Abstract

Disturbances are integral to the structure and functioning of the boreal forest. However their effects upon the underground components in this ecosystem are still largely unknown. In this thesis, I describe the ectomycorrhizal and understory plant communities in the black spruce boreal forest of the Abitibi region, Québec, and discuss the effects that both forest fires and logging have on the ectomycorrhizal community, nutrient supply rates and decomposition rates. The ectomycorrhizal community from black spruce, characterized by morphotyping and molecular techniques was dominated by Cenococcum geophilum and three Piloderma species. The plant community was made up of a mosaic of vegetation patches, which are described in this thesis, as either Sphagnum dominated plots, which associated with Sphagnum, Gaultheria hispidula and Picea mariana; or ericoid/lichen dominated plots, which associated with Lichen and Vaccinium angustifolium. Statistical analysis revealed that the effect of the disturbances was largely insignificant to the ectomycorrhizal community, nutrient supply and decomposition rates, and most differences were between transects. However, both the understory plant community plot types and abundance of individual plant species were found to have significant correlations with the most abundant ectomycorrhizal species. This suggests that if we want to know how the ectomycorrhizal community will be affected by disturbances, we should look at changes in the plant community due to disturbances.