Influence of two exotic earthworm species with different foraging strategies on abundance and composition of boreal microarthropods

• Published in: Soil biology & biochemistry 2013-02, Vol.57, p.334-340
• Main Authors: Cameron, Erin K., Knysh, Kyle M., Proctor, Heather C., Bayne, Erin M.
• Format: Article
• Language: English
• Subjects: Acari; Agronomy. Soil science and plant productions; Astigmata; Biochemistry and biology; biogeochemical cycles; Biological and medical sciences; Boreal forest; boreal forests; Chemical, physicochemical, biochemical and biological properties; Dendrobaena; Earthworms; Ecosystem engineer; foraging; forest soils; Fundamental and applied biological sciences. Psychology; indigenous species; Invasional meltdown; Lumbricus terrestris; microbial communities; Non-native species; Oribatid mites; Oribatida; Physics, chemistry, biochemistry and biology of agricultural and forest soils; plant growth; Prostigmata; Soil science; Springtails; Zoology (interactions between soil fauna and agricultural or forest soils)
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2012.07.010

In North America, many species of European earthworms have been introduced to northern forests. Facilitative or competitive interactions between these earthworm species may result in non-additive effects on native plant and animal species. We investigated the combined versus individual effects of the litter-dwelling earthworm Dendrobaena octaedra Savigny, 1826 and the deep-burrowing species Lumbricus terrestris L., 1758 on microarthropod assemblages from boreal forest soil by conducting a mesocosm experiment. Soil cores from earthworm-free areas of northern Alberta, Canada, were inoculated with D. octaedra alone, L. terrestris alone, both worm species together, or no earthworms. After 4.5 months, microarthropods were extracted from the soil, counted, and identified to higher taxa. Oribatid mites were further identified to family and genus. Abundance of microarthropods was significantly lower in the treatment containing both species than in the no earthworm treatment and the L. terrestris treatment. Oribatida and Prostigmata/Astigmata differed significantly among treatments and were lowest in the treatment containing both earthworm species, followed by the D. octaedra treatment, although post-hoc pairwise comparisons were not significant. Within the Oribatida, composition differed between the control and L. terrestris treatments as compared to the D. octaedra and both-species treatments, with Suctobelbella and Tectocepheus in particular having higher abundances in the control treatment. Effects of the two earthworm species on microarthropods were neither synergistic nor antagonistic. Our results indicate that earthworms can have strong effects on microarthropod assemblages in boreal forest soils. Future research should examine whether these changes have cascading effects on nutrient cycling, microbial communities, or plant growth. ► Microarthropod abundance decreased in the presence of exotic earthworms. ► Oribatid assemblage structure also shifted when earthworms were present. ► Dendrobaena octaedra had larger effects than Lumbricus terrestris. ► Effects of exotic earthworms were not synergistic.