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Goal: Sustain Our Nation’s Forests and Grasslands Invasive Earthworms Have Unexpected Effects on Other Soil Organisms

Scientist holding an invasive earthworm in their gloved hand

An invasive earthworm of the species Amynthas agrestis used in this experiment. Chattahoochee National Forest, Georgia. Photo by Melanie K. Taylor, USDA Forest Service.


Invasive earthworms alter the structure and function of soil. Forest Service scientists show that these earthworms decrease the abundance of springtails, but act as a food source for centipedes. These changes are likely to alter the communities of other soil-dwelling organisms, with potential rippling effects on the forest soil food-web.


Invasive earthworms are known to dramatically alter the soil in North American forests. However, their impact on existing relationships in the soil food web is largely unknown. Scientists from the Forest Service, in collaboration with a visiting Chinese scholar, examined the effects of invasive earthworms on the relationship between predators (centipedes) and prey (springtails). They expected to find that invasive earthworms consumed leaf material, making it easier for centipedes to find springtails, thereby reducing the number of springtails. To accomplish this, the scientists experimentally manipulated combinations of invasive earthworms, centipedes, and springtails in the lab. To their surprise, the scientists found that the presence of invasive earthworms had a negative effect on springtails, but that the presence of centipedes did not. Further, centipedes benefited when combined with earthworms alone. Together, these results suggest that invasive earthworms might hinder the abundance of springtails on the forest floor and that the invasive earthworms may represent a novel food source for centipedes in North American forests. These changes could alter other relationships in the soil food web and the soil processes in which they participate.