The study results of coniferous stands and the description of stands in the southern taiga forests of the taiga zone within the Udmurt Republic (on the territory of the Yakshur-Bodya, Igrinsky and Kez forest districts) are presented. The climatic indicators of the study year are presented in comparison with the average long-term data for the studied areas. The taxational characteristics of forest stands are given, the indicators of the morphological profile, humidity, and cellulose-decomposing activity of forest litter are presented. Studies have shown that the cellulose-decomposing activity of forest litter depends on its moisture content, which is associated with the values of the basal area per hectar of stands in the studied sample areas. No differences in the indicator of cellulose-decomposing activity were found in the sample areas in the Igrinsky forestry. The highest values of this indicator were determined in the sample area No. 1 in the Kez forestry. The lowest values of the cellulose-decomposing activity of forest litter were observed in the sample areas No. 1 and No. 3 in the Yakshur-Bodya forest area. The physiological and biochemical parameters of Siberian spruce (Pícea obováta Ledeb.) were analyzed and compared in trees of good and satisfactory living conditions, which did not show statistically significant differences in the content of chlorophylls and carotenoids in the needles. A significantly high content of photosynthetic pigments and tannins in Siberian spruce conifers was found in the sample areas in the Igrinsky forest area. Similar results were obtained for individuals of a satisfactory living condition, with the exception of the content of tannins in conifers. It was found that the high content of chlorophyll a in Siberian spruce needles is usually accompanied by an increased content of tannins and a low concentration of ascorbic acid. It is shown that in general, the potential of Siberian spruce individuals associated with the biochemical level of the formation of adaptive reactions is highest in plants in the northern regions of the republic, i.e. in areas with more extreme growing conditions. Materials were obtained on the basis of which it is possible to develop a program for monitoring plantings and restoring forest stands.