||Sphagnum -dominated peatlands are dominating features across boreal zones that globally provide unparalleled ecosystem services owing to their ability to fix atmospheric CO 2 and store organic C as peat. In the following chapters, I present data from several experiments that cumulatively quantify the adverse effects imposed by increased N disturbance, and increased fire disturbance on N cycling in Sphagnum -dominated peatlands. My findings show that two years of experimental N additions to a burned bog, an unburned bog, and a poor fen failed to alter net ammonification, net nitrification and net N mineralization across all levels of N treatment. However, I show that increased fire frequency coupled with planet warming projections have the potential to double net ammonification, net nitrification and net N mineralization rates in Alberta, Canadian peatlands. I also put forward a revised N response model for Sphagnum , that demonstrates the tremendous variability in N cycling tendencies observed between pristine and N saturated Sphagnum mosses.