Underworld Invaders: watch out for those earthworms!
Did you know that the earthworms that you find in your backyard are actually not native to Canada?
These invertebrates were brought over when Europeans started colonizing this country. Therefore, these earthworms are classified as exotic species. Unfortunately, many exotic species negatively affect ecosystems in a variety of ways:
i) by displacing native species by outcompeting them for habitat or for food;
ii) exotic species can become overly abundant and “suffocate” the native ecosystem (since there are no native predators that feed upon them); and
iii) many of them affect the equilibrium of food chains to the point that ecosystems “collapse” leading to the extinction of native species.
We know that earthworms play an important role in aerating and mixing soil and adding organic matter into it. Also, many local animal species use earthworms as an important food source. So, do we need to worry about earthworms and their effects on our ecosystems in Canada?
There are concerns by scientists that earthworms may be detrimental to certain ecosystems, namely old growth forests. The mixing and stirring action of earthworms in soils can promote the growth of other exotic plant species. It has also been shown that areas with heavy earthworm infestations can alter the species composition of the understory (i.e. plant life growing under the forest canopy), which can negatively affect the breeding success of native animals and plants. On the other hand, scientists are conducting studies to see if earthworms may help to slow the effects of climate change. Scientists suspect that earthworms casts (i.e., earthworm poop) might help to store carbon into the ground, preventing its release back into the environment. Earthworms might have a negative effect on our local woodlots, but they might also be beneficial in helping to sequester carbon.
If you want to learn more about this fascinating research, read up on the current study being conducted by the Smithsonian Environmental Research Center by visiting their website.
Should we try to get rid of earthworms? This is not possible and they do play an important ecological role. But scientists do recommend that we take steps to prevent their spread in our ecosystems.
Here’s what we can do:
i) do not use earthworms as bait;
ii) do not dump soil in natural areas;
iii) do not transport firewood from one location to another; and
iv) clean your boots when you go from one location to another.