mountain pine beetle

historic range of mountain pine beetle

was widespread across BC and rocky mountains of AB

has been expanding north and east w climate change and forest management, however limited by jack pine (less reliable food source)

EM and Pl relationship

mutualistic, symbiotic - fungi needs pine for carbon, pine needs fungi for nutrients acquisition (EM breaks down OM w enzymes)

EM in soil modifies survival and growth of pines in particular - ex in NZ forestry w soil inoculation

how does tree mortality affect fungal communities in soils?

11 Pl stands in GP all differing in how much they are affected by MPB over few years

smaller proportion of EM fungi species present when there was a higher percent of Pl killed → carbon source is gone when trees are killed

DNA analysis determined that more saprotrophic/pathogenic/parasitic fungi species present after killed Pl - shifts in composition

how do changes in fungal communities affect seedling survival?

25% seedling survival in intact stands vs 1% in MPB stands

bit opposite from what we would expect - more light in MPB should have more recruitment of seedlings?

greenhouse experiment to test the role of fungi (soil inoculation from beetle killed, intact, or control and then ambient light and shade)

seedling defenses were higher w intact soil

seedling biomass was higher w intact soil and ambient light

questions from study 2

does soil inoculation improve seedling success in beetle killed stands? No

does the effect of soil inoculation depend on soil type? No, but soil type affects seedling survival and biomass

methods used to manipulate EM

1) culture fungi and use as inoculum - hard to do

2) transfer soils from donor to recipient sites - found no effect

3) inoculate seedlings with soil and transplant to field - tried

3) soil inoculation for seedlings in the field

15 sites in GP - sandy or loamy soils, quantified resident soil fungi for sites

found that root associated fungi were more similar in beetle killed and control inoculation than in intact inoculation - after 2 years

survival actually depended on the soil type (higher in sandy) rather than the inoculation, barely differed between the sites

different fungal communities did not change survival, height or shoot biomass