Trees as indicators of past climates and forest dynamics in Central Canada

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The research focuses on how environmental factors (e.g., climate, insect, disease, fire) affect tree growth and tree-ring formation. In Canada, trees produce annual tree rings and often live for many centuries. We can thus utilize them or their tree-ring characteristics to reconstruct conditions prior to recording by instruments. This capability allows us for example to gain information on climate variability prior to European settlement. To do so however, we need a clear understanding of how today's environmental conditions affect tree growth in various species and habitats. This research goes from studying wood anatomy to the quantification of the impact of large scale phenomena like insect outbreaks, forest fires, and climate extremes. Tree-ring research not only allows for a better understanding of growth but it also allows to foresee how future environmental changes brought by human activities and/or natural variations may impact Canadians and their environment. This research mainly focuses on central Canada. First, we will study tree-ring anomalies (e.g., false rings, frost rings) and the factors (e.g., insect, disease, drought, temperature) that trigger their formation. One of the questions arising from our research is why are trees in a given area not all recording a specific event? For example, what makes a tree a good recorder of drought and not another? Second, we intend to study the impacts of Lake Winnipeg hydrological changes on growth and wood anatomy of shoreline deciduous trees species. Third, the jack pine network of tree-ring chronologies that we are developing for Manitoba will be completed and will continue to be used to reconstruct dynamical processes like insect outbreaks and climate variability. Fourth, we will pursue our millennia forest fire reconstruction. This project involves to quantify and analyze the charcoal particles that were deposited in lake sediments over the last few millennia and that were produced by forest fires. Fifth, we will expand our research to wetlands and in particular to back spruce growth in peatland a habitat that has been little considered by tree-ring scientists despite their abundance in Canada and worldwide. We are interested in the potential that trees offers for long-term understanding of hydroclimatic changes. In conclusion, this research will allow to better understand tree growth and to better visualize the past and current variability in climate and other environmental factors in Interior North America. Given that our research is laboratory intensive, it does benefit both undergraduate and graduate students by providing many training and employment opportunities. The ecological information generated will also be helpful to forest managers (e.g., Parks Canada, Forestry Branch) as our research contributes to better manage these ecosystems.