Northern environments have been changing for millennia, but the pace of change is accelerating under current global warming and anthropogenic activities. The research of the CEN aims to specify the rate of these changes at different temporal and spatial scales in order to better assess their magnitude and to determine their consequences on the functioning of continental and coastal northern geo-ecosystems. The mechanisms through which these changes act on different ecosystem components and ultimately on ecosystem services are clarified thanks to the work of the CEN members. The study of feedback processes between system components and the determination of critical thresholds and tipping points between different states of ecosystems and geosystems is at the heart of our concerns. The transformation of the cryosphere (permafrost, lake ice, snow, glaciers) and its cascading effects on hydrology, aquatic and terrestrial food webs as well as the drinking water supply of northern communities are receiving particular attention. Numerical modeling of physical and biological processes supported by solid empirical field data as well as long-term monitoring allow to quantify the consequences of changes and to predict the trajectory of systems in the future. This research focus includes four research themes.

Project leaders: Esther Lévesque and Gilles Gauthier

Predictive models of the impacts of global warming and anthropogenic activities on the dynamics of geo-ecosystems are fed by paleo-environmental studies based on the analysis of various archives. The analysis of geo-indicators (e.g., stratigraphic layers, sediments, geochemistry, stable isotopes) and bio-indicators (e.g., diatoms, invertebrates, fossil pigments, DNA, pollen, tree rings) makes it possible to retrace the processes of transformation of northern landscapes and to reconstruct the history of changes over the past centuries or millennia. On one hand, these reconstructions provide information about the sensitivity of geo-ecosystems to climatic and environmental forcing and to their dynamics and equilibrium over time. On the other hand, studying the interaction of geological surface materials with vegetation, snow and ice cover sheds new light on the geomorphic processes that shape cold environments. Combining paleo-environmental reconstructions with the processes that govern the functioning of geosystems allows to anticipate the future trajectories of these environments and the species that are living in these habitats. Furthermore, it permits to develop adaptation, monitoring and conservation strategies.

Project leader: Reinhard Pienitz

Team: Antoniades, Dermot; Arseneault, Dominique; Bhiry, Najat; Boucher, Étienne; De Lafontaine, Guillaume; Francus, Pierre; Garneau, Michelle; Hétu, Bernard; Lajeunesse, Patrick; Lavoie, Martin; Payette, Serge; Rautio, Milla; Rochefort, Line; Simard, Martin.

Climate change is altering the nature and physics of aquatic ecosystems and their connectivity with the terrestrial environment, with major implications for their biological productivity and their microbial, plant and animal biodiversity. These changes also affect the pathway of contaminants (transformation, degradation, trophic transfers), whether they originate from atmospheric deposition or from local anthropogenic sources. The CEN researchers are studying the biogeochemistry of arctic lakes in relation to the acceleration of the hydrological cycle, the reduction of ice cover and the erosion and thawing of permafrost. Thermokarst lakes are of particular interest because they harbor a unique and little-known microbial diversity and are important sources of greenhouse gases. Peatlands are also experiencing significant changes and the net carbon balance of these ecosystems that are likely to produce large quantities of methane is still poorly understood. The response of aquatic ecosystems to climate change as well as climate feedback mechanisms represents a quantified input for global models. The CEN members also study changes in ice cover, hydrological regime and river flow, which control the expansion or contraction of aquatic ecosystems, as well as their effects on wildlife, plants and the inhabitants of the North. Particular attention is paid to the habitat quality, diet and movements of Arctic char, a species vulnerable to these changes and vital to northern peoples. Finally, transfers of freshwater and dissolved matter to the ocean are studied, especially in relation to permafrost thaw.

Project leader: Isabelle Laurion

Team: Amyot, Marc; Antoniades, Dermot; Babin, Marcel; Chokmani, Karem; Comte, Jérôme; Couture, Raoul Marie; Culley, Alexander; Dominé, Florent; Fortier, Daniel; Garneau, Michelle; Kinnard, Christophe; Langlois, Alexandre; Larivière, Dominic; Lovejoy, Connie; Moore, Jean-Sébastien; Pienitz, Reinhard; Pilote, Martin; Rautio, Milla; Sonnentag, Oliver; Vincent, Warwick F.

The impacts of global warming on terrestrial ecosystems are significant, either by their direct influence on the physiology of organisms or indirectly through their effects on the physical environment (e.g., snow) and the disturbance regime (e.g., fires). The rapid shrubification of the Arctic is transforming northern landscapes, thus requiring the study of its causes and consequences in relation to nutrient recycling, carbon sequestration, snow cover and the thermal regime of permafrost. The consequences of these changes on large herbivores such as caribou are being studied through long-term monitoring of their populations and those of their predators. These predators exercise major control over the tundra food web. However, this dynamic is sensitive to the presence of migratory species, which in their turn are influenced by the often anthropized environments they are using in winter or by the addition of new species (e.g., moose) whose range is shifting northwards. The CEN members are conducting long-term ecosystem monitoring coupled with studies on species behavior and ecophysiology and are characterizing the connectivity between northern ecosystems and the rest of the world generated by the seasonal movements of species. Thus, it is possible to model the dynamics of food webs on a seasonal basis and to evaluate their sensitivity to disturbances that occur in the North or elsewhere on the planet.

Project leader: Steeve Côté

Team: Berteaux, Dominique; Bêty, Joël; Boudreau, Stéphane; Dominé, Florent; Fauteux, Dominique; Festa-Bianchet, Marco; Gauthier, Gilles; Gravel, Dominique; Lecomte, Nicolas; Legagneux, Pierre; Lessard, Jean-Philippe; Lévesque, Esther; Pelletier, Fanie; Rochefort, Line; Simard, Martin; St-Laurent, Martin-Hugues; Tremblay, Jean-Pierre; Villarreal A., Juan Carlos; Vézina, François.

The study of the water cycle and the cryosphere is fundamental to address several issues of northern communities who are depending on the sustainability of drinking water sources and the accessibility to the territory in order to practice their traditional activities. Surface water used as a source for drinking water is vulnerable to depletion, browning caused by permafrost thaw as well as chemical and microbiological contamination. With global warming, the exploitation of groundwater becomes possible due to the melting of the ground ice which makes this previously frozen water source accessible and because of groundwater flow that gains in importance due to an increase of infiltration. However, the degradation of the main components of the cryosphere, i.e., snow, lake and river ice and permafrost, affects the quality of the resource and the accessibility of the territory. For a better understanding of the feedback loops between climate warming, cryosphere degradation and the water cycle, the CEN members are combining information from the SILA environmental station network with detailed in situ hydrogeological measurements and satellite remote sensing of snow and ice cover to develop a complete surface energy balance. The analysis of the composition of snow, ice and water makes it possible to assess their chemical and biological quality. The quality and vulnerability of the drinking water sources are studied not only at the source but also all along the treatment and distribution chain up to human consumption.

Project leader: Jean-Michel Lemieux

Team: Allard, Michel; Antoniades, Dermot; Bernier, Monique; Buffin-Bélanger, Thomas; Chokmani, Karem; Comte, Jérôme; Dominé, Florent; Fortier, Richard; Grenon, Martin; Kinnard, Christophe; Langlois, Alexandre; Larivière, Dominic; Laurion, Isabelle; Molson, John; Pienitz, Reinhard; Roy, Alexandre; Royer, Alain; Therrien, René.