INTEGRATED PALAEOECOLOGICAL INVESTIGATION OF BOTTOM SEDIMENTS FROM LAKE MANZHEROKSKOYE IN THE PIEDMONT ALTAI REGION

Abstract

Complementary spore-pollen, diatom and geochemical analysis of samples from upper 80 cmof lake sediments from Lake Manzherokskoye, situated in the western piedmont region of Altai Mountains, revealed correlations between trends in the local water content in the lake and changes in the surrounding dry land vegetation triggered by the change of the overall climate humidity. Ecological analysis of diatom complexes from the studied sediment section and reconstruction of pH variation based on diatom indicator-species revealed the following successions: 1 – a shallow water pool during downcore sedimentation; 2 – a sharp rise in the lake water content during mid-core sedimentation; 3 – following decrease of the lake level, and 4 – contemporary new rise of the water level in Lake Manzherokskoye. The reconstructed second stage of change in local conditions in Lake Manzherokskoye agrees with pollen data demonstrated change of dry land vegetation from birch forest-steppe to pine and Siberian cedar forests and, finally, to contemporary birch-pine anthropogenically transformed forest-steppe. During the sharp water rise stage the content of terrigenous elements increased in the lake sediments, whereas diatom complexes degraded considerably during this stage. Human influence on the landscape is seen in the top part of the studied lake sediment as indicated by findings of ruderal pollen (Triticum, Plantago, Cannabis, Secale, Fagopirum), as well as pollen of Quercus, which is exotic for Siberian flora. Changes in the diatom complexes in the examined section of the lake sediments point to a higher climatic sensitivity of the small and shallow Lake Manzherokskoye compared to the large and deep Lake Teletskoye.

Keywords

• palaeolimnology
• spore-pollen analysis
• diatom analysis
• plant cover
• ecological conditions
• piedmont altai region
• geochemistry of lake sediments