A frightened earthworm is a plant's best friend. Researchers testing the ecological role of the earthworm Pheretima aspergillum (pictured above) in an alpine meadow have found that when a beetle that preys on earthworms is present, plants grew more. The presence of the beetles also increased the quality of the deeper soil, reported this month in the Journal of Animal Ecology. When beetles were present, earthworms migrated to the deeper soil, probably to avoid the beetles' foraging range. The earthworms broke up this deeper soil, and nutrients and water moved into it. The researchers speculate that the enriching nutrients and water brought to this deeper soil may have been more valuable to plants than the improvements to the upper soil that occurred when the predatory beetles were absent and the earthworms remained in the upper soil. So the next time your outdoor plants aren't growing, it might not be because there aren't enough earthworms, but because the earthworms lack predators to hide from.
ScienceNOW, the daily online news service of the journal Science
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