Structure, composition and trophic ecology of forest floor predatory mites (Mesostigmata) from the boreal mixedwood forest of northwestern Alberta

  • Author / Creator
    Diaz Aguilar, Irma
  • The forest floor, including the L, F and H horizons is the habitat for numerous soil fauna whose ecological relationships affect various soil processes. The forest floor is closely associated with stand development in boreal forests, creating distinct biochemical and physical characteristics within the different organic layers. Under the premise that forest floor soil communities are closely associated with, and characteristic of a particular stand type. I used predator mites (Mesostigmata) dwelling in forest floors to study the impact of forest stand type on the structure and composition of these mite assemblages. Differences in species richness, dominance and assemblages were a consequence of forest stand type. Results further demonstrated the importance of coniferous trees in structuring mesostigmatan assemblages. Forest floor pH structured variation in mite assemblages and forest floor thickness were associated with habitat preferences. Thus, the variation in habitat changes from early seral stages to mature old-growth stands results in diverse predatory mite assemblages. A particularly interesting feature of the fauna was the great diversity of zerconid species of genus Mixozercon (Halašková, 1963), including M. albertaensis, M. jasoniana and M. borealis, species that are exclusively found in western boreal forests. I used nitrogen isotope analysis (δ15N values) to assess the trophic positions of mesostigmatan and some oribatid mites in relation to potential effects of forest harvest on soil food webs in coniferous and deciduous stands. The differences in δ15N separated the mites in three main trophic guilds: detritivores (only oribatid), omnivores (overlapping with predators) and predators. Each guild was further subdivided into subguilds based on feeding relationships. Isotopic nitrogen fractionation within the mites did not seem to be affected by their habitat (spruce vs aspen) or by clearcutting. Instead, the well-defined degree of isotopic fractionation observed within the food web may depend only on the predator-prey feeding relationships because the degree of isotopic enrichment (or depletion) of predator reflects its diet.

  • Subjects / Keywords
  • Graduation date
  • 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
    • Department of Renewable Resources
  • Specialization
    • Soil Science
  • Supervisor / co-supervisor and their department(s)
    • Quideau, Sylvie (Department of Renewable Resources)
    • Kishchuk, Barbara (Northern Forestry Centre, Canadian Forest Service, Natural Resources Canada)
  • Examining committee members and their departments
    • Spence, John (Department of Renewable Resources)
    • Proctor, Heather (Department of Biological Sciences)
    • Berch, Shannon (BC Ministry of Forests)
    • Landhausser, Simon (Department of Renewable Resources)