Forest and human health
With the development of society, people increasingly realize that forests have the functions of absorbing carbon dioxide and releasing oxygen, taking medicine, removing dust, sterilizing, purifying sewage, reducing noise, preventing sandstorms, regulating climate, indicating and monitoring toxic substances and so on. So many people began to feel the joy of the big forest in nature and realize the various benefits of the big forest to the human body. When you step into the green forest, you will suddenly feel comfortable and fatigue will disappear. Green in the forest not only brings beautiful scenery to the earth, but also acts on people's central nervous system through various senses, regulating and improving the body's function, giving people a feeling of tranquility, comfort, vitality and spirit, thus improving health. According to the investigation, the green environment can reduce the secretion of human adrenaline and the excitability of human sympathetic nerve to a certain extent. It can not only make people calm and comfortable, but also reduce the skin temperature of human body by 1℃-2℃, reduce the pulse by 4 -8 times per minute, and enhance the sensitivity of hearing and thinking activities. Scientists have proved through experiments that when the reflectivity of green to light reaches 30%-40%, it can stimulate people's retinal tissue properly, absorb ultraviolet rays harmful to human eyes in the sun, make eye fatigue disappear quickly, and have a bright spirit. According to the research, the plants in the forest, such as Chinese fir, pine, eucalyptus, poplar, juniper and oak, can secrete a monoterpene, sesquiterpene and diterpene gas "bactericide", which has an aromatic smell and can kill diphtheria, typhoid, tuberculosis, dysentery, cholera and other germs in the air. According to the survey, there are 4 million germs in the air per cubic meter in dry and forestless places, while there are only 600,000 germs on the boulevard and dozens in the forest. Photosynthesis of green plants can absorb carbon dioxide, release oxygen and absorb harmful gases. It is reported that 0.4 hectares of forest belt can absorb and assimilate 100000 kg of pollutants a year. 1 ha Cryptomeria fortunei forest can absorb 720 kilograms of sulfur dioxide every year. So the air in the forest is fresh and clean. According to Japanese scientists, there is a substance in forests and Yuan Ye-negative ions, which is extremely beneficial to human health. It can promote human metabolism, make breathing stable, lower blood pressure, be energetic and improve human immunity. It has been measured that there are only forty or fifty negative ions per cubic centimeter in urban houses, one or two hundred in tree-lined places, and more than ten thousand in forests, valleys and grasslands. In addition, forests also have the function of regulating microclimate. According to the measurement, the temperature of forest land is 3℃-5℃ lower than that of non-forest land in high temperature summer. In the cold and windy winter, the forest can reduce the wind speed and increase the temperature, thus playing the role of warm in winter and cool in summer. In addition, the leaves of plants in the forest have transpiration, which can increase the humidity of the surrounding air. In a word, forest is the main body of terrestrial ecological environment and the regulator of nature. Protecting the forest is to protect the environment where human beings live, that is, to protect themselves. Let's try our best to protect the big forest and let it benefit mankind!
If there is no forest
Many trees can absorb harmful gases, such as camphor tree, oleander, clove, maple, locust, Ailanthus altissima, Sabina vulgaris, Ligustrum lucidum, oak, willow, hibiscus, elm, Pinus massoniana, Platanus acerifolia and so on. ...
They have strong absorption capacity for toxic and harmful gases such as sulfur dioxide, chlorine gas and hydrogen fluoride. These gases usually have 1/4, which can be purified or turned into oxygen when passing through the green belt. Leaves have a strong adsorption and filtration effect on dust particles through their fluff, secreted mucus and oil. Each hectare of forest can absorb 50 ~ 80 tons of dust every year, and the dust content in the air of urban green space is generally less than half of that of non-green space. Many trees can secrete fungicides, for example, the fungicides secreted by pine trees can kill pathogenic microorganisms of diphtheria, dysentery and tuberculosis. The content of bacteria in the air in downtown area is 85% higher than that in green area. Trees can also absorb noise. A 40-meter-wide forest belt can reduce noise 10 ~ 15 decibels. Forests are so important that FAO has chosen "Forests and Life" as the theme of World Food Day in 199 1 year: not to plant trees, but to show how forests can help mankind achieve the goal of sustainable development; What needs to be emphasized is that forests have the function of lasting productivity, that is, while preserving the resource base for future generations, they can also meet the needs of the continuous development of current production; It is necessary to remind people that forests can not only provide food and fuel, but also have the most fundamental value of protecting the environment. If there is no forest, most of the life on land will be extinct, and most of the water will flow into the ocean; Oxygen in the atmosphere will decrease and carbon dioxide will increase; The temperature will rise obviously, and floods and droughts will occur frequently. Large-scale felling of forests, especially virgin forests, will undoubtedly affect and destroy the ecological function of forests, lead to ecological imbalance and environmental deterioration in local and adjacent areas, lead to frequent floods, intensified soil erosion, land desertification, river siltation, and even enhance the global greenhouse effect. The lush forest covering the earth is a huge and most precious "green wealth" forest in nature: human ancestors lived in the forest at the earliest. They collect wild fruits, catch birds and animals for food, make clothes out of leaves and skins, and build houses on branches. Forest is the hometown of human beings, from which human beings originated and developed. To this day, forests still provide us with all kinds of materials necessary for production and life. It is estimated that 300 million people in the world depend on forests for their livelihood. Forests provide all kinds of food, including fruits, seeds, nuts, roots, tubers, fungi and so on. In some forest areas in Thailand, 60% of food comes from forests. Animals in forest bushes also provide people with meat and animal protein. Wood has a wide range of uses, such as building houses, mining, building railways, building bridges, making paper and making furniture ... Forests provide employment opportunities for millions of people. Other forest products are also rich and colorful, such as turpentine, baking gum, insect wax, spices and so on. Are all raw materials for light industry. China and India have used medicinal plants for 5000 years. Today, most medicinal materials in the world still depend on plants and forests. In developed countries, the active ingredients in 1/4 drugs come from medicinal plants. Fuelwood is the main fuel in some developing countries. About 2 billion people in the world cook with firewood and charcoal. In some countries, such as Burundi and Bhutan, more than 90% of energy is provided by forests. It can be said that the forest is like the "dispatcher" of nature, regulating the circulation of air and water in nature, affecting the climate change, protecting the soil from wind and rain, and reducing the harm brought by environmental pollution to people. Forests are the real lungs of the earth, and every tree is an oxygen generator and a carbon dioxide absorber. A linden tree can absorb 16 kg of carbon dioxide a day, and 150 hectares of broad-leaved forests such as poplar, willow and locust can produce 100 tons of oxygen a day. If urban residents have an average of 65,438+00 square meters of trees or 25 square meters of grassland, the carbon dioxide they exhale will have a place to go and the oxygen they need will have a source. Forests can conserve water and play an important role in the natural circulation of water. "Green mountains are always there, and green water is always flowing." Trees are always associated with water. Part of the precipitation rainwater is intercepted by the canopy, most of it falls into the litter under the tree and is stored in the loose and porous forest soil, some of it is absorbed by the roots of plants in the forest, and some of it returns to the atmosphere through evaporation. 1 hectare of forest can evaporate 8000 tons of water a year, which makes the air in the forest area moist, increases precipitation, and makes it warm in winter and cool in summer, thus playing a role in regulating climate. Forests can prevent sandstorms and prevent soil erosion. As soon as the wind blows, block the way with the canopy to reduce the wind speed. The roots are long and dense, and hold on to the soil to prevent the wind from blowing away. Heavy rain falls into the forest, seeps into the deep soil and rock crevices, and slowly flows out in the form of groundwater, which can't wash away the soil. According to the records of Kenya in Africa, when the rainfall was 500 mm in that year, the sediment loss of agricultural land was 100 times that of forest area, and that of pasture land was 3000 times that of forest area. Aren't we going to stop desertification and soil erosion? The most effective helper is the forest. Photosynthesis of green plants can beautify our environment and make our living environment better. Forests can resist sandstorms and protect human beings. In recent years, due to the consumption of wood and forest products in consumer countries, the global forest area has decreased significantly, and nearly 10 million hectares of forests disappear every year. This is not only an internal problem of a country, but also an international problem. 197 1 The Seventh World Forest Congress decided to designate March 2 1 every year as World Forest Day, in order to arouse the attention of all countries to the green protector of mankind-forest resources, and realize the sustainable utilization of forest resources by coordinating the relationship between people and forests.
Edit the current situation of forest in this section.
However, many people don't seem to understand this. Not only do they not know how to cherish the forest, on the contrary, they are ruthlessly destroying it. Please see: "Hundreds of tractors and bulldozers rumbled, countless trees fell to the ground, animals were scared away, and the land was leveled. Then the flames spread everywhere, filled with smoke, birds whined and monkeys howled ... "This is the scene of the destruction of tropical forests in the Amazon basin of South America. It is said that millions of big trees are destroyed here every day. The destruction of forests did not begin today, nor did it just happen in the Amazon basin of South America. In the historical process of human development, forests have nurtured human beings like mothers and provided them with food, clothing, shelter and transportation. But since man mastered the technology of making and using fire, he began to attack his "hometown". From the Neolithic Age 654.38+0 million years ago, human beings developed rough herbivores and carried out slash-and-burn farming, which caused great damage to forests. It will get worse in the future. Four or five thousand years ago, the forest area in Europe accounted for 90% of the land area, but now it only accounts for 50%. The vast area of northwest China was also covered with dense forests 4000 years ago. Now, the forest is annihilated and the vegetation is destroyed. Many places have become dry plains with thousands of valleys and mountains. Particularly serious damage occurred in the past 100 years. With the development of social production, the process of deforestation, land reclamation, grazing, urban construction, timber logging, war damage and fire pests has greatly accelerated the shrinking of forest area in the world. Now, about 20 million hectares of forest disappear from the earth every year! World forest cover map
Over the years, Africa's forests have been cut down by more than half. In West Africa, for every tree planted, nearly 30 trees are cut down at the same time. Ivory Coast was originally one of the forest countries in Africa. In order to obtain the needed foreign exchange, nearly 300 thousand hectares of forest are cut down every year. 1963 still owned120,000 hectares of forest, and now there are only less than10,000 hectares left. Under the pressure of population explosion and over-exploitation of agriculture, forests in Asia are also in danger of disappearing. From 1980 to 2000, the forest area in Nepal will be reduced by 63%, in Sri Lanka by 59% and in Thailand by 55%. In the past 40 years, half the forests in Vietnam have been destroyed. 1970 The forest coverage rate in Thailand was as high as over 50%, but it has dropped to below 25% in just over ten years. The forests in Europe are all artificial forests, and the virgin forests have almost disappeared. Fires often occur in European and American countries. For example, in 1990 alone, Italy burned170,000 hectares of forest. Many forests in European countries are also destroyed by environmental pollution. The most worrying thing is the tropical rain forest, which is disappearing from the earth at an alarming rate. Since 1980s, Brazil, Indonesia and Zaire, the three major tropical rain forest growing countries, have cut down more than 2 million hectares of forests every year. According to a recent report, 1 1.3 million hectares of tropical rain forest were destroyed in 199 1 year, and 1 year reached 1 690,000 hectares, that is, forests in the past1year. 70% of the rainforests in the world have been destroyed! In the early days of human history, more than 1/2 of the earth was covered with green clothes, with a total forest area of 7.6 billion hectares. 65.438 million years ago, the forest area was reduced to 6.2 billion hectares, accounting for 42% of the land area. /kloc-it was reduced to 5.5 billion hectares in the 0/9th century, and forests can still be found everywhere in Europe, America, Asia and Africa. However, since the 20th century, deforestation has become increasingly serious. So far, there are only more than 4 billion hectares of forests in the world, and they are disappearing at a rate of 38 hectares per minute! There are many forests in China in history, not only in the south, but also in the north. There are lush forests on the banks of Weihe River where Beijing Lantian Apes lived 500,000 to 600,000 years ago, and in the Beijing area where Beijing Apes lived. However, there are not many forests in China now. 1988 forest area124.65 million hectares, accounting for only 3% of the world's forest area. The forest coverage rate is 13%, which is lower than the world average coverage rate by more than half. Forest destruction has brought us serious consequences. Soil erosion, sandstorm, climate imbalance, drought and flood are all related to large-scale forest destruction. The purpose of people destroying forests for land reclamation is to get more arable land and produce more food, but the result is counterproductive, crops are reduced and more and more people are hungry. People cut down forests in order to get more wood and fuel, but the result is also counterproductive. The more wood is cut down, the less wood there is. Some countries with rich forest resources are now wood importers, and 654.38 billion people in 22 countries do not have enough trees to supply their minimum fuel needs. Forests are closely related to human beings, close partners of human beings and an important part of the global ecosystem. Destroying forests means destroying the natural environment on which human beings depend, destroying the global ecological balance and affecting the food we eat and the air we breathe. No wonder a famous biologist said: "Any kind of deep disaster caused by human beings to the earth is nothing more than deforestation and destruction of forests today!" Take care of the forest. Deforestation is a foolish act of human beings. Don't do such a harmful thing. We should not only protect the existing forest resources, combine the utilization of natural resources with environmental protection, but also plant trees on a large scale, green the land, change the natural appearance and improve the ecological environment.