Abstract
Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.
Highlights
Recent and projected climatic warming has direct implications for fire-dominated disturbance regimes [1], at high latitudes where warming has been amplified [2]
The annual representative runs from ALFRESCO that were used for subsequent analyses had correlation coefficients of 0.904 and 0.922 for the warm and hot global circulation models (GCMs), respectively
Due primarily to the increase in the size of fires, the average area of winter habitat that burned per decade was 64 and 25% higher in the hot versus warm GCM for tundra and spruce, respectively (Table 1)
Summary
Recent and projected climatic warming has direct implications for fire-dominated disturbance regimes [1], at high latitudes where warming has been amplified [2]. A transforming wildfire regime is affecting ecosystem structure and function in the north by altering plant composition and successional patterns [8]. These shifts in vegetation alter the distribution and abundance of northern herbivores in different ways [9]. Wildfire may benefit some species, such as moose (Alces alces), by increasing early-successional habitats [10,11]. Wildfire may have negative effects on species dependent on late successional habitats, such as caribou (Rangifer tarandus) [11,12,13,14,15]
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