Four benefits of a tree.Trees can regulate climate,maintain the ecological balance.Trees through photosynthesis,inhaling carbon dioxide,spit out oxygen,so that the air clean and fresh.Acre of forest emit enough for 65 people breathe oxygen.2.Trees can prevent Wind sand-fixation,conserve soil and water,but also to absorb all kinds of dust,each mu of forest a year to absorb all kinds of dust 20-60 tons.3.trees can reduce noise pollution,.40-meter-wide belt can weaken the noise 10-15 dB.4 .trees secretions can kill germs.open space per cubic meter of air there are 3,4 million bacteria,the forest,only 3,4 100.
