Dynamics of vegetation cover and quantitative palaeoclimatic reconstructions in the Western Sayan Mountains from the Late Glacial period to the present time according to a palynological study of the Yuzhno-Buybinskoe mire

Abstract

The aim of this research is an investigation of long-term palaeoclimatic changes. In this paper we present results of a palaeopalynological study of a high mountain peat-lake sediment core from the Yuzhno-Buibynskoe Mire in the Western Sayan Mountains covering the last 13000 cal yrs BP. In addition to qualitative palaeopalynological reconstructions we have performed quantitative reconstructions of T January, T July, and Annual precipitations using our own transfer functions constructed on 118 surface pollen spectra by a method developed by ter Braak and coauthors [16]. The results of the quantitative palaeclimatic reconstructions have demonstrated three types of climate changes in the study area from the Late Glacial period to the present time: cryo-arid climate in the Late Glacial period from 13000 cal yr BP to 11000 cal yr BP (I), humid moderate cool climate in the Middle Holocene (II) and humid cool climate in the Late Holocene after 5000 cal yr BP (III). The cold climate during the Late Glacial period was caused mostly by low winter temperatures combined with low annual precipitation, while the summer temperatures were equal or even higher than modern ones. This is characteristic for the anticyclone influenced areas. The winter temperatures and annual amount of precipitation considerably increased in all areas of the Altai-Sayan region during the early and middle Holocene times, when Atlantic cyclones reached this area. In the Late Holocene period we observe a gradual return to the climatic parameters of the pre-Holocene time.