The impact of non-native earthworms on regenerating forest communities in western Pennsylvania

During the last glacial period, earthworms native to the Eastern United States were extirpated, causing forest communities in Eastern North America to develop without the presence of earthworms for at least the last 20,000 years. Now, non-native earthworms from Asia and Europe, deliberately introduced through human actions, have invaded these forests. This invasion potentially may affect these ecosystems' composition and function, although to date no research has assessed the impact of non-native earthworms on forest communities of Western Pennsylvania. The environmental impact of non-native earthworms varies by species, but generally they change soil composition, alter carbon: nitrogen ratios, and decrease phosphorus abundance. By altering the soil composition and chemistry, these non-native earthworms have a cascading effect on forest plant communities. This study specifically seeks to enumerate the impact of non-native earthworms on new-growth forest communities across the Wisconsin glacial boundary in Pennsylvania.