We examined concentrations of nitrogen (N) and phosphorus (P) and δ 15 N value in Sphagnum sections Acutifolia and Cuspidata inhabiting hummocks and hollows from 8 bogs along a transect from ~45 to ~55 °N in Ontario/Quebec. The N concentration in Sphagnum declined from South to North, correlating with a decrease in atmospheric N deposition. Although the overall N concentration was larger in hollows than hummocks, the pattern was inconsistent across the sites.There was a proportionally larger decline in P concentration from South to North and an overall larger P concentration in hollows than hummocks, but there were inconsistent differences across the sites. The N:P ratio ranged from 12:1 to 29:1, driven primarily by the variation in P concentration. Ratios of N and P concentration in Sphagnum capitulum:stem averaged 1.2:1, suggesting nutrient resorption from stem to capitulum during growth; the ratio rose with increasing N and P concentration in the capitulum. The δ 15 N value of Sphagnum rose from ~-6‰in the South to ~-1‰ in the North, correlated with the decrease in Sphagnum N concentration and with a rise in water table. We interpret this to indicate a greater dependence on N 2 -fixation for N acquisition in the northern and wetter sites.