Multi-proxy evidence of the abrupt 8.2 ka paleoclimatic event from a small mountain lake in the Czech Republic
Abstract
The 8.2 kiloyear event was the most abrupt climatic cooling to occur during the Holocene. Currently there are very few detailed records describing ecosystem responses to the event from inland Central Europe.
Here, we present multi-proxy evidence from a sediment profile from Prasilske Lake, a small tarn in the Bohemian Forest, Czech Republic (49°05' N, 13°24' E; 1079 m a.s.l.; 4.2 ha; max. depth 17 m; catchment area 0.65 km^2; anoxia near bottom). In a 2.2 m long sedimentary sequence, we identified a series of erosion events correlated with the 8.2 ka cooling identified by increases in Ti and Rb (microXRF), decreases in LOI, and increases in magnetic susceptibility.
To reconstruct the lake-catchment response, water invertebrate fauna remains (chironomids, caddisflies, alderflies, bryozoans), diatoms, water and terrestrial plant macroremains, bark beetle remains, pollen and charcoal were analyzed. An initial phase of erosional activity likely began with a fire event within the catchment ~8500 cal. yr BP, which allowed for the rapid succession replacement of an open Pinus-Betula dominated landscape to a more enclosed Picea dominated system.
Our results document subsequent increase in presence of primary attack bark beetles (Ips typographus, Pityogenes chalcographus, Pityophthorus pityographus, and Polygraphus poligraphus) and changes in water fauna and diatom assemblages. The 8.2 ka event was characterized by sharp increase in both littoral and profundal chironomid taxa (genus Heterotrissocladius, Microtendipes, Procladius, Tanytarsus, and Zavrelimyia), higher diversity in the other macrozoobenthos, and dominance of heavily silicified planktonic diatoms (Aulacoseira spp.) suggesting intensive mixing of the lake water and improvement of oxygen conditions near the bottom.
Based on this sensitive natural archive, we conclude that the climatic deterioration likely had a greater environmental impact in inland Central Europe than previously assumed. The study was supported by the Czech Grant Foundation (Project 16-06915S - EUROPIA).