Worms that help your garden are ravaging US forests.

The article "Worms That Help Your Garden Are Devastating U.S. Forests" first appeared on AZ Animals.

Many count earthworms Earthworms are the wriggling, unsung heroes of the environment. Their positive impact on the environment is twofold. Earthworms are among the most efficient detritivores and coprophages in nature, consuming large quantities of decaying organic matter and animal waste. They also serve as an important food source for many creatures in ecosystems, including birds. However, most people don't know that earthworms are actually an invasive species in North America.

Since the first European settlers arrived in the 17th century, earthworms have been slowly but surely destroying the regenerative capacity of North American forests. Simply put, these earthworms are so efficient at decomposing organic matter that they transform once-fertile soil into dry, bare earth. Humanity may be reducing forest cover, but invasive earthworms may be the primary cause of forest degradation in the Midwest and Northeast. Meanwhile, scientists and government agencies are racing to find ways to prevent earthworms from destroying forests.

Unsuccessful arrival

Earthworms are easy to miss. They're small, agile, and hide in the soil, surfacing only at certain times of day. Their inconspicuousness is likely why they found their way into the forests and ecosystems of North America. The arrival of large groups of European settlers in North America in the 18th and 19th centuries brought with them countless agricultural products and the soil to grow them. This provided European earthworms, like common earthworms, with a convenient delivery system to the continent. As people spread across North America and established farms, earthworms also spread.

Asian earthworms, particularly the aggressive jumping worms, arrived later. Many of them arrived in North America as unintentional "stowaways" in the soil of introduced plants around the end of the 19th century. Thanks to the development of the bait industry and the commercialization of compost and mulch, Asian earthworms spread across the continent over long distances.

North American forests thrived for millennia without earthworms and their voracious appetites. Now, the continent's forests are under serious threat as the decaying forest floor, which supports flora and fauna, is being destroyed at an alarming rate.

Forest litter

North American forests once thrived on a layer of spongy organic matter called the forest floor. Composed of fallen leaves, pine needles, and decaying bark, it sits above the humus, which in turn sits above the mineral soil. The importance of the forest floor cannot be overstated. It serves as a permanent breeding ground for native tree seedlings and wildflowers. Its moist, spongy consistency also prevents sudden temperature changes. It also provides shelter and food for many creatures, including insects, birds, small mammals, and salamanders.

Under natural conditions, the decomposition of the litter layer takes years. However, with the widespread spread of invasive earthworms, this process occurs too quickly for the litter layer to recover. Jumping worms, in particular, use their voracious appetite to gnaw through the top few centimeters of soil. In just one season, jumping worms can completely consume organic matter accumulated over decades.

Extreme effects

Rapid depletion of the litter layer has a catastrophic impact on North American forests. Rich, loose soil turns into hard, dry clods of earth. This sets off a chain reaction. The lack of fertile soil deprives plant roots of support. Native plants are unable to germinate. The roots of mature trees become vulnerable to deadly pathogens.

Soon, the forest food chain collapses. Birds that build nests on the ground lose the material they need for their nests, and salamanders starve to death as all the insects that thrive in the fallen leaves disappear. The only plants capable of coping with this dry, inhospitable soil are invasive, non-native weeds such as garlic mustard and buckthorn. In a year or less, the forest floor, which had lasted for centuries, disappears, leaving behind only invasive plants and a near-total absence of life.

A risky answer

Accelerating forest loss in North America has forced scientists and government agencies to go on the offensive. However, the problem is that there is no effective way to eradicate invasive earthworms. Once they establish themselves in a forest ecosystem, they are difficult to eliminate without serious consequences. Any pesticides designed to kill earthworms will also destroy other soil organisms and fungi and will likely leak into nearby freshwater sources.

In response, authorities are exploring various methods to stop the spread of earthworms. One of the latest approaches involves using organic fertilizers made from tea seed flour. However, no one yet knows exactly what impact these organic fertilizers have on native insects. In some states, such as Wisconsin, jumping worms are classified as invasive species, making their import, transport, and sale illegal. Many forest services now post warnings about these earthworms, and many ask people entering forests to clean their shoes of soil and dirt. Commercially, nurseries and land managers have begun selling bare-root seedlings instead of those grown in soil.

Only time will tell whether humans can develop an effective method to stop the spread of forest-destroying earthworms without harming other ecosystems.

The article "Worms That Help Your Garden Are Devastating U.S. Forests" first appeared on AZ Animals.