Question: Are there any trees that let out more oxygen than others?

Laurence Perreault Levasseur answered on 16 Jun 2014:

This is a very interesting question, and a very important one! It’s also fairly complicated to answer. There are a few things that make this a bit less straightforward to answer.
-First, trees both produce oxygen, during photosynthesis, and burn oxygen, during respiration. You can think of this as photosynthesis producing food, mostly in the form of sugar, and respiration as burning that food to produce energy, which allows the cell to work. Photosynthesis happens only when there is sunlight, but respiration can happen all the time;
-Depending on how much sunlight there is (how long is the day and how intense sunlight is), a tree can produce more or less oxygen;
-Depending on how big a tree is (or how old), it can produce more oxygen (if it’s bigger and has more green areas, usually these are just the total leaves areas), but if it’s bigger it also need more energy to survive, so more respiration which burns oxygen.

Overall, from these three points you can probably guess that different species of tree will produce more or less of oxygen, but also how old a tree is and where it lives will change how much oxygen it produces.

If you want to know which tree produces the most oxygen, the trick is to look at how fast a tree grows. This is because a tree uses sugars for 2 purposes: growing and energy production by burning. Energy production burns back the O2 that was released in the atmosphere when the sugar was produced by photosynthesis, so the burnt sugar doesn’t produce any net O2. But the sugar that is used to grow doesn’t use any O2, so that process really produces some net O2 in the atmosphere.

Therefore, the fastest growing tree (in terms of the tree that increases its total mass the most) will be the one producing the most net O2. This means that indeed, young trees (faster growing) produce more O2 than old tree who almost don’t grow anymore, or do so very slowly (as we expected!).