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Studying past forests through lake mud

Climate warming will inevitably alter the southern forests of southeastern Québec. However, these regional environmental changes must be compared to a reliable baseline in order to be properly understood, for example, to determine if their variability deviates from the normal. Unfortunately, there is very little old-growth forest—forest that has not been disturbed by humans—left in this part of the province.

One way around this is to study pollen produced by trees and plants that has been trapped in lake mud for centuries, or even millennia. Using a sediment core extracted from Étang Fer-de-Lance, Jeannine-Marie St-Jacques, a professor in the Department of Geography, Planning and Environment at Concordia University, was able to reconstruct the forest history of the Mount Orford area.

In doing so, she and her colleagues discovered, to their great surprise, that the earliest anthropogenic disturbances date back to well before the British Conquest in 1760, which marked the beginning of European settlement of the area. In fact, according to the researchers, traces of human impact go back as far as 1550 and are the result of a native farming practice probably attributable to the St. Lawrence Iroquois.

To be confirmed, these results will have to be replicated on sites as sensitive as Mount Orford. As Mount Orford is situated between the sugar maple-basswood domain and the sugar maple-yellow birch domain, the area around Mount Sutton is on the team’s radar. This work will also be useful in guiding future ecosystem-based management of southern forests in southeastern Québec. For example, it could provide points of comparison to guide independent climate reconstruction work by other researchers.