Altitudinal differentiation of the acid-base properties of the river valley peat soils of Kuznetsk Alatau

In the complex structure of the vertical altitudinal zonality of the Altai-Sayan mountain country, peat soils were almost not represented. The aim of this research was to develop a topographic series of peat soils of the Kuznetsk Alatau. The studied peatlands were confined to the basins of the Belyi Iyus and the Chernyi Iyus rivers and located at different hypsometric levels of the relief on the Eastern slope of the Kuznetsk Alatau, at 1543, 1087, 832, 622, 579 and 547m above sea level (See Fig. 1). As a criterion of vertical structural organization of soil, we used acid-base properties: water pH (water extract), salt pH (extract of 1M KCl) and general potential - nonexchangeable acidity (extract of 1M CH₃COONa). The determined value of acidity was multiplied by an empirical coefficient 1.75. The sum of exchangeable cations (by Kappen-Hilkovits) was found in the extract of 0.1M HCl, in which the Ca⁴++Mg²+ was determined by complexometric titration. According to the difference between the sum of exchangeable cations and Ca²++Mg²+, we identified the content of other (unidentified) cations. The degree of soil saturation with bases, expressed in %, was calculated as the proportion of exchangeable bases in 0.1M HCl solution to the sum (exchangeable bases + nonexchangeable acidity). The F-diagrams, constructed on the basis of water pH, salt pH and saturation of soil absorbing complex (SAC) with exchangeable calcium and magnesium, describe the acidic trace of soil formation and simulate the acidification of top soil horizons in the course of peat genesis (See Fig. 2). High-precision regression model was proposed for the prediction of exchangeble acidity value (рН^) by the value of active acidity (рН_Ш0).№г^ the methods of multivariate statistical analysis (discriminant, multidimensional scaling), we grouped peat soils into three clusters with acid-base characteristics. The parameter of SAC saturation by alkaline-earth cations and pH salt value makes the dominant contribution to the organization of peat soil clusters with a final prediction 89% (See Table 3, Fig. 4). In the structure of vertical soil zones of the Altai-Sayan mountain country, particularly of the Eastern slopes of the Kuznetsk Alatau, the geochemical associations (clusters) of peat soils were identified: a) acidic and unsaturated by calcium and magnesium (<30-50%) on the whole profile within the boundaries of alpine tundra and subalpine complexes at the altitude of 1500-1100 m; b) slightly acidic and slightly saturated with bases (50-70%) within the mountain-taiga zone of dark coniferous forests 1100-800 m a.s.; c) neutral and moderately saturated with alkaline-earth base (70-90%) associations of peat soils within the zone of subtaiga-forest-steppe 800-500 m a.s. (See Table 4). Chorological organization of peat soils is in accordance with the hydrochemical zoning of underground waters and high-zone structure of the vegetation cover at automorphic sites. However, in the forest zone of wetlands of the Kuznetsk Alatau eastern slope, regardless of acid-base properties of peat soils, spruce forests mainly form, reflecting the main characteristics of soil hydromorphism. In this regard, the status of indigenous groups of swamp spruce forests can be considered as sufficient objective criteria of a regional climate change towards dryness. The paper contains 5 Figures, 5 Tables and 33 References.

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