The relative influences of climate and volcanic activity on Holocene lake development inferred from a mountain lake in central Kamchatka
The relative influences of climate and volcanic activity on Holocene lake development inferred from a mountain lake in central Kamchatka
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DOI：
10.1016/j.gloplacha.2015.06.012
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发表时间：
2015-11
影响因子：
3.9
通讯作者：
A. Self;A. Klimaschewski;N. Solovieva;V. Jones;E. Andrén;Andrei A. Andreev;D. Hammarlund;S. Brooks
中科院分区：
文献类型：
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作者：
A. Self;A. Klimaschewski;N. Solovieva;V. Jones;E. Andrén;Andrei A. Andreev;D. Hammarlund;S. Brooks
沉积物序列取自俄罗斯远东堪察加半岛中央山脉的一个封闭的高海拔湖泊（非正式名称橄榄背湖）。该序列通过放射性碳和年代学测定年代，并用于多代理分析（摇蚊、花粉、硅藻）。尽管全新世白令海峡气候的演变主要是由全球强迫机制驱动的，但火山活动或植被动态等区域控制导致了空间异质响应。本研究旨在重建水生和陆地生态系统过去的变化，并将气候驱动的响应与对区域或局部环境变化的响应分开。大型植物的放射性碳测年给出的基础日期为 7800 年 BP。取芯终止于火山灰层，因此该湖的沉积在此日期之前开始，可能是在当地冰川退缩后的全新世早期。最初，流域植被以桦木和桤木林地为主，具有开放、潮湿、水生和半水生生境的镶嵌结构。在 7800 至 6000 卡路里 BP 之间，硅藻推断的湖水 pH 为 4.4-5.3，湖中的摇蚊和硅藻组合最初以少数嗜酸/耐酸类群为主。西伯利亚矮松花粉频率从 5000cal yr BP 开始增加，阈值分析表明，Pinus pumila 在 4200 cal yr BP 和 3000 cal yr BP 之间到达流域。其范围的扩大可能是由于阿留申低压系统的加强和冬季降雪的增加而介导的。硅藻推断的 pH 值重建表明，在经历了最初的低 pH 期后，pH 值逐渐从 5500 cal BP 上升到 1500 cal BP 时的 pH 5.8。这种全新世 pH 值升高的趋势在湖泊记录中并不常见，但最初的低 pH 值可能是直接或间接由全新世中期强烈的区域火山活动造成的。摇蚊推断的 7 月气温重建表明，凉爽期介于 3200-2800 卡路里 BP 和 1100-700 卡路里 BP 之间，温暖期介于 2800 至 1100 卡路里 BP 之间。摇蚊和硅藻 DCA 分数从大约下降。 6000 cal yr BP，表明这些水生组合的成分发生变化。相比之下，花粉 PCA 分数的下降被推迟，大约开始于 2017 年。 5100 卡路里每年血压。结果表明，虽然流域植被主要对气候变化做出反应，但湖泊内的生物群和湖水化学却对当地的环境条件做出了反应。
A sediment sequence was taken from a closed, high altitude lake (informal name Olive-backed Lake) in the central mountain range of Kamchatka, in the Russian Far East. The sequence was dated by radiocarbon and tephrochronology and used for multi-proxy analyses (chironomids, pollen, diatoms). Although the evolution of Beringian climate through the Holocene is primarily driven by global forcing mechanisms, regional controls, such as volcanic activity or vegetation dynamics, lead to a spatial heterogeneous response. This study aims to reconstruct past changes in the aquatic and terrestrial ecosystems and to separate the climate-driven response from a response to regional or localised environmental change. Radiocarbon dates from plant macrophytes gave a basal date of 7800 cal yr BP. Coring terminated in a tephra layer, so sedimentation at the lake started prior to this date, possibly in the early Holocene following local glacier retreat. Initially the catchment vegetation was dominated byBetulaandAlnuswoodland with a mosaic of open, wet, aquatic and semi-aquatic habitats. Between 7800 and 6000 cal yr BP the diatom-inferred lake water was pH 4.4–5.3 and chironomid and diatom assemblages in the lake were initially dominated by a small number of acidophilic/acid tolerant taxa. The frequency ofPinus pumila(Siberian dwarf pine) pollen increased from 5000 cal yr BP and threshold analysis indicates thatP.pumilaarrived in the catchment between 4200 and 3000 cal yr BP. Its range expansion was probably mediated by strengthening of the Aleutian Low pressure system and increased winter snowfall. The diatom-inferred pH reconstructions show that after an initial period of low pH, pH gradually increased from 5500 cal yr BP to pH 5.8 at 1500 cal yr BP. This trend of increasing pH through the Holocene is unusual in lake records, but the initially low pH may have resulted directly or indirectly from intense regional volcanic activity during the mid-Holocene. The chironomid-inferred July temperature reconstruction suggests cool periods between 3200–2800 cal yr BP and 1100–700 cal yr BP and a warmer period between 2800 and 1100 cal yr BP. Chironomid and diatom DCA scores decline from ca. 6000 cal yr BP, indicating compositional changes in these aquatic assemblages. In comparison declines in pollen PCA scores are delayed, starting ca. 5100 cal yr BP. The results suggest that while catchment vegetation was responding primarily to climate change, the biota within the lake and lake water chemistry were responding to localised environmental conditions.