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.
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.”