SOIL-LANDSCAPE RELATIONSHIPS IN THE TAIGA OF NORTHWESTERN RUSSIA HIGHLIGHT THE DIFFERENCES IN THE U.S. AND RUSSIAN SOIL CLASSIFICATION SYSTEMS

Abstract

Relatively little work has been published about soils in northwestern Russia, and soil-parent material-vegetation relationships are not well established for this region. Seven pedons developed on late-Pleistocence glacial deposits in the northern, middle, and southern taiga zones of northwestern Russia were described and classified according to the official classification systems of both the United States and Russia. Morphological descriptions and laboratory data that included pH, particle size distribution, selective dissolution analysis, and carbonate equivalent were used for classification. Psamments (Podzols) with Bs and Bhs horizons are most common in the northern taiga, where parent materials are dominated by felsic till and glacial outwash, and vegetation is mostly evergreen conifers. Parent material heterogeneity in the middle taiga promotes soil diversity. Soils on thin calcareous till over limestone are Rendolls (Soddy-calcareous soil); soils on thick calcareous till are Cryalfs (Podzolic soil), and those on slightly calcareous glacial-lacustrine deposits are Psamments (Podzol), with much weaker spodic character than the soils of the northern taiga. Vegetation in the middle taiga varies from broadleaf, deciduous trees on highly calcareous soils, to evergreen conifers on the weakly calcareous soils. The southern taiga region soil formed on calcareous two-layer till is a Cryept (Soddy-podzolic soil) under evergreen conifer forest. Soil properties are clearly linked to the composition of the glacial deposits and to the forest vegetation. We also show that strongly podzolized soils, as indicated by albic horizons and significant subsoil accumulations of carbon and oxalate-extractable Al and Fe, nonetheless fail U.S. taxonomic criteria for spodic material and Spodosols, primarily on the basis of soil color.