Forest before the earthworm invasion (left) and after (right). Scott Loss, nrdc.org
It is estimated that, in an intact North American forest, therefore without earthworms, it takes 5 years or more for a maple leaf to completely disappear; in a forest with earthworms, less than 2 years. We have noticed that, in the affected sectors, several species no longer seem able to regenerate as before: trilliums, ferns, Canada yew and even the jewel of the Quebec forest, the sugar maple (Acer saccharum). Instead, a maple introduced from Europe and which had therefore evolved in the presence of earthworms, the Norway maple (A. platanoides), seems to be carving out the place of the master in the "new North American forest". to the detriment of our native tree.
The effect on forest animals is also often disastrous. For example, there has been a decline in the abundance of some insects and mammals living in the undergrowth as well as birds that nest on the ground. The populations of several species of salamanders are in free fall as a result of the invasion of exotic earthworms, because their food (insects and other small invertebrates) lives mainly in thick litter.
