The relative influences of climate and volcanic activity on Holocene lake development inferred from a mountain lake in central Kamchatka

• Published in: Global and Planetary Change
• Main Authors: Self, A. E., Klimaschewski, A., Solovieva, N., Jones, V. J., Andren, E., Andreev, A. A., Hammarlund, Dan, Brooks, S. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2015
• Subjects: Geology; Diatoms; Pollen; Chironomids; Holocene; Kamchatka; Climate; aleutian low
• Online Access: https://lup.lub.lu.se/record/8539685; https://doi.org/10.1016/j.gloplacha.2015.06.012

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 by Betula and Alnus woodland 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 4.4-53 and chironomid and diatom assemblages in the lake were initially dominated by a small number of acidophilic/acid tolerant taxa. The frequency of Pinus pumila (Siberian dwarf pine) pollen increased from 5000 cal yr BP and threshold analysis indicates that P. pumila arrived 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 diatominferred 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 midHolocene. The chironomid-inferred July temperature reconstruction suggests cool ...