On average, one tree converts one tonne of CO2 into 1.1 m³ of wood. One cubic metre of wood therefore contains 0.9 tonnes of CO2. However, the amount of CO2 absorbed by a tree depends on many factors, including the type of tree, its age, its health and the environment in which it grows.

Deciduous oak trees, are estimated to absorb around 4.6 tonnes of CO2 per year and per hectare. 

It is also important to note that Swiss forests absorb around 2 tonnes of CO2 per hectare per year. This offsets almost a fifth of the CO2 emissions caused by traffic.

Finally, it should be noted that trees convert CO2 into carbon through photosynthesis and store it in the biomass. Once the tree has been felled, the carbon remains fixed within the wood for a long time.

So this information should give you an idea of the importance of trees in absorbing CO2. They play a crucial role in the fight against climate change.