Forests can remove dust and filter sewage. Smoke, dust and waste gas emitted by industrial development seriously pollute the air and threaten human health. The folds and fluff on the leaves of tall trees, as well as the viscous oil and juice secreted by stomata, can intercept a lot of dust and have obvious blocking, filtering and adsorption effects. According to the data, spruce can absorb 8 8. 14 grams of dust per square meter every day, 9.86 grams of pine forest and 3.39 grams of elm forest. Generally speaking, the air dust concentration 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 the forest land of about 40 meters, and then with the increase of the distance through the forest land, the number of bacteria in sewage can be reduced to more than 90% at most.
Trees are experts in sterilization. Many trees secrete fungicides during their growth, killing all kinds of germs brought by dust. According to the survey, there are 4 million bacteria per cubic meter of air in department stores, 580,000 in boulevards, 100 in parks and only 55 in forest areas. The difference of bacterial content in the air between forest areas and department stores is more than 70 thousand times.
Trees are still natural reservoirs. The rotten layer of forest surface litter is increasing, forming a thick humus layer, which is like a huge ocean that absorbs rainwater, and has powerful functions of absorbing water, delaying runoff and weakening flood peak. In addition, the canopy can intercept rainwater, reduce the impact of rainwater on the ground, and maintain soil and water. According to the calculation, the canopy can block 10-20% of the precipitation, most of which evaporates into the atmosphere, and 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, prevent the land from being washed by rain, prevent soil erosion and prevent land desertification.
Desertification. There is no oxygen supply, and there is a barrier against wind and sand. The ecological environment is occupied and the laws of the biosphere are destroyed. The temperature will rise, causing irregular changes in the climate. After being cut down, the waste of trees will be burned, which will pollute the environment. Humans will slowly die of lack of oxygen! Birds have lost their homes, and the earth has lost flowers and birdsong. Eventually, we humans will be punished. Besides, we can't see the forest and there are no wild animals.