Seamless prediction and reconstruction of plant-water interactions in the boreal biome

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The overarching goal of my DG program is to enhance our ability to predict and reconstruct dynamic interactions between water and carbon cycles in cold boreal forests, at timescales ranging from days to millennia. This will generate much-needed improvements to our capacity to anticipate both short-term and long-term responses of boreal ecosystems to changes in the water cycle. It will also cast new light on critically important biophysical feedbacks that exist at the nexus of biosphere, atmosphere, and hydrosphere in the world's largest intact natural ecosystem. My group will make a significant leap forward in the field of dendroclimatology by seamlessly integrating timescales, water fluxes and ecophysiological processes, in a single, dynamic prediction continuum. Three complementary short-term objectives are formulated, each focussing on prediction problems relating to different timescales (weather- (SO-1), climate- (SO-2), and millennial-scale(SO-3)). SO1 will be dedicated to the prediction of short-term response to changes in water cycle properties. For example, how do short-term events affect the carbon storage capacity of forests? This is an important question because while climate change represents a long-term trend, the largest responses are usually triggered by extremes (dry / wet in our case). To shed light on these short-term responses, we will monitor growth and stable isotope fractionation in tree rings at a weekly timescale, and we will use a process-based model to simulate and predict observed changes. SO2 will focalize on predicting water-carbon cycling feedbacks in boreal forests in the context of climate change. Because water and carbon cycles are tightly coupled, climate change may impact one or the other, driving complicated feedbacks and retroactions that need to be quantified. To achieve this goal we will use eddy-covariance and tree ring stable isotope records simultaneously to constrain process-based modelling of large scale carbon-water cycle interactions. SO3 will aim at gaining knowledge on the millennial variability of hydrological cycle properties such as evapotranspiration, soil water content, precipitation, etc. We will then examine how Anthropocene changes in the water cycle depart from pre-industrial conditions and will attempt to attribute hydrological variability to external and internal mechanisms of forcing. The DG will enhance our capacity to forecast interactions and feedbacks between boreal water and carbon cycles in the face of climate change. It will also provide an original, dynamic, multi-scalar perspective on the evolution, vulnerability and fate of essential ecosystem services delivered by boreal forests : carbon storage and global warming mitigation through evapotranspiration.