The Role of Earthworms in Soil Formation

Despite being an important ecosystem engineer, earthworms cannot form soil alone. The role of earthworms in soil formation occurs through interactions with other soil-forming factors namely parent material, climate, topography, vegetation, and time. I begin by exploring questions about how earthworms interact with these soil-forming factors, namely, which of these affect earthworm activity and how earthworm activities can modify how these factors contribute to soil formation. Then, I examine how earthworms are involved in soil formation at various spatiotemporal scales. Earthworms form biostructures with dimensions of several millimeters (feces) to 1 to several meters (burrows); however, these biostructures affect soil processes that occur at smaller spatiotemporal scales as well as hydrologic and vegetative processes at much larger scales. Since earthworm biostructures persist in soil, they can have an impact on soil processes beyond the lifespan of an earthworm. I conclude with an analysis of the extent of earthworms and soil formation across spatiotemporal scales.