Fire, Lichens, and Woodland Caribou (Rangifer tarandus caribou) in Canada’s Boreal Shield

Threatened woodland caribou (Rangifer tarandus caribou) have experienced large range recessions and population declines across much of Canada’s boreal forest in the last century and have become a major focus of conservation efforts in the region. Habitat management strategies for woodland caribou seek to minimize the extent of human and fire disturbance on caribou ranges, but there remains conflicting evidence on the effects of fire on woodland caribou. Managers are also encouraged to identify and protect critical habitat for caribou populations, but critical habitat is defined using broad and descriptive definitions that may inadequately represent the functional characteristics needed by caribou. In this thesis, I set out to help refine habitat definitions for woodland caribou in the less studied western Boreal Shield by studying the interactions between fire, lichens, and caribou. I conducted field sampling in northwestern Ontario to map the biomass of ground lichens in a fire-driven landscape and linked this lichen biomass map to GPS collar locations of female caribou to assess seasonal selection for lichen biomass and refuge habitat. I also assessed the short-term response of caribou to fire in Ontario and Saskatchewan by comparing their pre-fire and post-fire space use. I developed a straightforward modelling framework to map lichen biomass that can be refined and adapted for other boreal caribou ranges. Lichen biomass was a strong predictor of winter habitat selection, suggesting lichen biomass maps could be used to improve the identification of winter habitat. I found caribou did not strongly alter their space use in response to fire, particularly during the calving season, suggesting we may need to broaden the interpretation of fire in habitat management strategies. My research provides insight into the ecology of woodland caribou in the western Boreal Shield, a less studied portion of the species range, and suggests changes to habitat management strategies could improve caribou conservation outcomes