Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark.
University of Copenhagen, IGN, Section for Forest, Nature and Biomass, Frederiksberg C, Denmark.
Glob Chang Biol. 2022 Aug;28(16):4882-4899. doi: 10.1111/gcb.16222. Epub 2022 May 27.
Wildfire frequency and expanse in the Arctic have increased in recent years and are projected to increase further with changes in climatic conditions due to warmer and drier summers. Yet, there is a lack of knowledge about the impacts such events may have on the net greenhouse gas (GHG) balances in Arctic ecosystems. We investigated in situ effects of an experimental fire in 2017 on carbon dioxide (CO ), methane (CH ), and nitrous oxide (N O) surface fluxes in the most abundant tundra ecosystem in West Greenland in ambient and warmer conditions. Measurements from the growing seasons 2017 to 2019 showed that burnt areas became significant net CO sources for the entire study period, driven by increased ecosystem respiration (ER) immediately after the fire and decreased gross ecosystem production (GEP). Warming by open-top chambers significantly increased both ER and GEP in control, but not in burnt plots. In contrast to CO , measurements suggest that the overall sink capacity of atmospheric CH , as well as net N O emissions, were not affected by fire in the short term, but only immediately after the fire. The minor effects on CH and N O, which was surprising given the significantly higher nitrate availability observed in burnt plots. However, the minor effects are aligned with the lack of significant effects of fire on soil moisture and soil temperature. Net uptake and emissions of all three GHG from burnt soils were less temperature-sensitive than in the undisturbed control plots. Overall, this study highlights that wildfires in a typical tundra ecosystem in Greenland may not lead to markedly increased net GHG emissions other than CO . Additional investigations are needed to assess the consequences of more severe fires.
近年来，北极地区的野火发生频率和范围有所增加，预计随着气候条件的变化，夏季变暖变干，这种情况还会进一步加剧。然而，人们对这些事件可能对北极生态系统的净温室气体（GHG）平衡产生的影响知之甚少。我们研究了 2017 年在格陵兰岛西部最丰富的冻原生态系统中进行的一次实验性火灾对二氧化碳（CO）、甲烷（CH）和氧化亚氮（N O）表面通量的原位影响，在环境条件和较温暖条件下进行了测量。2017 年至 2019 年生长季节的测量结果表明，燃烧区域成为整个研究期间的重要净 CO 源，这是由火灾后立即增加的生态系统呼吸（ER）和减少的总生态系统生产力（GEP）驱动的。开顶箱的增温显著增加了对照和燃烧区的 ER 和 GEP。与 CO 相反，测量结果表明，大气 CH 的整体汇能力以及净 N O 排放短期内不受火灾影响，但仅在火灾后立即受到影响。鉴于在燃烧区观察到的硝酸盐可用性明显增加，CH 和 N O 的影响较小令人惊讶。然而，这些较小的影响与火灾对土壤湿度和土壤温度没有显著影响一致。燃烧土壤中所有三种 GHG 的净吸收和排放对温度的敏感性均低于未受干扰的对照区。总的来说，本研究强调，在格陵兰典型的冻原生态系统中，野火除了 CO 外，不太可能导致明显增加的净 GHG 排放。需要进一步调查以评估更严重火灾的后果。
