The lack of understanding of possible relationships between soil nitrogen (N) availability indices and forest productivity in the oil sands region of Alberta may adversely affect reclamation practices and the development of reclamation policy for the region. This project was designed to investigate the foregoing relationships on natural, undisturbed stands and to recommend the best soil N availability indicators to use to evaluate soil N for achieving the maximum site productivity and for long-term monitoring of soil and vegetation performance in the region. Soil N availability indices evaluated in this project included several common field-based methods (available mineral N concentrations, in-situ N mineralization rates, potential N availability measured using the plant root simulator (PRS) probes) and laboratory-based measurements (extractable N, aerobic and anaerobic N mineralization rates). We attempted to correlate the above soil N availability indices with several forest productivity indices of three of the most common native tree species in this region. The measured forest productivity characteristics include foliar size of trees, annual tree growth ring width, and aboveground net primary productivity (ANPP). The results of our research showed that most N availability indices were correlated with productivity measurements in jack pine (Pinus banksiana) stands, while few N availability indices were correlated with productivity indices in trembling aspen (Populus tremuloides) and white spruce (Picea glauca) stands. Based on those results, we conclude that jack pine forest productivity is most likely limited by N availability and thus there are tight relationships between many soil N availability indices and forest productivity; while for aspen and white spruce stands, factors controlling forest productivity may be more complex (such as co-limitation of water availability) and thus there are poor N availability-productivity relationships. We recommend that for jack pine stands, laboratory based aerobic and anaerobic mineralization rates are the most cost effective methods for measuring N availability while for aspen and white spruce stands the in-situ N mineralization rate is likely the most appropriate method to determine soil N availability, as that index gave the best relationship with stand productivity. While this study helps to determine which method of measuring nitrogen availability is most appropriate for potential input to the land capability classification system (LCCS) for soil nutrient regime assessment, further research is need to evaluate the relationship between N availability indices and LCCS classes or reclamation performance, as the current project was conducted in natural forests and extrapolating into reclamation areas will be difficult without calibration between natural and reclamation sites; the natural sites in this study were used as an analog for future developed forest stands in the reclaimed area in the oil sands region.