树和人的关系（The relationship between trees and people）.doc

树和人的关系（The relationship between trees and people） The relationship between trees and people Since ancient times, forest trees have been quietly improving and beautifying human living environment. There are more than 7,000 kinds of plants in the plant kingdom, which are available for human consumption. Many plants have magical healing effects. There are about 5,000 to 6,000 folk herbs, and 40% of modern medicines come from nature. Scientists have also extracted cancer-fighting substances from plants such as mayton and yew Green plants are the pillar of the ecological balance, because the plant can purify water, can eliminate and reduce noise, can drought-tolerant sand-fixation, salinity, waterlogging resistance, can monitor the sulfur dioxide, pollution of fluorine, chlorine, ammonia, etc. Green plants depend on photosynthesis to sustain growth, absorb carbon dioxide and release the oxygen that humans sustain. According to the survey, in more negative oxygen ions in the air, after inhalation of the human body, can adjust the excitement and inhibition of the cerebral cortex process, improve the bodys immune ability, and has curative effect on chronic bronchitis, insomnia, etc. There are also many plants that secrete bactericidin, killing germs, such as eucalyptus, which kills TB, pneumonia and so on. A pine tree can produce 2 kilograms of bactericidin a day, which can kill bacteria such as diphtheria and dysentery. Use light energy to make oxygen. It is estimated that the earths annual incidence of solar energy is 5.4 x 1024 joules per year, and the annual fixed solar energy of green plants is about 5x1021 joules. These energies are the basis for the survival of all heterotrophic organisms, including humans and all kinds of animals. In addition, 3 billion years ago, the earths CO2 content was about 91 percent, almost no oxygen, and was not adapted to human survival. Its only about 300 million years ago to reach the modern level. These are all green plants. Each hectar