Million immigrants canyon

First, the history and natural landscape of the Loess Plateau

The Loess Plateau is a place where China's economy is backward and problems accumulate. The main problem is that the ecological environment is destroyed, which leads to a series of ecological disasters such as soil erosion, sandstorm and drought. In order to find out this problem, we must first find out what the natural landscape is like in the history of the Loess Plateau. Is it a forest area? Or a wasteland like this? Some people think that the Loess Plateau is not a forest area in history, but a grassland belt. This view does not conform to the objective reality. A large number of facts have proved that the Loess Plateau is indeed a forest and forest grassland area in history. This is the knowledge that scientists have done a lot of serious investigation and research on the Loess Plateau. For example, when Yang, a paleontologist in China, visited western Shanxi and northern Shaanxi in 1929, he came to the conclusion that the local area was originally a forest area based on a lot of textual research and investigation materials, and said with emotion, "It's terrible that our nation destroyed the forest." From 65438 to 0955, the investigation team of soil and water conservation in the middle reaches of the Yellow River of China Academy of Sciences clearly pointed out in the investigation report: "Judging from the remaining primitive vegetation, it is certain that the primitive vegetation in this area belonged to forests and forest grasslands before farming." This scientific conclusion has been confirmed by a large number of historical materials.

According to research, before Qin and Han Dynasties, the Loess Plateau was indeed a place with dense forests, beautiful scenery and beautiful environment. For example, Baichengzi, located in Jingbian County, northern Shaanxi Province, is an arid desert area in the Mu Us Desert on the northern edge of the Loess Plateau, but it was once a beautiful place with beautiful mountains and rivers, and was once the seat of Tongwan City (built in 407 AD), the capital of Daxia country. Helian Bobo, the king of Xia Dynasty, once praised when he built this capital: "The beauty of the four houses is close to Guangze and clear water, but I have traveled a lot, which is not as beautiful as Jos" (Yuanhe County Records). Nowadays, Baichengzi has been covered by vast sand sea, which shows that its ecological environment has changed greatly.

Gansu Longdong, Longxi, Lanzhou and Ningxia in the west of the Loess Plateau, which now presents the face of arid grassland, are also forest areas in history. According to the Records of Geography of Hanshu, there are many trees in Tianshui, Longxi and the mountains, and the people take boards as their rooms. It is the custom of forest dwellers to build houses with boards. It shows that this area was a forest area in Han Dynasty.

Another example is Li Daoyuan's Notes on Water Classics in the Northern Wei Dynasty: "Tianshui County, whose hometown is famous for building houses with boards" (see Notes on Water Classics, Volume 17, Wei Shui), which shows that board houses are very common. Until the Qing Dynasty, Anding (Dingxi County, Gansu Province) and Huining (Dulong Film and Gaolan Zaibi) still kept the custom of board houses.

The above shows that Longdong Loess Plateau used to be Dalin District. Who would have thought that places like Dingxi and Huining, where there are barren hills everywhere, nothing grows (in fact, nothing), firewood is extinct and the ecological environment is deteriorating to the extreme, were originally forest areas, and houses were built with wooden boards until the Qing Dynasty. Gulan is also a forest area. According to the records in the Book of Ancient and Modern Books, the ancient peak in the south of Lanzhou is "Lin Quansheng is the wonder of Lanzhou", and the water fork 60 miles southeast of the city is "beautiful scenery and lush bamboo trees" (there are still remnants of water fork forest). Now, Xinglong Mountain (Yuzhong County) near Lanzhou still preserves dense forests and is a beautiful scenic spot.

Liupan Mountain between Gansu and Ningxia provinces, called Dalongshan in ancient times, was once a large forest area. At the beginning of the Yuan Dynasty, when Genghis Khan levied Xixia, he camped in the northwest gorge of Liupanshan for the summer. Jiaqing's Pingliang Mansion states: "Liangdian Gorge is 70 miles south of Longde County, where Yuan Shizu used to spend the summer". It shows that until the Yuan Dynasty, Liupanshan was still a tree-lined place. After the Ming and Qing Dynasties, most of the forests in Liupanshan were destroyed by deforestation. However, until today, there are still dense forests in Jingyuan Mountain area in the south of Liupan Mountain.

Wuqu Mountain, north of Liupan Mountain, is also a forest area in history. According to the Inscription on the Construction of Huairongbao (near Dalasha in the northeast of Jingyuan County today) quoted by Zhang Antai in the New Tongzhi of Gansu Province in the Song Dynasty, the Wuqu Mountain and its branches in the Song Dynasty are all "lush forests and beautiful peaks".

Shanxi Province in the east of the Loess Plateau is mostly a forest area in history. Even in the Yuan and Ming Dynasties, trees were still flourishing. For example, the book Shun 'an once said at the edge of Shi Wen: "There are trees everywhere in Shanxi, which are simply invisible." According to the "Long Edition of Continuing the History as a Mirror", "Between the volcano and Ninghua, there are vast mountains and rivers." In Song Dynasty, the volcano army was in Hequ and Baode, and the Ninghua army was in ningwu county. It shows that at that time, the northwest of Shanxi from Ningwu to He Biao was lush with trees. The western part of Shanxi was called Xihe County in ancient times, which used to be a forest area. Notes on Water Classics describes the upper reaches of Fenhe River in Shanxi as "trees are shaded, clouds hang down and smoke rises". Gu's book "The Diseases of Countries in the World" describes that Luya Mountain used to be "the Great Wall of Wan Li with uneven trees and dry clouds covering the sun". During the Western Han Dynasty, Lin Mang, west of Luliang Mountain, was sparsely populated. There is only Linshui County in Suishui, and there is no county in the vast area to the north. Xihe County in ancient times was one of the main timber producing areas in China.

According to Notes on Water Classics: "The Northern Wei Dynasty (420-534 AD) built a palace in Luoyang, and the forest system was taken from Xihe River. In the Northern Zhou Dynasty (557 ~ 589), it was still "Luo Jing Woods, and the West River was full of trees". During the Tang Dynasty, the main logging center in Shaanxi was Zhou Gang (now Gangxian County, Shaanxi Province). In the Song Dynasty, the logging area extended southward to Shizhou (now Lishi, Fangshan and Zhongyang) and Fenyang, and now most of these places have become barren hills.

Hengshan Mountain, Wutai Mountain and the northern section of Taihang Mountain in the northeast of Shanxi were once densely forested areas. For example, Song Yaohui's Draft describes "dense forests" and "pine forests everywhere" in the northern part of Taihang Mountain. Liang Qingshan Zhi described Wutai Mountain in the Song Dynasty as "surrounded by Mengqingshan Mountain in Lin Lei, with mountains and valleys ringing". Written in the Ming Dynasty, the Biography of Hu Gao's Prohibition of Cutting contains: "Since ancient times, the five peaks have stretched for more than 700 miles, with trees towering into the sky and birds not crossing, and the country is still at the beginning." In the Ming Dynasty, palaces were built in Beijing, and most of the timber was taken from Daizhou (Wutai, Daixian, Fan Shi and Yuanping), which caused serious deforestation. "Ming Jing Shi Wen Edited" recorded the scene of deforestation at that time: "Hundreds of households are neighbors, so we can't catch them, but we can't ban them." The forest area was burned to ashes and the number of loggers was swept away. Only one million big trees are sold to Beijing every year. In this way, the forests of Hengshan Mountain and Wutai Mountain were swept away.

The south-central part of Shanxi is much warmer than the northwest, and the trees are more lush. According to the record of Taiping Yuhuan in Song Dynasty, there are many cypress trees in Xishan, Taiyuan. In the Northern Song Dynasty, the east and west mountains of Taiyuan were still "clouds of Cooper, Sophora japonica and wood" and were called "Jinxiu Mountain". Yuan Haowen of the Jin Dynasty said in the book "Crossing Jinyang Old City" that the West Hill of Jinci was "like a screen lying in the water, three hundred miles gloomy". In ancient times, there were many records about forests in the south and southeast of Shanxi. Shan Hai Jing mentioned that Zhongtiao Mountain and Taihang Mountain are luxuriant in trees and rich in bamboo. The Book of Songs describes the southern section of Taihang Mountain as a "pine and cypress mountain." Yecheng (Linzhang, Hebei), the capital of the Eastern Wei Dynasty, built palaces and used Shangdang materials. Licheng and Pingshun areas are "densely forested and easy to obtain materials." "Meng Qian Bitan" contains: "Gradually to Taihang, Songtai Feng", and so on.

The above historical data fully show that the Loess Plateau is indeed a region with widely distributed forests in history. It's a pity that "grassland theorists on the Loess Plateau" completely ignored such a large number of vivid historical documents. Even leaving aside historical data, the reality of forest distribution in the Loess Plateau is enough to prove that it belongs to the forest grassland belt. Now, the plantations in the northernmost part of the Loess Plateau are thriving, which is proof. For example, in Youyu County, which was once buried by quicksand, more than 654.38+00,000 mu of artificial forests (Larix principis-rupprechtii, Pinus tabulaeformis, Populus simonii, etc.) were built. ), known as the "oasis". Another example is Hequ, Yulin and Jingbian, which were attacked by the front of the Mu Us Desert. Hundreds of thousands of acres of artificial forests have been built, with lush trees. The reason is that there is more than 400 mm precipitation in the local area, and its habitat conditions allow forests to grow. It is originally a forest and forest grassland environment, otherwise it is difficult for forests to survive into forests. Forests in the northern part of the Loess Plateau can still grow well, not to mention the central and southern parts.

Second, the causes of ecological environment destruction in the Loess Plateau

It can be clearly seen from the above that the Loess Plateau before Qin and Han Dynasties was a forest and forest grassland. However, due to man-made destruction for a long time, a large area of forests gradually disappeared and became today's barren hills. Large-scale destruction of forests includes war damage, palace building, logging, deforestation and land reclamation. Among them, deforestation is the most serious and thorough destruction of forests. In the past two thousand years, the ecological environment of the Loess Plateau has been destroyed by continuous logging and reclamation. Since Qin and Han Dynasties, the Loess Plateau has experienced three climaxes of deforestation and land reclamation. The first time was a large-scale "reclamation" (organized reclamation by border guards) and "immigration" reclamation in the Qin and Han Dynasties. This large-scale "reclamation" has caused large-scale destruction of forests in northern Shanxi and northern Shaanxi. The second time was a large-scale "reclamation" in the Ming Dynasty, which caused unprecedented havoc to the ecological environment in the northern part of the Loess Plateau. According to textual research, in the early Ming Dynasty, the system of "ploughing fields" was vigorously promoted in northern Shaanxi (Yan 'an, Suide and Yulin areas) and northern Shanxi on the Loess Plateau, and the task of destroying forests and reclaiming land was imposed on every border guard. The Records of Diseases in Counties and Counties in the World records that "the land near the soldiers and guards in the world is divided into villages" in the Ming Dynasty. As soldiers and civilians scrambled to cut mountains and hoe fields, hills and hills covered with forest and grass were turned into farmland, making wasteland "crisscross among thousands of mountains and connected with hills and mounds". According to Shi Wen's Compilation, on the way from Yongning (now Lishi) to Yan 'an (Sui 'de), "that is, the cliff of the mountain, no matter how big or small it is, it is not cultivated". From here, we can easily see that the system of "reclaiming wasteland" implemented in the Ming Dynasty caused serious damage to the environment. The third reclamation was in the Qing dynasty, and the system of rewarding reclamation was implemented. The scope of reclamation moved from northern Shaanxi and northern Shanxi to southern Inner Mongolia, and millions of acres of grassland in the northern Loess Plateau and Ordos Plateau were reclaimed as farmland, which made the land desertification and soil erosion intensified.

It should be pointed out that the system of extensive cultivation and thin harvest has prevailed in the Loess Plateau since ancient times, and the agricultural proverb is "Don't hit a hundred burdens". Instead of choosing land suitable for farming, they used intensive cultivation to increase food production. Instead, it adopts the rotation system, releases Yamakaji by hook or by crook, plunders and expands cultivated land, and produces food by relying on natural fertility without fertilization. After planting for several years, the topsoil is lost, and when the fertility is used up, it will be abandoned. Choose another slightly better wasteland for farming. In this way, all the land covered by forest and grass has been shaved off, and the original forest and grass vegetation provenance has been destroyed and cannot be restored due to long-term endless reclamation. It can be seen that the failure of extensive planting and crop rotation system are the main bane of the complete destruction of the ecological environment in the Loess Plateau and the main cause of environmental deterioration.

Third, the ecological disasters caused by the destruction of the ecological environment in the Loess Plateau.

Forests are the "guardians" of the environment. After a large area of forest in the Loess Plateau was destroyed, it lost its ecological barrier and the ecological environment deteriorated seriously, which led to a series of disastrous consequences, such as the depletion of river water sources, soil erosion, intensified sandstorms, and increasingly frequent droughts and floods. This is a serious historical lesson. There are five main ecological disasters that still plague the Loess Plateau:

1. The hydrological conditions of the river have deteriorated seriously.

Deforestation will destroy the water conservation conditions, which will inevitably lead to the deterioration of river hydrological conditions, the sharp decline of water sources, the increase of sediment and the sudden rise and fall of water levels. Due to dense forests and lush vegetation, the ancient Loess Plateau has large and clear rivers. For example, the ancient Yellow River was called "Big River", and the water was very clear. The poem "Cutting Tan in the Book of Songs" said: "Cutting Tan on the ridge, the river is dry, the river is clear and the blue waves are rippling." Ge Tan belongs to Wei Ti in the national system. To the south of Wei is the Yellow River. From this poem, we can know that the Yellow River was clear in the Spring and Autumn Period. The tributaries Weihe River and Fenhe River had a large amount of water and clear water in ancient times. In BC 1 13, Liu Che, Emperor Wu of the Han Dynasty, took a boat trip to Shaanxi, and wrote the poem Autumn Wind: "The boat on the Fenhe River wants to help others and make waves." It can be seen that the Fenhe River had a large amount of water during the Western Han Dynasty, which allowed large ships to sail, but now the water volume has basically dried up, and many river sections can be crossed on foot. Weihe River was a vast river in the Tang Dynasty, with many sailboats and frequent water transportation. Li Pin, a poet in the Tang Dynasty, vividly described the scene at that time in his poem "Looking at the Night of Dongwei Bridge": "Qin has Wu Zhou, the dry wall is curved, people should stand in the mirror, and water flows in their hometown." At that time, Li Pin saw a large number of sailboats from his hometown in Jiangsu and Zhejiang docked at Weihe Bay in the north of Chang 'an, and the water was very clear. Now the Weihe River has changed beyond recognition. Like the Yellow River system, the hydrological conditions of Haihe River system have also deteriorated seriously. Therefore, the poor river runoff, water shortage, water level soaring and plunging, and serious disaster in the Loess Plateau are all adverse consequences caused by forest destruction.

2. Soil erosion is getting more and more serious.

Destroying forest and grass vegetation and making rain and runoff directly scour the loess ground will inevitably cause serious soil erosion. According to rough statistics, the area of soil erosion in the Loess Plateau is 360,000 square kilometers, accounting for 70% of the total land area, including 200,000 square kilometers in severely eroded areas. The annual soil loss is about 2.2 billion tons, and the average erosion modulus is 6 1 1 ton/(square kilometers per year). More than 70% of the soil enters the Yellow River, 5% enters the Haihe River, and the rest is intercepted by reservoirs and dikes. The Yellow River is the largest river in the world, with the largest sediment (about 654.38+600 million tons/year) and the highest sediment concentration (35 kg/m3). The most serious soil erosion in the Loess Plateau is in the loess hilly and gully region of northern Shaanxi, and its erosion modulus is generally above 1000 tons/square kilometer, and the downstream of Kuye River is as high as 350,000 tons/square kilometer. During the rainstorm season, there was a shocking situation of soil erosion in northern Shaanxi. According to the investigation,1July 6, 977, a rainstorm hit Yan 'an area, and Yanhe River washed away1100,000 tons of sediment in this rainstorm, and the highest sediment concentration in the flood that day reached 800 kg/m3. On June 1966, the Wuding River reached the record of sediment concentration per cubic meter of water 1390 kg. This is actually not water, but high-concentration mud. From here, we can imagine the severity of soil erosion in the Loess Plateau. Soil erosion is not only the main factor of low agricultural yield and economic poverty and backwardness in the Loess Plateau, but also the root cause of flooding in the lower reaches of the Yellow River. This is an urgent problem to be solved in the Loess Plateau.

The flood and drought disasters are getting more and more serious.

After the ecological environment of the Loess Plateau is destroyed, the climate and underlying surface conditions change, the air humidity decreases and the rainfall conditions decrease, which will inevitably lead to the intensification of flood and drought disasters. For example, local chronicles of south-central Shanxi recorded that there was no drought in ancient Shanxi. From the 24th year of Shang Dynasty to the year 2306 of Tang Gaozu (BC 1688 to AD 6 18), there was only one dry year of 16, with an average of 144. Later, as the forest destruction became more and more serious, the drought became more and more serious, which developed to once in 34 years in Yuan Dynasty and once in 5 years in Ming and Qing Dynasties, and reached the point of nine droughts in ten years in the Republic of China. So is the flood. According to the information provided by Zheng's History of Water Conservancy in China, in the nearly two thousand years before the Qin Dynasty, there were few floods in the lower reaches of the Yellow River, and the total * * * only overflowed seven times and diverted once, with an average of more than 200 years. After the implementation of "reclamation" in the Western Han Dynasty, the flood disaster was obviously aggravated, with as many as 12 times in more than 200 years. Since the Tang Dynasty, the floods in the lower reaches of the Yellow River have gradually increased, with an average of once every 10 year in the Tang Dynasty, 5.5 times every 10 year in the Song Dynasty, nearly twice a year in the Ming and Qing Dynasties, and four times a year in the Republic of China. The above situation fully shows that the flood and drought disasters in the Loess Plateau are mainly caused by the ecological environment.

The sandstorm is getting worse and worse.

The northern part of the Loess Plateau is close to the northwest arid area, with an annual precipitation of only about 400 mm, and the ecological environment is fragile. Once forests and grasslands are destroyed, it will cause land desertification or desertification. In fact, the Mu Us Desert in the northern part of the Loess Plateau evolved from the destruction of forests and grasslands. Now, the Mu Us Desert has expanded to the north of the Loess Plateau, and the vanguard has crossed the Great Wall and reached the Cape of Yu He, Yulin City (35km south of the city). Desertification has seriously threatened northern Shaanxi, northwestern Shanxi and southeastern Ningxia, and large areas of open sandy land have appeared in these places. Trees and grass must be planted immediately to control it, otherwise the consequences will be unimaginable.

It should be pointed out that the Mu Us Desert is not terrible, because its annual precipitation is between 300 mm and 400 mm, and the water content of the sand is very good and high (generally, the ground below 15 cm is wet). People call it "wet sand", and afforestation and grass planting are easy to survive. Therefore, there is absolutely a way to transform the Mu Us Desert. The masses in Yulin, Jingbian, Dingbian and Ningxia Yanchi in northern Shaanxi have successfully turned millions of acres of desert into Tian Liang, green land and orchards, which is a powerful proof.

5. The shortage of three materials (fuel, feed and fertilizer) is a serious problem.

The destruction of forest and grass irrigation will inevitably lead to the lack of firewood. In the coal-deficient areas of the Loess Plateau, the fuel problem is extremely prominent. In order to solve the problem of firewood burning, people are forced to dig roots and burn straw, which leads to burning cattle and horse manure, shoveling turf and digging grass roots, which will inevitably lead to an increasing shortage of feed and fertilizer, leading to a vicious circle. The most serious problems of "three materials" in the Loess Plateau are Dingxi, Gansu and Guyuan, Ningxia, where vegetation destruction is the most serious and fuel is extremely difficult. Straw, cattle and horse manure (even sheep manure) are almost burned as fuel, and even grass roots are dug up in some places, resulting in an extremely difficult situation in which livestock have no grass, land has no fertilizer and people have no food. According to the survey in Xiji County, in 1980, the county * * * consumed 250 million kilograms of organic fuel, including 654.38+23 million kilograms of grass roots, accounting for 48.4%, 83 million kilograms of livestock manure, accounting for 32.7%, and firewood150,000 kilograms, accounting for 5.7%. It can be seen that the main fuel comes from grass roots and feces, which can only last for half a year, and there is still no firewood for half a year. The people were forced to devote most of their labor to finding firewood, and almost everything that could be burned on the ground was searched clean, and their lives were in an unprecedented predicament. This is nature's merciless punishment for deforestation, reclamation and environmental destruction. Practice tells people that the consequences of deforestation and land reclamation are extremely serious, and will eventually come to the desperate situation of "three materials". Who would have thought that Dingxi, Gansu Province, which used to be Dalin District, had destroyed the ecological environment and homes due to long-term deforestation. By the early 1980s, it had been reduced to a desperate situation of bare land, no grass roots, no firewood, no fertilizer and no food. This is a painful lesson that the whole world should remember.

In order to help the people in Dingxi and Xihaigu (formerly) Gugu (formerly) areas get rid of their difficulties, since the mid-1980s, the state has adopted special assistance policies for "Sanxi" (Dingxi, Xihaigu and Hexi) areas. Vigorously planting grass and trees and restoring vegetation have alleviated the problem of "three materials", but they have not been fundamentally solved. Planting grass and trees, building basic farmland, returning a large number of farmland to forests and grasslands, and restoring and improving the ecological environment are the keys to get out of the predicament.