The Effect of Local Environmental Factors on the Stable Carbon Isotopic Composition of Soils in the Olkhon Region.

Autor: Golubtsov, V. A., Vanteeva, Yu. V., Voropay, N. N., Vasilenko, O. V., Cherkashina, A. A.
Zdroj: Moscow University Soil Science Bulletin; Dec2022, Vol. 77 Issue 4, p284-294, 11p
Abstrakt: Spatial and depth-profile variations in stable carbon isotopic composition of soil organic matter have been studied in the central part of the western coast of Lake Baikal. The contrasting landscape structure and significant climatic variability of the area strongly affect the soil stable carbon isotopic composition. The δ13С values of organic matter and litter vary in the range from –27.93 to –18.19‰ and indicate the predominance of C3-pathway vegetation. However, in the steppe landscapes, single representatives of plants with C4 and CAM photosynthesis types have been noted. The δ13С values increase in the direction from the forest soils of the foothills of the Primorsky Range to the steppe soils of the Olkhon Plateau. This trend reflects a decrease in humidity, the main limiting factor of the soil development in the Olkhon region. Insufficient moisture determines the stable carbon isotopic composition of soil organic matter through 13C discrimination in plant tissues. Regardless of the soil-forming conditions, δ13С values increase with the depth in the soils of the studied area. However, the gradient rates are determined by local combinations of environmental factors. According to the differences in the slope coefficients of linear regressions (β) in the studied soils, more intensive carbon turnover is assumed in the soils of coastal landscapes, negative landforms, and the slopes of northwestern exposures. Under such conditions, air masses from Lake Baikal cause a significantly lower drying of the soil profile in summer and provide a more favorable water and temperature regime for microbiological activity. At the same time, β variations are not accompanied by significant fluctuations in C/N ratio and pH values, which may indicate an insignificant role of edaphic factors and overlapping of their influence by the effect of moisture deficiency on the carbon turnover intensity in the soils of the Olkhon region. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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