Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 Helsinki, Finland.
Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 Helsinki, Finland.
J Environ Manage. 2018 Dec 15;228:405-415. doi: 10.1016/j.jenvman.2018.09.051. Epub 2018 Sep 20.
Rising air temperatures and changes in precipitation patterns in boreal ecosystems are changing the fire occurrence regimes (intervals, severity, intensity, etc.). The main impacts of fires are reported to be changes in soil physical and chemical characteristics, vegetation stress, degradation of permafrost, and increased depth of the active layer. Changes in these characteristics influence the dynamics of carbon dioxide (CO) and methane (CH) fluxes. We have studied the changes in CO and CH fluxes from the soil in boreal forest areas in central Siberia underlain by continuous permafrost and the possible impacts of the aforementioned environmental factors on the emissions of these greenhouse gases. We have used a fire chronosequence of areas, with the last fire occurring 1, 23, 56, and more than 100 years ago. The soils in our study acted as a source of CO. Emissions of CO were lowest at the most recently burned area and increased with forest age throughout the fire chronosequence. The CO flux was influenced by the pH of the top 5 cm of the soil, the biomass of the birch (Betula) and alder (Duschekia) trees, and by the biomass of vascular plants in the ground vegetation. Soils were found to be a CH sink in all our study areas. The uptake of CH was highest in the most recently burned area (forest fire one year ago) and the lowest in the area burned 56 years ago, but the difference between fire chronosequence areas was not significant. According to the linear mixed effect model, none of the tested factors explained the CH flux. The results confirm that the impact of a forest fire on CO flux is long-lasting in Siberian boreal forests, continuing for more than 50 years, but the impact of forest fire on CH flux is minimal.
气温升高和降水模式变化正在改变北方生态系统的火灾发生规律（间隔、严重程度、强度等）。火灾的主要影响据报道是土壤物理和化学特性的变化、植被压力、多年冻土退化以及活动层深度增加。这些特征的变化影响二氧化碳（CO）和甲烷（CH）通量的动态。我们研究了在连续多年冻土下的西伯利亚中部北方森林地区土壤中 CO 和 CH 通量的变化，以及上述环境因素对这些温室气体排放的可能影响。我们使用了一个火年代序列的区域，最后一次火灾发生在 1、23、56 年和 100 多年前。我们研究中的土壤是 CO 的源。CO 排放最低的是最近燃烧的区域，随着森林年龄的增长，CO 排放从火年代序列中的所有区域增加。CO 通量受土壤顶层 5cm 的 pH 值、桦树（Betula）和桤木（Duschekia）树木的生物量以及地被植被中维管束植物的生物量影响。所有研究区域的土壤均为 CH 汇。CH 的吸收在最近燃烧的区域（一年前的森林火灾）最高，在 56 年前燃烧的区域最低，但火年代序列区域之间的差异不显著。根据线性混合效应模型，测试的因素都没有解释 CH 通量。结果证实，森林火灾对 CO 通量的影响在西伯利亚北方森林中持续时间很长，超过 50 年，但森林火灾对 CH 通量的影响最小。
