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Barking up the wrong tree in old-growth controversy?

Careful forest management can have important role in climate change fight, experts say
The value of young forests compared with old growth is understated, say some experts  

In the lead-up to last week’s announcement that the B.C. government will defer logging on 2.6 million hectares of old-growth forest, the conversation was sometimes muddied with invocations of “deforestation” and climate change as reasons to halt logging of old-growth forests in B.C.

Whereas the argument 20 years ago was that West Coast old-growth and primary boreal forests in Eastern Canada should be spared from logging for biodiversity reasons, climate change and the role forests play as carbon sinks has increasingly been cited by environmentalists as a reason to make old-growth and primary forests off limits to logging.

While there are good scientifically grounded arguments for preserving as much old growth as possible (keeping carbon in the bank), there are equally sound arguments that younger, sustainably managed working forests are better carbon sinks over the longer term.

Bigger concerns from a climate change perspective are forest fires, which can turn a forest from a carbon sink to a carbon source overnight, and the amount of wood debris that is wasted in logging operations.

When Canada last week signed a pledge to end deforestation by 2030 at COP26, environmental groups like were quick to point to the pledge in demanding that B.C. deliver on its promise to halt old-growth logging.

But cutting down trees to make wood products and replanting the trees that were cut is not deforestation. Quite the opposite: sustainable forestry has the potential to increase forest carbon sinks, according to the Intergovernmental Panel on Climate Change (IPCC).

“A sustainable forest management strategy aimed at maintaining or increasing forest carbon stocks, while producing an annual sustained yield of timber, fibre or energy from the forest, will generate the largest sustained mitigation benefit,” the IPCC Working Group 3 said in its section on forests.

Deforestation is the permanent removal of trees – either through illegal logging or to clear land for development or agriculture – the consequences of which are the permanent loss of carbon sinks. But logging per se is not deforestation if the trees that are cut down are replanted, which is what happens in Canada’s managed forests.

One of the benefits of forestry, from a climate change perspective, is that when trees are turned into products like lumber, furniture and engineered wood products, the carbon is sequestered for decades. And as a building material, wood has much lower emissions intensity than concrete and steel. Fuels or products (bioplastics, for example) that are made from wood waste have a much lower carbon intensity than those made from fossil fuels.

When it comes to the sequestration of carbon in living trees, there are good arguments to be made that old-growth forests already contain massive stores of carbon, are more resistant to the forest fires and therefore should be left alone.

But there are also good arguments to be made in favour of working forests – forests managed to actively generate revenue from multiple sources – because younger, faster-growing trees can do a better job of soaking up CO2.

Like a retiree who has money in the bank but is no longer earning an income, an old-growth tree has a lot of carbon in the bank but may no longer be absorbing as much CO2 as younger, faster-growing trees.

“The fundamental scientific finding that the uptake of carbon in old forests is much lower than in young and middle-aged forests is not disputed,” said Werner Kurz, one of Canada’s leading authorities on forestry carbon accounting and eight-time contributor to IPCC assessments.

He is quick to point out, however, that that isn’t an argument for converting all older forests to secondary forests. Old and younger forests each have a role to play in natural climate solutions.

“Young forests have less carbon stock,” Kurz said. “So, they are smaller trees, there’s less carbon in them, but the trees are growing much faster than old forests. So young forests are much larger carbon sinks than old forests. But it is also true that if you cut an old forest, you may be releasing some carbon into the atmosphere.”

One genuine concern about forestry from a carbon accounting perspective is the amount of wood that is wasted, which means squandered sequestration potential. This is forestry’s equivalent of the natural gas sector’s fugitive methane problem.

Hadi Dowlatabadi, a University of British Columbia physicist specializing in climate change statistical modelling and an IPCC contributor, said about half of the carbon stored in a tree is above ground. The rest is stored in the soil and roots, some of which is lost when trees are cut down. It takes several years before regrowing trees make up the deficit.

Dowlatabadi said as much as 25% of the carbon in a tree may be wasted in the form of leaves, branches, bark and stumps left on the forest floor after logging, where it either decays or is burned.

“In North America, the leaves and branches are left at the harvest site, and that is 50% of the harvest itself,” Dowlatabadi said. “So we only use 25% of the carbon in whatever use we have for it.

“The rest, depending on moisture conditions and slash-burning regimes, turns to methane and has a really high GHG-forcing effect, and then to CO2 or to CO2 directly. Tree-cutting is a major source of carbon release.”

Better management practices aimed at recovering more of that wood debris for use in pulp mills or bioenergy would reduce the amount of sequestered carbon that is wasted.

“That’s one of the biggest areas of opportunity.… Can we collect that forest residue and put it to a better use instead of burning it in a slash pile?” said Kate Lindsay, senior vice-president of the Forest Products Association of Canada.

Done right, sustainable forestry may do a better job of carbon sequestration than conservation.

“Nordic countries such as Sweden or Finland, where forests have been managed intensively for decades, have demonstrated that management can increase their forest carbon stocks while at the same time harvesting large volumes of wood to support a bio-economy,” Kurz said.

“Even managing a small portion of B.C.’s forests (less than 10%) more intensively could greatly enhance forest sinks and remove more carbon from the atmosphere.”

According to updated estimates by B.C.’s Old Growth Technical Advisory Panel, 31.5% of old growth in B.C. is already protected. Of the 7.7 million hectares of old growth containing big, ancient and rare trees, 2.6 million hectares (34%) is protected. Deferrals announced last week would double the amount of old tree, big tree and ancient tree old growth that would be protected.

Ideally, a natural climate solutions plan for forests and forestry would see as much old-growth forest preserved as possible (keeping carbon in the bank), with forestry occurring mostly in second-growth forests.

The reality is that there’s not enough second growth in the coastal forest sector to support the forest industry as it is currently constituted. About half of the annual allowable cut for the coastal forest sector is old growth. So doubling the amount of old-growth protection will have huge economic costs for B.C., especially coastal communities dependent on forestry.

Ultimately, how much old growth is made off-limits to logging in B.C. may depend on what First Nations have to say about it.

Some, like the Huu-ay-aht, are involved in forestry and are invoking treaty rights and the United Nations Declaration on the Rights of Indigenous Peoples in asserting their authority within their territories when it comes to land management and environmental stewardship.