OOS 51-6
Factors affecting the distribution of earthworms in North America: A collaborative project involving faculty at primarily undergraduate institutions and their students
The presence and abundance of earthworms in forests and other natural habitats is associated with changes in nutrient cycling and forest-floor biodiversity. Assemblages of earthworms in North America often include a combination of native and exotic species from different places that have arrived at different times. Areas affected by the Wisconsinan Glaciation may be inhabited exclusively by exotic species that have arrived since European colonization. Invasions are apparently ongoing, and the distributions of many species may be dynamic. Twenty-three members of the Ecological Research as Education Network (EREN) from 16 states are currently participating in this ongoing project. We aim to (1) better understand the current distributions of earthworm taxa in North America, and (2) discern the relative influence of anthropogenic and non-anthropogenic factors in limiting earthworm distributions. Participants are sampling earthworms using chemical (mustard) extraction and collecting a variety of associated environmental data.
Results/Conclusions
To date, about 80 sites and 2,500 earthworm specimens have been included in the project database, with approximately 70% of specimen determinations confirmed by the project principal investigators and their students. Proper identification of taxa has been the greatest challenge to the success of the project. In response, we have held identification workshops at EREN meetings and have created a set of instructional films available online. This remains a challenge with approximately 30% of submitted specimens requiring editing of the taxonomic determination. Not surprisingly, the so-called “peregrine” lumbricid earthworms are most well-represented in the database. Native species and species with limited habitat preferences (e.g., Eiseniella tetraedra) have been less frequently recorded. However, these records may allow for valuable additions to our understanding of habitat use in these species. Preliminary analysis indicates a significant role for both anthropogenic (e.g., distance to roads) and non-anthropogenic (e.g., soil pH) factors in limiting distributions. This promises to inform the management of natural areas currently uninhabited by earthworms or certain species of earthworms. Participants are additionally reporting success in using this project to meet curricular goals in ecology and conservation. In participating in this project, students come to better understand the taxonomy and ecological function of this important group and, more broadly, the role of animals (including exotic ones) in affecting ecosystem function in North American forests.