Vegetation and Climate in the North of the Minusinsk Basin in the Late Holocene: A Record from Shira Lake Resolved by Decade

Abstract

The results of studying the bottom sediments of meromictic Shira Lake, located in the northern part of the Minusinsk Basin, are presented. The sediments are represented by varves, annual layered series, which make it possible to reconstruct the history of the regional natural environment with a high resolution. The age model is based on seven ¹⁴C dates. The proposed new palynological record from the upper part of the Shira-2021-II-1 core extends the previous record by 530 years, providing the reconstruction of the regional natural environment for the past 2980 calibrated years with an average resolution of 21 years. The reconstructions show a humid regional climate 2980–2650 BP, with the climate of the basin itself being more arid, providing the existence of steppe and meadow–steppe assemblages around Shira Lake for the past 2980 years. The trend of changes in the Artemisia/Chenopodiaceae pollen ratio, considered as an indicator of available moisture for plants, suggests a slight increase in the moisture level in the Minusinsk Basin in 2980‒70 BP and a noticeable decrease in the past 70 years. However, the increase was interrupted by short-term intervals of increased climate aridization. The reconstructions have shown that changes in vegetation around Shira Lake in the Late Holocene were mainly caused by large-scale circulation processes that changed the regional moisture balance. The steppe assemblages were the most sensitive to moisture changes on a decadal scale. Like the previous pollen record, the new one does not have clear pollen indicators of anthropogenic influence on vegetation. Only a noticeable increase in the birch pollen content in the past 50 years may indicate planting of greenery around the resort areas.