Grant: Discovery Grants Program - Individual

Climate change will have particularly strong impacts on temperate and boreal ecosystems because of their location at high latitudes around the globe. These ecosystems are crucial in the global carbon cycle. At the same time, Canada encompasses both the largest extent and highest density of surface waters on the planet, with literally millions of lakes (>1ha) and countless streams/rivers covering a surface equivalent to that of Nova Scotia. The large C stocks of forest soils participate to significant dissolved organic carbon (DOC) exportation to surface waters. Several regions in Canada are already experiencing increasing DOC hydrological transport which is at the origin of the so called "browning" phenomenon. Browning impacts aquatic life, transport of pollutants and contamination of the aquatic food web as well as provision of drinking water. Moreover DOC is the main fuel for CO2 emissions from inland water bodies and higher DOC also promote better condition for CH4 emissions by increasing water temperature and raising the probability of lake hypoxia. Many causes have been advocated to explain the recent increasing DOC trends including changes in climate and atmospheric depositions. Changes in the precipitation and temperature regimes predicted to occur with climate change (and in nitrogen depositions) will further modulate the timing and delivery of DOC to surface waters. It is thus important to develop predictive models of lake DOC trajectories in the future. The proposed research program is organized into two objectives aimed at better understanding the role of climate and atmospheric depositions chemistry on DOC production in forested components and the mechanisms of DOC exportations from watersheds to surface waters: 1.Identifying the large-scale drivers of short and long-term DOC concentration and composition variation in tree leachates, soil solution and streams in three different forest types. 2.How large scale drivers, terrestrial carbon fluxes and catchment characteristics interact to control short and long-term DOC variations and composition in eastern Canadian surface waters? The novelty of this research program is that it will integrate the data issued from long-term monitoring of calibrated watersheds (including the forest and lake compartments) within a conceptual framework that will lay the foundation of a process base model who can predict the exportation of DOC from terrestrial to aquatic ecosystems. Such a model will be essential to predict future DOC trajectories in response to climate change and atmospheric deposition. This research will bring terrestrial and aquatic ecologists to work together. The data derived from this program will also directly benefit to the work of other researchers trying to predict GHG emissions from inland waters given that DOC is the main fuel for GHG emissions.