Exotic earthworm (Oligochaeta: Lumbricidae) assemblages on a landscape scale in central Canadian woodlands: importance of region and vegetation type

摘要

A growing understanding about the impacts of earthworms (Oligochaeta: Lumbricidae) on ecosystem processes and forest restoration necessitates an examination of their role in Canadian forests where they have become invasive. Little is known about the landscape-scale responses of earthworm populations to different regional characteristics and vegetation types within Canada鈥檚 central woodlands. We examined the regional variation of earthworm species richness, biomass, and assemblage composition across a range of four municipal regions (from south to north: Halton, Wellington, York, and Simcoe) and four habitat types (deciduous forest, mixed forest, tree plantation, and meadow) with varying soil characteristics in woodlands of south-central Ontario, Canada. In general, earthworm communities differed by region but not by habitat type. The most southern regions supported the highest earthworm species richness, biomass (i.e., i>Lumbricus/i> and i>Octolasion/i>), and density, and this was associated with a south鈥搉orth gradient in soil characteristics. Assemblage composition differed by region but not by habitat type. The observed south鈥搉orth gradient suggests an underlying effect of invasion spread associated with human settlement and density. Our results provide baseline information about earthworm communities in south-central Ontario forests and will enable managers to plan for the increasing role of earthworms in Canada鈥檚 future forests.