ИСТИНА

Digital soil mapping may reflect both spatial continuity of soil properties that is believed to be a benefit of digital maps comparing with traditional maps of soil taxa. However, in some cases the users require a map of discrete polygons, which represent either taxonomic or functional soil classes. We analyzed the variability of acidity and organic carbon content in several contrasting soilscapes within the Russian Plain and Eastern Fennoscandia. In most soilscapes the spatial variability was relatively low, and the differences in soil properties were related to erosional short-distance redistribution of soil material. The soilscapes with contrasting soil polygons were detected by a specific hump-like form of semivariograms rather than by high absolute values of variation. The continual maps of soil properties may be transformed into discrete maps using indicative kriging or other methods of grouping. However, the resulting polygons hardly correspond to the limits of taxonomic soil groups, because the diagnostic properties of soil taxa seldom correlate with such properties as pH values or organic carbon percentage in surficial horizon. We propose using functional rather than taxonomic groups for discrete digital soil mapping , concentrating on soil productivity, limiting factors for soil use and soil-related ecosystem services.