Oil and gas extraction in the Athabasca oil sands region has increased anthropogenic nitrogen (N) emissions over the past two decades. This study quantified atmospheric N deposition and assessed the potential implications of increased N deposition in aspen (Populus tremuloides Michx.) and jack pine (Pinus banksiana Lamb.) stands located on reclaimed sites. Nitrogen deposition was significant on these sites, and in all cases was dominated by ammonium. Bulk precipitation was significantly greater than throughfall, which indicates canopy uptake of N in both stand types. In aspen stands, positive relationships were found between ammonium deposition, and N isotope signature in forest floor, foliage, and roots, suggesting that biocycling of N was taking place between soil and plants. However, in pine, the lack of similar relations together with high soil nitrate concentrations indicated that the N cycle was more open, potentially leading to leaching losses.