Tree rings as indicators of hydrological changes and past climate

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Tree-ring analysis has a long history of providing environmental proxies (e.g., temperature, drought, insect outbreak). In Canada, trees produce annual tree rings, they are widely distributed and often live for centuries. We can thus use tree-ring traits to reconstruct conditions prior to instrumental records. A long-term objective of my research is to uncover new tree-ring traits and to evaluate their use as proxies. In recent years, anatomical abnormalities in tree rings have become widely used as indicators of extreme climate events. For example, frost and light rings provide information about temperature anomalies and they can help gauge future climate projections in light of past and current climates. Interestingly, light rings are inversely related to maximum latewood density, a widely used summer temperature proxy. Maximum latewood density can also be approximated by measuring the blue reflectance of trees rings; a technique largely underutilized in North America. Another area in which the University of Winnipeg DendroEcology Laboratory is having significant impacts is dendrohydrology. We are leaders in the use of flood rings and year-to-year measurements of earlywood vessels to study long-term hydrological variability in boreal systems. Our latest work with diffuse-porous species has allowed to identify a novel hydrological proxy in the form of periodic tangential band of vessels. The proposed research will develop along two main axes. The first is dendrohydrology. We will expand our work temporally, geographically, across species and hydrological regimes. Second, we will explore the utility of blue reflectance in Canadian dendroclimatology taking advantage of our large wood collection. Two studies will be led on hydrological systems in Manitoba including Lake Winnipeg. Another will determine how ring-porous species American elm respond to flooding. A 4th one will evaluate the possibility to reconstruct historical flooding for the upper Ottawa River. A 5th study will focus on the response of diffuse-porous species to flooding. A 6th one will aim at reconstructing the Holocene flood dynamics focusing on Lake Duparquet's tributaries, Quebec. At least, four projects will also deal with blue reflectance and involve students completing an honours thesis. In conclusion, this research will allow to better understand tree growth and to better visualize how future environmental changes brought by human activities and/or natural variations may impact Canadians and their environment. It will be helpful to the Canadian Hydropower sector and water resource managers. This research program will provide many projects for both undergraduate and MSc students. Given it is laboratory intensive, it will also provide many training and employment opportunities. Given the strong commitment of the University of Winnipeg towards campus indigenization, a portion of my research time will also be going to provide training opportunities to Indigenous students.