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

本研究是围绕一个新的概念框架构建的，即北方沼泽的氮(N)循环如何随着火灾发生后的时间和实验增加的N的变化而变化。不同年龄（自最近一次火灾以来的时间）的沼泽地点将在模拟降雨中接受升高的N输入。新的见解将获得：生物固氮的重要性，作为一个新认识的主要输入氮到这些沼泽；覆盖在沼泽表面的泥炭藓是泥炭持续积累的主要贡献者，作为从氮固定或雨雪中获得新氮的守门人；以及氮输入与沼泽在积累的泥炭中隔离氮和碳(C)的能力之间的联系。北方泥炭地只覆盖了地球陆地表面的3-4%，但泥炭储存了世界土壤碳的25-30%和世界土壤氮的9-16%。泥炭地是一个持续的大气二氧化碳净汇。加拿大西部的沼泽一直处于泥炭地存在的气候梯度的干燥端，因此对持续的气候变化特别敏感，包括温度升高，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，大气氮沉降正在增加。澄清加拿大西部沼泽中氮和碳循环之间的联系将提高预测泥炭中氮和碳储存如何受到持续气候变化的影响的能力。该研究将支持研究生和本科生的论文；在项目的第2年和第4年，pi将在加拿大阿尔伯塔省的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.