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Above- and below-ground effects of an exotic ecosystem engineer in the boreal forest Open Access


Other title
ecosystem engineer
Type of item
Degree grantor
University of Alberta
Author or creator
Cameron, Erin K
Supervisor and department
Bayne, Erin (Biological Sciences)
Examining committee member and department
MacKenzie, M. Derek (Renewable Resources)
Proctor, Heather (Biological Sciences)
Classen, Aimee (University of Tennessee)
Macdonald, Ellen (Renewable Resources)
Department of Biological Sciences
Date accepted
Graduation date
Doctor of Philosophy
Degree level
Species invasions are increasing worldwide and are impacting populations, communities, and ecosystems. Non-native species that are ecosystem engineers, such as earthworms, may be particularly likely to have large impacts due to their ability to modify both biological and physical characteristics of their environment. Using a combination of field and laboratory studies, I examined above- and below-ground effects of non-native earthworms in the boreal forest of Alberta. I found no evidence that earthworm species facilitate each other’s invasions or have synergistic effects, as would be expected in an invasional meltdown. In a mesocosm experiment, the litter-dwelling earthworm Dendrobaena octaedra and the deep-burrowing species Lumbricus terrestris did not facilitate each other’s survival or reproduction. Similarly, although the two earthworm species significantly influenced microarthropod abundance, oribatid assemblage structure, and leaf litter depths, they did not have synergistic effects. Further, white spruce (Picea glauca) growth and colonization of white spruce roots by mycorrhizal fungi were not affected. Earthworms impacted other taxa via both direct trophic interactions and ecosystem engineering. In laboratory experiments, changes in soil structure associated with earthworm burrowing had strong effects on both microarthropod movement and plant root growth. In contrast, a field study indicated that distributions of American robins and earthworms were strongly correlated, suggesting the two groups are linked via predation of earthworms by robins. Although this research indicates non-native earthworms are affecting a variety of taxa in the boreal forest, there is limited awareness of earthworm invasions among the public. Consequently, a combination of increased research, public education, and regulations will likely be needed to effectively manage earthworm invasions in Alberta.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Cameron, E. K., and E. M. Bayne. 2011. Canadian Journal of Zoology 89:1223-1230.Cameron, E. K., K. M. Knysh, H. C. Proctor, and E. M. Bayne. 2013. Soil Biology & Biochemistry 57:334-340.Cameron, E. K., H. C. Proctor, and E. M. Bayne. 2013. Effects of an ecosystem engineer on belowground movement of microarthropods. PLoS ONE 8:e62796.Cameron, E. K., M. W. Zabrodski, J. Karst, and E. M. Bayne. 2012. Ecoscience 19:29-37.Cameron, E. K., and E. M. Bayne. 2012. Diversity and Distributions 18:1190-1198.

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