VEGETATION AND CLIMATE CHANGES IN THE SOUTHERN URALS IN THE LATE GLACIAL AND HOLOCENE DERIVED FROM POLLEN RECORD OF LAKE BOLSHOE MIASSOVO<a href="#FN1">¹</a>

Abstract

A spore-pollen analysis of a 526 cm sediment core retrieved from Lake Bolshoe Miassovo, Southern Urals, was carried out. The obtained data made it possible to reconstruct the vegetation cover in the lake’s catchment area and the climatic situation of the region for 13 400 cal yr BP, which significantly expands and complements the paleogeographic chronicle of the Southern Urals. It was found that in the range of 13 400–12 700 cal yr BP in the conditions of a relatively warm and dry climate of Allerød, periglacial forest-steppe formations were widespread in the studied region. Steppe herb communities and birch-pine sparse woodlands with spruce grew on open landscapes. The pine degradation and replacement of spruce with more cold-resistant larch was most likely caused by a cooling in the period of 12 700–11 700 cal yr BP, which corresponds to the Younger Dryas. The periglacial forest-steppe formations are replaced by birch forests since 11 700 cal yr BP. The significant changes in the vegetation cover of the lake’s catchment area indicate warming and humidification of the climate at the beginning of the Holocene. The dominance of birch forests in the interval of 11 300–10 300 cal yr BP, probably, corresponds to the second half of the Pre-Boreal period. The distribution of pine and spruce in the range of 10 300–8300 cal yr BP indicates a warming of climatic conditions in the Boreal period. Since 8400 cal yr BP the proportion of broad-leaved species in the tree stand increases. The broad-leaved species cover reached its peak between 6000–4500 cal yr BP at the end of the Atlantic - the beginning of the Sub-Boreal period (Holocene climatic optimum). Some cooling of the climate was observed in the range of 4500–2000 cal yr BP, which presumably corresponds to the Sub-Boreal and the beginning of the Sub-Atlantic period. The birch forest with spruce and broad-leaved species grew in the lake’s catchment area. Some aridization and warming of the climate in the Sub-Atlantic period in the range of 1800–1000 cal. yr BP led to an increase in the role of pine and a reduction of spruce in the area around the lake. Since 1800 cal yr BP the vegetation of the territory adjacent to Lake Bolshoe Miassovo was similar to the modern one: pine-birch forests with an admixture of dark coniferous and broad-leaved species prevailed on the territory.