Scientific Amercian Magazine, March 2009
Headline: Invasive Earthworms Denude Forests in U.S. Great Lakes Region
Worms, such as the night crawler, eat leaf litter which acts as a rooting medium for new growth
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The earthï½*worms, Groffman reports, ç”°ome into an area with a thick organic mat, and two to five years later that layer is gone.
As a result, some northern hardwood forests that once had a lush understory now have but a single species of native herb and virtually no tree seedlings. Evidently, earthworms change the forest soils from a fungal to a bacterial-dominated system, which speeds up the conversion of leaf detritus to mineral compounds and thereby potentially robs plants of organic nutrients.