Abstract <p>The influence of the ecological and geographical factors of the phytocenotic environment on the state of soil microbial cenoses has been studied in Skeletic Cambisols, Albic Podzols, and Albic Luvisols (Loamic)) on test plots located from south to north in Eastern Fennoscandia. The chemical properties, composition, and ecophysiological parameters of the microbial community of the upper organic soil horizons (O) formed under old-age spruce forests have been studied. There is a general tendency for the thickness of the forest litter to increase from the southern taiga (2–4 cm) to the northern taiga (6–9 cm). We have identified 46 species assigned to four main phyla—Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes—in the microbial communities of the forest litter in the studied old-age spruce forests by chromatography–mass spectrometry of microbial markers. The abundance of bacterial species gains maximum in southern areas and is minimal in northern areas: 46 and 40 species, respectively. Non-spore-forming bacteria represented by the Proteobacteria and Actinobacteria phyla are dominants in the microbial community of the soils. Basal respiration is the highest in soils of the southern and middle taiga subzones, where it ranges within 18–45 µg C–CО₂/(g h). Basal respiration of soils in the northern taiga is 2–4 times lower than in southern territories: 8–10 µg C–CО₂/(g h). The trends of microbial biomass carbon pattern (C_mic) are similar. The C_mic value for the southern and the middle taiga subzones is similar (2779–3504 µg C/g), but it is 1.5 times lower for the northern subzone (1978–2302 µg C/g). There is a general tendency to a decrease in the enzymatic activity (cellulolytic activity of catalase) of soils from the southern to the northern plots. The data obtained may be the basis for environmental monitoring.</p>