Non-native anecic earthworms (Lumbricus terrestris L.) reduce seed germination and seedling survival of temperate and boreal trees species

• Non-native earthworms (EW) may reduce the recruitment of forest understory plants.
• Seeds of 14 tree species were germinated and grown in the presence/absence of EW.
• EW reduced % seed germination of seven tree species.
• EW reduced seedling survival of three tree species.
• The introduction of EW in forest ecosystems may alter forest tree diversity.

Recent studies have shown that the introduction of non-native earthworms in previously earthworm-free soils may have negative impacts on the recruitment of certain understory plant species in northern temperate forests. There is a need, therefore, to understand the mechanisms that may underlie this phenomenon. A microcosm study was conducted to test the effects of the anecic earthworm, Lumbricus terrestris L., on the number of days for germination, % seed germination, seedling survival and seedling biomass of 14 tree species native to southern Quebec (Canada). Seeds of these species were germinated and grown in the presence or absence of L. terrestris. The presence of earthworms significantly reduced % seed germination of seven tree species, as well as seedling survival of three tree species. The germination date of three tree species was significantly affected, either positively or negatively, by the presence of earthworms. Earthworms had no effect on seedling biomass. Results suggest that the introduction of L. terrestris into forested ecosystems of southern Québec may potentially alter overstory composition through several mechanisms that differentially affect the recruitment of various tree species in the understory.