Soil fungi after pine beetle outbreak: Diagnosis of fungal community composition and treatment of outplanted seedlings with tailored soil inoculum

• Author / Creator

  Fellrath, Evan G

• Soil fungal communities play vital roles in boreal forests as key organisms that cycle nutrients, facilitate uptake of resources for mycorrhizal plants, and store carbon. Forest disturbances often result in shifts in soil fungal community composition, yet, it is unclear if these effects are consistent across soils widely varying in abiotic properties. I used the landscape-scale outbreaks of mountain pine beetle in lodgepole pine forests of western Alberta to elucidate whether soil physical and chemical properties underpin soil fungal community composition and function after disturbance. In addition to characterizing fungal communities across the landscape, I also tested whether pine seedling performance (survival and height) differs when grown with soil inoculum from different sources (beetle-killed, undisturbed, or no inoculum) after being outplanted into beetle-killed pine forests. I found two groups of soil fungi in beetle-killed forests: those inhabiting soils with greater ammonium and silt content (‘Loamy Sites’), and those inhabiting soils with higher phosphate and sand content (‘Sandy Sites’). Across all sites, saprotrophic fungi were more diverse than ectomycorrhizal fungi, yet Loamy Sites were more diverse in both functional groups compared to Sandy Sites. Indicator ectomycorrhizal fungi present at the two site groups corroborated previous research outlining nutrient preferences, yet indicators were not necessarily representative of disturbances in previous studies. Survival of seedlings did not differ by inoculum type. Pine seedling heights differed among inoculation treatments, yet only in those outplanted to Sandy Sites. These results indicate that the composition and function of soil fungal communities after beetle outbreaks diverges based on physical and chemical properties of soils. I also demonstrate that seedlings grown with tailored soil inoculum differ in performance when outplanted into beetle-killed forests, but site variation modifies seedling outcomes. Though the result of this insect outbreak appears uniform at the tree canopy level, future research should exercise caution when predicting consequences of fungal community structure and function within these forests. A seemingly homogenous aboveground disturbance includes substantial variation belowground. Further work is necessary to investigate the long-term succession of soil fungal communities relative to soil abiotic properties, as well as the influence of inoculation treatments on performance of outplanted seedlings.

• Subjects / Keywords

  • next-generation sequencing
  • soil nutrients
  • Pinus contorta
  • community composition
  • soil fungi
  • soil texture
  • diversity
  • Dendroctonus ponderosae
  • inoculum

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-aj1w-w327

• License

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