How do you calculate how much CO2 a forest capture?

The world’s forests capture huge amounts of carbon dioxide every year. They are one of the keys to reducing the pace of global warming. But how do you calculate how much carbon dioxide is stored on one hectare of the forest? There is no recognized standardized method for this and we want to know how much carbon dioxide is bound in our forests.

Here is how we at Arboreal calculate the amount. 

First, we calculate the dry weight of the tree trunk under the bark. With the Arboreal Forest app, we get an estimate of the volume under bark (scmub) for different tree species. Part of this volume consists of water. If we would dry the tree, the volume would decrease. Most species shrink between 9-15% in volume when dried  We therefore assume that the reduction is 12% in volume.

There are many sources of density of different tree species for many different tree species. They are stated when the wood contains 12% moisture, but we want to know the density of the wood when it contains 0% water. Practical tests show that the density drops by about 11% when it does not contain any water.

Now we can calculate the dry weight of the tree trunk under the bark. The carbon content is about 50% in the trunk and to get the corresponding weight in carbon dioxide, you multiply by 3.67.

Carbon is not only found in the trunk, there is a lot of carbon stored in the branches, stump, foliage, and roots. It differs between different tree species and dimensions. In this calculation model, it is the biggest uncertainty factor. We have chosen to multiply the trunk’s carbon dioxide by 95% to estimate the content of the entire tree.

The formula is therefore as follows:

Volume (scmub/ha) x 0.88 x 0.89 x Density x 0.5 x 3.67 x 1.95 = CO2 ton / hectare