Skatter, H.G., Kansas, J.L., Charlebois, M.L., and Balicki, B.


In boreal forests, wildfire is a dominant ecological process that affects the distribution and abundance of terrestrial lichens, the principal winter food for Woodland Caribou (Rangifer tarandus caribou). Fires commonly destroy the lichen mat, and there is a succession in the cover and composition of terrestrial lichens since time of burn. Currently, management agencies in Canada operate with a threshold of 40 years before habitat is considered suitable for Woodland Caribou following a wildfire. This study used two independent datasets to analyze short-term and long-term progression of terrestrial forage lichen cover following wildfire in the Boreal Shield of northern Saskatchewan, and compared these data with similar studies in other caribou ranges. Terrestrial forage lichens were found to recover 20-50 years faster in Jack Pine (Pinus banksiana) stands than has been reported from previous studies from the boreal forest and tundra habitats, and average cover peaked at 21-30 years after fire in Jack Pine stands. After this peak, lichen cover decreased and remained relatively low between 41-90 years. A secondary increase in cover occurred between 101-150 years. Cladina mitis/arbuscula was the dominant species, and was, of the three preferred forage species analyzed, the one that recovered most quickly after fire whereas C. stellaris and C. rangiferina appeared later. Forage lichen cover was lower in spruce (Picea spp.) stands than in Jack Pine stands. Based on forage lichen cover alone, we conclude that Jack Pine stands as young as 21-30 years may provide a more suitable supply of forage cover for Woodland Caribou than do intermediate aged stands between 50 to 90 years old; however, optimal habitat may not occur until approximately 100 years after fire. Our results help explain how Woodland Caribou have persisted for several thousand years in the Boreal Shield of Saskatchewan, an environment with high fire frequency and extent, as a matrix of relatively young and old mature habitats may be more suitable for caribou than vast areas of intermediate aged habitats. These findings may have important management implications for Boreal Woodland Caribou. Based on forage supply, this bi-modal pattern of lichen recovery observed in the Boreal Shield of Saskatchewan suggests that it may be more appropriate to include two phases of caribou habitat availability in models, rather than applying a single threshold after which habitat is deemed suitable.

Canadian Wildlife Biology and Management. 2014. 3-1: 1-14