Issue 58
October 13, 2005

Weather Trivia

 You Asked Us

Environment Canada's knowledgeable specialists answer questions about wildlife, air pollution, water, weather, climate change and other aspects of the environment.

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How do you calculate oxygen production of a tree? Do coniferous trees produce more oxygen than deciduous trees in North America?

On average, one tree produces nearly 260 pounds of oxygen each year. Two mature trees can provide enough oxygen for a family of four.

As for which tree produces more oxygen, this is complex as not all trees are created equal. The more a tree produces nutrients (sugars) to grow, the more oxygen it releases as a by-product. Depending on the species, this can vary quite a bit. Age is also an important factor. A healthy young tree, which is growing vigorously, produces significantly more oxygen than a mature tree whose growth rate has slowed down considerably.

The fastest growing trees are species such as poplar which produce more oxygen during this rapid growth. However, slower growing trees such as oak and maple have longer lifespans and produce oxygen for a greater number of years, so their net benefit could be greater than some faster growing trees that do not grow for as many years.

In the specific comparison of deciduous and coniferous trees, in general, the physiology of deciduous (broadleaf) is more rapid than coniferous (evergreen leaves) – deciduous trees work harder. Leaf characteristics are more directed to active photosynthesis and therefore produce more oxygen. Coniferous trees, though still green in winter, are generally inactive and in some cases may even absorb oxygen in winter rather than producing it.

So, all in all, the average deciduous tree in North America is likely to produce more oxygen than the average coniferous tree.

That said, in certain situations a coniferous tree could produce more oxygen than a broad-leafed tree. This is because additional factors like climatic adaptation, location, local light intensity, and leaf morphology all affect the rate of trees' physiological processes, which is key to oxygen production.