The Holocene vegetation and fire history of Western Caucasus (Russia) reconstructed by multi-proxy data from the high-altitude Lake Khukoтезисы докладаТезисы
Аннотация:The new multi-proxy records of the Holocene environmental and climatic changes in theWestern Caucasus revealed from mountainous Lake Khuko (Caucasus State NaturalBiospheric Reserve, 1744 m a.s.l.) are presented. Palaeoecological analyses of a sedimentcore for loss on ignition, pollen, plant macrofossil and macroscopic charcoal allowed us todetermine five principal climatic phases with several subphases since 10.5 ka BP. The agemodel is based on seven AMS 14C dates, supplemented by 210Pb data for the uppermostpart of the sediment core. Warm periods (10.5-6.7, 6.7-5.5, 3.5-2.4, 0.8-0.5 ka BP) werecharacterized by expansion of forests, typical of modern low and middle mountain zones,as indicated by the increase in abundance of Quercus, Ulmus, Corylus and Tilia in thepollen assemblages. Cold periods (5.5-3.5, 2.4-0.8, and 0.5 ka BP-present) are marked by aconsistent decrease in organic matter content in lake deposits and possibly higher intensityof the catchment erosion. The changes in pollen assemblages (for instance peaks of Abies,Picea, and Pinus) suggested a potential elevational decline in the boundaries of vegetationbelts and expansion of high-altitude woodlands. Abrupt changes in the lake ecosystem wereidentified between 4.2 and 3.5 ka cal BP marked by a short-term variation in sedimentregime and the extremely high concentration of macroscopic charcoal particles, probablycaused by intensive fires and climatic fluctuations in the Western Caucasus region duringthe 4.2 ka event. The study was supported by the Megagant project (agreement No 075-15-2021-599, 8.06.2021) of the Ministry of Highest Education of Russia.