Earthworms can change the chemistry of carbon in forest soils and litter. Researchers at the Smithsonian Environmental Research Center are trying to figure out the impact of earthworms on forest soils, and how they may change soil chemistry.

Although we may think that earthworms are everywhere, they were actually introduced into North America by early European settlers, and have slowly spread out as people settled more areas.  I remember digging in Adirondack soils and finding earthworms only right around lakes and ponds, where they had been carried by fishermen.  Earthworms spread very slowly – on their own, they would only spread about 200 km in the 10,000 years since the last glaciers wiped out existing soils.  Most earthworm movement is by people carrying bait or moving soils in nursery material.

The impact of earthworms on carbon in soils is not obvious.  Earthworms consume leaf litter and carry organic matter deep into the soil.  Their work could increase carbon deep in the soil. But since they also consume leaf litter, they may strip the insulation off soils and increase temperatures, causing loss of carbon to microbial respiration.

Earthworm action has profound effects on soil processes. The Smithsonian project should help us understand their impacts on carbon storage in soils.  Since soils can store vast quantities of organic carbon, and could offset a lot of mankind’s industrial carbon dioxide emissions, understanding the role of earthworms is important.

The earthworm project is a joint effort between Purdue University, the Smithsonian, Johns Hopkins University and the University of Utrecht.

Picture: The earthworm, Lumbricus terrestris. Picture courtesy of Purdue University.

Links:

• Earthworm activity can alter forests’ carbon-carrying capabilities- Purdue University
• Earthworms, P. Bohlen 2002 – chapter from Soil Encyclopedia. Archbold Biological Station. (pdf)

Research by Peter Curtis (Ohio State University) and colleagues shows that northern Michigan forests can store an average of 0.65 tons C per acre per year. This rate of storage is higher than earlier estimates such as those used to develop the Kyoto Protocol, and is consistent with other recent studies that show that temperate forests are more efficient carbon sinks than previously thought.

The use of forests as purchasable carbon offsets will become more attractive as we learn more about how much carbon forests can store. However, there is so much variation in the factors that influence carbon storage in forests that prolonged, broad research like that discussed in this article will be needed at many more locations.

Links:

Press release: Scientists Point To Forests For Carbon Storage Solutions

Research Paper:

Christopher M. Gough, Christoph S. Vogel, Hans Peter Schmid, and Peter S. Curtis. Controls on Annual Forest Carbon Storage: Lessons from the Past and Predictions for the Future. 2008. Bioscience 58(7): 609-622.

Cross posted at Sustainable Kentucky/Green Kentucky