Mathilde Robitaille

Université de Montréal
M.Sc. candidate

Supervisor: Stéphanie Pellerin
David Pothier, Université Laval
Start: 2022-05-01
End: 2024-04-30


Influence of spruce budworm control on understory plant communities and on woodland caribou habitat
A spruce budworm (SBW) epidemic has caused repeated defoliation in many fir and spruce stands since its appearance on Quebec’s North Shore in 2006. The defoliation of trees in general and their mortality can induce changes in the species composition of understory communities. For example, an increase in the amount of light reaching the ground accelerates the development or promotes the recruitment of new plant species and therefore modifies the composition of understory communities, future tree stands, and the alpha and beta diversity patterns. These new plant species could support higher densities of mooses, and predators such as gray wolves and black bears, which could have consequences for populations of woodland caribou, a species highly at risk in some areas. Sprays of the biological insecticide Bacilius thuringiensis ssp. kurstaki (Btk) could mitigate potential adverse effects of SBW on woodland caribou habitat. Therefore, this study aims to determine if there are empirical relationships between Btk aerial spraying, the degree of defoliation caused by SBW and the development of understory vegetation. Through these relationships, it will then be possible to assess the influence of the control of SBW epidemics on caribou habitat.


Caribou, TBE, SBW, Btk