RUI: Post-fire Nitrogen Cycling in Boreal Bogs - Critical Unknowns Explored

这项研究围绕着一个新的概念框架来构建，即北方沼泽中的氮(N)循环如何随着火灾后的时间和实验上扩大的N的函数而变化。不同年限(自最近一次火灾以来的时间)的沼泽地点将在模拟降雨中获得更高的N输入。将在以下方面获得新的见解：生物固氮作为这些沼泽中氮的主要输入的重要性；覆盖在沼泽表面的泥炭苔藓作为守门人从固氮或雨雪中获得新获得的氮的作用；北方泥炭地只占地球陆地表面的3%-4%，但却储存了世界土壤碳的25%-30%和泥炭土壤氮的9%-16%。泥炭地代表着大气二氧化碳的持续净汇。加拿大西部的沼泽一直处于泥炭地所在的气候梯度的干燥端，因此对持续的气候变化特别敏感，包括气温上升，以及野火频率和严重程度的增加。此外，在加拿大西部，大气氮沉降量历史上一直很低，但由于阿尔伯塔省北部油砂开发产生的氮排放正在增加。澄清加拿大西部沼泽N和C循环之间的联系将增强预测泥炭中N和C储存可能如何受到持续气候变化影响的能力。这项研究将支持研究生和本科生；PI将在项目的第二年和第四年在加拿大艾伯塔省的Meanook生物研究站教授泥炭地生态学课程。

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.