Quantitative Estimates of Paleoenvironmental Changes in the Late Holocene in the South of the East European Plain as Recorded in the Magnetic Properties of Soils

Abstract

Information about the past evolutionary changes in the soil cover is essential as a retrospective basis for long-term forecasts of soil development under the changing climatic conditions, and also for understanding the present-day problems of desertification and land degradation in the south of the East European Plain. The principal task of the present study was to estimate quantitatively the shift of the boundary between the steppe and desert-steppe zones in this region during the late Holocene under the impact of global climate variations. The properties of about 100 paleosols of archaeological sites widely represented in the region were used for quantitative reconstruction of paleoprecipitation, paleotemperature, and climate aridity. To obtain regional calibrations, the dependences of the magnetic properties of modern soils on climatic parameters in the south of the East European Plain were analyzed in detail. Samples of 35 soil profiles along the 1500-km-long Voronezh–Volgograd–Astrakhan–Elista–Voronezh transect were used. This transect crosses several natural climatic zones with gradients in the annual precipitation of about 500 mm/yr and in the annual temperatures of about 3°C, which allowed us to obtain reliable relationships between the climatic parameters and the properties of recent soils. Limitations for paleoclimate reconstructions based on the magnetic properties of soils in the range of mean annual precipitation <600 mm/year were identified. Cartographic reconstruction of changes in the De Martonne aridity index (IDM) using GIS modeling methods and paleopedological data indicates that the Volga–Don interfluve has undergone repeated changes in the climatic situation over the past 5000 years resulting in the shifts of the boundaries between soil-geographical zones to distances of up to 200–300 km.