Aim: Previous studies conducted at the tree line in northwestern Québec suggested that the forest tundra was created over the last 3000 years by deforestation as a result of the combined action of forest fires and climatic cooling. Our objectives were to:(1) validate at a larger spatial scale the time frame of the last 3000 years; (2) verify if the opening process was more pronounced during particular time periods; and(3) confirm that fire was the triggering mechanism. Location: Seventeen lakes from the forest tundra of northern Québec. Methods: Pollen records were analysed to determine the date of landscape opening, as interpreted by the time of decrease towards present-day values of the ratio of Picea pollen percentage to pollen percentage of the taxa typical of open forest tundra landscapes (Betula, Ericaceae, Cyperaceae and Poaceae). Results: Landscape opening in northern Québec started c. 3220 cal. BP. (calibrated years before present) and was more pronounced between c. 2040 and 890 cal. BP. Nospatial pattern was observed in the dates of landscape opening. Main conclusions: The suggestion that landscape opening in the forest tundra occurred over the last 3000 years was validated at the scale of northern Québec. A period of more pronounced opening was identified between 2040 and 890 cal. BP and could be related to increased fire occurrence. Absence of a spatial pattern in the dates of landscape opening provides further confirmation that fire was the triggering mechanism.