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Biodiversity of soil arthropods in a native grassland in Alberta, Canada: obscure associations and effects of simulated climate change Open Access


Other title
climate change
body weight
Type of item
Degree grantor
University of Alberta
Author or creator
Newton, Jeffrey S.
Supervisor and department
Proctor, Heather C. (Department of Biological Sciences)
Examining committee member and department
Adl, Sina M. (Soil Science, University of Saskatchewan)
Cahill, JC (Department of Biological Sciences)
Chang, Scott X. (Department of Renewable Resources)
Quideau, Sylvie A. (Department of Renewable Resources)
Department of Biological Sciences
Date accepted
Graduation date
Doctor of Philosophy
Degree level
Soils have traditionally been treated as a “black box” due to the challenges of studying this complex medium. The living component of soil consists of a complex network of roots and mostly very small, highly abundant, and extremely diverse group of microbes, protists, and other invertebrates. In my thesis I explore the diversity of subterranean ants living in a native grassland in Alberta, Canada, and their symbiotic relationship with root-feeding aphids and mealy bugs (Hemiptera: Sternorrhyncha). I identify multiple species of ants and Sternorrhyncha, with varying degrees of specificity of their symbiosis. I also conclude that there is little species-level host-plant specificity. The latter part of my thesis concerns mites and springtails, which are the most abundant soil micro invertebrates. Biomass of these extremely small organisms is difficult to assess, and as a result many estimation formulae based on body size measurements have been published. However, these estimation methods have rarely been tested. I review published formulae and tested them with newly acquired mite-weight data. While some formulae strongly over- or under estimate mite biomass, other models perform remarkably well. Using abundance and biomass data, I present the results of the effects of a summer of drought on native grassland soil mites. While drought normally negatively affects most soil arthropod densities, I observed an increase. While the mechanism is not yet clear, this result suggests that some grassland soil mite taxa may be able to benefit from drought conditions. Finally, I study how changes in environmental conditions, like predicted climate change, may affect native grassland communities. A full-factorial design was used, including a warming, drought, added precipitation, low intensity defoliation, and high intensity defoliation treatments. Results showed that all treatments affected the studied mite assemblages, but the effects differed per mite taxon. In summary, I have shown that the abundance and diversity of soil biota not only still offer opportunity for discovery, but also react to environmental changes in a way that allows them to be used as biomonitors. These responses vary according to which taxa are being studied, emphasizing the importance of not oversimplifying this rich and complex community.
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
Newton JS, Glasier J, Maw HEL, Proctor HC, Foottit RG, 2011. Ants and subterranean Sternorrhyncha in a native grassland in east-central Alberta, Canada. Canadian Entomologist 143 (5): 518-523Newton JS and Proctor HC, 2013. A fresh look at weight-estimation models for soil mites (Acari). International Journal of Acarology 39 (1): 1-14

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