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| I haven't read the article yet but it sounds like some of the statements by earthworm researchers may have been taken out of context or exaggerated.
~ 36 species or earthworms have been identified in IL (~ half native and ~half invasive exotics). Most of the species found in agricultural soils are invasive exotics because they tend to be more tolerant of agricultural practices.
The key thing to keep in mind is that the Upper Midwest was mostly depopulated of earthworms by glaciation.
The forest ecosystems that developed after the glaciers retreated had very few worms. The arrival of invasive worms has accelerated decomposition of surface litter which increases nutrient availability, causes surface soils to warm up more quickly, causes nuts to be more visible to squirrels and other nut eaters...
The most nutrient responsive plants in once diverse plant communities start crowding out slower growing plants.
Fewer nut tree saplings establish because fewer nuts escape the nut eaters... very tight nutrient cycles become leaky...
On thing to keep in mind is that the species of worms invading and changing forests in the Upper Midwest are not just random worms transplanted from Europe and Asia. These are the toughest and most aggressive species... kind of like the dandelions of the worm world.
Another thing to keep in mind is that the same effects of worms that are valuable in agriculture (accelerated decomposition and nutrient cycling) are a major change in the forest ecosystems of the Upper Midwest.
Joel
WIU Agriculture
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Earth worms are bad ???
