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European spruce bark beetle Ips typographus is an important driver of ecological processes in spruce stands, with severe effects on forestry economies. To prevent bark beetle outbreaks, early detection of infestations is a crucial step in forest management. It is expected that bark beetle infestation modifies biochemical composition of wood and needles, alters physiological responses in the early stage of infestation, which results in the reduction of tree growth and ultimately a tree death. Therefore, we studied the differences in biochemical composition of wood, content of photosynthesis-related pigments, shoot morphology, and growth between the healthy Siberian spruce trees (Picea obovata) and trees which were infested by I. typographus. The study was performed in five experimental plots established in the south of the Udmurt Republic in the European part of the Russian Federation. Three infested and three non-infested trees were chosen on each plot. Our results showed no significant effect of bark beetle infestation on the content of main structural components of wood – holocellulose (cellulose and hemicellulose) and lignin. On the other hand, we found differences in the content of extractive substances in the wood. Specifically, we found a higher tannin content in the non-infested trees. The content of photosynthesis-related pigments differed between the non-infested and infested trees as well. Unexpectedly, bark beetle infestation caused the overproduction of both pigment types rather than their degradation. Moreover, we observed that a higher amount of total extractive substances positively affected the incremental growth, whereas tannins supported the growth of shoots and needles.

As a result of global climate changes, negative processes have been recorded in the coniferous forests of the Northern Hemisphere. Similar processes are observed in the Urals, including in Udmurtia. In the course of this research, archival analysis methods were used, as well as field research methods. In the process of analyzing archival materials in the Urals, a reduction of spruce forests was observed. If in the 20th century the share of spruce forests in the region was 50%, then in the 21th century it decreased to 35%. As a result of this research, it was revealed that the most unfavorable sanitary condition was recorded in the boreal–subboreal zone of Udmurtia, with a sanitary condition index of 3.2 (from 2.62 to 3.73). The main reason for the unfavorable sanitary condition of spruce forests was the vital activity of Ips typographus L. According to our research, in 11 sample plots out of 18, a high score for sanitary condition was associated with the vital activity of bark beetles. The correlation coefficient of the index of the sanitary condition of plantings and the number of individuals of Picea obovata Ledeb. affected by Ips typographus L. was0.93. Bark beetle activity has increased in the 21th century, which is associated with changing climatic factors. Unstable precipitation over recent years (differences of more than 100 mm) and an average temperature increase of 1.2 °C were observed in the region. The most significant increase in temperature over the past 10 years was observed in winter, which in turn affected the high survival rate of insect pests.

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.

A study of the root systems of tree species, their distribution in soil in horizontal and vertical directions, expressed by quantitative and qualitative indicators in the form of architectonics, underground phytomass, volume, surface, area and root saturation, answers many questions regarding the growth and development of tree plants. The growth conditions and species characteristics of plants have a significant effect on the formation of the root system.The studies were carried out in the large industrial center of the Ural region of Izhevsk in plantations of various environmental categories, i.e. plantings of the residential zone and plantings along the highways. As a zone of conditional control, a city park of landscape type named after S.M. Kirov. The objects of the study were coniferous species: the representative of the local flora such as European spruce (Pícea ábies L.) and the introduced species — Blue spruce (Picea pungens Engelm.), prevailing among the coniferous species used in the city’s landscaping. In the course of the research, the peculiarities of P. pungens and P. ábies in the formation of the root system in an anthropogenic environment were revealed, manifested in a change in the root saturation index of the meter soil layer, the length of the roots, the ratio of root fractions and their distribution in soil horizons. The total root saturation of a meter layer of soil is higher in P. pungens, but under the conditions of the highest technogenic load in the mainline stands, this indicator is higher in P. ábies. In park plantings in both species, the maximum root saturation was noted in the first soil horizon, while the anthropogenic load in P. ábies increased in the second horizon, and in P. pungens in the third soil horizon. The proportion of different root fractions also changes. P. pungens increases the proportion of semi-skeletal roots, P. ábies increses skeletally, and in conditions of high anthropogenic load it makes half-skeleton and suction roots.