Back to blog | December 17 2021 | Lucas Moreau | Candidat au Doctorat en sciences forestières, Université Laval

Keeping a critical eye on forest carbon accounting

This may not be a subject you had in mind, but here are some very simple elements to consider in order to take a more critical look at everything that is said about forest carbon and its accounting.

Whether it is for meeting international climate change targets, provincial targets, carbon credit generation, or perhaps even considering carbon in provincial forest management, forest carbon is increasingly present in our lives. This issue becomes central to the development of public policies. Regulations are almost non-existent and competition is raging among stakeholders.

While international carbon accounting is largely overseen by the Intergovernmental Panel on Climate Change (IPCC), the carbon market is now a “jungle”.

This is why, when we are dealing with forest carbon analysis, it is very important to look at the methodology that is used. Is it a study that was done under the IPCC guidelines? An accounting for certified and recognized carbon credits (VCS, Gold standard)? Or a methodology that is not transparent? Not recognized?

Questioning the source of the analyses we are looking at is the first critical look we should always take.

Now, it is also important to understand that the basis for forest carbon accounting is its analytical framework. In other words, what elements are considered in our forest carbon accounting? The forest or wood products? Substitution? All of these things together?

Are we looking at the annual flow only or their sum in a cumulative flow?

Depending on the factors considered in the calculation, the conclusions for the same ecosystem may be completely different! And since a picture is worth a thousand words, here is a representative example of the Québec boreal commercial forest to illustrate the importance of this analytical framework.

The illustration used here represents the carbon dynamics within a forest stand following a CPRS (cutting with protection of regeneration and soil) conducted in year 1 of the simulation. All positive values represent emissions to the atmosphere (carbon source) and negative values for sequestration (carbon sink).

Let’s first look at the Annual flow: Forest curve. It illustrates the dynamics of carbon in an annual carbon accounting in the forest ecosystem only. The effect of harvesting is clearly visible in the year of disturbance, and the following years are also emissions (positive values) due to decomposition of debris on the ground. Twenty years must go by after cutting for annual carbon sequestration due to vegetation growth to become more significant than decomposition emissions.

The Annual flow: Forest + Products + Substitution curve represents an accounting of annual forest ecosystem carbon fluxes, substitution, carbon storage in wood products and their degradation. It still takes 20 years for the stand to return to an annual carbon sink. However, there is a lot of sequestration in year 1, which results from taking substitution into account (considered a sequestration flow)!

The Cumulative flow: Forest + Products + Substitution curve represents exactly the same thing as the Annual flow: Forest + Products + Substitution curve, but the annual values were added together to create a cumulative curve. Here, it takes more than 50 years for the amount of sequestration to offset the emissions generated during the first 20 years. So, even if by 20 years the vegetation sequesters carbon, this stand will have a net sequestering effect more than 55 years after cutting!

These examples perfectly illustrate that for a single stand, multiple accounting readings may exist. None of them are false, but it is up to us to take a critical look at the resulting conclusions.

Now, did you know that despite all of these elements that you can now critically look at, there are still a very large number of them that have not been mentioned in this post?

The main point is that in the fight against climate change, carbon and greenhouse gases are only part of the issue. There are many other phenomena that impact what is called the Earth’s radiative forcing[1]  ( Page 32[CL(1] ) that can be significantly impacted by forest management. The complexity of this role is being researched all over the world, namely in Québec.

Thus, I invite you to learn more about all the elements covered in this article to sharpen your critical eye and, in a broader sense, your understanding of forest carbon dynamics!

[1] Radiative forcing represents the amount of additional energy retained in the atmosphere in the form of heat due to a climate phenomenon that may influence the climate.

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