Spatial and temporal distribution of earthworms in a temperate intercropping system in southern Ontario, Canada

Abstract

Earthworms are known to increase soil bulk density, soil porosity, mixing of organic matter, and to strengthen aggregation of soil particles. They perform important functions in the maintenance and stabilization of the soil matrix. Historically, temperate intercropping research has focused on the above-ground benefits of adding trees into the agricultural landscape. Earthworm research in temperate intercropping systems has been non-existent to date. More emphasis on studying below-ground components, such as earthworms, is required in order to better understand the mechanisms of intercropping ecosystem function. The purpose of this study was to examine seasonal changes in distribution and abundance of earthworms under a temperate intercropping system in southwestern Ontario, Canada. Sampling occurred during the spring and summer of 1997 at the University of Guelph's Agroforestry Research Station, Guelph, Ontario. Earthworm samples were collected at various distances from the tree rows. Significant variation in both earthworm biomass and density were found between the three tree species sampled. Total mean earthworm density was 182 m^-2 within the poplar rows, 71 m^-2 within the silver maple rows, and 90 m^-2 within the white ash rows. A marked difference was also observed in the distribution of earthworms within the tree rows and the field area. For example, total mean density within the tree rows for poplar was 182 individuals m^-2, as compared to total mean densities of 117 and 95 individuals m^-2, two metres and six metres into the field from the tree, respectively.