Contrasting Variants of Soil Development at Archaeological Sites on Floodplains in the Forest-Steppe of the Central Russian Upland

The soils of archaeological sites on river floodplains with contrasting history of the Holocene soil evolution in the south and north of the forest-steppe zone on the Central Russian Upland have been studied. The conditions for the meadow-chernozemic soil development on the high floodplain in the lower course of the Savala River (Voronezh oblast) were most favorable in the Early Holocene (10.3-9 ka BP); 9 ka BP, the soil humus profile was two times deeper than it is today. The most intensive alluvial sedimentation (0.5 mm/yr) was typical of the Late Pleistocene and Early Holocene (11-8.3 ka BP), while in the Middle and Late Holocene, the rate of the upward growth of soils decreased to 0.05 mm/yr. The underdevelopment of modern chernozemic-meadow soil profiles suggests an alternation of accumulation and denudation (including deflation) of fine-earth particles on the soil surface in the Late Holocene. On the floodplain in the upper course of the Oka River (Orel oblast), the development of a monogenetic profile of medium-deep leached chernozems with the humus content of more than 7% and humus stocks in the upper meter of at least 450 t/ha took place in the Holocene. Before the beginning of the second millennium AD, the alluvium sedimentation rate was no more than 0.02 mm/yr; in the recent millennium, it has increased up to 1 mm/yr. The specificity of changes in the bioclimatic conditions and spatiotemporal specificity of anthropogenic disturbances of the natural environment caused the metachronous Holocene evolution of floodplain soils in the studied regions. The importance of radiocarbon dating of organic matter of uneven-aged soils for paleopedological and paleogeographic reconstructions is shown.