Earthworms Stabilize Soil Carbon at Sites Exposed to Elevated Carbon Dioxide

Newswise — The Science

Often overlooked, earthworms actually play a key role in Mother Nature’s carbon sequestration process, according to findings in Soil Biology and Biochemistry. Carbon dioxide, from gasoline and coal combustion, among other sources, can cycle from the atmosphere, to tree foliage, to the soil, and back to atmosphere relatively quickly. However, a species of earthworms slows that process, keeping leaf- and root-derived carbon in the soil.

The Impact

The findings suggest that earthworm presence (or absence) and species are important factors contributing to the fate of increased plant litter produced as a result of rising atmospheric carbon dioxide concentrations.

Summary

A collaborating research team conducted a laboratory incubation experiment with two species of earthworms plus isotopically labeled soil and plant materials from the Oak Ridge, Tennessee, sweetgum Free-Air CO₂ Enrichment (FACE) site. Compared to experimental treatments without worms, the presence of either earthworm species increased the formation of soil macroaggregates (greater than 250 micrometers in diameter). The invasive European earthworm species, which feeds on both plant residues and soil organic matter, incorporated significant amounts of leaf- and root-derived carbon, in addition to soil-derived carbon, into newly formed aggregates. In contrast, the native earthworm species, which feeds mostly on soil organic matter, produced almost twice as many aggregates, but hardly any of the carbon in these aggregates was derived from the added plant materials.

Funding

This work was funded in part by the National Science Foundation (Grant DEB-0919276), University of Illinois at Chicago, and University of Puerto Rico at Utuado. In addition, the work was supported by the Office of Biological and Environmental Research within the U.S. Department of Energy Office of Science through Argonne National Laboratory, under contract DE-AC02-06CH11357, and through UT-Battelle, who operates Oak Ridge National Laboratory, under contract DE-AC05-00OR22725.

Publications

Y. Sánchez-de León, J. Lugo-Pérez, D. H. Wise, J. D. Jastrow, and M. A. González-Meler, “Aggregate formation and carbon sequestration by earthworms in soil from a temperate forest exposed to elevated atmospheric CO₂: A microcosm experiment.” Soil Biology and Biochemistry 68, 223-30 (2014). [DOI: 10.1016/j.soilbio.2013.09.023]