Policy and management responses to earthworm invasions in North America

Abstract

The introduction, establishment and spread of non-native earthworm species in 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 belowground foodwebs. However, many areas of North America have either never been colonized by introduced earthworms, or have soils that are 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. Finally, we discuss methods to regulate the importation of earthworms and earthworm-containing media so that introduction of new exotic species can be minimized or avoided. Although our focus in this paper is necessarily North American, many of the management and policy options presented here could be applicable to the problem of earthworm invasions in other parts of the world.