ИСТИНА

The temporal and spatial variability of climatic changes during the Late Holocene in the Southern areas of Eastern Europe is still uncertain. For the forest-steppe areas of the Russian Plain many scientists starting from V.V. Dokuchaev suggested multiple shifts of steppe and forest landscapes based on intricate borders between Chernozems, Phaeozems and Luvisols. The study of paleosols of archaeological sites provides further insight on landscape dynamic of the Early Iron Age. During that time the area was inhabited by sedentary tribes that introduced fortified settlements, allowing studying soils buried under the banks of fortifications. Three settlements of the Early Iron Age (Gorodets culture) were studied in the center of the Russian Plain (Lipetsk region) 5-10 km apart from each other (Ksizovo, Muchino and Degtevoye sites). The modern landscape is typical for the forest steppe areas: patches of broad-leaved forests surrounded by agricultural lands. Surface soils are Greyzemic Luvic Phaeozems (Loamic) on carbonate or non-carbonate loess with the following sequence of horizons: Ah-AhB-Bt-BCk-Ck. The thickness of humus layer is about 30 cm. The lower part of humus and AhB horizons show greyzemic features - abundant uncovered sand and silt grains. A sequence of Bt horizons goes below 100 cm with well-formed clay and humus-clay cutans covered by siltans. Carbonate horizons follow below. All settlements were built in the vicinity of the Don River valley on the upland highly dissected by ancient gullies. The elevation of upland surfaces is about 170-180 m a.s.l. Fortification banks with preserved height of 1,5 – 2 m are situated on a narrow promontories formed by a junction of several gullies with steep slopes. Elevation above the gully bottoms is up to 27 m. The bank of Ksizovo site is dated by the 5th century BC, while Mukhino and Degtevoye sites show two banks each due to multiple uses by successive tribes. In Mukhino there are banks of the 5th century BC and the 5th century AD, in Degtevoye – banks of the 5th and 3rd centuries BC. Altogether soils buried under these banks in similar landscape positions on loess sediments constitute a chronosequence. The most ancient soils of the sequence (the 5th century BC) are similar to modern ones (Greyzemic Luvic Phaeozems (Loamic) with greyzemic features in the lower part of Ah and AhB horizons (color is 10YR 3/2). Ped surfaces and trans-horizon cracks in Bt horizons are covered with clay cutans. The thickness of humus layer is about 30 cm. Slight effervescence from HCl due to diagenetic carbonates from the bank carbonate material in buried soil may starts from the surface (Mukhino site) though carbonate horizon with a set of carbonate neoformations starts below 100 cm. Younger soils of the sequence (the 3rd century ВС) are presented by Luvic Phaeozems also but color of the lower part of the Ah horizon is 10 YR 5/2 indicating the continuing forest environment. Soils under the youngest bank (the 5th century AD) are presented by Greyzemic Luvic Chernozems indicating the onset of steppe environment. There are no greyzemic features in the upper horizons. Carbonates start from 85 cm; and carbonate accumulations are presented by white soft spots and hard nodules. The studied soil chronosequence record environmental changes of centennial scale – shift of forest-steppe to steppe during Late Holocene. That shift is indicated by changes in carbonate profile and the presence or absence of greyzemic features. These features are indicators of environmental changes for the Late Holocene in the forest-steppe area. On the other hand, clay cutans, being presumably formed earlier, show sustainability to environmental changes of the studied range. Due to a combination of stable and unstable features the studied soils are polygenetic showing features both of forest and steppe pedogenesis.