Variations of stable carbon isotopic composition of soil organic matter in mountain-depression environments of Fore-Baikal region
V. A. Golubtsov1, A. A. Cherkashina1, Yu. V. Vanteeva1, N. N. Voropay1,2, S. M. Turchinskaya3
1V.B. Sochava Institute of Geography SB RAS, Irkutsk, Russia
2Institute of Monitoring of Climatic and Ecological Systems SB RAS, Tomsk, Russia
3Institute of Geography RAS, Moscow, Russia
Keywords: soil ecology, Оґ13С, carbon turnover, south-western Casbaikalia
Abstract
An analysis of depth-profile and spatial variations of the stable carbon isotopic composition of soil organic matter is presented to identify the main factors that determine the dynamics of organic carbon in the mountain-depression environments of the Baikal region. Soil organic matter is characterized by δ13С values from -29,6 to -24,9 ‰. Changes in δ13C values in the altitudinal profile correlate well with changes in landscapes and reflect the influence of climatic factors on13C discrimination during photosynthesis of C3 plants. The heaviest stable carbon isotopic composition characterizes the soils of subalpine and steppe landscapes. In taiga soils, depletion of the isotopic composition by13C is observed. To compare the soil carbon turnover intensity δ13C values were regressed linearly against log-transformed carbon contents yielding absolute values of these slopes (β). The distribution of β values in the altitudinal profile suggests a reduced intensity of carbon turnover in the soils of the steppes and the subalpine belt due to the limitation of these soils in terms of moisture and temperature, respectively. Under the taiga conditions characterized by more favorable ratio of temperatures and humidity the dynamics of soil organic matter is controlled mainly by the litter quality and the nitrogen availability.
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