Defense of David Voyer’s thesis – Doctorat en sciences forestières – Tuesday, January 28, 2025 at 9 a.m.!
You are cordially invited to the David Voyer thesis defense, held on Tuesday, January 28, 2025, at 9 a.m., at the Envirotron Pavilion, room EVT-1240.
Login link for those wishing to attend online: https://ulaval.zoom.us/j/67852104766?pwd=ThZV8rbfUjTKYa1dzL9fyPGdBSs02H.1
Jury members :
President: André Desrochers – Faculty of Forestry, Geography and Geomatics, Université Laval
Research supervisor: Alexis Achim – Faculty of Forestry, Geography and Geomatics, Université Laval
Co-supervisor: Fabio Gennaretti – Canada Research Chair in Dendroecology and Dendroclimatology, University of Québec in Abitibi-Témiscamingue
UL Examiner: Alexandre Morin-Bernard – Faculty of Forestry, Geography and Geomatics, Université Laval
Non-UL examiner: Yan Boucher – Department of Basic Sciences, University of Quebec at Chicoutimi
External examiner: Mathieu Lévesque – Swiss Federal Institute of Technology Zurich
Thesis Title: Wood Quality and Growth of Sugar Maple (Acer saccharum Marsh.) at the Northern Limit of Its Range
Abstract:With the growing impact of climate change and rising temperatures, the future of sugar maple stands at the northern limit of their range is increasingly uncertain. One plausible scenario is that these stands could benefit from climate change, potentially making them more desirable for producing high-quality timber. However, the current quality of these stands appears to be lower than what is typically observed further south, presenting significant challenges for their current profitability and management. It has thus become essential to better understand the factors influencing the current quality of sugar maple in order to anticipate its future evolution and support the implementation of high-quality forest management strategies.
A comprehensive dendrochronological sampling system was established to analyze the growth patterns of these northern stands and the proportion of wood discoloration and heart rot affecting them. Results from the first chapter showed that the presence of sporophores and cracks, as well as diameter and average temperature at a given site, were crucial aspects for quickly assessing the internal quality of sugar maple. These findings revealed that, in general, the western balsam fir-yellow birch bioclimatic subdomain is the area in Quebec with the highest proportion of wood discoloration and heart rot.
Subsequently, the second chapter demonstrated that heartwood discoloration was related to tree age and growth declines. Regarding this latter point, one of the worst periods of growth declines for sugar maple, occurring between the 1970s and 1990s, was strongly correlated with the proportion of heartwood discoloration currently observed at the northern limit of this species.
In the third chapter, we determined that, in addition to tree age and surrounding competition, late spring frosts and droughts partly contribute to the observed growth declines. Finally, in the fourth chapter, we found that sugar maple could indeed benefit from climate change at its northern limit, despite the increased occurrence of climatic events such as droughts. Thus, the forest management strategies we implement today have the potential to accelerate anticipated changes in these stands, provided they enhance the resilience of these populations to climatic events.