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Wildfire history of the boreal forest of southwestern Yakutia (Siberia) over the last two millennia documented by a lake-sedimentary charcoal record
Biogeosciences ( IF 3.9 ) Pub Date : 2020-11-11 , DOI: 10.5194/bg-2020-415
Ramesh Glückler , Ulrike Herzschuh , Stefan Kruse , Andrei Andreev , Stuart Andrew Vyse , Bettina Winkler , Boris K. Biskaborn , Luidmila Pestryakova , Elisabeth Dietze

Abstract. Wildfires, as a key disturbance in forest ecosystems, are shaping the world’s boreal landscapes. Changes in fire regimes are closely linked to a wide array of environmental factors, such as vegetation composition, climate change, and human activity. Arctic and boreal regions and, in particular, Siberian boreal forests are experiencing rising air and ground temperatures with the subsequent degradation of permafrost soils, leading to shifts in tree cover and species composition. Compared to the boreal zones of North America or Europe, little is known about how such environmental changes might influence long-term fire regimes in Russia. The larch-dominated eastern Siberian deciduous boreal forests differ markedly from the composition of other boreal forests, yet data about past fire regimes remain sparse. Here, we present a high-resolution macroscopic charcoal record from lacustrine sediments of Lake Khamra (SW Yakutia, Siberia) spanning the last c. 2200 years, including information about charcoal particle sizes and morphotypes. Our results reveal a phase of increased charcoal accumulation between 600–900 CE, indicative of relatively high amounts of burnt biomass and high fire frequencies. This is followed by an almost 900-year-long period of low charcoal accumulation without significant peaks, likely corresponding to cooler climate conditions. After 1750 CE fire frequencies and the relative amount of biomass burnt start to increase again, coinciding with a warming climate and increased anthropogenic land development after Russian colonisation. In the 20th century, total charcoal accumulation decreases again to very low levels, despite higher fire frequency, potentially reflecting a change in fire management strategies and/or a shift of the fire regime towards more frequent, but smaller fires. A similar pattern for different charcoal morphotypes and comparison to a pollen and non-pollen palynomorph record from the same sediment core indicate that broad-scale changes in vegetation composition were probably not a major driver of recorded fire regime changes. Instead, the fire regime of the last two millennia at Lake Khamra seems to be controlled mainly by a combination of short-term climate variability and anthropogenic fire ignition and suppression.

中文翻译:

过去两千年来西南雅库特(西伯利亚)北方森林的野火历史,由湖沉积的木炭记录所记录

摘要。野火是对森林生态系统的主要干扰,正在改变世界的北方景观。火灾情况的变化与多种环境因素紧密相关,例如植被组成,气候变化和人类活动。北极和北方地区,特别是西伯利亚北方地区的森林正经历着不断升高的空气和地面温度,随后永久冻土层退化,导致树木覆盖率和物种组成发生变化。与北美或欧洲的寒带地区相比,人们对这种环境变化如何影响俄罗斯的长期火灾状况知之甚少。落叶松为主的东西伯利亚落叶性北方森林与其他北方森林的组成明显不同,但是有关过去火灾情况的数据仍然很少。这里,我们提供了一个高分辨率的宏观木炭记录,这些记录来自最后一个c的卡姆拉湖(西伯利亚雅库特西南部)湖相沉积物。2200年,包括有关木炭颗粒大小和形态的信息。我们的研究结果表明,在600-900 CE之间,木炭积累逐渐增加,这表明燃烧的生物量相对较高,火频率较高。随后是将近900年的低碳积累期,没有明显的高峰,这可能与气候条件凉爽相对应。1750年,CE火灾频率和相对生物质燃烧量再次开始增加,这与气候变暖和俄罗斯殖民之后人为土地开发的增加相吻合。在20世纪,木炭总积累量再次下降到非常低的水平,尽管发生火灾的频率较高,但可能反映出火灾管理策略的更改和/或火灾情况向更频繁但更小的火灾转移。不同木炭形态的相似模式,以及与来自同一沉积物核心的花粉和非花粉古植物形态记录的比较表明,植被组成的大规模变化可能不是记录的火势变化的主要驱动力。取而代之的是,最近两个千年来,卡姆拉湖的火灾状况似乎主要是受短期气候变化和人为引发和抑制火灾的双重影响。不同木炭形态的相似模式,以及与来自同一沉积物核心的花粉和非花粉古植物形态记录的比较表明,植被组成的大规模变化可能不是记录的火势变化的主要驱动力。取而代之的是,最近两个千年来,卡姆拉湖的火灾状况似乎主要是受短期气候变化和人为引发和抑制火灾的双重影响。不同木炭形态的相似模式,以及与来自同一沉积物核心的花粉和非花粉古植物形态记录的比较表明,植被组成的大规模变化可能不是记录的火势变化的主要驱动力。取而代之的是,最近两个千年来,卡姆拉湖的火灾状况似乎主要是受短期气候变化和人为引发和抑制火灾的双重影响。
更新日期:2020-11-12
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