TRANSFORMATION OF SOILS OF THE EAST EUROPEAN FOREST-STEPPE UNDER CONDITIONS OF THE CENTENNIAL CLIMATE FLUCTUATIONS.

Climate change is the leading factor in the development of soil formation. As our studies have shown, not only long-term (for centuries), but also centennial (for decades) climate fluctuations can lead to the noticeable change in the areas and contours of soil ranges in the forest-steppe zone of the central part of Eastern Europe. In order to study the peculiarities of transformation of soil contours in time, the authors carried out the comparative analysis of large-scale (1:50000) soil maps conducted in different phases of the centennial helioclimatic cycle: heat-dry (1970s) and cool-wet (1990s). 4 administrative districts of the Belgorod oblast on the total area of 5770 km2 were chosen as model territories. The territories of agrolandscapes with the predominance of arable chernozems were studied. The analysis was conducted by the software package ArcGIS 10.2, using the tools of vector analysis (soil maps) and raster (grids of steepness and exposure of slopes) data. Comparison of soil maps showed that during this period 71.1% of the studied chernozems area did not change its status. On the remaining territory the changes of the soil contours were observed. It was revealed the transformation of Chernic Haplic Chernozems into Chernic Luvic Chernozems within typical forest-steppe, and Chernic Calcic Chernozems into Chernic Haplic Chernozems in southern forest-steppe - mainly on the flat interfluves. In the cool - wet phase of the centennial helioclimatic cycle the expected period of the chernozem sois leaching fell at frequent thaws in the cold half of the year. On slope lands during the observed period, the characteristic event was the increase of the Solonetzic Chernozems (Luvic Chernozems Sodic) areas. The reason of salinization - solonetzation of soils during the centennial phase of climatic moistening is seen in the increase of amplitude of seasonal soil wetting with the attaining by the front of seeping moisture the rock layers with the increased concentrations of salts and with their subsequent tightening in the top soil layers. The most probably periods of implementation of this process were the spring periods (moisture accumulation after snow melting and uplifting of soil solutions saturated with ions of easily soluble salts during soil warm-up). [ABSTRACT FROM AUTHOR]