Exploring the influence of local controls on fire activity using multiple charcoal records from northern Romanian Carpathians
Exploring the influence of local controls on fire activity using multiple charcoal records from northern Romanian Carpathians
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DOI：
10.1016/j.quaint.2018.03.042
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发表时间：
2018-09
影响因子：
2.2
通讯作者：
G. Florescu;B. Vannière;A. Feurdean
中科院分区：
文献类型：
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作者：
G. Florescu;B. Vannière;A. Feurdean
虽然我们对火灾活动的关键驱动因素（气候，植被和人类）的理解有所改善，但关于这些驱动因素的相对重要性以及它们在空间和时间尺度上的变化仍然存在相当大的不确定性。值得注意的是，我们使用沉积木炭记录作为重建过去火灾活动的一种方式，缺少的是当地控制燃烧的作用，以及不同木炭大小，源区和沉积环境类型之间的关系。为了解决这些问题，我们在一个小的气候均匀的区域内使用了七个沉积木炭记录，但在罗马尼亚东部喀尔巴阡山脉的异质植被和人类历史。在时间尺度上，我们发现更均匀的火灾历史在全新世早期和中期（11000 -6000卡年BP），此后变得更加异质。这表明，气候产生了更强的影响，在全新世早期的火灾活动，而当地的控制（植被类型和负载，土地覆盖和利用）变得更加重要，在全新世中期和晚期。在海拔梯度上，我们发现针叶林，树线和亚高山植被之间的火灾活动趋势的差异，可能会导致燃料供应的变化，以应对海拔气候梯度和人为影响的程度的变化。对于针叶林，人类活动增加了生物量燃烧约2000-1500卡年BP通过使用火打开森林。在林线-亚高山地区，人类活动增强火活动的时间较早，从8000到4500卡年BP，并通过清除减少燃烧活动，从而减少燃料负荷，从约。3000卡/年BP。我们对宏观木炭粒度级的测定表明，在所有地点，150-300 μm的部分所占比例最高，其中大部分可能与局部和区域火灾的结合有关，而不是严格地与局部火灾活动有关。湖泊提供了更高的木炭流入量和更大尺寸的木炭颗粒比泥炭，这表明，泥炭-湖泊沉积物岩性过渡在同一记录可以有助于在表观木炭沉积速率的埋藏变化。
Although our understanding of key drivers of fire activity (climate, vegetation and humans) has improved, considerable uncertainty remains regarding the relative importance of these drivers and how they vary across spatial and temporal scales. Notably missing from our use of sedimentary charcoal records as a way to reconstruct past fire activity is the role of local controls on burning, and the relationships between different charcoal sizes, source area and types of depositional environment. To address these issues, we used seven sedimentary charcoal records within a small climatically homogenous area, but with heterogeneous vegetation and human history in the Eastern Romanian Carpathians. On a temporal scale, we found more homogenous fire histories during the early and mid Holocene (11,000–6000 cal yr BP), which became more heterogeneous thereafter. This suggests that climate exerted a stronger influence on fire activity during the early Holocene, whereas local controls (vegetation type and load, land cover and -use) became more important over the mid and late Holocene. On an elevation gradient, we found discrepancies in trends in fire activity between the coniferous forest, treeline and subalpine vegetation that could have resulted from variability in fuel availability in response to changes in the elevational climate gradient and degree of anthropogenic impact. For the coniferous forests, anthropogenic activities enhanced biomass burning from ca 2000–1500 cal yr BP through the use of fire to open up the forests. For the treeline – subalpine areas, humans enhanced fire activity earlier, i.e., from 8000 to 4500 cal yr BP, and reduced burning activity through clearance and hence decrease in fuel load, from ca. 3000 cal yr BP. Our determination of macro-charcoal size-classes show that the 150–300 μm fraction is present in the highest proportion at all sites, with most of this fraction perhaps connected to a combination of local and regional fires, and not strictly to local fire activity. Lakes provide higher charcoal influx and larger sizes of charcoal particles than peat, and this suggests that peat - lake sediment lithological transitions within the same record can contribute to a taphonomic change in apparent rates of charcoal deposition.