Rapid environmental change in boreal Canada and its projected impact on woodland caribou

Although the boreal forest of North America is often portrayed as wild and pristine, the northeastern part of the province of Alberta, Canada, is an intensely industrial landscape modified by numerous anthropogenic activities. These changes are compounded by an extremely active natural wildfire regime, and this region is projected to experience some of the most profound vegetation changes in the boreal biome. The aim of this study is to estimate the degree of future environmental change from multiple sources (anthropogenic and natural) and illustrate its potential impacts on an emblematic—and endangered—boreal species: the woodland caribou (Rangifer tarandus ssp. caribou). We accomplished this through a model of large-scale caribou dynamics modulated by changes in dominant vegetation, which in turn affects nutritional quality, predation risk, and capacity for movement across the landscape. Even under the most conservative scenario, results suggest major potential shifts in vegetation occurring as early as the next few decades, whereby the coniferous forest cover is rapidly eroded, replaced by deciduous forests and graminoids. These changes, driven by an acute moisture deficit, are also likely to translate into a more active, but potentially novel wildfire regime, the parameters of which remain uncertain. Large-scale vegetation changes, in conjunction with high levels of anthropogenic fragmentation, will almost certainly be detrimental to woodland caribou populations. Whereas currently essential lichen food sources will invariably diminish in the future, edible biomass levels may remain sustainable; similarly, the capacity for movement may not be dramatically impaired. Rather, it is the change in predation intensity that is the most likely to cause massive caribou declines (including local extirpations) by increasing the abundance of other ungulate species (notably white-tailed deer) that attract the caribou’s main predator: the gray wolf. Given that the upcoming shifts in vegetation and disturbance regimes are likely to degrade caribou habitat in much of northeast Alberta, we propose that current conservation efforts focus on those areas that are most resistant to change, such as large peatland complexes and fire refugia, in order to maximize the preservation of key herds.