Environmental and Climatic Changes Between 3 and 5ka BP in Southeastern Ukraine

Abstract

Pedological and palynological data from Eneolithic and Bronze Age settlements in the steppe zone of eastern Ukraine show that the transition from the mild climate of the Atlantic period (6,500-5,500 BP) to the more continental climate of the Subboreal was marked by considerable impoverishment of the floristic composition and by reduction or disappearance of several mesophilic and thermophilic taxa. Within this general background, there were also rhythmic oscillations between wet climate stages marked by expansion of forest-steppe, with dry climate stages marked by expansion of steppes. Five such shifts have occurred between 5,500 and 2,500 BP, The strongest aridification occurred between about 4,100 and 3,500 BP. It is marked by the decrease of humus accumulation, biogenic activity and chemical weathering in the soils, which became rather loess-like and contain deep desiccation fissures. Pollen data show sharp reduction of forest areas, significant xerophytization of steppe vegetation, and drying of flood plain swamps. The forest-steppe landscapes of the Early Subboreal were replaced by Artemisia-Gramineae steppes representing the shift through three phytogeographic subzones. None of the Holocene climatic fluctuations was as sharp and contrasting when compared with the preceding and following stages, In studied regions, no major paleoenvironmental changes were observed within that interval that could be clearly ascribed to human impact. The Mid-Subboreal aridification is therefore considered to be of natural origin.