Simulating the effects of climate change on fire regimes in Arctic biomes: implications for caribou and moose habitat

Wildfire is the primary ecological driver of succession in the boreal forest and may become increasingly important within tundra ecosystems as the Arctic warms. Migratory barren-ground caribou (Rangifer tarandus granti ) rely heavily on terricolous lichens to sustain them through the winter months. Lichens preferred by caribou can take 50 or more years to recover after being consumed by wildfires. We simulated effects of climate change on the fire regime within the winter range of one of the largest caribou herds in the world, the Western Arctic Herd, to assess how their forage may be impacted. We forecast that the total area burned (AB) in the near term (2008–2053) will be 0–30% greater than during our historic reference period (1950–2007) depending on the climate model (CGCM3.1 or ECHAM5) considered. Further into the future (i.e., 2054–2099), we forecast AB to increase 25–53% more than during our reference period. In contrast to the entire study area, which contains both tundra and boreal forest habitats, we forecast that the amount of AB in tundra alone will increase (0–61%) in the near term. Simulated highquality caribou winter range, as indexed by tundra and spruce habitat that had not burned in 50 years, decreased modestly (,6%) in the near term over the entire study area. Simulated changes were more dramatic within the herd’s core winter range, with declines in high-quality caribou winter range approaching 30%. Conversely, moose habitat was projected to increase by 19–64% within the core winter range in the near term. The simulated declines in the quantity of core winter range in the future due to larger and more frequent fires could impact caribou abundance through decreased nutritional performance and/or apparent competition with moose. These impacts would likely be detrimental to the subsistence users that rely on this resource. Additionally, changes in the fire regime and decreases in caribou abundance could amplify feedback mechanisms, such as decreasing albedo, by facilitating shrub growth that may hasten climate-driven changes to the composition and structure of vegetation communities in the