This research is structured around a novel conceptual framework for how nitrogen (N) cycling in boreal bogs changes as a function of both time-since-fire and experimentally augmented N. Bog sites of different ages (time since the most recent fire) will receive elevated N inputs in simulated rainfall. New insights will be gained into: the importance of biological N2-fixation as a newly recognized major input of N into these bogs; the role of Sphagnum mosses, which cover the bog surface and are the major contributors to ongoing peat accumulation, as the gatekeepers of newly acquired N from either N2-fixation or rain and snow; and the linkages between N inputs and the ability of bogs to sequester both N and carbon (C) in the accumulating peat.
Boreal peatlands cover only 3-4% of the Earth's land surface, yet store 25-30% of the world's soil C and 9-16% of the world's soil N in peat. Peatlands represent an ongoing net sink for atmospheric carbon dioxide. Bogs of western Canada persist at the dry end of the climatic gradient across which peatlands exist, and hence are especially sensitive to ongoing climate changes that include increasing temperature, as well as increasing wildfire frequency and severity. Further, in western Canada, atmospheric N deposition historically has been low, but is increasing because of N emissions from oil sands development in northern Alberta. Clarifying the linkages between N and C cycling in western Canadian bogs will enhance the ability to predict how N and C storage in peat may be influenced by ongoing climate change. The research will support graduate and undergraduate thesis students; the PIs will teach a Peatland Ecology course at the Meanook Biological Research Station, Alberta, Canada, in years 2 and 4 of the project.
