It is generally recognized that where earthworms are abundant they can exert significant influence on the structure and function of soils. Compared to other biogeographic regions of Earth, however, surprisingly little is known about the earthworm fauna of the western hemisphere and their role in soil processes. This book is the first comprehensive review and analysis of the state of understanding of earthworm biogeography and ecology in North America. Topics of in-depth discussion include earthworm systematics, biogeography and ecology, influences on soil structure and ecosystem nutrient dynamics, and implications for ecosystem management. Each chapter provides a general review and statement of current understanding, an assessment of current research problems, recent developments and advances, and priorities for future research and applications. This book is a must for researchers and students studying the soil-related facets of terrestrial ecology.