The objective of this study was to use foliage analyses conducted in 1967, 1988 and 2011, to assess the evolution of the nutritional status of balsam fir (Abies balsamea) stands at the Montmorency Forest (Québec). The elemental composition of balsam fir needles varied greatly over the 45-year study period. Between the 1967 analysis and that of 2011, the foliar nitrogen concentration decreased by 5.7%; the potassium concentration in 1-year-old needles, by 13.5%, and the magnesium concentration in 2- and 3-year-old needles, by 18%. The mineral concentrations in the tissues analysed in 1988 were much lower than those of the other 2 samplings. This decrease can be explained partly by the choice of the stands sampled, the increase of atmospheric acid precipitation since the 1970s, the effects of past insect outbreaks, and climatic extremes. Potassium concentrations in 1-year-old needles were lower than values reported elsewhere for balsam fir. The decreases in foliar potassium and magnesium concentrations from 1967 to 2011 suggest a loss of soil fertility in this region over the last 45 years.