1. Forests are air purifiers. With the rapid development of industrial and mining enterprises and the sharp increase in the use of fossil fuels for human life, polluted air is mixed with a certain amount of harmful gases, threatening humans. Among them, sulfur dioxide is a harmful gas that is widely distributed and harmful. All living things have the ability to absorb sulfur dioxide, but the absorption speed and ability are different. The plant leaves have a huge area and absorb sulfur dioxide much larger than other species. According to measurements, the sulfur dioxide in forest air is 15-50% less than in open land. If it is a summer with high temperature and humidity, the forest will absorb sulfur dioxide faster due to the vigorous physiological activities of the forest trees. When the relative humidity is above 85%, the forest absorbs sulfur dioxide 5-10 times faster than when the relative humidity is 15%.
2. Forests have natural epidemic prevention effects. Trees can secrete highly lethal fungicides, which kill germs and microorganisms in the air and have certain health effects on humans. Someone has measured the amount of bacteria in cubic meters of air in different environments: 1,000 in parks where people flow, 30,000 to 40,000 in busy streets, and only 55 in forest areas. In addition, the amount of fungicides secreted by trees is also considerable. For example, one hectare of juniper trees can secrete 30 kilograms of fungicides every day, which can kill diphtheria, tuberculosis, dysentery and other germs.
3. Forests are natural oxygen plants. Oxygen is the basic condition for human life. The human body must breathe oxygen and emit carbon dioxide every moment. A healthy person will not be fatal if he does not eat or drink for three or two days, but he will die if he is deprived of oxygen for a few minutes. This is common knowledge. According to literature, to survive, a person needs to inhale 0.8 kilograms of oxygen and emit 0.9 kilograms of carbon dioxide every day. During the growth process, forests absorb large amounts of carbon dioxide and release oxygen. According to research, for every 44 grams of carbon dioxide absorbed by trees, they can emit 32 grams of oxygen; the leaves of trees produce one gram of glucose through photosynthesis, which can consume all the carbon dioxide contained in 2,500 liters of air. According to theoretical calculations, every cubic meter of wood grown in a forest can absorb about 850 kilograms of carbon dioxide from the atmosphere. In the peak growth season, one hectare of broad-leaved forest can absorb one ton of carbon dioxide and produce 750 kilograms of oxygen every day. According to the information, 10 square meters of forest or 25 square meters of grassland can absorb all the carbon dioxide a person breathes out and supply the required oxygen. It is true that trees also absorb oxygen and emit carbon dioxide at night. However, because the amount of carbon dioxide absorbed during the day is very large, almost 20 times that at night, the side effects at night are very small in comparison. Globally, forest green spaces process nearly 100 billion tons of carbon dioxide for humans every year, provide 60% of clean oxygen for the air, and absorb suspended particulate matter in the atmosphere. They have the ability to greatly improve air quality and reduce greenhouse gases. , reduce thermal effects.
4. Forests are natural mufflers. The harm of noise to human beings has become more and more serious with the development of AD and transportation industry, especially in cities and towns. According to research results, when the noise is below 50 decibels, it has no impact on people; when the noise reaches 70 decibels, it will have obvious harm to people; if the noise exceeds 90 decibels, people will not be able to work for a long time. Forests act as natural mufflers and have a very good anti-noise effect. Experiments have measured that parks or forests can reduce noise by 5-40 decibels, which is 5-25 decibels more effective than the natural attenuation effect of open spaces at the same distance from the sound source; car tweeters can reduce noise by 5-40 decibels when passing through a 40-meter-wide lawn, shrubs, and trees. The multi-layered forest belt can reduce noise by 10-20 decibels, which is 4-8 decibels more than the natural attenuation effect of open land. Planting trees on city streets can also reduce noise by 7-10 decibels. To have a good sound attenuation effect, in the city, there must be a forest belt of at least 6 meters wide (forest canopy) and 10 and a half meters high. The forest belt should not be too far away from the sound source, generally between 6-15 meters.
5. Forests have a regulating effect on climate. The dense forest canopy can absorb, scatter, and reflect part of the solar radiation in summer, reducing ground warming. Although most of the forest leaves have withered in winter, the dense branches can still reduce the wind speed blowing across the ground, reduce the air flow, and play a role in thermal insulation and moisturizing. According to measurements, the temperature in the forest in summer is 2-4°C lower than that in urban open space, the relative humidity is 15-25% higher, and the temperature is 10-20°C lower than the temperature of asphalt concrete pavement. Because the roots of forest trees penetrate deep into the ground, they continuously absorb water from the deep soil for transpiration of the trees, causing the forest to form fog normally and increase precipitation. Through analysis and comparison, the annual precipitation in forested areas is 10-30% more than that in non-forested areas. According to foreign reports, in order for forests to play a protective role in the natural environment, their green coverage must account for more than 25% of the total area.
6. Forests change low air currents, prevent sandstorms, reduce floods, conserve water sources, and maintain soil and water. Due to the obstruction and friction consumption of forest trunks, branches and leaves, the wind speed will be significantly weakened when entering the forest area. According to information, dense tree crowns in summer can reduce wind speed by up to 50%. The wind speed does not change much beyond 200 meters before entering the forest; after passing through the forest, it takes about 500-1000 meters to resume the speed before passing through the forest. Human beings use this function of forests to afforestation and control desertification.
The rotting layer of litter on the forest floor continues to increase, forming a thick layer of humus, which is like a huge sponge that absorbs rainwater. It has strong functions of absorbing water, delaying runoff, and weakening flood peaks.
In addition, the tree crown has a intercepting effect on rainwater, which can reduce the impact of rainwater on the ground and preserve water and soil. According to calculations, the forest canopy can resist 10-20% of precipitation, most of which evaporates into the atmosphere, and the rest falls to the ground or penetrates into the soil along the trunks to become groundwater, so a forest is a reservoir. The root system of forest vegetation can firmly fix the soil, protect the land from rainwater erosion, prevent soil erosion, and prevent land desertification.
7. Forests can remove dust and filter sewage. Industrial development and emissions of soot, dust, and waste gas seriously pollute the air and threaten human health. The wrinkles and hairs on the leaves of tall trees, as well as the sticky oil and juice secreted from the stomata, can capture a large amount of dust and have obvious blocking, filtering and adsorption effects. According to data, per square meter of spruce can absorb 8.14 grams of dust per day, pine forest can absorb 9.86 grams, and elm forest can absorb 3.39 grams. Generally speaking, the concentration of flying dust in the atmosphere in forest areas is 10-25% lower than in non-forest areas. In addition, forests are also very capable of purifying sewage. According to foreign research, when sewage passes through the forest land of about 40 meters, the bacterial content in the water can be reduced by half. Then as the distance through the forest land increases, the number of bacteria in the sewage becomes the largest. can be reduced to more than 90%. 6. Forests change low air currents, prevent sandstorms, reduce floods, conserve water sources, and preserve soil and water. Due to the obstruction and friction consumption of forest trunks, branches and leaves, the wind speed will be significantly weakened when entering the forest area. According to information, dense tree crowns in summer can reduce wind speed by up to 50%. The wind speed does not change much beyond 200 meters before entering the forest; after passing through the forest, it takes about 500-1000 meters to resume the speed before passing through the forest. Human beings use this function of forests to afforestation and control desertification.
The rotting layer of litter on the forest floor continues to increase, forming a thick layer of humus, which is like a huge sponge that absorbs rainwater. It has strong functions of absorbing water, delaying runoff, and weakening flood peaks. In addition, the tree crown has a intercepting effect on rainwater, which can reduce the impact of rainwater on the ground and preserve water and soil. According to calculations, the forest canopy can resist 10-20% of precipitation, most of which evaporates into the atmosphere, and the rest falls to the ground or penetrates into the soil along the trunks to become groundwater, so a forest is a reservoir. The root system of forest vegetation can firmly fix the soil, protect the land from rainwater erosion, prevent soil erosion, and prevent land desertification.
7. Forests can remove dust and filter sewage. Industrial development and emissions of soot, dust, and waste gas seriously pollute the air and threaten human health. The wrinkles and hairs on the leaves of tall trees, as well as the sticky oil and juice secreted from the stomata, can capture a large amount of dust and have obvious blocking, filtering and adsorption effects. According to data, per square meter of spruce can absorb 8.14 grams of dust per day, pine forest can absorb 9.86 grams, and elm forest can absorb 3.39 grams. Generally speaking, the concentration of flying dust in the atmosphere in forest areas is 10-25% lower than in non-forest areas. In addition, forests are also very capable of purifying sewage. According to foreign research, when sewage passes through the forest land of about 40 meters, the bacterial content in the water can be reduced by half. Then as the distance through the forest land increases, the number of bacteria in the sewage becomes the largest. can be reduced to more than 90%.
8. The forest is the habitat of a variety of animals and the growth place of many types of plants. It is the most active area for biological reproduction on the earth. Therefore, forests protect biological diversity resources; and whether they are around cities or in remote suburbs, forests are highly valuable natural landscape resources.