Anticipating the consequences of climate change for Canada’s boreal forest ecosystems

Abstract

Canadian boreal woodlands and forests cover approximately 3.09 × 106 km2, located within a larger boreal zone characterized by cool summers and long cold winters. Warming since the 1850s, increases in annual mean temperature of at least 2 °C between 2000 and 2050 are highly probable. Annual mean temperatures across the Canadian boreal zone could be 4–5 °C warmer than today’s by 2100. All aspects of boreal forest ecosystem function are likely to be affected. Further, several potential “tipping elements” — where exposure to increasing changes in climate may trigger distinct shifts in ecosystem state — can be identified across the Canadian boreal zone. Approximately 40% of the forested area is underlain by permafrost, some of which is already degrading irreversibly, triggering a process of forest decline and re-establishment lasting several decades, while also releasing significant quantities of greenhouse gases that will amplify the future global warming trend. Warmer temperatures coupled with significant changes in the distribution and timing of annual precipitation are likely to cause serious tree-killing droughts in the west; east of the Great Lakes, however, where precipitation is generally nonlimiting, warming coupled with increasing atmospheric carbon dioxide may stimulate higher forest productivity. Large wildfires, which can cause serious economic losses, are expected to become more frequent, but increases in mean annual area burned will be relatively gradual. The most immediate threats could come from endemic forest insect pests that have the potential for population outbreaks in response to relatively small temperature increases. Quantifying the multiple effects of climate change will be challenging, particularly because there are great uncertainties attached to possible interactions among them, as well as with other land-use pressures. Considerable ingenuity will be needed from forest managers and scientists to address the formidable challenges posed by climate change to boreal ecosystems and develop effective strategies to adapt sustainable forest management practices to the impending changes.

An uncertain future for woodland caribou (Rangifer tarandus caribou): The impact of climate change on winter distribution in Ontario

“…Second, the preferred habitat type of woodland caribou identified within our models (e.g., dense coniferous forest) was currently found in greater quantity in the southwestern portion of northern Ontario. If distributions of preferred habitat shift in response to climate change (as has been suggested by other studies; e.g., Lui, 1990;Parker et al, 2000;Price et al, 2013) our predictions of woodland caribou occurrence would follow changes in landscape patterns of this habitat. Thus, future woodland caribou ranges will not be a straightforward northerly shift, but a function of several sources of uncertainty including habitat, climate and linear disturbances across northern Ontario.…”

The pyrogeography of eastern boreal Canada from 1901 to 2012 simulated with the LPJ-LMfire model

“…Wildland fires are the most important natural disturbances in Canada's eastern boreal forest, but non-fire and human disturbances also have considerable effects (Price et al, 2013) and may influence fire activity trajectories indirectly. Integrating a range of forest disturbances into a DGVM could improve the accuracy of forecasting and modelling climate change effects on Canada's eastern boreal forest.…”

“…These phenomena are expected to lead to an increase in the frequency and size of fires in eastern boreal Canada in response to the on-going global warming (Ali et al, 2012). Effects of these changes in seasonal onset and dryness are such that the average size of spring wildfires could be multiplied by a factor of 3 for each additional 1 • C of warming (Ali et al, 2012;Girardin et al, 2013a;Price et al, 2013). An increase in area burned would affect both forest management plans and fire suppression strategies.…”

No growth stimulation of Canada’s boreal forest under half-century of combined warming and CO 2 fertilization

“…drought impacts | climate change | dendrochronology | normalized difference vegetation index | ecology C ircumpolar boreal forests are estimated to store ∼53.9 Pg of carbon or ∼14% of terrestrial vegetation biomass (1). These regions are currently experiencing accelerated changes, including warmer and longer growing seasons, tree line expansion, species migration, increased frequency and severity of drought, and increases in the frequency and severity of disturbances (2)(3)(4)(5)(6)(7)(8)(9)(10). These changes create uncertainty about the boreal forests' future role in the global carbon cycle (11).…”