| reduced density and nest survival of ground-nesting songbirds relative to earthworm invasions in northern hardwood forests. | european earthworms (lumbricus spp.) are spreading into previously earthworm-free forests in the united states and canada and causing substantial changes, including homogenization of soil structure, removal of the litter layer, and reduction in arthropod abundance and species richness of understory plants. whether these changes affect songbirds that nest and forage on the forest floor is unknown. in stands with and without earthworms in the chequamegon-nicolet national forest, wisconsin (u.s.a.) ... | 2011 | 21797927 |