Analysis of surface wetness changes in the Maly Labysh mire in south of Western Siberia during the last two millennia

Abstract

In this study we investigate peat deposits of a transitional sedge-Sphagnum mire by using a testate amoeba analysis to reconstruct the paleohydrology of the mire for the last two millennia. The Maly Labysh mire is located in a river floodplain in low mountains in the south of Western Siberia. The goal of our research is to evaluate the water table depth changes in the mire due to regional and continental climate changes in the late Holocene. Two short-term dryings of the mire surface in 2100-1900 and 1600-1400 yr BP have been revealed. Afterwards, an unusual shift in the oligotrophic conditions on the mire surface is documented between 1400-1100 yr BP. This indicates some weakening of the influence of the nearby river likely due to a decrease in the precipitation. Then, starting at ca. 900 yr BP the mire gradually came back to transitional conditions again, and its surface moisture remained moderately high without notable fluctuations. The close consistency of the thus revealed periods of short drying with similar events in the development of other lake and bog sediments in the south of Western Siberia indicates the fact of predominant influence of westerlies on the formation of the regional climate.