Trees are integral part of our life. They are quite crucial for our survival as they are consumed and used in many ways by us. We all know that trees produces oxygen, an important key that keeping us alive, But have you ever wondered how much oxygen a tree produces?. The answer may vary as it depends upon several factors, like, species of tree, its age, its health, and also on the tree's surroundings.

Trees release oxygen when they use energy from sunlight to make glucose from carbon dioxide and water. Like all plants, trees also use oxygen when they split glucose back down to release energy to power their metabolisms. Averaged over a 24-hour period, they produce more oxygen than they use up; otherwise there would be no net gain in growth.

It takes six molecules of CO2 to produce one molecule of glucose by photosynthesis, and six molecules of oxygen are released as a by-product. A glucose molecule contains six carbon atoms, so that's a net gain of one molecule of oxygen for every atom of carbon added to the tree. A mature sycamore tree might be around 12 m tall and weigh two tonnes, including the roots and leaves. If it grows by five per cent each year, it will produce around 100 kg of wood, of which 38 kg will be carbon. Allowing for the relative molecular weights of oxygen and carbon, this equates to 100 kg of oxygen per tree per year.

A human breathes about 9.5 tonnes of air in a year, but oxygen only makes up about 23 percent of that air, by mass, and we only extract a little over a third of the oxygen from each breath. That works out to a total of about 740 kg of oxygen per year. Which is, very roughly, seven or eight trees worth.

So, the final conclusion is 7 - 8 trees would be enough to produce the amount of oxygen consumed by one person. This seems like quite comfortable number of trees we require. But is it comfortable enough? Let's take it little more further. Let's try to find out how many trees do we need to produce enough oxygen for 6 billion people on this earth? On the basis of our outcome it should be around 42 - 48 billion. There are 36,794,240,000 acres on the earth, 70% of which is water. Taking into account that we can grow 700 average trees on an acre. Now lets think of the other parts of the earth on which you cantt grow trees - high mountain peaks, marshy areas, tundra, North and South Poles, Greenland, deserts (30% of land area). . . .Do you still think we have comfortable number of trees around to cut them every now and then......?????