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Aim Present northern distribution limit of jack pine (Pinus banksiana Lamb.) follows the northern limit of continuous open boreal forest in western Canada, but not in eastern Canada where it is located further south. We tested the hypothesis that fire plays a more important role than climate in explaining the present position of the northern distribution limit of jack pine.Location An experimental jack pine plantation was set up in 1992, c. 300 km north of the present distribution limit of the species, in the Boniface river area of northern Qu e ebec (57°43¢ N, 76°05¢ W).Methods Climate and fire data were used to compare sites at and north of the present distribution limit of jack pine. In 2001, surviving individuals from the plantation were measured (total height, annual shoot elongation, basal diameter, and presence/absence of cones).Results Climate data from the ten weather stations used in this study did not show major differences. The northern limit of jack pine distribution is closely associated with the occurrence of fires larger than 200 ha. Survival of the planted jack pines was 31%. About 25% of the surviving pines qualified as normal, single-stem individuals; the others were slightly uprooted and/or showed marks of erosion or foraging. Cones were produced, although no viable seeds were found. Main conclusionsThe low number of degree-days above 5°C at the plantation site could explain why the seeds were not viable. However, such climate conditions are not sufficient to prevent growth, as was shown by annual shoot elongation measurements. Most of the surviving jack pines from the Boniface river plantation are relatively healthy and follow a normal developmental programme. Low fire frequency and small fire size are amongst the main factors that prevented P. banksiana from migrating further north or east following deglaciation in northern Qu e ebec and Labrador.Keywords Climate, fire, jack pine, Pinus banksiana Lamb., present northern distribution limit, plantation trial, postglacial migration, eastern Canada, western Canada. R e esum e eObjectif La limite septentrionale actuelle de r e epartition du pin gris (Pinus banksiana Lamb.) suit la limite nord de la forêt bor e eale ouverte continue dans l'Ouest du Canada, mais pas dans l'Est où elle est situ e ee plus au sud. Nous avons test e e l'hypothèse selon laquelle le feu joue un rô le plus important que le climat pour expliquer la position actuelle de la limite septentrionale de r e epartition du pin gris.