|Callaham, Jr., Mac|
Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2005
Publication Date: 9/1/2006
Citation: Callaham, Jr., M.A., Gonzalez, G., Hale, C.M., Heneghan, L., Lachnicht Weyers, S.L., Zou, X. 2006. Policy and management responses to earthworm invasions in North America. Biological Invasions. 8:1317-1329. Interpretive Summary: Non-native earthworms are invading natural ecosystems in North America and leading to changes in nutrient cycling and affecting regeneration of natural vegetation. It is necessary to identify factors influencing the natural spread of current invasive species so that proper management, policy or regulations can be instituted to minimize or prevent the invasion of other non-native earthworms. Soil temperature, moisture, and pH were factors influencing the establishment of non-native earthworms; however, human industrial activity (e.g. fishing bait, horticulture, vermicomposting) is the major avenue of introduction. Regulation of earthworm containing media in non-domestic imports can be accomplished using a decision tree to identify suspect materials and potential hazards. Materials containing unidentified species or their reproductive propagules (cocoons) should be flagged, isolated, and investigated before they are allowed to be imported. Land managers, researchers, policy makers, and industrial service providers can benefit from the information collected to understand and manage the potential threat of non-native invasive earthworm species in order to protect our natural areas.
Technical Abstract: The introduction, establishment, and spread of earthworms not native to North America have been ongoing for centuries. These introductions have occurred across the continent and in some ecosystems have resulted in considerable modifications to ecosystem processes and functions associated with above- and below-ground foodwebs. However, many areas of North America remain that have never been colonized by earthworms, or that have soils still inhabited exclusively by native earthworm fauna. Although several modes of transport and subsequent proliferation of non-native earthworms have been identified, little effort has been made to interrupt the flow of new species into new areas. Examples of major avenues for introduction of earthworms are the fish-bait, horticulture, and vermicomposting industries. In this paper we examine land management practices that influence the establishment of introduced species in several ecosystem types, and identify situations where land management may be useful in limiting the spread of introduced earthworm species, and we identify methods to regulate the import of earthworms and earthworm-containing media so that introduction of new exotic species can be minimized or avoided.