Turning up the heat in a northern hardwood: Response of soils and trees to summer and winter climate change

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Climate change is threatening the capacity of forests to provide its various services by causing, among other events, milder winters and increased freeze-thaw cycling in the soil and drier and warmer summers that create water stress for plants. Canada is committed to maintaining forests that are resilient to current and imminent global change. To forecast forest response to climate change, scientists have recently recognized the need to develop models not just based on regional climates, but also based on the reorganization of interactions between tree species and between trees and soils as well as possible feedbacks. The long-term objective of this research program is to characterize soil-plant interrelationships and nutrient cycling in eastern Canadian temperate deciduous forests under a changing climate. In the next 5 years, the research program will continue to strengthen the predictive framework of the response of forests to climate change by running novel manipulative field experiments to assess how soil warming during the growing season and decreased snow cover during winter affect soil carbon dynamics at the northern limit of temperate deciduous forests. To do so, changes in soil organic carbon levels, forms and stability, organic carbon from soil microbial biomass, soil respiration, leaf litter decomposition rates, fine root biomass production and microbial communities and dissolved organic carbon leaching rates will be measured under various treatments which include growing season soil warming only, winter snow removal only, a combination of both and reference (control) plots. Soil nutrient availability using ion-exchange resins and conventional soil chemical extraction methods as well as seed germination rates, seedling survival, growth, water use, foliar nutrition and root mycorrhizal fungi associations will also be assessed. These experiments are not matched elsewhere due to site location, number of replicated plots, the fact that both growing season and winter climate change are experimentally tested and that interactions between trees and soils at recruitment and juvenile growth stages are investigated under experimental climate change in the field. This research program is thus a very unique and essential piece of research for: (1) measuring present and estimating future states and dynamics of forests, (2) improving simulation models of forest response to climate change and thus pin-pointing the best possible adaptation strategies to climate change, and (3) training HQPs to gain further understanding of forest functioning under a changing climate and transfer this knowledge to the public and private forest sectors involved in forest management decision-making.