Global worming: massive invasion of North America by earthworms revealed

Human activities cause major ecological changes by reshuffling the spatial distribution of species. The extent to which this process affects belowground biota is a critical issue because soil organisms play a key role in ecosystem functioning and maintenance. However, the magnitude of the reshuffling of soil species remains unknown so far because of the lack of a historic baseline. Here, we begin to fill this gap with the largest spatiotemporal database of native and alien earthworms in North America. Our results reveal that the entire continent is being invaded by non-native earthworms through a variety of pathways. We show that these aliens bring novel ecological functions in most regions and thus represent a major threat to native ecosystems. Our findings demonstrate that earthworms, and most likely other soil organisms, represent a major but overlooked pool of invasive species with strong ecological impact. They need to be better integrated in control and mitigation strategies.