Thoughts on old-growth logging

Last fall Antony Pak gave a great presentation on biogenic carbon - which included some statistics on the carbon sink/source balance for BC forests - which showed that forests have an outsized effect on the province’s carbon emissions. Currently emissions due to forest fires and pine beetle infestation are termed natural disturbances and excluded from the accounting. This surprised me, and I decided to do a little more digging.

Is old growth logging sustainable?

Here’s what the literature says about old growth forests:

  1. To have a shot at keeping planetary warming below 2 degrees (a level required to avoid catastrophic crop failures and biodiversity collapse) intact forests must be maintained [Watson et. al. 2018].
  2. Assumptions that forests become net carbon emitters are based on observations of even-aged plantations, and in fact old-growth forests continue to sequester carbon both above and below ground [Luyssaert 2008, Wirth 2009, Stephenson 2014].
  3. Conversion of old growth to secondary growth forests results in net emissions to the atmosphere, even including carbon sequestered in wood products [Nunery & Keeton 2010, Trofymow 2008].
  4. Logging increases the likelihood of fire for moist forests and rainforests. For dry forests logging increases fire risks unless thinning is aimed at removing fuel loads accumulated unnaturally due to fire suppression [Lindenmayer 2009], releasing massive amounts of CO2 that are not included in carbon accounting.
  5. Beetle infestations of forests have long been linked to logging activities, where residues provide fertile breeding grounds, leading to outbreaks [Lejeune 1961, Aukema 2016] again the resulting emissions are excluded from carbon accounting.

Given the above, and considering that logging old-growth inherently leads to conversion to secondary growth, current LCA assumptions do not cover logging from old growth forests, e.g.:

WWF Quantis Biogenic Carbon Footprint Calculator, 2020

“The study is limited to managed natural forests and existing forest plantations, where the forest is assumed to regrow after harvesting. Deforestation, followed by land use change (e.g., from natural forest to agriculture), as well as afforestation projects (e.g., conversion of grassland to forest plantation) are outside the scope of this study.”

Therefore, it appears that LCAs for wood products assume that the timber is not being logged from old-growth forests.

How are old-growth forests being protected?

The various forestry certifications take the following stance:


SFI prohibits conversion of one forest cover type to another type except in justified circumstances, such as dealing with disease


CSA Z809-16 requires that ‘conservation of old-growth forest attributes’ is included in the public participation process under Criterion 1. It appears that CSA certification does not preclude logging old-growth forest.


Forest conversion to plantations or non-forest land shall not occur,
except in circumstances where conversion:
a) entails a very limited portion of the Forest Management Unit; and
b) does not occur on High Conservation Value Forest areas; and
c) will enable clear, substantial, additional, secure, long term
conservation benefits across the Forest Management Unit.

The NDP provincial government of BC recently commissioned a strategic review in old forests and has announced that they are deferring 352,739 ha of old forest harvesting. Although this leaves 3.75 million hectares of old forest available for harvest.

What can architects and engineers do?

Salvage timber is clearly the most sustainable, but unlikely to meet demand. For me I will be recommending a preference for SFI and FSC over CSA timber, and where possible specifying plantation harvest timber. I also think it’s necessary to make sure that LCA assumptions are clear, and possibly a separate LCA is required for old-growth harvest (not that I would condone harvesting old-growth).


Aukema, B. H., McKee, F. R., Wytrykush, D. L., & Carroll, A. L. Population dynamics and epidemiology of four species of Dendroctonus (Coleoptera: Curculionidae): 100 years since J.M. Swaine. (2016) The Canadian Entomologist, 148(S1), S82–S110. Cambridge University Press.

Lejeune, R., McMullen, L. and Atkins, M. Influence of logging on Douglas fir beetle populations. Forestry Chronicle, 37(4): 308-314. (1961)

Lindenmayer, D.B., Hunter, M.L., Burton, P.J. and Gibbons, P. Effects of logging on fire regimes in moist forests. Conservation Letters, 2: 271-277. (2009)

Luyssaert, S., Schulze, ED., Börner, A. et al. Old-growth forests as global carbon sinks. Nature 455, 213–215 (2008).

Nunery, J.S., Keeton, W.S., Forest carbon storage in the northeastern United States: Net effects of harvesting frequency, post-harvest retention, and wood products, Forest Ecology and Management, Volume 259, Issue 8, (2010) Pages 1363-1375,

Stephenson, N., Das, A., Condit, R. et al. Rate of tree carbon accumulation increases continuously with tree size. Nature 507, 90–93 (2014).

Trofymow, J.A., Stinson, G., Kurz, W.A. Derivation of a spatially explicit 86-year retrospective carbon budget for a landscape undergoing conversion from old-growth to managed forests on Vancouver Island, BC, Forest Ecology and Management, Volume 256, Issue 10, 2008, Pages 1677-1691,

Watson, J.E.M., Evans, T., Venter, O. et al. The exceptional value of intact forest ecosystems. Nat Ecol Evol 2, 599–610 (2018).

Wirth C. Old-growth forests: function, fate and value–a synthesis. In Old-growth forests (2009) (pp. 465-491). Springer, Berlin, Heidelberg.


Thank you for this - it is most helpful. Had you thought of writing an article summarizing thee points for wider distribution?

Hi Frank, I hadn’t thought about it, but I’d be keen to collaborate on an article that goes into a bit more depth. With work being so busy at the moment I’m not sure I could find the time otherwise.

Thanks for this, Will. Some good thoughts/info. Coincidentally I have been think much about in the same lines and in discussion elsewhere learned that old growth forest are capable of exponentially more carbon conversion than 2nd growth/new forests. I haven’t done too much digging, but as far as I understand it has to do with he biodiversity of old-growth and, more importantly, the age of the trees (As trees age, their climate benefit grows | CBC News). While another study suggests the diversity the forest and the condition of the soil plays an important role as well (As trees age, their climate benefit grows | CBC News). I would conclude is important to protect our old-growth forests and specify wood from 2nd growth trees, but also look for alternative carbon sequestering materials of fast-growing plants like bamboo and straw.

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A critical issue, especially when material substitution based carbon assessments can further exaggerate underlying assumptions about carbon from forestry. I think Canada is perhaps somewhat unique among developed economies in that the vast majority of wood and wood products in Canada are sourced from old-growth, not just archetypal BC coastal old growth, but inland boreal across the country. We (ie cement and concrete) have argued that just as cement and concrete manufacturing needs a drastic transformation of technologies and practices (e.g. commercial scale carbon capture utilization and storage) so too does the Canadian forest sector need to modernize toward low carbon fibre sources, which almost certainly means a full retreat from logging in in-tact forest. Current LCAs make it hard to differentiate wood products from best practice forestry companies from those that cling to business as usual. This of course runs counter to one of the objectives of LCA and EPDs which is to identify and reward low-carbon leadership.

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Thanks Will. You bring up some important issues. I was at that webinar by Anthony Pak. With all the timber industry propaganda overwhelming the LCA industry, it was very refreshing. The slide showing the huge carbon emissions of BC fires compared to building carbon was striking. Promoting the creation of tinder boxes from healthy forests is self defeating from a carbon viewpoint. New research in Colorado by Veblin shows that most of our burned areas will not be coming back naturally. Recently, I was discussing this with ecologist Chad Hansen. Chad shared some of his research on regeneration after fires. Natural forests regenerate well. After they are logged or turned to secondary forests, they have much more difficulty. Concrete and steel are getting a bad shake.

Old growth and more mature forests definitely sequester more carbon. These are some of the most productive carbon sinks that exist. Proforestation is the practice of promoting development to later seral stages. Intact forests need to be preserved. There is some movement in promoting this practice so that the green building industry can more legitimately sequester carbon in building products such as CLT. However, unless the wood is FSC certified, those realizations will not be met. SFI is a timber industry created greenwash project . FSC ensures that the carbon removed from the forest is only as much as is regenerated. Plantations take pressure off off healthy forests but do not replace them.

Ecosystem services is another area completely unaccounted by LCA. In semi-arid Colorado, our state motto is “Whiskey is for drinking, water is for fighting.” We have a state law, Manage Forests to Promote Watershed Health. The economic contribution of the outdoor industry eclipses the timber industry and fossil fuels. The list goes on.

Much of the trouble with wood LCAs lies in the Product Category Rules. I have no problem labeling them as woefully inadequate. There are 2 of them in use now. One is to be redone this year. The other was last year. I think that the good one was done by SCS. Unfortunately, it is not used all that much. Last year, there was an effort to get a disclaimer concerning forest management practices, but it was watered down a lot by the timber industry interests. They are putting massive efforts into the green building industry but are totally insincere.

One of the big goals of mass timber is to create more demand for wood. The timber industry wants to use that demand to utilize their own special brand of fire policy. That would be to remove the trees so that they don’t burn.

As a note, in EN 15804:2012+A2:2020, old growth forest would be considered native forest -“Native forests exclude short term forests, degraded forests, managed forest, and forests with short-term or long-term rotations”. “CO2 uptake related to the carbon content of biomass entering the product system from native forests is set to zero.” CO2 emissions from the biomass at end of life or use of fuel are considered as “land use change” and are modelled in the module in which they occur. So use of this kind of timber will have the same impact as plantation timber, without the benefit of sequestration.

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