Organisms

Most insects living in hardwood forests rely upon the forest floor for food and protection. Since earthworms eliminate the forest floor, not only will the number of insects decrease, but also the variety. (UMN 2005)

Amphibians and reptiles that live in hardwood forests are especially adapted to the moist and cool conditions of the forest floor. When the forest floor is removed, they no longer have this protection from predators and from drying out. With a decrease in the number of insects, a critical food source is diminished which can lead to additional stresses. (UMN 2005)

(Image from Minnesota DNR website)

Different mammals will be affected according to their dependence on various aspects of the ecosystem. For example, small mammals like voles rely on the forest floor for protection and food. With fewer insects and fungi, their preferred foods, these small mammals will probably die back after earthworms remove the forest floor. If the voles disappear, weasels are threatened because voles are a food source for them. Medium sized mammals like raccoons, hare, and porcupine will also find less food after earthworms invade and will probably look for other habitats to supply their needs. Large mammals like white-tailed deer and bear are only occasional visitors to hardwood forests. If they find their food source has disappeared, they will simply move on and look elsewhere and spend less time in the forest. (UMN 2005)

(Image of vole from http://www.taiga.net/wmac/consandmanagementplan_volume3/graphics/photos/vole.jpg)

Birds that breed and nest in the hardwood forests rely on the forest floor for both food (mostly insects and seeds) and nest sites. With no forest floor, there will be no nest sites for ground nesting and few insects. With fewer plants, there will be fewer seeds. Other birds use the layers of vegetation that seedling, sapling and shrubs provide for nesting and food. When these layers die back, important nest sites disappear along with important sources of berries and seeds for food. As a result, we would expect to see and hear fewer birds in our forests after earthworms invade. (UMN 2005)

Herbivory in a hardwood forest ecosystem can have a severe impact when earthworms reduce the diversity and quantity of the remaining plant species (including the plant roots, leaves and twigs.) White-tailed deer are an important mammalian herbivore in hardwood forests in Minnesota. They particularly like to eat many of the native herbaceous plants that grow in these forests because they do not have bitter or toxic substances in them. When earthworms, invade the deer population will continue to consume these diminishing plants until they are eliminated from the ecosystem. (UMN 2005)

(Image of white tailed deer from http://www.dcwild.com/images/Mammals/White-Tailed-Deer-2.jpg)

Jack-in-the-Pulpit is one native plant species that has bitter tasting or toxic substances in their leaves, as do many exotic plant species. Deer and other herbivores will avoid eating these plants. After some time, they may take over the forest understory where earthworms are present. (UMN 2005)