Invasion of Exotic Earthworms into North America and Other Regions - Earthworm Ecology - page 71

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Invasion of Exotic Earthworms
into North America and Other
Regions

Samuel W. James

Department of Life Sciences, Maharishi University of Management,
Fairfield, Iowa, U.S.A.

Paul F. Hendrix

Institute of Ecology and Department of Crop and Soil Sciences,
University of Georgia, Athens, Georgia, U.S.A.

CONTENTS

Introduction ......................................................................................................................................75
Criteria of Exotic Earthworm ..........................................................................................................77
Characteristics of Earthworms That Make Them Invasive .............................................................78
Mechanisms of Earthworm Invasion and the Dynamics of Invading Populations.........................79
How Do Invasive Earthworms Interact with Native Earthworms? .................................................80
How Do Invasive Earthworms Interact with Other Organisms?.....................................................81
Effects of Exotic Earthworms Invasions on Ecosystem Processes.................................................82
What Can be Done about Exotic Earthworm Invasions? ...............................................................83
Acknowledgments ............................................................................................................................86
References ........................................................................................................................................86

INTRODUCTION

Invasions of earthworms and their redistribution around the globe involve only a small proportion
of the overall diversity of earthworms, but the phenomenon is very widespread. It is safe to say
that few places occupied by humans are free of introduced exotic earthworms. Those few areas
would be environments that are inhospitable to earthworms because of either climate or soil
characteristics; otherwise, it is almost certain that there will be foreign earthworms in most soils
affected by human activity. In this chapter, we discuss the timing and extent of earthworm move-
ments, how and when they came to the attention of scientists, and how to be sure an earthworm
is exotic in a particular location. Then, we explore several ecological aspects of exotic earthworm
species and their invasions into new habitats and regions. The ecological aspect includes the general
biological features contributing to the ability of an earthworm species to be invasive or simply to
be transported inadvertently by humans; the dynamics of invasions; the biotic interactions of exotic
earthworms with other groups of organisms, including native earthworms; and the potential for
ecosystem-level effects of these invasions.

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