Consistency of the Iksinskoe bog dynamics with extreme Holocene climate events

Abstract

Abstract This research is devoted to the response of the southern taiga oligotrophic Iksinskoe bog to extreme Holocene climatic events. Based on data of preliminary geological exploration and 14 C-dated cores-analogues of this bog, a spatio-temporal model of paludification and vegetation succession from 11 paleosurface chrono-slices is created. It has been shown that the global dry cooling events of about 8200, 5900, 4900, and 2800 cal yr BP influenced the bog dynamics. Their direct impact is through the formation of a long-term thawing seasonal frost and permafrost water pressure as well as palsa. Their indirect impact is through a permafrost degradation and a subsequent warming. The cooling of 2800 cal yr BP had the maximum effect due to a drying and cryogenic peat accumulation stopping over a large area of the bog. During the subsequent warming of 2450 and 1900 cal yr BP there was a significant increase in the water content of the bog surface, and a phased oligotrophization of paleophytocenoses took place. The direct and indirect impacts of extremely dry Holocene cooling caused active paludificating, catastrophic changes in the paleophytocenoses, high water content of the surface, and reduced the depth of peat deposits of the Iksinskoe bog.