservation, soil and water conservation, develop water-saving irrigation, and build sewage treatment plants. Make up for the economic losses caused by the upstream area taking care of the downstream water use and prevent drought and desertification. It can be said that this investment and financing mechanism can achieve a win-win situation for the whole basin. Fourth, strengthen the management of groundwater resources, adopt policies and measures to restrict the exploitation of groundwater resources, crack down on illegal exploitation of groundwater resources, and prevent the groundwater level from falling.
3.4 Combat poaching, rationally use pesticides, advocate ecological prevention and control, and realize the sustainable development of agriculture, forestry and Maki Ka. Intensify the crackdown on the indiscriminate hunting and catching of wild protected animals, and curb or reduce the indiscriminate hunting and catching of wild animals; Encourage the use of biological pesticides, restrict the use of high-residue pesticides, prohibit the use of highly toxic pesticides, protect and develop natural enemy insects and wild animals, control pests and rodents in forest and grass ecology by ecological control technology, curb the reproductive harm of pests and rodents, and naturally control pests and rodents below the economic threshold, so as to prevent the degradation and desertification of farmland in woodland and grassland, ensure the sustainable utilization of land resources, realize the coordination and unity of ecological, economic and social benefits, and realize the ecological economy of agriculture, forestry and animal husbandry.
3.5 Establish the examination and approval system of land environmental impact assessment for production and construction projects. Implement the system of project ecological environment evaluation and demonstration and project approval, and measure the advantages and disadvantages of all construction projects with standards conducive to industrial and agricultural production, sustainable development of ecological environment and economy, and sustainable utilization of land ecological environment and resources. Through evaluation and demonstration, select the best and eliminate them. For production and construction projects with high energy consumption, high water consumption and high sewage discharge that are not conducive to the ecological environment of terrestrial vegetation, restrictions, suspension, prohibition, closure and transfer shall be adopted to prevent temporary economic growth.
3.6 Take the prevention and control of corruption as a supporting measure to prevent and control desertification. Establish a system of bidding, construction, procurement, supervision and reimbursement for ecological construction materials such as sand prevention and control ecological projects and seedlings and seeds, curb bureaucratic corruption at the grassroots level and departments, and ensure that special funds for sand prevention and control are really used for sand prevention and control. The establishment and implementation of the national public bidding procurement and supply system for construction projects, medical devices and products have stopped the unhealthy trend of corruption in related links, saved expenses and done good things well; National ecological construction projects such as sand prevention and control should also take this as a lesson, establish a public bidding procurement supply system, curb corruption and do a good job in sand prevention and control construction projects.
3.7 Strengthen publicity and education, and enhance the people's awareness of sand prevention and control. Through all-round, multi-level and regular publicity and education on ecological construction and protection, we will organize, plan, produce and broadcast ecological public service advertisements that can raise people's awareness of sand prevention and control, create a good atmosphere of cultural public opinion, and let everyone in the whole society and all walks of life, especially those living in arid and semi-arid areas in the west, have the awareness of saving water, prevent and control sand, protect the environment from the depths of their minds, and establish a "glorious protection of land resources and environment, shameful destruction of land resources and environment"
refer to
[1] Concise Forestry Dictionary Science Press, edited by Northwest Forestry College, 1980
[2] Forest Ecology and Soil Science, edited by Northeast Forestry College, China Forestry Press 198 1.
[3] Beijing Forestry College Editor Meteorology China Forestry Press 198 1
[4] Zhu Zhenda. Liu Shu. Desertification process and control division in northern China. China Forestry Press 198 1.
[5] Wang Tao's research and practice on desertification control in China, China Desert 200 1.2 1( 1).
[6] Geng Kuanhong. China Sandstorm Climate Science Press 1986.
[7] Wang Yue. Etiological diagnosis of desertification in China China desert 2002.22(4)
[8] Shi Deming. Evaluation and Protection of Fragile Ecological Environment in China, Liang Yin Journal of Soil and Water Conservation 2002. 16( 1).
[9] Sheng Chengfa. Su Jianwei's discussion on some concepts of pest control. Journal of Ecology 2002. 22(4)
[10] On April 26th, 2002, China Green Times reviewed the sandstorm in the spring of 2002. On May 8th, 2002, the glaciers in the Himalayas were melting rapidly. On May 9th, 2002, the farmland around Qinghai Lake will be returned to forest and grassland next year.
[1 1] China Youth Daily 2002.4. 17 Curbing sandstorms does not rely on manpower to borrow natural resources.
[12] Gansu Daily On April 2, 2002, land desertification in China showed an overall deterioration trend.
About the author: Song Bingyang, male, Han nationality,1born in June 1959, is a native of Yongxin Township, Jingyuan County, Baiyin City, Gansu Province. 1998 12 Graduated from Correspondence College of Central Party School with a bachelor's degree. Now he is an engineer of Baiyin Forestry Bureau, a member of Baiyin Forestry Society, an information officer of China Talent News, a correspondent of China Green Times, provincial and municipal radio and television newspapers, municipal radio and television stations, Baiyin Daily and other news media. He often writes some news, newsletters, comments, essays, etc. In my spare time. Read more than 200 articles in national, provincial and municipal newspapers, radio stations and TV stations, and publish, exchange, award-winning academic papers, design schemes, knowledge contests and many other items in national, provincial and municipal publications and conferences. Participated in the completion of a number of scientific research achievements won the third prize of the Ministry, the first and second prizes of the province, and the first and second prizes of the city. And actively provide legislative suggestions, and draft 99 draft regulations and suggestions to the Standing Committee of the Provincial People's Congress, which is of great help to the smooth introduction of measures to prevent and control desertification in Gansu; He also made suggestions and suggested that "China Forest and Water Ecological Environment Protection and Construction Week" be held, which was paid attention to and praised by relevant leaders such as the National People's Congress Standing Committee (NPCSC), the Standing Committee of the Provincial People's Congress, the General Office of the Provincial Government, the Provincial Forestry Department, the Green Committee Office, and the deputies of the Tenth National People's Congress, and considered that "this is a good thing". Therefore, the representatives of the Gansu delegation of the Tenth National People's Congress took it as one of the proposals submitted to the First Session of the Tenth National People's Congress. Its achievements have been compiled into China Encyclopedia Scholar Biography, China Dictionary of Successful Talents and other classic works, and summarized by China Forestry, China Green Times, Xinhua News Agency, People's Voice, Gansu Forestry, Provincial and Municipal Radio Stations, Provincial and Municipal Radio and Television Newspapers, Baiyin Daily, Baiyin Social Sciences, and Daily.
Causes and control countermeasures of land desertification in parts of western China
(abstract)
Song Bingyang Yang Xiaomin
Land desertification is a public hazard in the world, and 14% of the world population is directly threatened by desertification. In western China, there are large areas of desertified land in Gansu, Xinjiang, Qinghai, Ningxia, Inner Mongolia, Shaanxi, Tibet, Sichuan, Chongqing, Guizhou, Yunnan, Guangxi and other provinces and cities, showing a trend of "local control and overall deterioration", resulting in direct economic losses of 54 billion yuan every year.
The factors causing land desertification in some parts of western China include natural factors and human factors, among which the natural factors are mainly less precipitation, water shortage and uneven distribution, strong sunshine evaporation, high altitude and windy weather, scarce vegetation, strong soil erosion and wind erosion in most western provinces, which are the objective internal causes of land desertification; Human factors mainly include deforestation, over-exploitation of forest and grass vegetation resources, blind reclamation and overgrazing, unreasonable development and utilization of water resources, indiscriminate application of pesticides, indiscriminate hunting of harmful insects and wild animals, industrial traffic construction and production, lack of understanding and rule of law, rampant bureaucratic corruption, disputes and wars, fire hazards and so on. These human factors are the social inducing factors for the development and intensification of land desertification. The long-term interaction of various natural factors and human factors leads to climate and soil drought, sparse or even disappearance of ground vegetation, which makes the land bare, lack of forest and grass vegetation protection and water nourishment, and suffers from various violations, gradually becoming fragile, barren, degraded and desertification. For a long time, many desertification areas have occurred from point to area, from less to more, or even in a large area, forming a trend of sand retreat and overall deterioration, making our production and living space smaller and smaller, threatened by desertification more and more seriously, and causing more and more losses.
From this point of view, it is imperative and very important to prevent and control land desertification in some parts of western China. All relevant departments of the whole society should work together with Qi Xin to take comprehensive measures such as law, administration, economy, technology and education, mainly including planting trees and grass, reasonable reclamation, limiting grazing, managing water resources well to ensure ecological water demand, protecting beneficial insects and wild animals, and establishing land for production and construction projects. Only in this way can we effectively curb the development trend of land desertification, protect the land resources and environment on which we live and develop, and realize the sustainable development of social economy and ecology.
1 year land desertification disaster distribution law
Land desertification is a geological disaster in arid and semi-arid areas, and its harm is to destroy farmland and worsen the environment.
Section 1 Development and Distribution Law of Land Desertification
The desert and sandy land in China are mainly distributed in the west and northwest between 37 and 42 north latitude, which is dangerous.
Table 5. 1 Statistical Table of Land Desertification, Desertification and Salinization
province
administrative region
Land, desert and desertification
Soil salinization
comment
zone
Occupy provinces and regions
zone
Average annual hair loss
Exhibition area
zone
Occupy provinces and regions
zone
Average annual hair loss
Exhibition area
k㎡
%
k㎡
k㎡
%
k㎡
Inner Mongolia
743854.7
63
3000
18300
1.55
In the past 30 years, 10.66 km ㎡ of desert and desertification land has been increased.
Henan Province
+
+
2 172
1.30
Saline-alkali land is decreasing.
Heilongjiang province
25300
5.5
666.7
0. 14
4.52
The saline soil at 1962 is144km2, and the saline soil at 1976 is 207.3k㎡
Hebei Province
9 1 13
4.86
7833.3
4. 17
Sandy land increases, while saline-alkali land decreases.
Shanxi province
12700
6. 13
7.4 1
+
Recently, the desert has spread to the southeast at a speed of 2.4 ~ 5.6 m/a.
Shanxi
+
+
50 16
3.22
Jiangsu Province
-
-
-9 13.3
0.98
Xizang
1500
0. 13
+
The desertification area is 65438 0.3 times larger than that in the early days of liberation.
Gansu
5333.3
1.37
228.7
1 120. 1
0,29
2.07
In the past 30 years, the salinization area is about 123900 mu, and the desertification area is 4947k㎡ km2.
Qinghai
2 1700
3.0
130
0. 18
+
Wind erosion area is 2.0 1km2.
Ningxia
16800
32
1 14.7
676
1.3 1
Saline soil is mainly distributed in Yinchuan Plain and Weining Plain, with an average yield reduction of more than 40 million Jin.
Liaoning province
5602
3.82
Xinjiang
423000
25.5
966.7
10800
0.68
Potential desertification area 1 .42km ㎡, 30500km ㎡ in 30 years, reducing salinization output1100 million kg.
Beijing
3 17.68
1.94
Since liberation, desertified land has been decreasing year by year.
Sichuan Province
+
+
+
+
Jilin province
47000
25
52.8 1
274
1.46
The desertified land area of 1984 is larger than that of 19581373km2.
Shandong (province)
-
-
-
14000
8.94
664.2
The annual loss of salinization is1.5 ~ 200 million yuan.
Anhui province
-
-
-
307. 1
0.22
total
1533000*
15.9*
4370.25
2370*
8 18000*
8.5***
* Based on other information.
* * Covered area (%)
* * * accounts for the national cultivated land area (%)
Note: "+":no statistics, "-":no such disaster, spaces indicate that the situation is unknown.
Harm Xinjiang, Gansu, Qinghai, Ningxia, Shaanxi, Inner Mongolia, Shanxi, Hebei, Liaoning, Jilin, Heilongjiang and other northern arid and semi-arid areas 12 provinces (sections, etc., 1993). There are 334,000 square kilometers of desertified land and 37,000 square kilometers of aeolian land in China, and the desert Gobi1162,000 square kilometers, * * *1533,000 square kilometers, accounting for 15.9% of the total land area, which has exceeded the total cultivated land area in China. The distribution of desertified land is as follows: 465,438+0% of the area is distributed in semi-arid areas on both sides of Daxing 'anling Mountains, and the wind and sand hazards are mainly in dry farming areas in crop ecotone; 32% is distributed in the desert grassland of arid grassland, and 27% is distributed in the arid desert area of western China.
In recent 40 years, the development of land desertification in China is very serious, and there is a trend of further expansion. According to the statistics of authoritative departments, from 1950s to 1970s, the desert land in China expanded at an average annual rate of 1.56 km2, and in 1980s it expanded by 21.000km2.. It is predicted that in the future, land desertification will expand at the growth rate of 1.32%, and the land reduced to desert will reach 2370km2 on average every year (Table 5.650
The harm of land desertification in the second quarter
China has a large population and little land, and the pressure of population on land resources is increasing day by day. Land desertification is one of the main factors leading to the deterioration of ecological environment. According to statistics, 60% of poverty-stricken counties in China are concentrated in sand areas, and the direct economic losses caused by sandstorms are as high as 4.5 billion yuan every year. The hazards of land desertification include: ① destroying cultivated land (Zhang et al., 1994) and agricultural production; (2) Degrade grassland and reduce the quality and quantity of animal husbandry; ③ Obstructing traffic (Zhang,1999d); (4) affect the engineering construction; ⑤ Destroy the ecological environment.
Investigation shows that land desertification is more serious and extensive than desert in terms of harm degree and scope. The development of desertification not only affects land quality and crop growth, but also forces the direction of land use to change with the change of surface morphology, which directly harms human economic activities and living environment.
The desertified land that has been formed in China is mainly due to unreasonable farming methods and excessive logging, reclamation, grazing and destruction, which leads to the degradation and disappearance of large areas of forests, grasslands and vegetation, as well as the fragile local ecological environment-drought, windy and loose soil. , accelerated the formation of desertification. There are 30- 100 windy days of magnitude 8 or above on the sandstorm line in Wan Li, northern China, and sandstorms often occur. Historically, Mazhuang used to be a place with beautiful water and fresh grass, many sheep, fat sheep and good natural environment, but now it has become a sandy land, and some people can't even survive. In the past 30 years, with the development of economic construction in Inner Mongolia, large-scale deforestation, large-scale reclamation and development without scientific basis, and overgrazing have expanded desert and desertification land by nearly 654.38+006,600 km2 at an annual rate of 3000km2. Because of the same factor, the desertified land in Jilin Province increased by 1373km2 in 1984 compared with 1958, and the development speed was faster in recent ten years. The sandstorm line in the north of Yumen City, Gansu Province moves southward at an average annual development speed of 500 meters10km, and the newly-increased desertified land is about 87.3km2 The desertified land in Ningxia 19 1 km2 is enlarged by 2666.7 1km2, and the annual wind erosion depth is 3-5 cm, and the particles in the cultivated layer are fine. Decades ago, underdeveloped or underdeveloped provinces and regions also appeared or further aggravated desertification. The damage caused by land desertification to these provinces and regions is very serious.
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