Lowering the rate of timber harvesting to mitigate impacts of climate change on boreal caribou habitat quality in eastern Canada.

Many boreal populations of woodland caribou (Rangifer tarandus caribou) have declined in Canada, a trend essentially driven by the increasing footprint of anthropogenic disturbances and the resulting habitat-mediated apparent competition that increases predation pressure. However, the influence of climate change on these ecological processes remains poorly understood. We evaluated how climate change will affect boreal caribou habitat over the 2030-2100 horizon and in a 9.94 Mha study area, using a climate-sensitive simulation ensemble that integrates climate-induced changes in stand dynamics, fire regime, and different levels of commercial timber harvesting. We assessed the relative importance of these three drivers under projections made using different radiative forcing scenarios (RCP 2.6, 4.5, 8.5). Habitat quality was estimated from resource selection functions built with telemetry data collected from 121 caribou between 2004 and 2011 in 7 local populations. At the beginning of our simulations, caribou habitat was already structured along a south-to-north increasing quality gradient. Simulations revealed changes in forest cover that are driven by climate-induced variations in fire regime and scenarios of harvesting levels, resulting in the loss of older coniferous forests and an increase in deciduous stands. These changes induced a generalized decrease in the average habitat quality and in the percentage of high-quality habitat for caribou, and in a northward recession of suitable habitat. Timber harvesting was the most important agent of change for the 2030-2050 horizon, although it was slowly replaced by changes in fire regime until 2100. Our results clearly showed that it is possible to maintain the current average habitat quality for caribou in future scenarios that consider a reduction in harvested volumes, the only lever under our control. This suggests that we still have the capacity to conciliate socioeconomic development and caribou conservation imperatives in the face of climate change, an important issue debated throughout the species distribution range.

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Déclaration de conflit d'intérêts

Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Yan Boulanger reports financial support was provided by Natural Resources Canada. Martin-Hugues St-Laurent (UQAR) reports financial support was provided by Fonds de recherche du Quebec Nature et Technologies, Fonds de recherche forestière du Saguenay Lac-St-Jean, Natural Sciences and Engineering Research Council of Canada, Canada Economic Development for Quebec Regions, Conseil de Industrie Forestière du Québec, Fédération Canadienne de la Faune, Fondation de la Faune du Québec, World Wildlife Fund for Nature, and Resolute Forest Products Inc. Martin-Hugues St-Laurent (UQAR) reports administrative support was provided by Université du Québec à Rimouski. Martin-Hugues St-Laurent (UQAR) reports equipment, drugs, or supplies was provided by Essipit First Nation. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.