Abstract <p>Anthropogenic factors of soil acidification/alkalinization change the natural protolytic balance of soils. The degree and direction of such changes are determined by the level of acid/alkaline load and soil stability (acid–base buffering capacity). The article summarizes the results of a study of the sources of buffering capacity of taiga soils in the European northeast of Russia. It is shown that the buffering capacity of soils that develop under the same climate conditions and are similar in lithological features depends on the hydrological conditions of the microrelief elements and, accordingly, on the composition and functioning of biocenoses. The variability of the nature and structure of soil buffering is revealed in the layer with the most active action of biotic factors, namely, in organogenic and eluvial horizons. The similarity of the illuvial horizons of genetically different and geographically isolated soils is determined by their insignificant transformation by soil processes, which is manifested in the absence or reduced content of direct products of soil formation: organic, Al-, and Fe-organic compounds and minerals of the soil chlorite group. The materials can be used for soil-chemical monitoring and for predicting soil changes under the influence of pollution with acidic and alkaline compounds.</p>