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

  • Author / Creator
    Newton, Jeffrey S.
  • 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.

  • Subjects / Keywords
  • Graduation date
    Fall 2013
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
  • Specialization
    • Ecology
  • Supervisor / co-supervisor and their department(s)
  • Examining committee members and their departments
    • Chang, Scott X. (Department of Renewable Resources)
    • Adl, Sina M. (Soil Science, University of Saskatchewan)
    • Cahill, JC (Department of Biological Sciences)
    • Quideau, Sylvie A. (Department of Renewable Resources)