A new study has discovered that old-growth forests in Sweden store far more carbon than the industrial tree plantations that are rapidly replacing them, with soil accounting for most of the difference.
The untouched forests in Sweden store 72 percent more carbon than managed forests, locking away greenhouse gases in spruce, pine, and needle-covered soils. Researchers from Lund University in Sweden and Stanford recently (March) published this in the journal Science.
But the loss of untouched primary forest is happening rapidly: the rate is six times that of tropical rainforest loss in the Amazon, which is striking because boreal forests are often seen as ‘stable’.
Timber and biofuel
Acres of pristine old-growth forest in Sweden have been transformed into managed forests. There, loggers cut down an area once every century to supply the growing European market for timber and biofuel.
That turns out to be precisely detrimental to the environment, because the so-called ‘production forests’ continue to absorb much less CO2 than the original old-growth forests.
Soil makes the difference
It is – surprisingly enough – not so much the trees but the soil that makes the difference. Old-growth forests can store more carbon in their soils alone than production forests do in trees, dead wood, and soil combined. Why the soil of production forests stores less carbon is not yet clear.
So if you cut down old-growth forest, you lose carbon storage not only above but also below ground. Carbon storage is important for the climate: the more CO2 that is stored, the less is released into the air. This also means that protecting intact forests is more effective than replanting or managed forestry.
Up to 8 times more storage capacity
Experts already knew that old-growth forests store more CO2, but the difference – 2.7 to 8 times more – turns out to be much greater than was always assumed.
To put that in perspective, restoring carbon storage in Sweden’s managed forests to the level maintained by primary forests would mean keeping nearly 8 billion tons of carbon dioxide out of the atmosphere.
That’s equivalent to Sweden’s cumulative emissions from burning fossil fuels over the last two centuries and hundreds of times larger than the country’s current annual fossil CO2 emissions.
The conclusion of the study is clear in any case: “If we care about the climate, we must limit the harvesting of timber from old-growth forests.”
