During photosynthesis, trees absorb carbon dioxide, and store it above and below ground – locking it away until they die and decay.

Forest floor photo

This long-term carbon sequestration makes forests one of our best defenses against climate change. But what will happen as temperatures rise?

Conventional wisdom says as soils warm and forests become more productive, the increase in leaves, sticks, and other organic materials that fall to the ground will add even more carbon to the soil.

Myrna Simpson
U. of Toronto researcher Myrna Simpson.

So scientists tested this theory by sprinkling leaves, twigs, roots, and other organic debris on a forest floor. To their surprise, instead of fixing more carbon in the soil, it stimulated bacteria and fungi. This made the organic material decay faster and accelerated the release of carbon dioxide back into the atmosphere.

Professor Myrna Simpson, a researcher at the University of Toronto Scarborough, says that could make the problem worse.

SIMPSON: “It’s increasing the amount of greenhouse gases that are going into the atmosphere which can then accelerate the whole global warming process.”

Warmer temps could change forest soil chemistry, speedup CO2 emissions. Click To Tweet

More studies are underway in other forests to determine if the results are similar. But this research indicates that forest management strategies may need to change.

Reporting credit: Pam Memmott/ChavoBart Digital Media.
Forest Photo: Copyright protected.

More Resources
Increased cuticular carbon sequestration and lignin oxidation in response to soil warming
Global warming is changing organic matter in soil: atmosphere could change as a result
Organic soil matters
Long-term doubling of litter inputs accelerates soil organic matter degradation and reduces soil carbon stocks
A carbon sink that can’t be filled

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