No 3 (2025)

The concepts of climax and sustainability of forest communities were considered using forests of native spruce formations of the taiga zone of European Russia as an example. Objects and methods. Native spruce forests of different ages, different dynamic states and evolutionary formations were selected by a random sample from the general database of spruce communities of the taiga zone of the European North. A total of 30 spruce forests from all taiga subzones were selected. Results and discussion. The structure of age series and analysis of different generations’ trees volumes in forest stands were studied to determine the successional position of spruce forests. Biogeocenoses with no more than two excesses of tree volumes (50 % or more of the forest stand wood stock) in adjacent age generations cannot be considered forests of the climax dynamic state, but are treated as communities of transitional phases of dynamics. Spruce forests with relatively uniform distribution of tree volumes within generations of adjacent positions in the age series of the forest stand correspond to a stable state to the greatest extent, which significantly increases the time period of their stable structural position, close to the climax state. Statistical analysis of the relationship between age and volume of trees in biogeocenoses of different successional positions confirms these expectations: the relationship between predictors is “high, close” — R² > 0.8. Conclusion. A forest community can reach a climax stable state with a relatively uniform distribution of tree volumes in age generations, constituting more than half of the age series of the forest stand.

Old-growth forests with very old trees are important ecosystems for nature and humans. There are practically no publications regarding their structure in the Altai Mountains. The objective of the study is to identify old-growth forests in the Altai Mountains using structural and successional criteria of the old-growth stage based on the analysis of the structure of their tree storey. In these forests, 29 sample plots were laid in 8 study areas on 4 mountain ranges. Their tree storey is dominated by Siberian pine and Siberian larch. The average maximum age of pine was 410—590 years, larch — 360—560 years, the average age of the main generation of trees was equal or less. These uneven-aged stands are morphologically complex, with 1—3 tree storeys and 2—4 generations of trees. Ontogenetic spectra of the Siberian pine coenopopulation are complete, while those of the larch are incomplete. Siberian pine dominates as seedlings. Age distributions of tree coenopopulations have an inverse J-shaped, uneven, multimodal form. A distinctive feature of these forests is the presence among the age parcels (gap mosaics) the parcels with dominance of the g3 (g3+g3–ss+g3–s) state individuals, with the possibility of their further transition to individuals of other growth forms: “livingstump” or “living log”. Due to the latter, it is possible to extend the ontogenesis of individual trees by another ≈200 years. And the complete ontogenesis of a tree with further transition to another growth form can be 700—800 years or more. In the absence of catastrophic impacts, old-growth forests of Siberian pine and larch can exist indefinitely. Criteria for old-growth forests in the Altai Mountains have been clarified.

Studying the growth of woody plants is extremely important due to the need to assess the response of vegetation to the ongoing climate change, especially in the mountainous regions of the Subarctic, where an increase in surface air temperature has been observed in recent decades. This paper presents the results of a study of the radial growth patterns of Dahurian larch (Larix gmelinii (Rupr.) Rupr.) at four altitudinal levels of the forest – mountain tundra ecotone on the Putorana Plateau slopes of western and eastern exposures. A comparative analysis of the radial growth magnitude and dynamics of trees belonging to 4 different age groups in forest stands of different density and altitudinal position was carried out. It was found that the radial increment’s sensitivity was higher in older trees, indicating that climatic factors had the greatest impact on their growth. It was discovered that young trees of the same age at higher hypsometric levels had higher morphometric characteristics values compared to those growing down the slope in more closed-up stands. The results of the study showed that intraspecific competition under these conditions had a greater impact on the growth of young trees than climatic factors. It was found that, while the climatic conditions in the study area underwent general improvement, no increase in the width of annual rings was observed in adult trees in recent decades. It was found that morphometric parameters and the width of annual rings in young trees had greater values on slopes of the eastern rather than the western exposure.

In Russia, given the observed trend of increasing demand for growing high-quality planting material of year-old Scots pine (Pinus sylvestris L.) seedlings with a closed root system, an increase in the planned share of them planted during reforestation up to at least 30% of the total volume comes off as natural. The objective of the study is to analyse starter mineral treatment via the means of prolonged-release fertilisers and to assess their effectiveness for growing year-old seedlings of P. sylvestris as regards their development rate and changes in their inventory and biometric indicators. The methods used were agrochemical analysis of soil, manual biometric counting of seedlings and statistical analysis. The object of the study is starter mineral treatment introduced into the cell packs with wet high-moor peat of high acidity. Starter mineral treatment using urea capsules allows achieving 98% seed germination, reducing the rate of calendar development of year-old P. sylvestris seedlings from the seeds of the XI forest seed region until they reach standard parameters with less thinning. Growing P. sylvestris seedlings with the introduction of potassium monophosphate, phosphate rock, encapsulated urea in doses of 0,0369, 3,7647, 0,1159 kg/m3, respectively, allows seedlings to reach the largest root collar diameter of up to 2,2±0,4 mm before the age of one year. The use of encapsulated urea with hydroquinone for a total dose of 0,1162 kg/m³ stimulates the growth of seedlings in stem height the most, reaching 17,9±1,4 cm. In the experimental variants, unlike in the control with “Aquarin 5” fertiliser and a 0,5 cm layer of pine sawdust, the formation of verticils was noted. The experimental variant using urea capsules is the most effective variant of starter application of mineral treatments. It allows to reach a stem height of 16,8±1,4 cm and a root collar diameter of 2,2±0,4 mm with the lowest thinning percentage equal to 16,7% of the control, up to 38,3%, after their random sampling for agrochemical analysis and removal of dead seedlings.