Floodplain soils on the soil map of the Russian Federation, scale 1 : 2.5 m, 1988, in the Russian soil classification, 2004

The largest area of taiga gley-differentiated soils on the Soil map of Russian Federation, scale 1:2.5 M, is located in the north of West Siberia. Small areas are dispersed over the northwestern European Russia, Eastern Siberia and the North-East. Interpretation of taiga gley-differentiated soils in terms of Russian soil classification system (2004) is rather ambiguous owing to high diversity of ecological conditions where these soils occur, as well as variability of soil morphological, chemical, and physicochemical properties in diverse mapping units. Comparing properties of taiga gley-differentiated soils described in the Program of the map (1972) and in regional publications with the diagnostic criteria for soil types in some orders of the Russian classification system made it possible to find adequate names and taxonomic position for these soils. Thus, taiga gley-differentiated soils in the middle and northern taiga of Western Siberia proved to be allocated to several orders: weakly differentiated and gleyed soils with a brown profile were referred to the order of organo-accumulative soils as shallow-peat gleyic soils; their more hydromorphic variants - taiga gley-differentiated shallow-peat soils were defined in the order of gleyzems, as peat gleyzems, soil with morphologically differentiated profile having a particular cryogenic structure were qualified for svetlozems and iron-illuvial gleyic svetlozems in the order of cryometamorpic soils, and for eluvial-metamorphic soils of the same order in case of cryogenic structure was absent. Taiga gley-differentiated soils in their northwestern area are confined to varved clays and correspond to (soddy-)eluvial-metamorphic gleyic soils.