Junior high school debate competition
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■2. Destruction and reconstruction
More than 200 years ago, the French philosopher Chateau Blaine said: "The forests and grasslands in the barbaric period became deserts in the civilized period." Some people also said, "Man walked through the earth and left footprints in the desert." Although this statement is excessive, it is not unreasonable. Facing the boundless fertile land desertification, ecologist holloway also said: "The desert is man-made, and the climate only provides suitable conditions." However, human beings are smart. They can learn from their failures and rebuild the destroyed ecology. After all, man can conquer nature.
There are many examples at home and abroad that tell us that human beings are not completely powerless to the deteriorating ecology. Through scientific and human efforts, nature can be revived and pollution can be restored and purified.
Soil erosion can be stopped. In the past, people thought that the ecology of tropical rain forest was very fragile, and it was difficult to recover after being destroyed by rain. In tropical and subtropical red soil areas in southern China, soil erosion is really serious. According to the investigation and statistics of southern 1 1 provinces and regions, the area of soil erosion has reached 690,000 square kilometers, accounting for more than 30% of the national territory. Thickness of topsoil washed every year 1 cm. The surface has been eroded by typhoon and rainstorm for many years, some of which are hardened and some are desertified, leaving only a layer of red weathering crust. The ground is criss-crossed, gravel is everywhere, nothing grows, and the rich tropical rainforest has become a barren land. These barren areas can grow forests again, which will inevitably go through the evolution process from herbs to shrubs, from shrubs to tall trees. Without thousands of years, it is impossible to restore ecology.
People can understand nature, heal the wounds of nature and accelerate the pace of natural rehabilitation. South China Institute of Botany of China Academy of Sciences and Guangdong Dianbai County Soil and Water Conservation Experimental Extension Station have successfully rebuilt more than 6,000 mu of artificial forest community. In order to accelerate the natural succession process of plant communities, they adopted the transformation of previous arbor communities and the configuration of multi-level and multi-species broad-leaved mixed forests to achieve the purpose of short-term growth and accelerated recovery. Now, in the artificial forest community, trees, shrubs and herbs grow alternately. During the barren slope period, the amount of surface sediment erosion reached more than 0/000 kg per mu/kloc, and now it is only 0.2 kg per mu. The content of soil organic matter increases greatly, the temperature range decreases and the humidity increases. More than 400 species of insect specimens, 65,438 species of vertebrates and 38 species of soil microbial fungi were collected in the forest. Due to the ecological improvement, the rice yield per mu in the nearby countryside has increased from 50 to 65,000. Under the careful care of human beings, nature finally recovered its wonderful youth.
Serious pollution can also be eliminated, and the Thames in Britain is a big river that successfully purifies pollution.
A century and a half ago, the Thames was clean and clear, with green water rippling and water reaching the bottom of the canal. The rich aquatic products in the river supply the fish market in London. Later, factories were built on both sides of the river, and the sewage from the factory continued to flow into the Thames. The colorful dirty water from soap factories, gas factories, tanneries and paper mills all flows into this river, and the Thames has gradually become a seriously polluted river.
Dr. Alvina Wheeler, a biologist at the British Museum, made a survey in 1957. In the 20-mile Thames, there is no oxygen for nine months of the year. From London to Grefsater, there are no creatures, no insects, no fish, and even birds are gone. The Thames began to stink, and sometimes even the windows of parliament buildings along the river hung sheets soaked with disinfectant.
From 196 1, Britain began to seriously harness this river, and factories along the river generally built sewage treatment plants, which treated 200 million gallons of sewage every day and transported the remaining 5 million tons of sludge every day.
After a long period of treatment, the river became clear and the oxygen content in the river reached 36%. Aquatic plants grow in the river and fish schools reappear. A net was cast and a heavy fishing net was pulled up. The net is full of shrimps, lobsters, mussels, crabs, perches, red-footed snipes, geese, geese, magpies and ducks and other birds that spend the winter here. The Thames is alive again, fish are swimming again, and tourists are flocking to it.
Desertification land can also become an oasis again. Over the years, deserts have attacked human beings again and again, burying fertile fields, devouring villages and destroying cities. "The morning is fertile soil, and the evening is yellow sand. I don't know where my home is. I ran away with my child on my back and starved to death to feed wolves and crows. " It is a portrayal of the harm of sandstorm.
However, deserts can also be managed. People in Yulin area of our country rely on grass and trees to turn a large number of deserts into farmland and pasture.
Yulin area is located in the southern edge of Mu Us Desert in the northern part of the northwest loess plateau, with the ancient Great Wall crossing it, and about 25.6 million mu in the northern part is in the sandstorm area. Historically, it used to be an agricultural and pastoral area with lush forests and grass. After the Tang dynasty, due to excessive reclamation and years of war, vegetation was greatly destroyed and desertification became more and more serious. Around 1949, the barren sand has crossed the Great Wall Line 10 km, and continues to press southward at a speed of 3-8 km per year. Yulin people planted grass and trees on more than 7 million mu of desert land, greening the desert. By the end of 1983, the total area of planted grass in the whole region had reached16.63 million mu, and 62 forests over 10,000 mu had been built. In addition, three large shelterbelts with a total length of more than 850 kilometers have been built along the Great Wall, 2.7 million mu of Hongdong forest belts have been built along the Yellow River, and 6.5438+0.7 million mu of apple forest belts have been cultivated on both sides of domestic highways. The vegetation coverage rate in the whole region reached 2 1%, the average wind speed decreased by 49%, and the 8.62 million mu of quicksand in the whole region was basically fixed or semi-fixed, reaching more than 5.5 million mu, of which 520,000 mu was transformed into fertile land.
The great change of Dongshan Island is another vivid example: Dongshan Island is an island in southern Fujian with an area of 192.5 square kilometers, and it is the second largest island in Fujian Province. Thirty years ago, the sand dunes on the island were continuous, and the wind and sand were rolling. There was no land to grow and no firewood to cook. There was only one road, which was impassable when it was windy, and the wind and sand moved. Small sand dunes as high as 1~2 meters suddenly piled up on the road. There is a local saying: "Dongshan Island is a bad place, with more wind and sand, less rainfall, more sweet potatoes and less rice." According to historical research, in the past 100 years, there were 103 villages and 1000 houses, and more than 30,000 acres of fertile land were buried, so people left their homes and fled to other places.
Dongshan Island is surrounded by the sea and belongs to the south subtropical maritime monsoon climate. According to statistics, the annual rainfall is about 1000 mm, which does not belong to desert climate. So where did the landscape of sand dunes come from? People found the reason from the history books. It turns out that Dongshan Island has always been an important place for coastal defense. However, in the Yuan, Ming and Qing Dynasties, there were heavy troops stationed, and frequent military activities caused the forests in Dongshan to be destroyed continuously. By the early days of the founding of the People's Republic of China, there were few shaded banyan trees in Dongshan Island, only a little fengshui forest. As a result, the wind blew hard, flying sand and stones, flying dust, sandstorm fighting, strong wind helped Javert, and Dongshan Island became desert.
Thirty years later, Dongshan Island changed the world. The barren slopes, undulating sand dunes and dusty yellow sand of Tongshan are all gone, replaced by green forest belts, lush crops, lush mountains and green reservoirs. This is the result of 30 years' efforts by soldiers and civilians in Dongshan Island, such as planting trees, drilling wells to find water, building reservoirs and transforming sandy land. The forest coverage rate has increased from 0.6% in the early days of liberation to 36.5%, and Dongshan Island is covered with green clothes and full of vitality.
The past and present changes of Dongshan Island once again tell us a truth: the desert is man-made, so is the oasis, and the climate only provides suitable conditions.
Some destroyed special ecology can be restored through people's efforts. The once devastated Galapagos Islands have now recovered their natural ecology through people's efforts.
The Galapagos Islands, located in the east of Ecuador, is a research base for species evolution. Darwin, the founder of the theory of evolution, once conducted detailed research here, which provided rich materials for the masterpiece Origin of Species. Therefore, UNESCO calls it an "international heritage".
The Galapagos Islands are also the largest natural museum in the world. Due to the unique natural conditions, there are penguins in the Antarctic, seals in the Arctic, lizards and giant turtles unique to the equator, and various exotic birds. Animals from all over the world settle here.
However, with the increase of immigrants and the reproduction of livestock, the natural ecology has been seriously damaged. Goats have eaten the shrubs on the island, and giant turtles, flamingos and seals are in danger of extinction. This international heritage is facing a serious threat.
In order to save this precious international heritage, scientists on the island first surrounded the chief culprit of ecological damage, killing 50 thousand wild goats, thus protecting the vegetation on the island. Artificial insemination and artificial breeding are also used to breed giant turtles and giant eagles, greatly increasing the number of these endangered animals. Today, the island is covered with trees and flowers, and this "international heritage" is reborn.
■3. Part and whole
Nature is a harmonious whole, and there is a harmonious relationship between all things, between a system, between organisms, between organisms and inorganic circles, between large organisms and microorganisms; Environment and human beings are a harmonious whole. There is a certain structure between them, which is interconnected by material flow and energy flow to form a whole. When dealing with the relationship between man and nature, we must establish a firm concept of the whole and correctly handle the relationship between the part and the whole.
DDT is a pesticide invented by human beings, which has made great contributions to the struggle against pests and diseases, and the inventor also won the Nobel Prize. However, today, after weighing all its advantages and disadvantages, it has stopped production and use. This decision is the result of overall consideration.
DDT was synthesized by a German chemist in 1874, but its function was unknown for a long time. 1940, Swiss scientist paul muller discovered its function, and used it to quickly control the harm of potato beetles.
1944, an epidemic typhus occurred in Naples, Italy, and the doctors were at a loss. Later, DDT was used, and the transmission was controlled within two or three days. So DDT was widely used and became the best-selling pesticide in the world, with an annual output of 400,000 tons. Similar organochlorine pesticides were also produced in large quantities.
However, DDT is a poison with stable chemical properties, and 80% remains after one year. It enters rivers, lakes and oceans, inhibits the growth of algae and poisons fish, shrimp and shellfish. When the DDT content in water reaches1.1100000, carp will die within 48 hours. As long as the DDT concentration exceeds 554.38+0 billion, crabs can be killed 100%.
The increase of DDT content in water not only harms aquatic organisms, but also threatens the safety of fish-eating birds. DDT will inhibit the reproduction of birds, making them lay abnormal thin-shell eggs and even unable to have offspring at all. Previous investigations in 37 countries found that 1 18 species of wild birds contained DDT. Some carnivorous birds, such as vultures, falcons, herons and pelicans, die in large numbers, and some are on the verge of extinction.
The pollution of organochlorine pesticides such as DDT will eventually affect human health. They enter the human body through air, water, food and other channels, and accumulate in human fat and liver tissue. Today, most foods we eat-grains, fruits, fish, meat, eggs, vegetables, honey, tea and so on. -Contains DDT, even babies born in Lian Gang are not spared, because breast milk contains DDT. DDT damages human liver and central nervous system, and inhibits normal physiological activities. Whether DDT can induce cancer is inconclusive, but experiments have proved that organochlorine pesticides can cause cancer in mice.
The use of DDT temporarily reduced the cold damage of insects, but after a period of time, pests and diseases will come back and become more fierce. It turns out that in nature, all kinds of creatures depend on each other and restrict each other, and there is a wonderful ecological balance relationship. Many pests have their own natural enemies, such as ladybugs that eat cotton aphids, Trichogramma that parasitize pine caterpillars and so on. Pesticides such as DDT often kill their natural enemies while killing pests, and even these natural enemies can't stand the attack of pesticides. As a result, some pests lost their original ecological control, multiplied rapidly and broke out into disasters.
Now, there is hardly a place on earth where DDT can't be found. Air, soil, water and creatures have become their hiding places everywhere. Even the uninhabited North and South Poles and the snow-covered Himalayas have their molecular ghosts wandering around. Eskimos living in the frozen Greenland have never used and contacted DDT, but now they have found traces of DDT.
From a local point of view, DDT is effective and has made great contributions to pest control; Generally speaking, it pollutes the environment, kills the natural enemies of pests, encourages the harm of pests, harms birds, fish and mammals through the life chain, and finally harms human beings. Therefore, it is absolutely necessary to stop the production of this pesticide.
■4. Needs and possibilities
Man is not only a positive factor to regulate the relationship between man and nature, but also the chief culprit to worsen the relationship between man and nature. Forest reduction, soil erosion, biological extinction, air pollution, etc. are all caused by human activities in the final analysis. In the final analysis, it is related to population growth, which is the contradiction between the possibility of material production and the environmental capacity of human growth demand. When people get the necessities of life, they will more or less have an adverse impact on the environment. On the one hand, in order to survive, people have to ask nature to cut down forests for heating, building houses and cooking; Burning wasteland to get food; Kill wild animals and eat meat. On the other hand, the results of human activities often cause pollution, such as the exhaust gas emitted by human cars and the pollution of the environment by garbage. In short, the population size and its growth rate have an important impact on the environment. There are many people, many demands and fast resource consumption. Once the population demand exceeds the possibility of material production, even some renewable resources, such as water and atmosphere, lose their ability to update. The more people there are, the greater the harm to the environment, and any remedial measures can only reduce but not eliminate the impact of population growth on the environment.
Population growth will lead to over-planting or over-grazing, which will lead to regional land degradation or desertification. According to FAO's estimation, the growth of the world's livestock has caused serious damage to many pastures, and about 6 million hectares of land in the world become deserts every year. In order to feed the growing population, 8 million hectares of land in Asia are destroyed for temporary farming every year. The leisure period of land will inevitably be shortened, which will lead to the decrease of natural plant community species and the deterioration of soil structure. Gorillas and chimpanzees in Africa are on the verge of extinction because the mountains they grow in are being reclaimed for farmland; The number of gibbons and Indonesian orangutans in Hainan Island, China is also decreasing day by day, which is also due to the reduction of forests due to the excessive population pressure. From the distribution of soil erosion, there is a remarkable feature; Places with high population density are more important than places with low population density, places with convenient transportation are more important than places with inconvenient transportation, near mountains are more important than distant mountains, and areas that develop first are more important than those that develop later. This shows that overpopulation is an important cause of ecological deterioration. The increase of population also forces people to farm on eroded land on steep slopes and red soil in hot and humid areas, resulting in soil erosion and land productivity reduction.
The impact of rapid population growth on the environment is manifested in more and more pollutant emissions. Under the condition of imperfect control technology, the massive consumption of resources means the aggravation of pollution. Taking solid waste as an example, in 1977, Japan's garbage discharge was 4 1 260,000 tons, which was equivalent to the average discharge per person per day 1062 grams, which was 500 grams more than that in 1960, an increase of1times.
Industrial countries emit more pollutants than developing countries. Some people think that an American pollutes the earth more than 100 Asians. The population of the United States accounts for about 6% of the world's population, and the pollutants emitted account for about 40%. Modern agriculture has a greater impact on the environment. For example, the pollutants produced by 3 million farmers in California are 100 times higher than those produced by all farmers in India.
This duality of human nature requires us to keep the population growth in harmony with natural resources. If the population growth rate exceeds the burden of natural resources, it will inevitably cause serious ecological problems and exhaust resources. At the same time, population growth should be consistent with the evolutionary ability of the natural environment. If the pollution caused by population increase exceeds the natural load, it will inevitably cause serious pollution problems, cause ecological deterioration and affect human survival and development.
■5. Trees and grass
For some reason, people have a prejudice that it is important to plant trees in order to improve the ecology, but they don't care about planting grass. People often weed while planting trees. Farmers are constantly weeding, and school students, government workers and army soldiers weed in schools, government agencies and military camps every year, so that nothing grows, and grass seems to be the enemy of ecology.
The prejudice against grass has a long history. Shennong once tasted a hundred herbs. At that time, grass had a good reputation. However, in the Warring States and Qin Dynasties, the reputation of "grass" went from bad to worse. Mencius once said, "When you are in opposition, you are called a rough minister", and "Lushi Chunqiu" said that "the vegetation is filthy". Everyone regards grass as a derogatory term. During the Tang and Song Dynasties, people called thatched cottages thatched cottages, and poets Du Fu and Bai Juyi lived in such shacks. The feudal rulers called the peasant rebels "bandits". In short, anything that touches the cursive character is not good enough. Some people in modern times often refer to bad taxis as "poisonous weeds", which are completely eliminated like "weeding". In a word, people hate weeds. Actually, weeding is very harmful. In addition to grass, the soil loses the protection of grass, the soil is easy to lose, and the wind is easy to wreak havoc. Where there is grass, it can prevent wind and sand. The so-called inch grass can shelter the wind. Many school authorities mow grass, and when the wind suddenly rises, it will hit the sand. In fact, there is no need to weed, the grass is very lush. Isn't it beautiful? Some pastoral areas also use weeding to "ask the grassland for grain", which leads to poor grain planting and poor grassland protection. A large number of precious grasslands have been desertified.
Grass is not only harmless from the cold, but also beneficial. Grass is a huge factory for fixing solar energy. According to statistics, the energy accumulated by organic matter produced by green grass every year is about equivalent to the energy consumed by the whole world every year. These organic substances greatly improve the fertility of soil and enrich the life materials in the world. About two-thirds of the organic matter produced by grass is underground, and 1/3 is above ground. The underground part can improve the soil, and the aboveground part is a good forage. Grass is an important link in human food chain. With grass, there will be cattle, sheep and rabbits, and there will be meat and milk. Grass is also a supplier of nitrogen in the ecosystem. Leguminous forage can fix nitrogen in the atmosphere and convert it into organic matter. An acre of alfalfa can fix 28~36 kg of nitrogen in three years, which is equivalent to 90~ 1 10 kg of ammonium nitrate. The protein of leguminous forage can reach more than 20%, and these protein can be directly used by animals.
Grass is also a pioneer in improving ecology. It has a short growth cycle and strong vitality. The endless grass on the plain comes and goes with the seasons. Wildfire never completely devours them, but they grow taller in the spring breeze. Grass has a strong reproductive ability. Many grasses can reproduce asexually through rhizomes, tubers, bulbs, bulbs, tubers and small bulbs, and some grasses such as Bermuda grass and crabgrass can reproduce adventitious roots on stems. Grass can produce a large number of seeds, and a single seaweed can produce 35,000 seeds. Planting grass is an important way to transform the ecology. Although China has a long history of planting grass and has made great progress since the founding of the People's Republic of China more than 60 years ago, there is still a big gap compared with some developed countries. Britain's grass planting area is about equal to its cultivated land area; The artificial grassland in New Zealand is 13~ 14 times that of cultivated land. The areas planted with grass in the Soviet Union and the United States are also 17.4% and 14.7% of cultivated land, respectively. In a well-afforested country, it is almost impossible to see bare soil and green grass everywhere. And China has only 1% up to now.
The soil layer of wasteland (0~30 cm) in most parts of northern China is mostly sandy soil, and the physical sand particles are generally above 80%. Without vegetation and vegetation protection, it is easy to cause wind erosion and desertification. But most of these areas belong to arid and semi-arid areas, mostly desert Gobi desert. There is plenty of sunshine and large temperature difference here, which is beneficial to the accumulation and growth of plant nutrients. But it is windy, sandy, dry and rainy here, which is not conducive to afforestation of crop growth. It is possible to plant some adaptable grasses, which can not only survive, but also change the ecological conditions here to some extent, and even provide good conditions for afforestation and farmland development. In recent years, Yining County of Xinjiang has planted grass on 90,000 mu of land to transform barren slopes. Now, the grassland is lush, with a coverage rate of 80%, which has transformed the climate, reduced sandstorms and increased feed. 1970 Xinjiang Turpan desert botanical garden is also paved with sand-fixing herbs. Since 16, it has not only fixed quicksand to protect surrounding villages, but also built a botanical garden integrating exotic flowers and herbs, which has become a famous tourist attraction in Turpan. Located 72 meters below the standard sea level, this desert botanical garden can also be called the lowest botanical garden in China. Therefore, I advise you not to underestimate the grass. Of course, planting grass is bound to compete with growing grain for land, but as long as it is handled properly, planting grass and growing grain can complement each other. When dealing with the relationship between man and nature, we should not only see big trees, but also see grass. We should establish a correct concept of greening. Greening means not only planting trees, but also planting grass.
■6. Losses and excess
When dealing with the relationship with natural creatures, human beings must pay attention to the degree. Losing your degree is not only bad but also harmful.
The Soviet Union was severely punished for its careless treatment of wolves. At first, the Soviets thought that the wolf was the enemy of Siberian reindeer, and it killed reindeer, resulting in a sharp decline in the number of reindeer. People naturally think that reindeer will grow faster if wolves are eliminated. So a large-scale campaign to kill wolves was launched. Almost killed the wolf.
After the wolf was killed, the number of reindeer really soared. However, the number of reindeer soon exceeded the load of the forest, and reindeer often ran out of the forest to feed on the edge of the city. One year, a continuous snowstorm, reindeer lack of food, physical decline, more than half of them died. Only then did people discover that wolves played a certain role in the normal survival of reindeer. First of all, the wolf is a control machine, which keeps the reindeer population at a certain number, not too much, thus maintaining a relative balance with the space and food in the forest. Secondly, wolves are seed selection machines. When it chases reindeer, the old, weak, sick and disabled reindeer often become food for wolves, leaving strong offspring, giving the strong more opportunities to manage their offspring, and keeping the reindeer herd full of vitality. Third, it is the quality of reindeer. Wolves keep spying on reindeer, forcing them to keep keen sight and hearing, and wolves keep chasing reindeer, forcing them to keep running, thus maintaining their vitality. Once the wolves disappear, reproduction will be out of control and over-bred. Due to the loss of enemies and little running activities, the reindeer's physique has greatly declined, and most of them died of hunger and cold in the snowstorm year.
Later, the Soviet Union learned its lesson and released the wolf. Wolves feed on reindeer, and the number is increasing, and now it has reached more than 65438+ ten thousand. When wolves exceed their quota, they begin to endanger deer, and then cattle, horses and other livestock. According to statistics, 50,000 cows and horses die from wolves every year, and countless other poultry. Seeing that wolves were a disaster, Soviet authorities dispatched helicopters, falcons and motorcycles to kill them. 1983, 15000 wolves were killed. Now there are fewer wolves, what will happen to reindeer? People are waiting to see. However, this example of the relationship between wolves and reindeer vividly tells us a truth: "People must pay attention to the creatures and inorganic substances in nature. Loss and surplus are harmful, and it is best to be moderate, so that a better balance can be achieved naturally and all kinds of creatures can get their places.
■7. To love nature is to love human beings.
Nature is the storehouse of human beings, providing them with all kinds of food and medicine. Nature is the cradle and courtyard of human beings, which provides a suitable environment for human beings. The destruction of nature will inevitably destroy human food banks and drug banks, and will inevitably destroy human cradles and courtyards. Therefore, loving nature means loving human beings themselves.
There are millions of plants, animals and microorganisms in nature. They are a treasure house of life and an important resource for human beings. Destroying them will deprive mankind of available resources. The destruction of tropical forests by human beings is the greatest destruction of biological resources.
A century ago, tropical forests covered twice the area of Europe. But now it has been reduced to half of this area, and a large area of rainforest equivalent to the size of Britain is burned or cut down every year. By the end of this century, there will be few large rainforests left, and only a part may remain in Brazil and Zaire. Tropical forest area is one of the richest and most diverse areas in the biosphere. It is estimated that there are 3 million different kinds of plants, animals and microorganisms in these rainforests. So far, scientists have only named and classified about 1/6.
In fact, more than half of the living things on earth live in the warm and dark areas of these tropical rainforests. For example, Panama, a small country in Central America, has as many plant species as all the plants in Europe. There are 654.38 million species of insects in North America, but in the Amazon basin, 42,000 species of insects can be obtained by sampling in two acres of forest, and scientists have only identified 5% of them. According to the current rate of deforestation, in the next 30 to 40 years, more than 1 10,000 species of plants, animals and microorganisms will become extinct, accounting for more than 25% of all species on earth, and they will disappear forever before human beings realize it. At present, more than half of the drugs prescribed by pharmacists come from wild plants and animal resources, many of which come from tropical regions. According to the National Cancer Institute, tropical plants are the main warehouses of cancer drugs, and the loss of these resources is a major setback in the fight against cancer. Genetic engineering has been born and is expected to develop into a major sector of the world economy. In this case, it can be considered that the gene storage in the rainforest is one of the most precious natural resources of human beings, and if it disappears, its loss is incalculable.
There are green mountains and green waters, red flowers and green trees, and sparkling clouds in nature, which create a suitable ecological environment for human beings. Barren mountains and rotten water are not suitable for human survival. If we cherish nature and make it beautiful forever, we will provide a good environment for mankind. If we don't take care of it, it will inevitably lead to the deterioration of the living environment.
On the contrary, caring for nature will make human beings have a good ecological environment and a beautiful home. The changes in Yulin County, China also fully illustrate this point.
Yulin county is a mountainous area composed of rocky mountains and loess hilly areas. The five tributaries of Zhangzhuohe River are evenly distributed throughout the county. The banks of these major tributaries and tributaries are fertile "Rice River".
In ancient Yulin, it was once a place of "shady birds". Before War of Resistance against Japanese Aggression, there were nearly 654.38 million mu of forests at the source of Zhang Zhuo River, accounting for 4.3% of the county's total area. In the future, because farmers went up the mountain to destroy forests for land reclamation, there were 1. 7 million farmers in the county to reclaim land in the teachers' college area, and the water and forest land in the upper reaches of the Zhang Zhuo River was reclaimed into farmland. 1945 only160,000 plants were left, leaving 20,000 mu of residual forest. Due to the destruction of forests, the ecosystem is out of balance, soil erosion in mountainous areas, and the land of rivers is washed away. Miliangchuan on both sides of Zhangzhuohe River was washed away by the flood and turned into a barren sand wasteland. After liberation, the local people planted 6.5 million trees and afforested more than 220,000 mu, accounting for 9.2% of the total area. In particular, 75,000 mu of large-scale flood control and revetment forests have been built on both sides of the Zhangzhuo River, like two green belts, which firmly bound the Longzhangzhuo River and benefited the people of Yulin. Before 1949, in Shiyuan village, the river was more than 4 meters deep after the rain, and the water was still turbid for three or four days. By 1954, the forest land increased, but the flood decreased after the rain, only 1 m deep, and the water flow decreased 1/3. After 9 hours, the flood became clear and drinkable. In the 20-kilometer-long reach of the upper reaches of Zhang Zhuo, the clear water began to flow, and the mountains were really green, and the Zhanghe River was green. The combination of trees, shrubs and grass in the riparian forest belt protects farmland and riverbed from being washed away, reduces sandstorm and increases harvest.