Mountain pine beetle outbreak and ectomycorrhizal feedback: the ecology of recovery in beetle killed forests

  • Author / Creator
    Cigan, Paul W
  • The expansion of mountain pine beetle (Dendroctonus ponderosae; MPB) into naïve host ecosystems has been met by gaps in two key areas of research: (A) affects on the chemistry of forest soils, and (B) impacts on the regeneration of tree seedlings. To investigate linkages between both, we paired observational field and experimental greenhouse studies. In the field study, we used a natural continuum of recent (0-3 yrs) MPB-caused tree mortality (0-84%) in naïve lodgepole pine-dominated (Pinus contorta) forests in northwestern Alberta, to quantify impacts of MPB outbreak on: (1) input rates of pine needle-derived nutrients; (2) supply rates of plant-available nutrients; (3) concentrations of soil phenols. We found positive associations between tree mortality and pine needle nutrient concentrations (of nitrogen, phosphorus, potassium, calcium, and magnesium) and inputs (of nitrogen and phosphorus). The supply rates for plant available nitrate, and concentrations of soil phenols were altered by MPB disturbance. In the greenhouse study, we tested the main effects and interactions of (1) light intensity, (2) pine needle litter addition, and (3) soil inoculation on first-year growth of seedlings of lodgepole pine and white spruce (Picea glauca). Soil inoculation had the greatest impact on accumulations of biomass, and sugar and starch reserves. Seedlings of lodgepole pine grown with inocula originating from uninfested stands had enhanced biomass accumulation relative to controls; accumulation was reduced when seedlings were inoculated with soils from MPB-infested stands. Changes in soil microbial communities may limit pine regeneration following outbreak, but field studies are needed confirm this effect.

  • Subjects / Keywords
  • Graduation date
    Spring 2014
  • Type of Item
  • Degree
    Master of Science
  • 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.