Assessing impacts of climate change, extreme weather events and management regimes on biogeochemical and hydrological cycles in Canadian forest ecosystems

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Canada's forest ecosystems, which represent about 40% or 397 Mha of the country' surface area, are being severely affected by climate change and extreme weather events such as droughts, flooding, and heatwaves. Climate warming is therein accelerating the hydrological cycle, thereby altering the growth, water balance, disturbance regimes (insect, fire), soil plant nutrient cycling and associated feedbacks (IPCC 2013, 2018). Changes in the composition, structure and functioning of forest ecosystems can affect regional climate and hence enhance the vulnerability of water resources and human communities. Developing a clear understanding of functioning of forest ecosystems and their response to climatic change and extreme events is urgently needed to maintain (or enhance) their capacity to sequester atmospheric CO2, and preserve ecosystem services. This proposal will investigate the impact of changes in forest hydrology and nutrient cycling on the carbon sequestration potential of three different age conifer and a deciduous forest and explore how these forests will respond to future climate change and extreme weather events. It will assess how different forest management treatments (e.g. variable retention harvesting (VRH)) will impact the forest growth trajectory, energy exchanges, hydrological processes in response to future climatic stresses and extreme events (e.g. drought, heat). This research will utilize ground based (e.g. eddy covariance, soil CO2 efflux, sapflow, biometric) and airborne (e.g. drone and satellite remote sensing) datasets to explore, how different age- and -species forests as well as management regimes (thinning intensities and spatial patterns) influence stand water use and productivity and response to extreme events and environmental variability. Proposal will also focus on to further develop a process- based integrated biogeochemical and hydrological model to enhance predictive capabilities of energy, water, carbon and nutrient cycles at stand and watershed scales across Canada. It will build on existing modelling work where C and N coupled Canadian Land Surface Scheme Canadian Terrestrial Ecosystem Model (CLASS-CTEM-N+) has been incorporated in the MESH Hydrological system to develop an integrated hydrological and biogeochemical model, called MESH-CTEM. Quantification of the responses of managed forests to climate change will help environmental planners to develop climate adopted forest management practices. MESH-CTEM modelling work will allow exploration of post-disturbance (management and/or fire) growth trajectories of Canadian forests under climate change in different watersheds and climate zones across Canada. Further development of CLASS and CTEM models will help to advance predictive capabilities of the Canadian regional and global climate models such as Canadian Earth System Model (Can-ESM) and provide an assessment tool to generate scenarios of future climate for policy development by the Federal Government.