No 3 (2023)

Under the conditions of climate changing, the biospheric role of forest cover is increasing, as well as the relevance of research on the carbon depositing capacity of the world’s forests. These studies include an assessment of the trees’ and stands’ biological productivity, which includes not only phytomass, but also the basic density (BD) of stem wood and bark. In our study, allometric models of the BD of wood and bark of 9 forest-forming tree species of Northern Eurasia have been developed, including such independent variables as the tree age, the stem diameter, as well as the average temperature of January and average annual precipitation. The structure of a mixed-effects model is applied, in which the affiliation of the source data to each of the tree species is encoded by a set of dummy variables. Based on the space-for-time substitution principle, the obtained patterns of BD changes in spatial climatic gradients are used to predict their changes in temporal gradients. The effect of Liebig’s law of limiting factor in predicting BD in spatial and temporal climatic gradients has been confirmed. The revealed patterns of changes in the BD of wood and bark in temperature and precipitation gradients completely repeat the previously established patterns of changes in phytomass and net primary production of trees and stands of Eurasia in the same gradients. This means that the climatic conditionality of the studied indicators of biological productivity has a common nature for both quantitative and qualitative indicators of trees and stands.

The problems of transition of Scots pine (Pinus sylvestris L.) from the stable state to an unstable equilibrium and the change of equilibrium population to non-equilibrium as a result of the global warming are discussed. The purpose of the research is to study the state of the southern and central forest-steppe Scots pine populations’ generative sphere on the basis of its seed fullness, assess their vital state in 2020 compared to 2016 – the year of the pine forests’ destabilisation, as well as compared to the state of the steppe populations in the abundant year of 2017. The objects of the study were the central and southern forest-steppe pine populations growing in the ecologically favourable territory of the Voronezh and Belgorod regions. In 2015, their transition from equilibrium to a slightly nonequilibrium systems was recorded. The level of seed fullness in the Stupino and Belgorod populations decreased by 25.6 and 24.6%, respectively, the number of seeds by 37.7 and 22.4%, and the mortality rate of ovules increased by 3.9 and 4.0 times. Comparison of the seed productivity indicators in 2013, 2016 and 2020 showed that at present both plantations can be considered equilibrium systems. The central population has returned to the regional norm (stable equilibrium), the southern one is in a state of unstable equilibrium. The analysis of variance revealed a significant (57.8%) influence of the HTC factor on the generative sphere of the Belgorod population on the basis of full grain. In the last decade, the number of optimal years in the CCR has decreased from 7–8/10 years to 5. It takes 3 optimal years to return pine forests to equilibrium. High rates of the global warming can lead to an imbalance and re-destabilization. A further reduction in the number of optimal years makes it almost impossible for pine forests to return to the regional norm.

Data on the influence the grey heron (Ardea cinerea L., 1758) colonies have on the dynamics of tree ring parameters in pine plantations are presented. It is shown that the beginning of the stands colonisation by the grey heron can be quite accurately determined by analysing the dynamics of the annual tree rings parameters, especially the width of their late layer and the optical density of wood (the values of the former are lower in the control stand, and of the latter one are higher there). Grey heron colonies begin to appear in pine forests since as early as 10–12 years old, when the height of the trees reaches 5–6 m, and the diameter of the trunk at a height of 1.3 m from the soil surface is only 7–8 cm. In the first 15–20 years, they have a positive influence on the annual growth of trees, especially on the width of the late layer of wood and the thickness of the cell walls, but then the picture changes to the opposite. The total residence time of heron colonies in one place is about 35–40 years, after which they move to new places due to the forest stands coming into disarray or even facing complete destruction. To reduce the likelihood of the grey heron colonies appearance, which in many cases have a negative impact on the state of forest biogeocoenoses, it is necessary to stop creating pure pine forests near water bodies, giving preference to spruce, birch, poplar or linden-oak plantations.

Peat litter of moss-woody composition was studied in swamp birch (Betula pubescens Ehrh.) forests of the grass-mossy forest types in the northern part of the Ob and Tom interfluve (geographical coordinates N 56°23′186″, E 084°32′519″). The litter samples are characterized by a low base saturation of 35.6%; an acidic reaction (\({\text{p}}{{{\text{H}}}_{{{{{\text{H}}}_{2}}{\text{O}}}}}\) 4.0); and an ash content of 8.9%. The average content of macro- and microelements forms the following descending series, mg/kg: Ca₅₁₀₅ > Fe₄₂₀₁ > Al₃₆₁₄ > K₉₈₆ > Mg₈₉₃ > Mn₄₆₈ > Sr₂₃₀ > Na₁₅₃ > > Zn₅₁ > Pb₁₃ > Cu_6.8 > Ni₅ > Cr_4.6 > Co_2.9 > Cd_0.2. According to the factor analysis, the mineral component composition of the litter during the plant residues destruction is 57% determined by the variability of the heavy metals content, 37% by the content of alkali, alkaline earth, Zn and Cd. Using the tree clustering method, the morphometric fractions of plant fragments (derivatives) were organized as follows: >10 mm, [(10–5) + + (5–3) + (3–2) + (2–1)] and [(1–0.5) + (0.5–0.25) + <0.25] mm. Discriminant analysis showed 100% fit in the corresponding group. Al and Ca make the greatest contribution to the prediction. As plant fragments decompose, heavy metals and aluminium gradually accumulate while alkali and alkaline earth metals get washed away, the processes being most active at the fermentation stage. The distribution of mineral components in litter derivatives is consistent with their humus state. In small morphometric fractions, compared to large fragments, the ratio (∑HA + ∑FA)/polysaccharides expands, the C/N value gets lower, humic and fulvic acids accumulation occurs mainly for the 1st fraction ones. Peat litter is characterized by an average, moderately dangerous level of pollution: the total pollution index (Zc) is 18. The toxicants composition is dominated by Pb and Zn – chemical elements of the hazard class I.

The danger of stem pests’ mass reproduction in the Leningrad Region and the Republic of Karelia is increasing. However, data on their populations’ state in the northwest of the European part of Russia are scarce and very heterogeneous. They include materials from articles and reviews of the sanitary and forest pathology state, which are in turn based on completely different methodological approaches to obtaining information. Generalisation and analysis of data on the increase in the number of stem pests that pose a danger to coniferous forest stands in the north-west of the European part of Russia, taking into account the materials of scientific reports and forest pathology monitoring, is an urgent task of this paper. The greatest danger to spruce stands is the European spruce bark beetle Ips typographus (Linnaeus, 1758), which forms large-scale centres of mass reproduction. The main factors causing the beginning of the formation of breeding centres are weather conditions (hurricane-force winds and the formation of windblows, an increase in the growing season temperature and a lack of precipitation). At the end of the 20th–beginning of the 21st century, the Leningrad R-egion saw an increase in frequency of the stem pests’ mass reproduction outbreaks, especially the European spruce bark beetle. Since the second half of the 20th century, breeding outbreaks have been also observed in the Republic of Karelia. In the Murmansk region, stem pests do not have a noticeable effect on the forest stands condition. These trends correspond to the temperature increase trends in the Leningrad region and Karelia and an insignificant temperature change in the Murmansk region. Additional nutrition for the pine beetles and sawyer beetles in cases of their mass reproduction is an underestimated factor in the forest stands weakening, which significantly affects the growth and condition of surrounding plantations. The appearance of invasive species, such as the small spruce bark beetle Ips amitinus (Eichhoff, 1872) (Curculionidae: Coleoptera), is a potential danger, but at present this species does not show significant activity in pine and spruce forests in the north of the European part of Russia.

The article provides an analysis of historical data on the organisation and state of geoecological research in the mountain forests of the North Caucasus and Russia. On the example of regional monitoring of mountain forest ecosystems, the organisation of the multi-purpose nature management within mountain watersheds is demonstrated. Based on the results of the experimental materials obtained from a long-term monitoring at complex forest-hydrological stations, as well as the results of active experiments, recommendations are given for forest management in the mountains. An example of obtaining information by field methods is shown, as well as computer modelling of forestry development in mountainous regions. The scientific principles and ecological bases of farming in the mountainous regions forests are proposed.