Ecosystem engineers
Lowly earthworms keep house, sequester seeds
Unlike Richard Scarry’s Lowly Worm, real worms don’t drive cars or go to school. But the wriggly creatures appear to live a more purposeful life than previously thought. Earthworms deliberately gather and bury ragweed seeds from around their burrows, reports a new study in the Journal of Applied Ecology.
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The findings fit with recent work documenting how nonnative earthworms are changing U.S. northern forests. Though native worms were wiped out from the northern United States in the last glaciation — only persisting south of the ice sheet and permafrost — European worms then arrived with settlers. The newcomers are slowly changing northern deciduous forests by eating through the leaf litter and “duff” that native plants need to thrive.
“Worms do a great job in gardens, it’s true,” comments Cindy Hale of the University of Minnesota Duluth. “But take the same organism and put it in a native hardwood forest that’s evolved over 10,000 years earthworm-free, and the worms change everything about the ecosystem. The physiology, the chemistry — they have a profound effect on nutrient cycling.”