Earthworms are friends to gardeners, recycling plant debris into plant nutrients. But, do they contribute to the climate-change problem?
Some climate researchers have suggested they might. When dead leaves and other plant matter enter the soil, the carbon they hold is stored away from the atmosphere. But, earthworms recycle that material. Does that release the plants’ carbon back into the air?
To answer that question, a team of scientists from China and the U.S. recently measured what happens to the carbon that earthworms digest. They compared the carbon emissions from small pots of soil and decomposing leaves. Some of the pots contained worms, others didn’t.
The researchers found that feeding by earthworms did release an initial burst of carbon dioxide into the air. But after that most of the carbon remained in the soil in the stable form of worm droppings.
This was only one study, but it hints that earthworms may store more carbon in the soil than they release into the air.
In the Southwest, dry soils pose a big threat to worms, but the little invertebrates are tough. A group of scientists at Colorado State University in Fort Collins recently tested them to learn how they deal with drought.
It turns out that earthworms can wrap themselves up into a tight ball and create a protective coating of mucus to retain their body water. In this state many of them can survive for weeks until the next rain.