Home – Home – Jornals – Siberian Journal of Forest Science 2026 number 2

Stable carbon isotopes are widely used in environmental sciences to study physiological, ecological, and biogeochemical processes associated with ecosystem, regional, and global carbon cycles, providing information on various temporal and spatial scales. The study was conducted in forest ecosystems of the middle and northern taiga subzones of Central Siberia. The δ¹³C composition of the tree, shrub, dwarf shrub, and moss-lichen vegetation layers, fungal fruiting bodies, litter, and soil cover of the studied forests was analyzed. A pronounced δ¹³C gradient was observed across vegetation layers in forest ecosystems. δ¹³C values n the biomass of aboveground components of ecosystems ranged from -34.0 ± 1.0 ‰ in the green moss glittering woodmoss ( Hylocomium splendens (Hedw.) Schimp.) of the middle taiga to -23.8 ± 0.8 ‰ in the wood of Gmelin larch ( Larix gmelinii (Rupr.) Kuzen.) growing in the northern taiga. Both the lowest and highest δ¹³C values were found in the lowest, moss-lichen layer. The tree layer of the studied middle taiga ecosystems is characterized by lower δ¹³C values in the leaf apparatus compared to the northern taiga stands, reflecting their higher productivity and the degree of discrimination (Δ) of the heavy carbon isotope during photosynthesis. The heavier isotopic composition of the subordinate vegetation layers in the northern taiga forests indicates a reduced canopy effect. Isotope fractionation during soil organic matter mineralization leads to an increase in δ¹³C values with depth in all studied ecosystems. However, based on the dependence of δ¹³C values on soil carbon content, which varies with depth, an increased carbon turnover rate (β) was detected in larch soils in the permafrost zone. This is presumably due to post-pyrogenic dynamics of root detritus input, rather than the intensity of mineralization processes.

The article presents the 37-year dynamics of survival of different populations of Scots pine ( Pinus sylvestris L.) (climatypes) tested in provenance trial growing in the southern taiga of the Krasnoyarsk Krai on disturbed sod-podzolic sandy soil. A significant ( p < 0.001) negative correlation of this indicator with the duration of the frost-free period at the point of origin is shown. For a group of climatypes with a frost-free period of > 125 days, a significant ( p < 0.05) negative correlation with precipitation in May-June was shown, which confirms the creation of a water shortage at the test site for this group of climatypes. In the comparative analysis, the climates were divided into sectors according to the continentality of the climate type. The best survival within each sector is often noted in pine trees from taiga zones. During the analysis, climatypes from broad-leaved forests and forest-steppe zones were noted, which have relatively high survival values and are not similar in terms of forest conditions to the test site.

The drained peat soils were studied (Drainic Hemic Histosols). The drained area of the mesotrophic swamp is occupied by young pine forests ( Pinus sylvestris L.) - sedge-sphagnum, reed, and mixed-grass-nettle at interchannel lanes of 94, 47, and 25 m, respectively. The average annual level of swamp waters - 23.2 ± 9.9, 42 ± 11 and 70.2 ± 16.0 cm characterizes the conditions of weak, moderate and intensive drainage. During May-October of three years, environmental indicators characterizing the aerophysical properties and volume humidity of soils were studied. In the ranked series of volume humidity, the 81-100 % class dominated in conditions of weak drainage, 20-60 % - moderate, and < 20-40 % - intensive drainage. In soils with moderate and intensive drainage, good aeration conditions prevailed (air capacity 21-90 %), the oxygen content in the aeration pores corresponded to atmospheric, and the class of redox potential, characterizing intensive oxidative processes, prevailed. In weakly drained soils, variants of good air capacity and to varying degrees of unsatisfactory (< 10-20 %) were equally common. The oxygen content of the soil air in 18 % of the relative frequencies dropped to 11-16 %. Against the background of mainly oxidative processes, weak reducing (300-400 mV) were observed in 9 % of the frequencies. In order to quick predict the air properties of peat soils when planning measures of drainage in peat lands, paired adequate models of the relationship between aerophysical parameters and volumetric humidity by the type of linear function and a quadratic parabola were constructed. According to the linear regression coefficients, an increase in humidity by 1 % is accompanied by a decrease in air capacity by 0.91 %. The points of extremum (maximum) of the parabolic function of volume humidity - 35.9 % and oxygen of soil air - 20.6 %, corresponding to atmospheric content, are calculated. The critical points of a maximum humidity of 42.9 % and a redox potential of 619 mV characterize the intensive development of oxidative processes. Based on the constructed model, a range of volume humidity of 65-80 % is predicted, which ensures a moderate course of oxidative reactions (redox potential 500-600 mV), preventing accelerated (unproductive) «combustion» of peat deposits. The range of application of regression equations is 8 (13) - 97 (93) % of the volume humidity.

The article presents data on the dynamics of natural restoration of the Siberian stone pine ( Pinus sibirica Du Tour) under the canopy of light coniferous and deciduous forests and in logging areas carried out by selective logging in the Central ecological zone of the Baikal natural territory, Baikal mountain forest region. Periodic fires including catastrophic ones in 2015-2017 constrain considerably Siberian stone pine forests development here postponing their formation for many years due to absence of a stable Siberian stone pine undergrowth. In a series of areas, especially on the slopes of northern expositions of the Morskoy Ridge, self-seeding of Siberian stone pine did not occur due to the fires, which destroy generative tree stands. Long-term secondary forest of other formations and typology form on the site of burnt here Siberian stone pine taiga. It is stated that around the ridge, under the canopy of mixed light-coniferous and deciduous forests, a rather sustainable Siberian stone pine undergrowth with a stable annual growth forms. Presence of Siberian stone pine undergrowth in these forests on self-seeding base indicates positive dynamics for Siberian stone pine forests formation under these conditions for forests growth. Evidently, it is reasonable to create conditions for forests keeping with available potential for Siberian stone pine taiga formation in the areas of the studies.

The article discusses the method of constructing growth tables of the uneven-aged larch ( Larix Mill.) stands grouped into economic groups of forest types. The method is based on typical growth lines of forest survey indicators obtained by converting absolute values into indices of 106 tables of the growth rate of larch. Affine transformations of age series significantly reduced the absolute variability of inventory indicators, and reduced it to zero at the age of 100. The probability types of growth in height, diameter, and species number were found through regression relationships between these indicators and the classes of bonitet and thinning types. The last two indicators were taken as independent variables. The thinning pattern of larch stands with age fits into 12 typical lines. The difference in indices between thinning types 1 and 12 at the age of 20 reaches 72 %, and at the of 220, it reaches 86 %. The relationship between thinning types and class of bonitet, types of growth of height, diameter is moderate, reliable. There is no relationship between thinning types and classes of density. Different density in 100 years can have a thicket of one thinning type and vice versa. Absolute values of the number of stems, average heights and diameters in 100 years are determined by regression equations of the relationship of these indicators with classes of bonitet. In other ages, their values were found by multiplying the indices of the standard lines by the absolute values of the indicators in the base age. The species number was determined using the species height. As a result, growth tables were constructed for uneven-aged larch stands grouped into economic groups of forest types. The productivity of the developed tables differs slightly from the productivity of normal larch stands. The proposed method of constructing growth tables can be used in modeling the growth of stands with a limited number of test plots.

The photosynthetic activity of Scots pine ( Pinus sylvestris L.) needles growing in swampy forests in the subzones of the northern and middle taiga of the European Northeast has been studied. Some ecological aspects of photosynthetic fixation of carbon dioxide by needles in sphagnum and sedge-sphagnum pine forests are considered. The features of the daytime and seasonal dynamics of photosynthesis and its relationship to environmental factors are revealed. It has been established, that in summer, during the daytime, the intensity of photosynthesis largely depends on the intensity of solar radiation. There is a positive relationship between pine photosynthesis and temperature and humidity during the day. The daily productivity of photosynthesis of pine needles growing in the middle taiga sphagnum pine during the growing season has been determined. The fixation of carbon dioxide by needles is greatest in summer under favorable light, thermal and edaphic conditions, about 50 % of carbon was absorbed during photosynthesis in July. The linear dependence of the daily productivity of photosynthesis on the air temperature and the total photosynthetically active solar radiation per day is shown. It has been established that the daily photosynthetic productivity of pine needles within the taiga zone of the Komi Republic decreases with increasing geographical latitude. The optimal values of the main environmental factors have been determined, at which the maximum level of photosynthetic activity of needles is manifested during the summer growing season. The variability of the light and temperature optima of pine photosynthesis in the zonal aspect has been revealed.

This paper presents comparative estimates of the input volumes and fractional composition of plant litter in a 15-year-old cereal birch forest and a 25-year-old tallgrass alder-willow birch forest, representing the initial stage of tree and shrub vegetation overgrowth on an abandoned arable land in the Cherepovets district of Vologda Oblast. The total litter input averages 1942 kg ha/year and does not differ between the biogeocenoses. 85.2 % of the litter is classified as the active fraction. The predominant fractions for the biogeocenoses are birch ( Betula L.) leaves and twigs, as well as alder ( Alnus Mill.) and willow ( Salix L.) leaves. The cereal birch forest, in contrast to the tallgrass alder-willow birch forest, is characterized by higher inputs of aspen ( Populus tremula L.) seeds and leaves and lower inputs of willow fractions (branches and leaves). Maximum litter fall input occurs in August-September (27-35 % of the annual input). The peak in the cereal birch forest occurs at the end of August, and in September in the alder-willow tall-herb birch forest. The minimum litter fall input for both types of biogeocenoses occurs during the dormant period (November-March) - 15 % of the annual input per month. The average input of carbon with litter fall is 861.5 kg C/ha/year, and nitrogen - 22.8 kg N ha/year.

The article analyzes the achievements and studies of the famous Siberian scientist, Candidate of Agricultural Sciences (PhD) Vadim Ivanovich Polyakov in the field of forest survey, forest management, forest use, forestry and protective afforestation in the northern, central and southern parts of Central Siberia for the period from 1980 to 2018. V. I. Polyakov made a significant contribution to the study of the dynamics of black fir-Siberian stone pine forests in the middle mountains of the Western Sayan. Based on the study of the dynamics and structure of mortality, the stability of tree stands with age, the average and maximum lifespan of Siberian stone pine ( Pinus sibirrica Du Tour) and Siberian fir ( Abies sibirica Ledeb.) were assessed. He also proposed a Markov model of the growth of stands, constructed taking into account the influence of factors of self-thinning of tree stands. Using factual material V. I. Polyakov revealed the cyclical nature of forest formation in Siberian stone pine forests of different ages, and determined the ages of quantitative, technical and natural maturity of Siberian stone pine and Siberian fir generations. He devoted considerable attention to research into the patterns of growth, development, vital status and productivity of forest stands in the impact zone of the enterprises of the Norilsk Nickel Polar Division, as well as production and experimental forest crops from coniferous tree species growing in the southern taiga and forest-steppe regions of Krasnoyarsk Krai. He provided invaluable assistance in the development of regulatory materials for the survey of protective forest stands of various functional purposes, as well as in the study of their current state, growth rate, structure and biological productivity in the steppe and dry steppe zones of Krasnoyarsk Kray, Republics of Tyva and Khakassia. V. I. Polyakov developed algorithms and programs for compiling taxonomic characteristics of stands based on the measurement data of registered trees and corresponding computer thematic databases of stationary observations, which significantly facilitate tracking of monitoring objects. A list of the main scientific publications of V. I. Polyakov is presented, which gives an idea of the subject matter of his studies, its geography and significance.

This article is dedicated to the 95^th anniversary of the outstanding scientist, Academician of the USSR Academy of Sciences and the Russian Academy of Sciences Alexander Sergeevich Isaev. It presents historiographic materials and the author’s personal recollections of the life and work of A. S. Isaev.