Reducing the greenhouse effect. The greenhouse effect caused by CO2 gas which release pollutants into the air and accumulates in the atmosphere. The tree is a "glutton" CO2 greedy. In its growth, shaping the tree trunk, mainly from carbon is absorbed for photosynthesis. A tree can absorb 6 kg of CO2 per year. Because it's 1-acre (± 4047 m2) of forests containing young trees absorb 2.5 tons CO2/tahun. Trees reach maximum capacity to absorb CO2 around the age of 10 years. A tree planted in urban areas (which in fact have higher levels of pollution CO2) equivalent in value to the absorption of CO2 by 15 trees in the forest. 

"If you think for one year ahead, plant seed.
If you are thinking ten years ahead, plant a tree. "

The sentence above is a wise Chinese proverb that has existed since 500 years before Christ. In the past it was very well aware of the importance of trees. This sort of ironic, because in those days, the number of trees that cover the earth's surface relatively more from now. Also, the level of development that causes the pollution is still not as high as today. However, the existence of a tree has been realized very well benefit, reflected in the wise words above. Why a tree is so important, to the extent seen as "enough stock" to live ten years into the future? The answer is none other is because a tree is not able to provide many benefits. In the past, the tree is a provider of shade, food, and firewood for people. Now, at times more complex forms of life, the role of trees was also increased. Here you can see 30 reasons why trees are very useful for human life.