Is land desertification the same as land desertification? What's their difference?

Land desertification desert is the product of arid climate. There were deserts on the earth long before human beings appeared. However, there is no insurmountable boundary between the desolate desert and the fertile grassland. With water, lush plants can grow in the desert and become an oasis full of vitality; Without water and plants, green space can quickly degenerate into a piece of rubble. In order to get more food, people ignore the climate and land conditions, open up wasteland casually and overgrazing; In order to solve the fuel problem, regardless of the consequences, cut trees and mow grass at will. Arid and semi-arid areas were originally short of water and windy, but now the land has been ravaged, the vegetation has been destroyed, the precipitation is less, and the wind is getting stronger and stronger. Strong winds strongly erode the topsoil, sand is more and more, and sand dunes are slowly developing. This makes arable land a desert unsuitable for grazing and farming.

Land desertification is simply land degradation, also called "desertification". The concept of desertification was defined by the United Nations Conference on Environment and Development in 1992: "Desertification refers to land degradation caused by drought disasters in arid, semi-arid and semi-humid areas due to climate change and unreasonable human economic activities. 1June 1996 17 On the second World Day to Combat Desertification and Drought, the secretariat of the United Nations Convention to Combat Desertification issued a communiqué, pointing out that the phenomenon of desertification in the world is still intensifying. More than 654.38+0.2 billion people in the world are directly threatened by desertification, of which 654.38+0.35 billion people are in danger of losing their land in the short term. Desertification is no longer a simple ecological and environmental problem, but has evolved into an economic and social problem, bringing poverty and social instability to mankind. By 1996, the global desertification land has reached 36 million square kilometers, accounting for 1/4 of the total land area of the earth, equivalent to the total land area of Russia, Canada, China and the United States. There are more than 65,438,000 countries affected by desertification in the world. Although people all over the world are fighting against desertification, it is expanding at a rate of 50,000 to 70,000 square kilometers per year, which is equivalent to the area of Ireland. By the end of the 20th century, the world will lose about 1/3 of cultivated land. Desertification is one of the most serious disasters among many human environmental problems. For people threatened by desertification, desertification means that they will lose the most basic survival foundation-the disappearance of fertile land.

In a narrow sense, desertification refers to the process of environmental change similar to desert landscape in the original non-desert area, which is destroyed by excessive economic activities of human beings. Because of this, any land with desertification process is called desertification land. Desertification land also includes places where sand dunes move forward and invade under the action of wind, and sand dune activation areas where the original fixed and semi-fixed sand dunes produce quicksand activities due to vegetation destruction.

Desertification in a broad sense refers to the total process of natural environment degradation in arid, semi-arid or even semi-humid areas (including salinization, grassland degradation, soil erosion, soil desertification, narrow sense desertification, vegetation desertification, sand dune forward movement and invasion in historical period, etc.). ) due to the comprehensive effect of human and natural factors.

Worldwide, in the United Nations Convention to Combat Desertification in Countries Experiencing Serious Drought and/or Desertification, Particularly in Africa, adopted by 1994, desertification refers to land degradation in arid, semi-arid and dry sub-humid areas caused by various factors, including climate variation and human activities.

This definition clarifies three issues:

(1) "Desertification" is produced and developed under the influence of many factors, including climate variation and human activities;

(2) "Desertification" occurs in arid, semi-arid and dry sub-humid areas (the ratio of annual precipitation to potential evapotranspiration is between 0.05 and 0.65, but excluding polar and sub-polar areas), and the background conditions and distribution range of desertification are given.

(3) "Desertification" refers to land degradation in arid, semi-arid and dry sub-humid areas, which puts desertification in the global framework of land degradation, thus defining its regional scope.

In the late 1960s and early 1970s, the severe drought in the sub-Saharan region of West Africa caused unprecedented disasters, which made the international community pay great attention to the land degradation in the global arid areas. The word "desertification" began to spread. According to the data of the United Nations, at present, 1/5 of the population and 1/3 of the land in the world are affected by desertification. 1In June 1992, the World Conference on Environment and Development listed combating desertification as a priority development and action field of the international community.1In June 1993, intergovernmental negotiations on the United Nations Convention to Combat Desertification in Those Countries Experiencing Serious Drought or Desertification (especially in Africa) began. The text of the convention was formally adopted. 19941In February 1994, the United Nations General Assembly passed a resolution to designate June 17 every year as "Global Day to Combat Desertification and Drought" from 1995, so as to publicize it to the masses. China is a party to this convention.

What is desertification? In the past, we often understood it as "the desert is expanding and spreading the sand in the desert to more and more fertile land", which is inaccurate. 1992 The definition adopted by the World Conference on Environment and Development is "land degradation in arid, semi-arid and sub-humid areas caused by various factors including climate and human activities". That is, the decline or loss of soil productivity caused by wind erosion, running water erosion and soil salinization is called desertification.

The desertification situation in China is very serious. According to the materials published by the desertification control office of the State Forestry Administration 1998 and other government departments, China is one of the countries with serious desertification in the world. According to the national survey of desert, Gobi and desertified land and the results of desertification survey, the area of desertified land in China is 2.622 million square kilometers, accounting for 27.4% of the national territory, and the population affected by desertification is nearly 400 million. According to the research of international cooperation projects in China, the United States and Canada, the direct economic loss caused by desertification in China is about 54,654.38 billion yuan+RMB.

Among the desertified land in China, the area of wind erosion and desertification caused by strong winds is the largest, accounting for 654.38+607 million square kilometers. According to statistics, since the 1970s, the desertification area alone has expanded at a rate of 2,460 square kilometers per year.

The desertification of land has created a material source for sandstorms. Therefore, sandstorms in northern China are commonly known as "black winds". Because dust storms are often opaque, they occur more and more frequently, with great intensity and wide range. 1On May 5, 1993, strong sandstorms occurred successively in Xinjiang, Gansu and Ningxia, causing 1 16 deaths or disappearances, 264 injuries, tens of thousands of livestock losses, 337,000 hectares of crops affected, and direct economic losses of 540 million yuan. 1April 1998 15-2 1 day, a strong sandstorm swept through the arid, semi-arid and semi-humid areas of China from west to east, passing through Xinjiang, Gansu, Ningxia, Shaanxi, Inner Mongolia, Hebei and western Shanxi. On April 16, the dust floating in the sky settled in Beijing, Tianjin and the north of the lower reaches of the Yangtze River, forming a large area of floating dust weather. Among them, Beijing, Jinan and other places met with the rain cloud system, so "mud rain" fell from the sky. In Yinchuan, Ningxia, because of the continuous dust, the plane was grounded and people even felt difficult to breathe.

According to records, from the 3rd century BC to 1949, there were 70 strong sandstorms recorded in * *, with an average of 3 1 year. There have been 7 1 times since the founding of the People's Republic of China 50 years ago. Although there is a great difference in standards between historical records and today's meteorological observations, it proves that there are more sandstorms than in the past, and there is no problem.

According to the analysis of Landsat image data of China 17 typical sand area, it is also proved that the desertification development situation in China is very severe. Mu Us Sandy Land is located at the junction of Inner Mongolia, Shaanxi and Ningxia, covering an area of about 40,000 square kilometers. In the past 40 years, the area of quicksand has increased by 47%, the area of woodland has decreased by 76.4%, and the area of grassland has decreased by 17%. Due to overgrazing and firewood cutting in the south of Hunshandake Sandy Land, the area of quicksand increased by 98.3% and the area of grassland decreased by 28.6% in just 9 years. In addition, Minqin Oasis in Gansu is shrinking, Populus euphratica forest and Liu Honglin in the lower reaches of Tarim River in Xinjiang are extinct, grassland in Alashan area of Gansu is degraded, and Haloxylon ammodendron forest disappears ... A series of grim facts have sounded the alarm for us.

The final result of land desertification is mostly desertification.

Types and Distribution of Desertification in China

There are four types of desertification land in China: wind erosion desertification, water erosion desertification, freeze-thaw desertification and soil salinization.

The land area of wind erosion and desertification in China is 6.5438+0.607 million square kilometers, which is mainly distributed in arid and semi-arid areas and in various types of desertification.

Desert is one of the largest and most widely distributed lands. Among them, there are about 876,000 square kilometers in arid areas, which are generally distributed in

West of Langshan Mountain in Inner Mongolia, north of Tengger Desert and Longshou Mountain, including the north of Hexi Corridor, Qaidam Basin and its north and west.

Northern Tibet. There are about 492,000 square kilometers in semi-arid areas, which are generally distributed in the east and south of Langshan Mountain in Inner Mongolia, passing through Hanggin Houqi,

Chengkou County, Wuhai City, passes through the east of Hexi Corridor to the west until Subei Mongolian Autonomous County, showing a continuous distribution.

The sub-humid arid area is about 239,000 square kilometers, mainly distributed in the east of the Mu Us Desert and the east of Inner Mongolia, east longitude 106 degrees.

The total area of water erosion and desertification in China is 205,000 square kilometers, accounting for 7.8% of the total area of desertified land. Mainly distributed in yellow.

The Wuding River, Kuye River and Tuwei River in the northern part of Tu Plateau are mainly distributed in the middle and upper reaches of Xiliao River and Daling River in Northeast China.

The upper reaches of this river.

The area of freeze-thaw desertification land in China is * * * 366,000 square kilometers, accounting for 13.8% of desertification land. Freeze-thaw desert

Cultural land is mainly distributed in high altitude areas of Qinghai-Tibet Plateau.

The total area of salinized land in China is 233,000 square kilometers, accounting for 89% of the total area of desertification. Comparison of soil salinization

The areas with concentrated contiguous distribution include Qaidam Basin, oases around Tarim Basin, alluvial plains and rivers in front of the northern foot of Tianshan Mountain.

Hetao Plain, Yinchuan Plain, North China Plain and Yellow River Delta.