VEGETATIONAL EVOLUTION IN THE TRANSCARPATHIAN LOWLAND (UKRAINE) DURING THE MIDDLE PLENIGLACIAL (POLLEN STUDY OF THE BEREGOVO I SITE)

Abstract

A reconstruction of the vegetational evolution during the Middle Pleniglacial has been carried out on the basis of a pollen study of the loess-palaeosol deposits from the Upper Palaeolithic site Beregovo I (Transcarpathian Lowland). The stratigraphy of the site is based on the Quaternary stratigraphical framework of Ukraine, the archaeological data and AMS 14C-dating. At the end of the Uday time of loess formation (Early Pleniglacial), forest-meadow ecosystems (with predominance of birch and pine in the forests) existed under the cold and wet climate of a stadial. Three main stages of vegetation development (with several phases) have been identified within the Vytachiv time (the Middle Pleniglacial). During the beginning of the first stage (the Early Vytachiv time, the formation of the lower Cambisol), coniferous and broad-leaved forest grew under the rather warm climate of an interstadial. The second phase of this stage was characterized by a spread of a forest-steppe. The warm interstadial climate, indicated by the growth of broad-leaved trees, became less humid. During the second stage of the Middle Pleniglacial (the Middle Vytachiv time, represented by loess-like deposits), a boreal forest-meadow vegetation spread under the cool climate of a stadial. The Aurignacian cultural horizon corresponds to the deposits of this stadial. Three phases of vegetation development have been recognized within the third stage of the Middle Pleniglacial (the Late Vytachiv time). During the first phase (the beginning of the upper Cambisol formation), there existed a forest-steppe with predominance of boreal trees. The climate was relatively cool and corresponded to a transition from a stadial to an interstadial. The second phase of this stage (the formation of the upper Cambisol) was characterized by forest-meadow vegetation with a spread of broad-leaved trees. This phase corresponds to an interstadial warming. During the third phase (the transition from the Cambisol formation to the incipient pedogenesis, AMS dated to 27-26.6 ka uncal BP), an elm-hornbeam forest with admixture of spruce grew on fertile loamy soils, and pine-birch forest occupied the sandy terraces. The climate was still warm and humid. After the end of the Middle Pleniglacial (the beginning of the Bug time), there occurred a spread of meadow vegetation. The decline of arboreal and broad-leaved vegetation indicated the much colder climate of a stadial. The reconstructed vegetation composition of the site demonstrates that the microclimate of the low terrace of the Tysa River was milder than in the sites located on the high river terraces. Broad-leaved trees were permanently present in the site vicinities: their pollen percentages increased during the periods of the formation of the interstadial soils and drastically decreased during the times of reduction of forest areas and formation of non-soil deposits. This enables the suggestion that refugia of broad-leaved trees could survive in the Transcarpathian Lowland during the stadials of the Pleniglacial (at least before the Last Glacial Maximum).