Аннотация:The spatial and intraprofile variations of soil δ13C values are assessed along with the corresponding environmental and edaphic factors in the Baikal region, a vast territory in the south of Eastern Siberia, which is highly heterogeneous in terms of physiographic conditions. The studied sites are located in the altitudinal range of 403–2315 m a.s.l., which defines a strong landscape and climatic gradient comprising mountainous tundra, subalpine grasslands, mountainous taiga, subtaiga, and steppe landscapes. The soil organic matter there considerably varies in the 13C/12C isotopic ratio corresponding to δ13C values characteristic of the plants with C3 photosynthesis. The δ13C values in topsoil organic matter vary from –29.50 to –22.98‰. The changes in δ13C values in the altitudinal profile correlate well with the changes in landscapes. The highest δ13C values are characteristic of the soils in mountainous tundra and steppe landscapes. Organic matter of taiga soils is depleted in 13C. A lower carbon turnover rate is observed in the steppe and mountainous tundra soils, which is explained by limited moisture and heat supply, respectively. The soils formed in taiga landscapes with their more favorable balance of temperatures and precipitation display a more intensive carbon turnover (β). The β values in forest soils correlate with the changes in pH, C and N contents, and the variations in C/N ratio in soil organic matter, thereby suggesting a considerable effect of the plant litter quality and microbiological activity on the carbon turnover in the regional soils formed under more favorable climatic conditions.
