Starting with the European settlers, humans have introduced earthworms from Europe and Asia into North American forests. These introductions continue through the transport of soil that contains non-native earthworms, such as during construction and through the release of non-native earthworms used for fishing. The effects of non-native earthworms are especially large in forests that did not have any native earthworms. For example, forests of the Great Lakes region did not previously have earthworms until humans introduced them. When non-native earthworms are introduced, the thick layer of leaf litter disappears quickly, thereby altering biogeochemical cycles. You conduct an experiment to compare the nitrogen cycle in soils with and without non-native earthworms. Predict the results of your experiment.

Originally, the nitrogen released by organisms when they die (or excrete waste products) is organic nitrogen, e.i., amino acids and nitrogenous bases in DNA. Ammonification is the property that decomposer organisms have to mineralize organic nitrogen in order to produce inorganic nitrogen in the form of ammonium (NH4+). In agroecosystems, earthworm activity can increase the ammonification rate. For example, Lumbricus terrestris is an invasive earthworm (which is native to Europe) that has been shown to increase both ammonification and nitrification (nitrate production) rates in the soil of different ecosystems.