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Young, Old, Chop or Not?

December 9th, 2008

By Paul Crossley

Old Growth Forest

The debate in a nutshell: which has a greater impact on the environment vis-a-vis carbon capturing/sequestration: Young trees or old growth?

Here’s the thing: By now we all know that trees serve to absorb carbon from the atmosphere, but which is better?

One argument states that old growth forest, such as those pictured, actually capture and retain more carbon emissions than any other ecosystem on a per acre basis.

The obvious value here is the notion that the Earth has a built-in defence to global warming and most environmentalists believe that old growth forests must be protected at all costs: Logging old growth trees would destroy the forest’s ability to store carbon. Cutting down such a tree will allow you to create wonderful furniture and other wood products, but then the slash burn and soil disruption will allow all of the carbon to escape. The argument contends that you can’t just replant a tree to replace the one you cut down.

The counter-argument goes something like this: As trees grow older, they lose their effective ability to sequester carbon. That’s why it’s better to have a younger, more vibrant stand growing, that’s healthy, that sequesters carbon.

Environmentalists generally don’t disagree that young trees can store carbon more efficiently. The issue is that cutting old trees to make way for younger ones is ridiculous since cutting down trees releases carbon.

The group which generally supports the cutting of old growth tends to be the Forestry industry. They counter the carbon-release argument by saying that as wildfires burn entire forests, vast quantities of greenhouse gases are released. The group may point to the fact that in the recent past, in just one year almost 10 million acres in the US were lost to forest fires, which in turn put about six tonnes of CO₂/acre into the air.

True enough, these figures are astonishing. But environmental groups will then argue that logging alone adds more carbon to the air per acre than do all of the wildfires.

Here are the calculated figures:

If you burn a forest, that forest will lose about 10% of the carbon. But the vast majority of the carbon will stay within the site (soil etc.). If you log the forest though, you will release about 50% of the carbon immediately. Clear-cut areas can release carbon for decades after.

Research tends to support the claims and figures provided by the environmental groups. But, are there environmentally sound alternatives to the products derived from forest logging?

It can be argued that using steel and concrete for house construction actually produces more carbon that a traditional wood-construction house.

So, what’s the solution? Is there one? Should we build with straw-bale or rammed earth? Should we insist on bamboo products? Should we strike a balance? Should we allow the ecomentality of the forestry industry dictate what the perceived impact really is?