Vol 109, No 12 (2024)

The changes in the species structure of the tree layer of northern taiga dwarf shrub-green moss pine-spruce forests and the spatial distribution of the main forest-forming species, namely Picea obovata Ledeb., Pinus sylvestris L. and Betula pubescens Ehrh., in the process of post-fire succession are analyzed (using communities with a fire age of 80, 150 and 380 years as an example). It is established that the forest-forming species of the studied communities differ in the dynamics of participation in the composition of the forest stand during succession. In the late succession community with a fire age of 380 years, the participation of Siberian spruce, Scots pine and downy birch in the tree layer by the basal area differs insignificantly and is, respectively, 30, 43 and 27%, i.e. at the subclimax stage, the studied communities are essentially birch-pine-spruce. The spatial distribution of Scots pine and Siberian spruce in the first half of the succession can be random or weakly aggregated. In the subclimax community, the spatial distribution of these species naturally differs: Scots pine is distributed randomly, Siberian spruce has a small-group distribution. The distribution of downy birch trees through the succession is aggregated to varying degrees.

The particular ontogeny of Anemonoides sylvestris was studied in the territory of the Melovitskiye Slopes Natural Monument (south-east of the Bryansk Region). 8 ontogenetic stages (juvenile, immature, virginile, young reproductive, mature reproductive, old reproductive, subsenile, senile) were distinguished in the development of root sprouts. The state of A. sylvestris coenopopulations was estimated in polydominant steppe meadows and steppe meadows with single generative trees. The ontogenetic spectra of A. sylvestris belong to left-hand type. The turnover of generations in the A. sylvestris populations can take place only when this ontogenetic structure is maintained. For both types of communities, minimum area and minimum number of the individuals for successful turnover have been identified. 150–180 individuals are needed to maintain the coenopopulations of A. sylvestris vegetatively. This number may be achieved on a smaller area with greater illuminance of the habitat.

Currants and gooseberries are berry crops widely used by humans. The key to high yields when obtaining new plant forms is the formation of fertile pollen. This is preceded by the processes of microsporogenesis and microgametogenesis. The most important is microsporogenesis, and especially meiosis – one of the critical stages in the development of the anther. References contain information on the general structure of the anther in representatives of the Grossulariaceae family, however, meiosis in representatives of Grossulariaceae has been studied fragmentarily, that served as the basis for our study – studying meiosis during microsporogenesis and screening Ribes L. and Grossularia L., species that undergo meiosis with minimal disorders in the conditions of St. Petersburg. The objects of the study were plants of the Grossulariaceae family. Among them, there were 8 species of Ribes and 2 species of Grossularia growing in the territory of the Peter the Great Botanical Garden (Komarov Botanical Institute of the Russian Academy of Sciences). R. alpinum, R. aureum, R. nigrum, G. divaricata, and G. acicularis are local to the flora of St. Petersburg. The study of meiosis was carried out according to the method of Topilskaya, Luchnikova, Chuvashina (1975) by preparing crushed temporary micropreparations. The results showed that meiosis in Ribes and Grossularia species occurs with deviations. The nature of meiosis disorders in all species of the Grossulariaceae family is similar: at the initial stages of the first and second meiotic divisions, chromosomes are thrown out beyond the spindle of division, delayed at the equator, lagging behind or running forward, chromosome bridges, cytomixis (single). At the end of meiotic divisions, micronuclei are detected (1–2 in local species, up to 6 in introduced species). At the stage of tetrad formation, micronuclei, dyads, triads and linear tetrads can be formed. The frequency of disorders at the beginning of meiosis in local species is lower compared to introduced ones and amounts to 12–25%; in Grossularia the frequency of disorders at the end of the first meiotic division is higher compared to Ribes and amounts to 20–31%, by TII the frequency of disorders in gooseberries decreases, most of all – in G. divaricata. The frequency of meiotic disorders varies in introduced species. The least numbers of cells with disorders at all, especially final stages of meiosis are in R. mandshuricum and R. spicatum. It was established that the frequency of disorders during the formation of microspore tetrads mainly correlates with pollen fertility, which was assessed by staining with acetocarmine according to the method of Romanova et al. (1988) (pollen stained with acetocarmine is considered morphologically formed). These correlations are quite pronounced in R. maximowiczianum, R. alpinum, R. hispidulum, R. nigrum, R. saxatile, R. spicatum. The maximum fertility of pollen grains (79.6–89.5%) is found in the local species: R. alpinum, R. aureum, R. nigrum, G. divaricata. Introduced plants are characterized by lower values of the amount of morphologically formed pollen, while the average percentage of fertile pollen, sufficient for pollination and fertilization processes, is found in R. hispidulum, R. mandshuricum, R. spicatum.

The paper reports the first record of Peltigera occidentalis for the lichen flora of the Khanty-Mansi Autonomous Area – Yugra, being its second indication for Western Siberia. A brief description of the specimen with information on the anatomy, morphology of the species, composition of identified secondary metabolites, locality and distribution is given. Morphological and chemical differences from similar species are discussed.