Plants have a huge leaf area and absorb more sulfur dioxide than other species. According to the measurement, the sulfur dioxide in forest air is less than that in open space 15-50%. If it is in summer with high temperature and high humidity, the absorption rate of sulfur dioxide by forests will be accelerated due to their vigorous physiological activities. When the relative humidity is above 85%, the speed of sulfur dioxide absorption by forests is 5- 10 times that when the relative humidity is 15%.
Second, the role of natural epidemic prevention has declined:
Trees can secrete fungicides with strong lethality, kill germs and microorganisms in the air, and have a certain health care effect on human body.
Third, the oxygen content drops:
On a global scale, forest green space can treat nearly 1000 billion tons of carbon dioxide for human beings every year, provide 60% clean oxygen for the air, and absorb suspended particles in the atmosphere, which has great ability to improve air quality; It can also reduce greenhouse gases and thermal effects. Fourth, noise pollution will be very serious. With the development of transportation, especially in cities and towns, noise is more and more harmful to human beings. According to the research results, noise below 50 decibels has no effect on people. When the noise reaches 70 decibels, it will cause obvious harm to people; If the noise exceeds 90 decibels, people can't work long hours. As a natural muffler, forest has a good anti-noise effect. Experiments show that parks or woodlands can reduce noise by 5-40 decibels, which is 5-25 decibels more than the natural attenuation effect in the open space with the same distance from the sound source. The car tweeter can reduce the noise 10-20 decibels when it passes through the multi-level forest belt composed of 40 meters wide lawns, shrubs and trees, which is 4-8 decibels more than the natural attenuation effect in the open area. Planting trees in urban streets can also reduce noise by 7-65,438+00 decibels. To achieve good noise reduction effect, it must be at least 6 meters (forest canopy) wide in the city.
Five, the climate has a regulatory role:
The dense forest canopy can absorb, scatter and reflect some solar radiation energy in summer, thus reducing the ground temperature rise. Although most of the leaves in the forest wither in winter, the dense branches can still reduce the wind speed blowing across the ground, reduce the air flow, and play the role of heat preservation and moisture preservation. According to the measurement, the temperature in summer forest is 2-4℃ lower than that in urban open space, and the relative humidity is high 15-25%. Compared with asphalt concrete cement pavement, the air temperature is lower 10-20℃. Because the roots of trees go deep into the ground, they constantly absorb the water in the deep soil for transpiration, which makes the forest form fog normally and increases precipitation. Through analysis and comparison, the annual precipitation in forest areas is higher than that in non-forest areas 10-30%. According to foreign reports, in order to protect the natural environment, the green coverage rate of forests should account for 20% of the total area.
Six, the forest to change the low-level airflow, can prevent sandstorms and reduce floods, water conservation, soil and water conservation:
Due to the blocking and friction consumption of forest trunks, branches and leaves, the wind speed entering the forest area will be obviously weakened. Data show that dense forest canopy can reduce the wind speed in summer by up to 50%. The wind speed changed little at 200 meters before entering the forest. It takes about 500- 1000 meters to recover the speed before crossing the forest. Humans use this function of forests to plant trees and control desertification.
The rotten layer of forest surface litter is increasing, forming a thick humus layer, just like a huge sponge that absorbs rainwater, which has powerful functions of absorbing water, delaying runoff and weakening flood peak. In addition, the canopy can also intercept rainwater, reduce the impact of rainwater on the ground, and maintain soil and water. According to calculation, the canopy can block 10-20% of the precipitation, and most of it evaporates into the atmosphere. The rest falls to the ground or seeps into the soil along the trunk to become groundwater, so a forest is a reservoir. The roots of forest vegetation can firmly fix the soil, protect the land from rain erosion, prevent soil erosion and prevent land desertification.
Seven, the forest has the function of dust removal, and the filtering effect on sewage becomes smaller:
Smoke and waste gas emitted by industrial development seriously pollutes the air and threatens human health. The folds and fluff on the leaves of tall trees and the viscous oil and juice secreted by stomata can stick a lot of dust and have obvious blocking, filtering and adsorption effects. The data show that spruce can absorb 8.14g of dust per square meter, and pine forest can absorb 9.86g.. The concentration of air dust in forest areas is lower than that in non-forest areas 10-25%. In addition, the forest has a strong ability to purify sewage. According to foreign research, the bacterial content of sewage can be reduced by half when it passes through 40 meters of woodland, and then it can be reduced to more than 90% at most with the increase of the distance through woodland.
Eight, animals are threatened:
It is also the growth place of many plants and the most active area of biological reproduction on the earth, so forests protect biodiversity resources; Moreover, whether around the city or in the outer suburbs, forests are extremely valuable natural landscape resources.
Due to the large consumption of forest wood resources, the forest area on the earth is getting smaller year by year, which has caused many environmental problems.
The harm of iodine deficiency after reading. Below 200 words is the writing method of reading: it is better to teach people to fish than to teach them to fish.
Format of feedback (in short):
The first paragraph summarizes the main contents of the book, what the author wrote and what he wanted to express.
In the second paragraph, choose a more important point, or what you think is important, and express it in your own words. Which do I think is better? What do I think?
The third paragraph combines real life and life in the book to express my true feelings, how life works, my feelings and what I have learned.
Do the above three points, then the feeling of reading this article will basically come out.
Of course, it is not necessarily just three paragraphs.
You can divide it yourself in the middle, as long as the details are appropriate.
However, the structural levels must be clear, reading and feeling should be combined, and the focus should be on "feeling".
There are usually three ways to write after reading: one is to abbreviate the outline, the other is to write after reading, and the third is to extract good sentences and paragraphs. The topic can be "After Reading" or "After Reading". ?
First of all, we must examine the questions clearly. When writing, we should distinguish what is primary and what is secondary, and strive to make "reading" grasp the key points and "feel" to write experiences. ?
Secondly, choose materials. Reading is the basis of writing. Only by reading carefully can we deeply understand the content of the article, so as to grasp the key points and grasp the thoughts and feelings of the article, and then we can have some feelings. Only by studying hard can we find the contact point of reading experience. This is the central idea of the article and the sentence that points out the central idea of the article. When writing a work, you can't cover everything. You should write down the changes in your thoughts and actions after reading it, and make a fuss about some of them. ?
Third, to write a post-reading feeling, we should start with a brief introduction to the contents of the read works, and then write our own experiences. The original content is often summarized in 3 ~ 4 sentences. In the end, most of them return to the works they have read. We should focus on the word "feeling" and remember to connect with our real life. ?
Finally, the points for attention in writing the post-reading feeling: ① Writing the post-reading feeling is by no means copying or simply repeating the original text, nor can it be played arbitrarily without the original text, but should be based on writing "experience". Write with true feelings. It should be a heartfelt feeling, not a "criticism letter" or a "guarantee". (3) Write unique and fresh feelings, and strive to have new ideas to attract or infect readers.
What are the hazards of selenium deficiency? Selenium deficiency in human body can lead to cancer, diabetes, cardiovascular and cerebrovascular diseases, which has been recognized by medical circles all over the world, and it is decided to hold an international seminar on selenium every four years.
Basic research also found that selenium can investigate cell division, differentiation and oncogene expression, and make the behavior of cancer cells change to normal; In vitro culture of animal and human hepatocellular carcinoma cell lines also showed that selenium supplementation blocked the occurrence of cancer. Professor Yu Shuyu, who is over 70 years old, and his research team were awarded 1996 "Klaus Schwartz Award" by the International Association of Bioinorganic Chemists for their achievements in "selenium preventing liver cancer".
What are the hazards of my calcium deficiency? (1) 99% of calcium constitutes bones and teeth. Calcium deficiency can easily lead to rickets, osteoporosis, loose teeth and falling off.
(2) Fatigue, backache, numbness of hands and feet, cramps, insomnia, dreaminess and irritability are also easy.
(3), allergies, colds.
Which countries lack tree resources, China and the Middle East?
The harm of water shortage in the critical period of water demand for trees 1. Trees can't grow without water. Different trees have different water requirements, and the same tree has different water requirements at different growth stages. In the process of tree growth and development, water supply is needed in every period, and only by meeting the water supply in every period can trees grow well. Grasping the law of water demand of trees is an important basis for water management of tree cultivation. The critical period of tree water refers to the period when trees are most sensitive and vulnerable to water in their life cycle.
Second, the lack of water in the critical period of tree water damaged the development of tree organs. The critical period of water demand for trees is not necessarily the period when trees need water most. The critical period of water requirement of various trees is different, but most of them are in the tetrad formation period of pollen mother cells, that is, vegetative growth is about to enter the reproductive growth period. Once water is scarce during this period, the development of sexual organs will be abnormal. Therefore, the critical water period of trees is related to the vigorous flower bud differentiation period.
Third, the lack of water in the critical period of tree water damages the quality of tree fruit. The critical period of water content of trees with seeds as harvest objects is the formation and development period of reproductive organs; The critical water period of trees with fruits (vegetative organs) as the harvesting object is in the most vigorous vegetative growth period. Once there is water shortage in this period, a large number of seeds will wither or be malnourished; Fruit will shrink in size, with low water content and reduced sugar, which is easy to be infected with pests and diseases.
Fourth, the lack of water in the critical period of tree moisture damages the quality of tree wood. For trees mainly harvesting wood, the critical period of tree water is the most vigorous period of tree growth. Once there is water shortage in this period, the growth rate of trees will slow down, the annual ring marks of tree rings will narrow, and the trunk will be thinner than the normal trees growing in the same period, which will easily form small old trees. Trees are malnourished, low in water content and prone to diseases and insect pests.
5. In the process of forest cultivation, the critical period of tree moisture affects forest quality and ecological environment. If the local precipitation conditions are not good, this period is the critical period when the local water conditions affect the growth of trees, which is also called the critical period of trees' climate for water. In the critical period of tree water, we should not only consider the sensitivity of trees to water, but also comprehensively consider the water demand characteristics of trees and local climate conditions, and strengthen water management in forest cultivation.
Missing Missing word group:
Boredom, fatigue, fatigue, lack, lack of steam, lack of support, lack of relief, lack of rest, fatigue, lack of roads, lack of sales, lack of relief, lack of interest, fatigue, lack of leisure, strike, embarrassment, fatigue, lack of people, lack of county and thirst.
What's the harm of getting sick easily due to lack of rest! Just like a running machine, if you don't have a good rest, it will break down.
How to combine words related to lack:
Lack, lack, gap, shortcoming, deformity, lack, scarcity, omission, lack of doors, vacancy, immorality, heritage, inadequacy