I am studying the contents of my compost bin. The large plastic container does a marvelous job of converting our household food waste and occasional leaf and grass clippings into dark, almost black, soil that is rich with nutrients. As I run my fingers through the coffee ground colored compost to determine its present state of decomposition I come across a mass of wiggling worms. These unbelievable creatures process small to medium food scraps and vegetable waste by eating the material, passing it through their bodies, and leaving behind a rich, soil-like material. The worms are lively as I handle them. They move quickly to avoid the daylight that I have just exposed them to, some tying themselves into knots with other nearby worms. One of nature’s miracles, no doubt, but recent research shows that in our region these wonderful food processor’s might have a very real down side.
For a few years I have been struggling with the concept that earthworms are not considered to be a native species to glaciated regions of the United States. The theory is that the glaciers annihilated the entire earthworm population in the last glacier age about 12,000 (or so) years ago. Native worms can be found south of this area, but at the rate they can repopulate an area they have probably only managed to move northward a few hundred miles over 12,000 years into the post glaciated region. The numerous worm populations that we do have, and they are widespread, are primarily worms that have been introduced over the last 300 years; first by the colonists, and later by agrarians, and most recently by those who might use them for bait in their angling pursuits.
As someone who has been around gardens my entire life I found this a bit horrifying. How could earthworms be a bad thing? This is a concept that it is difficult to reconcile in my small brain. Earthworms have almost a spiritual reputation amongst those who garden organically. Once called the intestines of the earth by Aristotle, and the subject of an entire book and many years of study by Charles Darwin, these small creatures have a magnanimous reputation for turning waste into plant food. Many poor soils have been reactivated for family food production with the earthworm’s help. There are so many positives about this wonderful creature that is very difficult for me to think of it in a bad light.
I have gathered from my readings that the biggest problem with earth worms in the northern climates is that they may be changing the natural ecosystems, particularly in forests. Forest ecosystems naturally decompose slowly. This allows a layer of partially decomposed fibric material to cover the forest floor. This “duff” layer is essential habitat to the many plants, including many native wildflowers, that cover the northern forest floor. Loss of these plants is much more than an aesthetic issue. Many of these plants may aid in the prevention of soil erosion and the removal of valuable nutrients in the forest ecosystem. These “understory” plants may also be part of the valuable equation and system that supports mycorrhizal associations in the soil where fungi live off the carbon the trees provide and inorganic nutrients are made available to the plant, in particular trees. This symbiotic relationship is fundamental to forest health. Worms, being the efficient processors of organic material that they are process all of the organic material laying around the forest floor at rapid rates effectively destroying the habitat for the native plants (and other native insects as well).
In New England there are numerous species of exotic worms that can now be found in our region. They are not restricted to agricultural farm fields and gardens, but have invaded native forests, both hardwood and conifer. Their impacts are typically evident by a sparse understory where herbaceous plants are found only scattered around the forest floor.
The good news is that earthworms move slowly. So slowly, in fact, that it is difficult to measure. If humans stop introducing the earthworm to new areas than many native forest ecosystems may be in their natural state for generations.
There are several ways that we who populate the post glaciated areas can help with this earthworm problem. Don’t introduce earthworms to compost piles, especially those that are close to the forest. Don’t dump worms or discard them carelessly. This is most important as it relates to those who fish with worms, especially near forests. Spread the word about worms and the fact that they may be a real problem for native habitats.
As I cover up the worms in the compost bin, I think about how much benefit they provide for our garden but given recent information there is apparently quite a risk. I have never bought worms for the compost. They seem to find there way into this dark dungeon where they thrive with little help from me. While I am considering this my adult aged son drives into our driveway and gets out of his black Toyota Corolla.
“Hey Dad,” he asks me, “would like to go fishing? You could grab some worms while you’re in the compost bin.”
I am a bit surprised by the irony of his timing.
“Yeah, I’d love to go fishing but let’s use some spinning lures today,” I reply.
My son looks at me inquisitively.
“They’re too expensive,” I say out loud adding to my previous thought, “in more ways than one. Don’t worry I will explain later.”
And with that I head for the shed to grab the fishing poles and tackle.
Written for www.wildramblings.com in July of 2009