As if all plants on Earth has created 53 billion tons of biomass (dry absolutely is 64%) then the forest occupies 37 billion tonnes (70%). And the trees of the forest will emit 52.5 billion tons (or 44%) oxygen for respiration of humans, animals and insects on Earth for about 2 years (S.V. Belov, 1976).The forest is the vegetation of the trees on the Earth's surface, a tremendous role for people such as: providing wood, firewood, climate, generate oxygen, water, plant and animal shelter and storing the rare genetic resources.A hectare of forest annually, creating about 300 biomass-500 kg, 16 tons of oxygen (pine forest plantation, 3-30 tons 10 tons).Each person a year need 4,000 kg O2 oxygen intake by the corresponding 1000-3000 m ² of green create a year.Air temperature is often lower than the forest ground temperature of about 3-5° C.Protect forests and prevent wind storm.The amount of soil erosion of forest land only by 10% the amount of soil erosion of the land without forests.The forest is the source of endless human genes, is of rare plant and animal species.So the proportion of land covered by forests of a country is an important environment security (land of forests ensure environmental safety of a optimal country is 45% of the total area ≥).
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