The article highlights the characteristics of structure and properties of organogenic horizons (OHs) in different-type forests of the middle taiga subzone (State Natural Reserve ‘Lyalsky’, Knyazhpogostsky District, Komi Republic). The authors studied the morphological properties of OHs (thickness, structure, fractional composition), determined their particular chemical characteristics (acidity, C and N content) and estimated the organic matter reserves and Corg in them. Median values for all indicators were calculated in Statistica 13.3. program. OHs of automorphic spruce and small-leaved forests of accumulative and trans-accumulative relief positions, which are closely underlain with carbonate-containing parent rocks, have relatively high values of pH (5.3–6.4), N content (1.4–1.5%), narrow C : N ratio (25–29) and increased content of microbial biomass (20–24 mg C/g soil in the upper OH layer). The above-mentioned peculiarities activate decomposition and trigger formation of relatively thin (5–6 cm) OHs with reserves of 37–54 t/ha in automorphic conditions. The moisture content rise in sphagnum spruce forests ensures organic matter conservation and increases the OH thickness to 15 cm and organic matter reserves to 85 t/ha. OHs in soils of green-moss and sphagnum pine forests, which grow on sandy sediments of eluvial relief positions, have acidic medium reaction (pH 4.2–4.5), low N content (0.9–1.0%), wide C : N ratio (44–48) and low content of microbial biomass (13–14 mg C/g soil in the upper OH layer). Unfavourable conditions of organic matter decomposition in green-moss pine forests contribute to the formation of OH with a thickness of 12 cm and total reserves of 73 t/ ha. Excessive moisture of OH in sphagnum pine forests responds for the increase in its thickness to 17 cm and organic matter reserves to 105 t/ha. In automorphic forests, the thickness and reserves of OH decrease along with the row: trunk → crown → window. In sphagnum forest types, we observe the opposite trend, which is probably related to a draining effect of trees. The OHs of forests, which grow in automorphic conditions, accumulate 15–40 % of the total carbon stocks within a meter-deep soil layer. In semi-hydromorphic conditions, they accumulate up to 49%.