The fundamental purpose of setting up China Arbor Day in China is to protect forests and plant more trees.
The growth of every big tree has a considerable positive effect on human society. Some foreign scholars have calculated the ecological value of trees: a 50-year-old tree produces about 365,438+0,200 dollars worth of oxygen; Absorbing toxic gases to prevent air pollution, worth about $62,500; Increase the value of soil fertility by about $365,438+$0,200; The water saving value is $37,500; Providing breeding grounds for birds and other animals is worth $365,438+$0,250; Resulting in a protein worth $2,500. Excluding the value of flowers, fruits and wood, the total value is about $ 196000.
Groups of trees can protect the ecosystem well. Compared with bare land, a hectare of woodland can store at least 3000 cubic meters more water. The water storage capacity of 1 10,000 mu of forest is equivalent to a reservoir with a cost of 1 10,000 yuan and a water storage capacity of110,000 cubic meters. Some experts predict that if forests are lost on the earth, about 4.5 million biological species will cease to exist, 90% of fresh water on land will flow into the sea in vain, and human beings will face serious water shortage. The loss of forests will increase the wind speed in many areas by 60%~80%, and hundreds of millions of people will be killed by wind disasters.
I especially recommend it.
In cities, street trees can also make beneficial contributions to human society. A tree can store the pollutants emitted by a car driving for one year 16 km. Many trees can absorb harmful gases, such as 1 hectare Cryptomeria fortunei forest, and can absorb 60 kilograms of sulfur dioxide every day. Others, such as Ailanthus altissima, oleander, Ginkgo biloba, Sycamore, etc., all have the function of absorbing sulfur dioxide. In densely populated cities lacking greening, there are 34,000 bacteria per cubic meter of air, which is 1 10,000 times that of forests. After planting a certain number of plants in cities, the amount of bacteria in the air can be reduced by about 80%. "Urban forest" can increase air humidity. An adult tree can evaporate 400 kilograms of water a day, which can not only increase the air humidity, but also reduce the temperature of the city and slow down the heat island effect. Urban forest belts and hedges can reduce noise, and 30-meter-wide forest belts can reduce noise by 6~8 decibels. Urban shelterbelt can slow down the wind speed, and its effective range is less than 40 times of tree height, in which the wind speed can be reduced by 50% in the range of 10~20 times.
I especially recommend it.
I especially recommend it.