Rastitel'nost' Rossii

The steppe vegetation of the North Caucasus, under centuries of human influence, has been almost completely replaced by croplands, orchards, and pastures. This has raised the important challenge of identifying plant communities and habitats of rare and endangered plant species in need of protection. The objective of this article is to present data on plant communities with the rare and protected species Eremurus spectabilis M. Bieb. growing in the Mineralovodskaya slopping plain and Lesisty Ridge in Stavropol Territory, North Caucasus. This study is based on 24 relevés of plant communities with E. spectabilis, carried out in 2019–2021 and 2023–2025 within the Predgorny and Andropovsky administrative districts of Stavropol Territory, on the magmatic mountains Zolotoy Kurgan, Dzhutsa, Sheludivaya, Yutsa, and Lysaya, as well as on the residual hills of the cuesta of the Lesisty ridge, referred to as the Sychevy mountains. Relevés were conducted within plant communities on sample plots 50 and 100 m2, with estimation (in %) the projective cover, total and of each species. In laboratory plant species coverage data were converted into scores using B. Mirkin scale: + — less than 1 % cover, 1 — 1–5 %, 2 — 6–15 %, 3 — 16–25 %, 4 — 26–50 %, and 5 — more than 50 %. Relevés were incorporated into the database “Vegetation of the Central Caucasus Laccolith Mountains”, developed using the TURBOVEG software and processed with the Juice program (Tichý, 2002). The syntaxonomic analysis was performed according to the Braun-Blanquet approach; the names of new syntaxa were assigned in accordance with the “International Code of Phytosociological Nomenclature” (2021). Differences in constancy were used when identifying diagnostic species of new associations and subassociations. The system of higher syntaxa is presented according to the compilation “Vegetation of Europe…” (2016) with additions. Soil descriptions of 4 profiles were conducted and 12 samples within soil profiles were collected to determine the soil physical properties, and chemical composition. Soil nomenclature is presented in accordance with the “Classification and diagnostics of Russian Soils” (2004) and the “Field Guide to Soils of Russia” (2008). Eremurus spectabilis is a perennial herbaceous plant of the Asphodelaceae family originally described in the Stavropol Territory. It is a xerothermic relict and a medium-duration ephemeral, up to height of 1–2 m. Its habitats are associated with dry, well-heated steppe rocky slopes, cliffs, and scree deposits. Eremurus spectabilis predominantly occurs within montane herbaceous-sward-grass steppes, in petrophytic vegetation assemblages, and in meadow-steppe communities. It also grows among shrubs and valley oak groves, juniper sparse woodlands, at forest edges, and in open woodlands. The species range extends from the Donbas, Crimea, and the North Caucasus to Lebanon, Iraq, southern Turkmenistan, Iran, Afghanistan, and Pakistan. Within the Russian Federation, the species exhibits a fragmented distribution. Its disjunctive areal indicates the relict nature of the current populations. Currently, the species population area is steadily declining due to habitat destruction and harvesting by local populations. It may be classified among species threatened with extinction. It is listed in the Red Data Book of the Russian Federation (2024) under conservation category 2 (species with declining population and/or distribution), with the status of a vulnerable species. Within its range in Russia, it is included in all regional Red Data Books. Syntaxonomic analysis revealed that plant communities with E. spectabilis posess block of diagnostic species that clearly distinguish them from communities of other syntaxa. Consequently, one new association and one new subassociation have been established. Nepeto pannonicae–Eremuretum spectabilis ass. nov. Holotypus — rel. 3, Table 2. Stavropol Territory, Predgornyy Disrict, 2 km W of v. Etoka, SE slope of the Dzhuza Mounthin. Coordinates, degrees (Crd) 43.918N, 42.98572E. Date: 04.06.2021. Plot size — 100 m2. Authors – T. M. Lysenko, K. V. Shchukina, V. Yu. Neshataeva. Diagnostis species — Delphinium schmalhausenii, Elytrigia trichophora, Eremurus spectabilis (dom.), Nepeta pannonica, Pyrethrum corymbosum, Vicia grossheimii. Teucrio chamaedris–Stipetum pulcherrimae eremuretosum spectabilis subass. nov. Holotypus — rel. 4, Table 3. Stavropol Territory, Predgornyy Disrict, 6 km NE of v. Etoka, S slope of the Zolotoy Kurgan Mounthin. Coordinates, degrees 43.939477N, 43.104638E. Date: 22.05.2023. Plot size —100 m2. Authors — T. M. Lysenko, K. V. Shchukina. Diagnostis species — Amygdalus nana, Eremurus spectabilis (dom.), Seseli varium. Nepeto pannonicae–Eremuretum spectabilis ass. nov. and Teucrio chamaedris–Stipetum pulcherrimae eremuretosum spectabilis subass. nov. are attributed to the alliance Festucion valesiacae Klika 1931 nom. conserv. propos order Festucetalia valesiacae Soó 1947 class Festuco–Brometea Br.–Bl. et Tx. ex Soó 1947. Communities with E. spectabilis are rare and require protection. Currently, these coenoses are protected on the magmatic mountains Yutsa, Dzhutsa, Lysaya, Sheludivaya, and Zolotoi Kurgan, which are nature monuments of regional significance. We recommend including communities of the discussed syntaxa among the rare plant associations requiring protection within the Russian Federation.

Kolyvanskoye Lake, one of the iconic lakes of Altai, the picturesqueness of which is due to the unique relief forms that appeared as a result of physical weathering of granite, has long attracted the attention of researchers. The lake’s water area is currently included in the boundaries of the natural monument of regional significance “Kolyvanka River Basin”, which received protected status in 2022. Floristic studies of Kolyvanskoye Lake have been conducted since the beginning of the 20th century by famous botanists — P. N. Krylov, V. I. Vereshchagin, P. G. Filchukova, A. V. Kuminova, E. I. Lapshina (Ilin, 1987). Special hydrobotanical studies of the lake were carried out by V. V. Ilin in 1974 (Ilin, 1987) and D. A. Durnikin with co-authors in 1996 and 2003 (Durnikin et al., 2005). The aim of our work is to identify the modern coenotic diversity of aquatic and semi-aquatic vegetation according to the Braun-Blanquet approach (1964), that was revealed based on 73 geobotanical relevés completed by the author in 2017 and 2023. It consisted of 4 classes, 6 orders, 7 alliances, 24 associations and one community: class Potamogetonetea —14 associations, Littorelletea uniflorae — 1, Phragmito-Magnocaricetea — 7, Charetea intermediae two associations and one community. The ass. Nymphaeetum sundvikii is described as new. Ass. Nymphaeetum sundvikii ass. nov. (Table 2, relevés 14–16, Fig. 1e). The diagnostic species is Nymphaea × sundvikii Hiitonen (dominant). Nomenclature type (holotypus hoc loco) — relevé 16 in Table 2 (field number 17-63): Altai Territory, Zmeinogorskiy district, Kolyvanskoye Lake, southeastern part of the lake, 51.35377° N 82.20195° E; 13.08.2017; author — L. M. Kipriyanova. This is one of the predominant associations on the lake. Depth range is 40–60 cm. There are 12 species in total, with average richness of 6.7 species per relevé. In modern syntaxonomic practice, associations with the dominance of hybrids of aquatic and semi-aquatic vegetation are usually distinguished as separate (Teteryuk, Solomeshch, 2003; Chepinoga et al., 2013). In the plant cover, among true hydrophytes, communities of the associations Trapetum natantis and Nymphaeetum candidae prevail. Quite significant areas are occupied by communities of the associations Nymphaeetum sundvikii and Hydrilletum verticillatae. It is shown that changes have occurred in the cover of the lake, namely: the thickets of Najas flexilis with Chara connivens and Callitriche hermaphroditica, have disappeared, while the ass. Hydrilletum verticillatae communities became widespread, which is likely due to global warming and an increase in the trophic status of the lakes. The significance of such dominants as Trapa natans, Nymphaea сandida, Phragmites australis remained stable. In general, Kolyvanskoye Lake was and remains a unique reservoir in terms of the state of species and coenotic diversity of aquatic vegetation. Minor changes in the species composition in recent years are apparently associated with the clarification of the species composition and not so important. The population of the key plant species, the water chestnut (Trapa natans), is in good state, its thickets occupy vast areas. The species and coenotic diversity of aquatic and semi-aquatic vegetation remains high. Kolyvanskoye Lake is distinguished by record diversity of charophytes, with 7 species recorded here (Kipriyanova et al., 2024). Such richness is apparently due to the very favorable environment conditions for macrophytes, its warming, sufficient diversity of ecotopes, and the significant age of the lake.

The brown bog-rush (Schoenus ferrugineus L.), a plurizonal European species, is calciphilous and confined to eutrophic habitats in mires and wet meadows, which often have groundwater springs. In the northwestern Russia, these are found in the west of the Leningrad and Pskov Regions (Boch, Smagin, 1987, 1993; Smagin 2008). In the north of the European part of Russia, S. ferrugineus communities are described in Karelia and the Murmansk Region (Kuznetsov, 2005, 2018; Kozhin, 2015), as well as in the Vologda and Arkhangelsk ones (Smagin, 2004, 2008, 2014). A number of works present information on flora of several small mires with the participation of S. ferrugineus in the Murmansk Region (Blinova, Uotila, 2013; Blinova, 2015; Liksakova, Koltsov, 2019). The first descriptions of S. ferrugineus communities in the northwest (Pskov and Leningrad Regions) and north of Russia (Vologda Region) are given in the M. S. Boch and V. A. Smagin papers (Boch, Smagin, 1987, 1993), who classified them as the ass. Primulo–Schoenetum ferruginei Oberd. 62, identifying three subassociations within it. Later, V. A. Smagin (Smagin, 2008, 2014) classified only communities in northwestern Russia (Leningrad and Pskov Regions) and in the Baltic region (Latvia, Estonia) as the ass. Primulo–Schoenetum ferruginei. In Karelia, the first descriptions of S. ferrugineus communities were made in the 1980s and 1990s; they were included in the ass. Schoenus ferrugineus–Campylium stellatum (Kuznetsov, 2005), identified using the topological-ecological method; however, without publishing full composition and characteristics. Over the past 15 years, V. A. Smagin has studied mires with Schoenus ferrugineus communities in the northwestern Russia in the Novgorod Region, as well as in the north of the European part in the Arkhangelsk and Vologda Regions, and identified a number of new syntaxa based on the ecological-floristic classification (Smagin, 2014; Smagin, Denisenkov, 2013; Smagin et al., 2015); however, tables of their full species composition have not been published. The aim of this article is a comparative analysis of Schenus-Hypnum communities in the European North and in the Baltic regions and the development of their unified classification according the ecological-floristic method. For a comparative analysis of the composition of newly identified syntaxa and the degree of their similarity with previously described syntaxa, data from a number of publications were used (Kask, 1965; Oberdorfer, 1977; Tyler, 1979, 1981; Dierssen, 1982; Laivinsh, Swars, 1993; Smagin, 2008, 2014; Ivchenko, 2012). To establish the degree of similarity of the considered syntaxa of the union Caricion davallianae in the European North and in the Baltic region (Table 4), a comparative analysis was performed using the Sørensen similarity coefficient (Vasilevich, 1969) and a similarity dendrogram was constructed in the PAST program (Hammer et al., 2001). Using the nonmetric scaling (NMS) method (Clarke, 1993), an ordination of syntaxa was performed taking into account species constancy. Species with constancy classes of at least III in at least one syntaxon were included in the analysis. As a result of the analysis of the species composition of the original community relevés and the composition of published syntaxa, supplemented by the results of cluster analysis and ordination, a number of syntaxa of Schoenus-Hypnum communities in the European North and the Baltic region were identified. The developed classification includes three associations, six subassociations, two variants, and one out-of-rank community. The ass. Primulo–Schoenetum ferruginei (W. Koch 1926) Oberd. 1957 in northwestern Russia is located at the eastern border of its range (Boch, Smagin, 1993; Smagin, 2008, 2014) and differs somewhat in composition from the Central European communities. A comparative analysis of syntaxa assigned to this association (Table 4, synt. 1–6) allowed us to distinguish two subassociations: typicum and salicetosum rosmarinifoliae subass. nov. The ass. Trichophoro–Schoenetum ferruginei (Booberg 1930) Gӧrs 1964, is widespread throughout Fennoscandia. It is confined to hardwater calciphilic mires with groundwater spring, as well as low ridges of eutrophic aapa mires, lakeside and coastal mires. The ass. Tomentypno nitentis–Schoenetum ferruginei Smagin ex Kuznetsov et Smagin ass. nov. was described in four mires with mineralized water outlets on the northern bank of Lake Vozhe (Arkhangelsk region) (Smagin, 2014) and in slope spring mires east of Lake Radionskoye and northwest of the Savino village in the Belozersky district of the Vologda Region (Boch, Smagin, 1993; Smagin, 2014). In these mires along with S. ferrugineus communities, reed communities with Schoenoplectus tabernaemontani are widely represented, which is also found in low abundance in a number of S. ferrugineus communities. Community Schoenoplectus tabernaemontani–Schoenus ferrugineus (Table 3, rel. 1–5, Table 4, synt. 15). The differentiating species combination (d.s.c.) includes diagnostic species of the alliance Caricion davallianae Klika 1934: Schoenus ferrugineus, Potentilla erecta, Campylium stellatum, Scorpidium cossoni, as well as Schoenoplectus tabernaemontanii, Molinia caerulea, Filipendula ulmaria, Ligularia sibirica, and Thelypteris palustris. Five times described in the Kholmsky district of the Novgorod Region south of the town of Kholm in the Solenoye mire with groundwater springs. In the plant cover of this mire, along with Schoenus species, communities of Schoenoplectus tabernaemontanii with the Cladium mariscus and without S. ferrugineus are represented (Smagin, 2014). All identified associations are assigned to the union Caricion davallianae, the syntaxa of which (with significant number of Atlantic and amphi-Atlantic species, some of which are diagnostic for the union and order) are distributed mainly in Western and Central Europe (Peterka et al., 2017). In this article, based on the analysis and synthesis of the authors’ data and literature, an ecological-floristic classification of Schoenus-Hypnum communities from Norway to the northern European part of Russia has been developed. For the first time, four subassociations, two variants, and one out-of-rank community are identified. The validity of the syntaxa is well supported by the results of cluster and ordination analyses. The syntaxa are clearly distinct geographically, due to the differences in their species composition because of the floristic characteristics of their distribution regions. Mires with Schoenus-Hypnum communities in northwestern and northern Russia require protection via organization the specially protected natural areas of varying status. In the Republic of Karelia, they are protected in Paanajärvi National Park, in the Pskov and Novgorod regions in the Izborsko-Malskaya valley and Batutinka river valley and mires in its catchment area, while in the Leningrad, Vologda, and Arkhangelsk regions, mires with S. ferrugineus are not yet protected.n Federation.

The Central Chernozem Nature Reserve is located in the southwestern part of the Central Russian Upland in the Kursk Region and consists of six sites with a total area of 5287.4 hectares. Virgin meadow steppes on the flat interfluves are protected on the territory of two of them — Streletsky and Kazatsky, organized in 1935. The article analyzes the vegetation of virgin steppes on the flat interfluves of Streletsky and Kazatsky sites under various protection regimes (4- and 5-year mowing rotation, 10-year mowing rotation with aftermath pasture, annual mowing and pasture regime) in comparison with communities with regular haymaking and pasture use, being here before the foundation of the Nature Reserve. Phytocenoses under absolutely protection regime are not considered in this article, and will be the subject of special publication. The study is based on 169 published relevés made over the period 1928–2015 (Komarov & Proskuryakov, 1931; Alekhin, 1935; Redulesku-Ivan, 1965; Averinova, 2005, 2010; Zolotukhin et al., 2015, 2017). All analyzed communities are assigned to the alliance Cirsio–Brachypodion pinnati Hadač et Klika in Klika et Hadač 1944 and the order Brachypodietalia pinnati Korneck 1974 nom. conserv. propos. of the class Festuco-Brometea Br.-Bl. et Tx. ex Soó 1947. The alliance and order unite the most mesophytic meadow steppes of the European part of Russia, located on the flat interfluves and slightly eroded slopes with well-developed chernozems and deep occurrence of carbonate bedrocks. Phytocenoses of this alliance on the flat interfluves have survived only in nature reserves. A comparative analysis of the species composition of two groups of phytocenoses — modern (2003–2015) and historical (1928–1963) — revealed a high degree of similarity, which is confirmed by the value of the Chekanowski–Dice–Sørensen coefficient (0.8). This value demonstrates the stability of the species composition of the studied virgin steppes over 87 years and allows to group all studied communities into the ass. Stipo tirsae–Bromopsietum ripariae Averinova 2010 nom. conserv. propos. (syn. Agrostio vinealis–Avenuletum schellianae Royer 1991 [syntax. syn.]) (Royer, 1991; Averinova, 2010). Dynamic processes in vegetation are shown at the level of syntaxa ranked below the association. Within the association two subassociations are established. Stipo tirsae–Bromopsietum ripariae subass. typicum (Table 1; Table 2; Table 5, syntaxa 1–4). The nomenclatural type, indicated in the original diagnosis of the association as a lectotype is automatically becoming the type of subass. typicum [Art. 5b], — Table 2, relevé 2: Streletsky site of the Central Chernozem Nature Reserve, quarter 20, section 15, flat interfluve, 02.07.1963, author — D. Redulesku-Ivan. Diagnostic species: Berteroa incana, Helichrysum arenarium, Jurinea arachnoidea, Sedum acre, Tephroseris integrifolia, Trinia multicaulis, Trommsdorfia maculata, Verbascum phoeniceum. The subassociation is established on the basis of 73 relevés made in 1928–1963 (Komarov & Proskuryakov, 1931; Alekhin, 1935; Redulesku-Ivan, 1965). Thus, this syntaxon encompasses virgin steppes on the flat interfluves of Streletsky and Kazatsky sites, existed before the foundation of the Nature Reserve and during the first decades of its operation. The communities of this subassociation are not represented in the current vegetation cover of the Nature Reserve. They transformed and occupied a new position in the syntaxonomic hierarchy. The subassociation contains four variants (typica, Erigeron acris, Hyacinthella leucophaea and inops), with communities differing in species composition, localization and time of existence. Stipo tirsae–Bromopsietum ripariae arrhenatheretosum elatioris subass. nov. (Table 3; Table 4; Table 5, syntaxa 5–11). Nomenclatural type (holotypus) — Table 4, relevé 3: Streletsky site of the Central Chernozem Nature Reserve, quarter 12, section 1, flat interfluve, 18.07.2005, authors — N. I. Zolotukhin, Е. S. Оbukhova. Diagnostic species: Arrhenatherum elatius (dom.), Calamagrostis epigeios, Campanula patula, C. rotundifolia, Centaurea jacea, Dactylis glomerata, Draba sibirica, Galium mollugo, Hypericum perforatum, Melampyrum argyrocomum. The subassociation is established on the basis of 69 relevés made in 2003–2015 (Averinova, 2005, 2010; Zolotukhin et al., 2015, 2017); syntaxon encompasses current virgin steppes on the flat interfluves of Streletsky and Kazatsky sites. The subassociation contains seven variants (typica, Agrimonia eupatoria, Campanula bononiensis, Dracocephalum ruyschiana, Odontites vulgaris, Polygonum aviculare and inops), with communities differing differ in species composition and localization. The established variants are links in the succession series (Fig. 8 and Fig. 9). To analyze the dynamics of phytocenoses in relation to changing environmental conditions DCA-ordination is used (Fig. 5). It showed that the main direction of meadow steppes succession is determined by the complex gradient of the hydrothermal regime of the upper soil horizons and illumination on the soil surface (axis 1). These factors directly depend on the intensity of aboveground phytomass removal. If it is insufficient, the mortmass accumulating on the soil surface contributes to moisture retention and shading. Under such conditions, more moisture-loving and shade-tolerant species gain an advantage. Therefore, the protection regime is crucial for the dynamics of the analyzed vegetation. The main direction of steppe vegetation succession, coinciding with axis 1, is mesophytization. It is not a transformation into a meadow, but that into a fringe vegetation of the class Trifolio–Geranietea sanguinei. These rules are common to all nature reserves of the European forest steppe. The process of steppe mesophytization, associated with the transformation into а fringe vegetation and subsequent sylvatization, occurs most rapidly in areas with an absolutely protected regime, which are not discussed in this article. The other protection regimes inhibit this process to varying degrees, but do not stop it completely. The annual mowing regime is the most preferable for the conservation of meadow steppes. Under this protection regime the phytocenoses have retained the greatest similarity with the «original» state of the steppes, characteristic of 1928–1934.

Braun-Blanquet classification of piedmont and mountain beech forests (formed by Fagus orientalis) was carried out, basing on 178 relevés collected in 2014–2018 in the North-Western Caucasus (N 43,5–44,8°, E 38,5–41,5°; Fig. 1). To reveal ecological interpretation of the developed classification, DCA-ordination of the data was done together with analysis of several environment variables (absolute elevation, geographical coordinates, cover of tree layer, calculated values in Landolt’s ecological scales). Resulting from the analysis carried out, 4 new associations were established (one of them includes 2 subassociations) within order Rhododendro pontici–Fagetalia orientalis Passarge 1981. Their floristic differentiation is shown in Table 2 and Fig 7. In the North-West Caucasus, most oriental beech forests belong to ass. Myosotido dissitiflorae–Fagetum orientalis ass. nov. (Table 3, holotypus of the association is relevé 12: author’s number 869, author N. E. Shevchenko, 16.07.2018, 43.782°N, 42.056°E, 1302 m above sea level, slope 8°SW). Besides subass. typicum (Table 3: 1–20), this association includes subass. piceetosum orientalis (Table 3: 21–30; holotypus is relevé 23: author’s number 572, author N. E. Shevchenko, 26.05.2017, 43.859°N, 40.948°E, 1022 m above sea level, slope 8°SE). Also assigned to the alliance are ass. Aro maculati–Fagetum orientalis ass. nov. (Table 3: 31–40; holotypus is relevé 37: author’s number 477, author N. E. Shevchenko, 17.05.2017, N 44.272°, E 40.477°, 776 m above sea level, slope 5°N), ass. Lonicero caprifolii–Fagetum orientalis ass. nov. (Table 4: 1–10; holotypus is relevé 3: author’s number 445, author N. E. Shevchenko, 14.05.2017, N 44.337°, E 40.491°, 592 m above sea level, slope 8°N), and ass. Polygonato verticillati–Fagetum orientalis ass. nov. (Table 4: 11–20; holotypus is relevé 11: author’s number 752, author N. E. Shevchenko, 04.07.2018, N 43.602°, E 41.636°, 1614 m above sea level, slope 10°NW). DCA-ordination (Fig. 7) revealed that the established syntaxa differ in their floristic composition in accordance with absolute elevation (vector Elev in Fig. 8) of the relevés. In addition, floristic difference between these syntaxa is consistent with environment parameters estimated by Landolt’s scales T (the averaged air temperature during the growth period) and N (soil nutrients) (Fig. 8). Thus, the forests of the typical ass. Myosotido dissitiflorae–Fagetum orientalis (both sybassociations) are confined to drained surfaces within the middle and high mountain belts. The communities of ass. Aro maculati–Fagetum orientalis are confined to wet fertile soils on flat surfaces within the middle mountain belt. The communities of ass. Lonicero caprifolii–Fagetum orientalis occur within the low and middle mountain belts, and even somewhere in the piedmonts. The forests of ass. Polygonato verticillati–Fagetum orientalis are confined to the upper forest boundary within the high mountain belt where this line is anthropogenic and conditioned by clearing for pastures. Revealed from the floristic comparison (Table 5, Fig. 10) of oriental beech forests and mixed fir-beech forests of several regions (North Turkey, East Bulgary, the Crimea, the Colchis, the Central Caucasus – Georgia, and the North-Western Caucasus) (Passarge, 1981, Korzhenevskiy, Kiselev, 1982; Korotkov, Belonovskaya, 1987; Didukh, 1996; Tatli et al., 2005; Frantsuzov, 2006; Tzonev et al., 2006; Yıldırım, Kılınç, 2011; Kavgacı et al., 2012; Willner et al., 2017; Çoban, Willner, 2019; Ermakov et al., 2023), the alliance Fagion orientalis Soó 1964 demonstrates strong heterogeneity corresponding with regions. For example, flora of the North-Western Caucasus beech and fir-beech forests includes none Mediterranean species, and the few Euxinian species are constant there, whereas there are various species that are character for European temperate broad-leaved forests (e. g. Ulmus glabra, Euonymus europaea, Moehringia trinervia, Luzula pilosa, Oxalis acetosella) are constant as well as some Caucasian species (e. g. Paris incompleta, Myosotis dissitiflora, Polygonatum glaberrimum). The named species differentiate the North-Western Caucasian beech and mixed forests from the ones in Euxinean subtropical regions. This reflects the difference between temperate climate in the North-Western Caucasus situated on the northern macroslope of the Greater Caucasus and subtropic climate on its southern macroslope and in other Euxinean regions (excluding the Crimea) (Alisov, 1947). The absence of Mediterranean and most Euxinean species is also character for beech forests investigated by H. Passarge (1981) in the Central Caucasus (Georgia), whereas these communities are positively differentiated, because of temperate continental climate, by some xeromesophilous species (e. g. Cephalanthera longifolia, Carex divulsa, Platanhera chlorantha) and the species of European temperate broad-leaved forests also. Furthermore, syntaxa of the Crimean beech forests also have clear floristic distinctions from North Turkey and East Bulgarian communities. Because of all this, the current alliance Fagion orientalis Soó 1964 cannot be considered as an appropriate syntaxone comprehending oriental beech and fir-beech forests of the listed regions. As the first step to revise the contemporary syntaxonomy of these forests, proposed is to establish a new alliance Myosotido dissitiflorae–Fagion orientalis all. nov. that will include the four new associations of the North-Western Caucasus, with ass. Myosotido dissitiflorae–Fagetum orientalis chosen as the holotypus of this new suballiance. In the Central Caucasus, a new alliance Carici divulsae–Fagion orientalis all. nov. is also proposed that will include the associations Dentario–Fagetum orientalis Passarge 1981, Polysticho–Fagetum orientalis Passarge 1981, and Lathyro laxiflori–Fagetum orientalis Passarge 1981 nom. corr. et mut. nov. (the former Orobo–Fagetum orientalis Passarge 1981 nom. inept.), with the last one chosen as the holotypus of the new alliance. As the next step, the former invalid alliance Abieti nordmannianae–Fagion orientalis Korotkov et Belonovskaja 1987 is proposed to validize and to add with subalpine broad-leaved forest associations Petasito–Fagetum orientalis Passarge 1981, Veratro–Fagetum orientalis Passarge 1981, and Pyrolo–Fagetum orientalis Passarge 1981.

This paper presents the brief biography of the Russian geobotanist N. M. Savich (1894–1990). Her life was long and dramatic. She faced criminal charges twice, accused of dissent and anti-Soviet statements. As a result, N. M. Savich was only able to actively pursue geobotany for a short period, from 1920 to 1936. Moreover, for three years of them (1930–1933), she conducted geobotanical research while in exile in Eastern Siberia. After 1936, she was denied employment in her field and was forced to work as a laboratory assistant at a district clinic. N. M. Savich was one of the first Russian phytosociologists whose association names comply with the rules of the «International Code of Phytosociological Nomenclature». This fact was first recognized in the publication by G. S. Taran (2004), who cited the names of four associations established by N. M. Savich: Phragmitetum communis Savich 1926, Eleocharitetum palustris Savich 1926 nom. corr., Caricetum gracilis Savich 1926, Caricetum aquatilis Savich 1926. Publication by G. S. Taran was noticed by the Czech geobotanist K. Šumberová, which was initially reflected in the work of her graduate student (Juříček, 2009), who named the plant community dominated by Carex acuta L. Caricetum gracilis Savich 1926. Then the first three of the above-mentioned association names appeared in the «Katalog biotopů České republiky» (“Vegetation of the Czech Republic”, the chapters on relevant associations within the class Phragmito-Magno-Caricetea, see Šumberová, 2011a, b, c). K. Šumberová transliterated the surname Savich into letters of the Czech alphabet, so it was written as Savič. She also performed the correction of the name Phragmitetum communis Savič 1926, which began to look like Phragmitetum australis Savič 1926 nom. corr. Subsequently, the name Caricetum gracilis also underwent a correction, which began to be used as Caricetum acutae Savič 1926 nom. corr. After the publication of the third volume of «Vegetace České Republiky», the above-mentioned names of associations with the authorship of N. M. Savič were established in Italy (Landucci et al., 2013; Lastrucci et al., 2023), the Asian part of Turkey (Özdeniz et al., 2017), France (Delcoigne, Thébaud, 2018; Terrin, Hamon, 2022), Montenegro (Stešević et al., 2020), Ukraine (Rozenblit, 2020), Austria and Slovakia (Willner et al., 2022). There are numerous other publications, both in Russia and abroad, in which the names of the associations Phragmitetum australis, Eleocharitetum palustris, Caricetum acutae appear, authored by N.M. Savich. In many cases, these publications transliterate Savich’s name as K. Šumberová did – Savič. Three years after the publication of «Vegetace České republiky» V. Chepinoga (2014) recognized another association name authored by N. M. Savich, namely, Glycerietum spiculosae Savich 1967. As can be seen, numerous precedents already exist for the use of association names established by N. M. Savich in syntaxonomy. The author proposes to introduce into scientific circulation additionally the following names of associations proposed by N. M. Savich: Alopecuretum pratensis Savich 1926, Beckmannietum eruciformis Savich 1926, Caricetum appendiculatae Savich 1967, Caricetum canescentis Savich 1926, Caricetum loliaceae Savich 1926, Caricetum pseudocuraicae Savich 1967, Caricetum salinae Savich 1926, Deschampsietum caespitosae Savich 1928, Equisetetum fluviatilis Savich 1928 nom. corr., Festucetum rubrae Savich 1926, Glycerietum fluitantis Savich 1926, Poetum trivialis Savich 1928, Poo angustifoliae–Veratretum albi Savich 1928 nom. invers.

Large-scale mapping of the vegetation of Saint Petersburg revealed the predominance of pine-spruce and spruce-pine stands among coniferous forests, to which both spruce (Picea abies) and pine (Pinus sylvestris) contribute in different proportions. For the purposes of geobotanical mapping reflecting vegetation dynamics, it is important to establish the dynamic category of such communities in order to clearly determine whether they should be classified in maps legends as spruce or pine formation, or their own category. This issue has been controversial for a long time. V. N. Sukachev (1908) argued that due to the lack of pine renewal, pine-spruce forests would necessarily turn into spruce ones. G. F. Morozov (1930), on the contrary, considered pine-spruce forests to be a stable formation for such habitats as sandy loam or loam soils of medium richness, without specifying their origin. Both the first and second theories have found their supporters. The purpose of the article was to study the dynamics of the pine-spruce forests of the studied territory by analyzing changes in all vegetation layers, species composition and structure of the ground cover in 2006–2024 and to establish their dynamic category. Three permanent sample plots occupied by pine-spruce forests were established for analysis. They are located in the southern taiga subzone, in two Saint Petersburg nature reserves (Fig. 1). Five observations on each sample plot (with intervals of 3–4 years) included complete taxation of the tree and shrub layers as well as the young growth; reveal of the whole species composition and determination of the vascular plant and moss ground species cover; identification of the ecological-coenotic groups and horizontal structure of the lower layers (Smirnov et al., 2006; Khramtsov et al., 2011); calculation of general and partial (separately for vascular plants and bryophytes) ground species turnover (Koch, 1957). NMDS-ordination (Bray-Curtis distance, «year» as the only factor) (Oksanen et al., 2013) was made to reveal if there is a trend in changes of ground species composition and cover. A brief characteristic of the three community types (Pineto-Piceetum oxalidoso-myrtillosum, Pineto-Piceetum myrtilloso-hylocomioso-sphagnosum and Pineto-Piceetum (oxalidoso-) myrtilloso-sphagnosum) are given in text with detailed information in tables. All of these are located on poor soils (sandy, sandy loam, drained peat). Spruce age ranges between 60 and 100 years, pine— between 80 and 140. General view of the communities is shown in Fig. 2–4. Results of 15–16 years of observations on the permanent sample plots showed that changes in species composition and horizontal structure in the studied forests (Table 1–6) are mostly related to local natural (windfalls and their consequences) and anthropogenic (ditch cleaning, soil dumping) disturbances; there are no replacements in dominant species. The ratio of pine and spruce stock within the stand is relatively constant (Fig. 5, 7, 9). Active self-thinning of the stands is observed: in the course of observation, the number of trees has decreased on average by 27 %. Hardwood trees (particularly birch) have been gradually falling out. In the period between observations, 1–2 pine trees and 2–11 spruce ones of different ages die. The resupply of the stands consists of spruce only. Due to the high intraspecific competition, it is very slow (on average, one individual per 4 years). The share of pine in the ratio of pine and spruce trees number is stable at all sample plots; for spruce its share is constant at ГЗ-3, while at two others it has increased due to hardwood trees dieback. Spruce trees are presented in more diameter gradations, than pine ones (Fig. 6, 8, 10). The overall turnover of the ground species composition over the entire observation period is similar at all sample plots, averaging about 50 %, mainly due to variations in the bryophyte species presence. Results of the NMDS-ordination (Fig. 11) shows that changes in ground species composition and cover are statistically insignificant at all plots (p = 0.17; 0.24; 0.92 for ГЗ-3, КБ-4 and КБ-6 respectively with p = 0.05 significance level). Data received fit the concept that pine-spruce forests will inevitably transform into pure spruce forests (Sukachev, 1908): spruce mean annual increment is much higher (Table 7), pine undergrowth is almost absent. However, since pine is greater resistant to such catastrophic impacts as fires and windthrows, its presence in stands will be substantial for a long time (taking into account pines current age and under maintaining the protected area regime — at least 40–50 years). The authors believe that spruce and pine trees in Saint Petersburg are in constant dynamic interaction; the restoration of spruce forests might have happen over a long period without fires (more than 200–300 years), but their recurrence near populated areas and highways is much more often (Andreyev, 2003). Our data on overall ground species and vascular plants composition turnover are close to data received by other researchers; as for ground bryophytes, the difference between turnover values is so high that we cannot definitely determine whether our data correspond to “normal” turnover or not. Consequently, the pine-spruce forests in Saint Petersburg on sandy and sandy loam substrates, as well as on drained peats, may be considered as relatively stable long-term secondary forest stands, which may be shown on maps of actual vegetation as independent units that are not subordinated to conventionally primary spruce forests.

The paper presents information on xerophytic grasslands on sands and sandy soils in steppe and forest-steppe zones at the Ob-Irtysh watershed. From the database, 255 relevés were selected that contained diagnostic species of the class Festucetea vaginatae Soó ex Vicherek 1972. At the next stage, the ratio of diagnostic species of this class to the class Festuco-Brometea Br.-Bl. et R. Tx. in Br.-Bl. 1947 was assessed, on the basis of which the syntaxonomical affiliation of the relevés was determined. Psammophytic vegetation belongs to two classes. In the studied area it is represented by three associations and one community. The specific features of West-Siberian psammophytic communities and their diagnosis were determined based on comparative analysis of new data and associations from the class described in Russian Federation (Golub et al., 1994; Maltsev et al., 2011; Demina, 2015; Dulepova et al., 2018; Korolyuk et al., 2019, 2023, 2024). For this purpose, we used cluster analysis (Ward method, Czekanowski-Dice-Sorensen similarity coefficient). The data set was stored and processed in IBIS 7.2 software (Zverev, 2007) and Statsoft Statistica v. 8.0. The identification of new syntaxa was done in accordance with the “International Code of Phytosociological Nomenclature. 4th edition” (Theurillat et al., 2021). The class Festucetea vaginatae and the order Festucetalia vaginatae Soó 1957 represent psammophytic vegetation in steppe and forest-steppe landscapes within the Black Sea – Kazakhstan steppe sub-region of the Eurasian steppe region (Lavrenko et al., 1991). The cluster analysis showed the isolation of the described syntaxa within the class Festucetea vaginatae (Fig. 6). From the diagnostic combination of the class and the order in Western Siberian communities, Artemisia marschalliana, Festuca beckeri, Gypsophila paniculata, Helichrysum arenarium, Kochia laniflora, Leymus racemosus, Linaria genistifolia, Scorzonera ensifolia, Silene borysthenica, Stipa borysthenica, Syrenia siliculosa are noted. At the same time, Achillea micrantha, Agropyron fragile, Astragalus varius, Carex colchica, Centaurea arenaria, Chondrilla juncea, Chondrilla graminea, Euphorbia seguieriana, Jurinea polyclonos, Jurinea cyanoides, Linaria odora, Linaria genistifolia, Potentilla arenaria, Secale sylvestre, Syrenia montana are absent or have low constancy (Table 2). The absence of these species can serve as an additional indication for the new syntaxa. The class Festucetea vaginatae on the territory of Siberia includes the only alliance Sileno borysthenicae–Cleistogenion squarrosae Korolyuk 2017 which we previously attributed to the class Festuco-Brometea (Korolyuk, 2014, 2017). Diagnostic species (D. s.) of the alliance: Androsace maxima, Artemisia frigida, Artemisia scoparia, Astragalus testiculatus, Carex praecox, Carex supina, Cleistogenes squarrosa, Erysimum canescens, Herniaria polygama, Jurinea schischkiniana, Koeleria glauca, Phleum phleoides, Polygonum gracilius, Polygonum patulum, Potentilla acaulis, Potentilla humifusa, Veronica spicata. Ass. Jurineo schischkinianae–Stipetum borysthenicae Korolyuk et Chupina ass. nov. (Table 1, rel. 1–15), holotypus — Table 1, rel. 6 (field no. 93-041), Altai Territory, Egoryevskiy District, 5 km north-west from Novoegoryevskoe village, glade in a pine forest, 51.75°N, 80.83°E, 14.06.1993, author — A. Yu. Korolyuk. D. s.: Arabidopsis thaliana, Dianthus versicolor, Euphorbia caesia, Jurinea schischkiniana, Kitagawia baicalensis, Pinus sylvestris (juv.), Pulsatilla patens, Silene baschkirorum, Silene chlorantha. These are psammophytic steppes widely distributed within the steppe zone in the Kulundinskaya, Kasmalinskaya and Barnaulskaya pine forest strips (Fig. 2, 3). Ass. Sileno borysthenicae–Cleistogenetum squarrosae Korolyuk 2014 (syntax syn. Scorzonero ensifoliae–Festucetum valesiacae Korolyuk 2014) (Electronic supplements: Table 1). D. s.: Artemisia frigida, Artemisia glauca, Astragalus testiculatus, Bromopsis inermis, Festuca valesiaca, Koeleria cristata, Medicago falcata, Nonea rossica, Stipa capillata. These are psammophytic steppes widely distributed in the Ob-Irtysh watershed. Its range is limited mainly by the steppe zone, only in the southwestern parts of the Kulunda and Proslaukhinskiy pine forests it covers the adjacent territories of the forest-steppe Priobskoe plateau (Fig. 2, 4). Com. Artemisia nitrosa–Koeleria glauca (Table 1, rel. 16–20) are coenoses on saline sands in conditions of close groundwater table, that occur as part of halophytic-steppe vegetation complexes (Fig. 5). The community area is limited to the south-west of Altai Territory. Their species composition is heterogeneous, with both halophytes character of the class Festuco-Puccinellietea Soó ex Vicherek 1973 and psammophytes. The ass. Gypsophilo paniculatae–Artemisietum glaucae Korolyuk 2014 (Electronic supplements: Table 2) is attributed to the class Festuco-Brometea according to dominance of diagnostic species of this class. It unites psammophytic variants of bunchgrass typical steppes in the steppe zone and with active participation of facultative psammophytes against the background of dominance of widespread steppe xerophytes, primarily bunchgrasses. D. s.: Artemisia frigida, Artemisia marschalliana, Cleistogenes squarrosa, Gypsophila paniculata, Helichrysum arenarium, Silene borysthenica, Stipa borysthenica. The association belongs to the alliance Carici supinae–Stipion zalesskii Korolyuk 2017 all. prov. that is distributed from the Southern Urals to the eastern regions of the West Siberian Plain. Data on the pattern of psammophytic communities of two classes is presented for the first time for the territory of Siberia (Fig. 2).

In the 1990s, agricultural land use across the Eastern Europe significantly declined, leading to widespread reforestation on former arable lands (Lyuri et al., 2010). In the Smolensk Region, the highest proportion of abandoned agricultural lands among the non-chernozem areas of the European Russia has been recorded (Ershov et al., 2022). An integrated analysis of successional dynamics in vegetation and soil is critically important for developing effective management strategies for post-agricultural ecosystems and understanding pathways for soil and vegetation restoration in forest ecosystems. The Smolenskoye Poozerye National Park, located in the ecotone of boreal and broadleaf forests and characterized by high landscape and cenotic diversity, serves as a unique model territory for such studies. Approximately 42 % of contemporary forests (50,000 ha) grow on former agricultural lands abandoned at various periods. Forested areas increased by 18 % between 1990 and 2015, with birch stands occupying 46 % and pine stands 10 % of the previously non-forested territories (Koroleva et al., 2018). The aim of this study was to identify similarities and differences in post-agricultural successions of vegetation in pine, spruce, and mixed coniferous-broadleaf forests. To analyze the dynamics of the parameters of the functional organization and species diversity of phytocenoses in relation to soil properties. The article examines 10–30-year-old stands and agrocenoses along with fallows of various ages on sandy agrozem grey-humus soils and loamy agro-podzolic soils. Field studies were conducted in 2021–2024. Vegetation relevés were carried out on sample plots 20×20 m for forest communities and 10×10 m for agrocenoses and fallows. 73 relevés were performed (Fig. 1). Soil cross-sections were dug at one per replicate stage of forest recovery, with 35 cross-sections in total. Soil samples for chemical analysis were taken from genetic horizons in 33. To investigate the dependence of functional organization and species diversity of post-agricultural phytocoenoses on soil properties, texture, pH, total carbon and nitrogen content, and available phosphorus and potassium were determined for each sample plot. Results are presented for the series and stages of post-agricultural succession. The characteristics of post-agricultural vegetation are provided in Tables 1, 3, and 4, photos of communities are given in the Fig. 3–11. Parameters of species diversity, richness, ecological-cenotic structure, and proportional contributions of life forms are detailed in Table 2. At the initial stage, all series were characterized by the dominance of Elytrigia repens, resulting in the prevalence of long-rhizomatous life forms and ruderal-meadow ecological groups. On fallow meadows in the pine and spruce series, taproot species dominate, whereas in the coniferous-broadleaf series, long-rhizomatous species maintain a slight prevalence. In young forests, short-rhizomatous species mostly dominate, though under richer soil conditions, differences between major life forms are less pronounced. Intensive anthropogenic impacts (plowing, fertilization, and herbicide application) partially obscure differences between the series caused by varying soil conditions. However, a clear trend of increasing community complexity is observed from the pine to the coniferous-broadleaf series. As in the initial stage, species diversity, species saturation, and richness increase from the pine to the coniferous-broadleaf series on the fallow meadow stage and surpass the levels recorded on the initial one. The minimum species richness for all stages and series occurs in fallow meadows of the pine series, likely due to the light texture and unstable moisture regime of the soils, which limit plant access to nutrients, particularly nitrogen. In this study, the maximum values of species diversity and richness were recorded on the young forest stage, with the highest levels observed in the coniferous-broadleaf series (Table 2). The leading factors differentiating vegetation on the early stages of post-agricultural succession, as shown by NDMS analysis (Fig. 12), are light availability, soil fertility (nitrogen richness and pH), and moisture. The ecosystems of the three chronosequences develop on substrates with diverse texture, fertility, and acidity (Fig. 13, Table 5). Agrozem soils in the pine and spruce series were formed on sandy-loamy and light loamy podzolized soils, respectively. Unlike the pine chronosequence, where subsoil layers are predominantly sandy, spruce series soils more frequently have at least light loamy texture, with no sandy subsoil. Coniferous-broadleaf forests develop on podzolic soils associated with medium to heavy loam. The 0–30 cm root zone of soils of the coniferous-broadleaf series differs most significantly from the pine and spruce ones in terms of texture, weighted average content of total carbon and nitrogen, and available phosphorus, while no significant differences were found in pH. From the pine to the spruce and coniferous-broadleaf series, the content of sand decreases and that of silt increases. The available phosphorus content is the highest in soils of the pine series, likely due to greater fertilization necessitated by lower natural fertility. Chemically, spruce series soils are closer to those of the pine series than to the coniferous-broadleaf ones. A distinctive feature of post-agricultural succession is the decrease of soil fertility on the initial stages as reserves of biogenic elements added through fertilizers are consumed (Lyuri et al., 2010). In the 0–30 cm soil layer of all three chronosequences from meadow to forest stages the pH value decreases by 0.6–1.0 times, and available potassium decrease by 1.4–2.6. A significant reduction in total carbon and total nitrogen content was observed in the spruce and coniferous-broadleaf series. For available phosphorus content, a significant decrease was identified only in the coniferous-broadleaf chronosequence (Fig. 13). Tree colonization in all series occurred within 2–3 years after the last plowing under favorable conditions, consistent with other studies (Ruskule et al., 2012; Moskalenko & Bobrovsky, 2014). The main factor determining the success of early-successional tree species invasion is the distance from diaspore sources. Most pine and birch seeds are dispersed by wind over distances up to 200–250 m. The results of correlation analysis between soil and vegetation parameters are presented in Table 6. A comparison of post-agricultural community development across the three chronosequences allows the following conclusions. The development of vegetation after plowing has ceased, can proceed in two ways: either rapid colonization by early successional tree species and the formation of young forests occurs, or perennial fallow meadows are formed. The first stages in all series are characterized by small proportion of annual species even in agrocenoses and the dominance of the weed fraction, among which weed-meadow species prevail, and among life forms, long-rhizome plants make the greatest contribution. The predominance of taproot species, considered characteristic of the first stages of post-agrogenic successions (Ipatov, Kirikova, 1997), is not confirmed by our data. Species diversity and richness increase from the agrocenosis and young fallow stages to the forest one, with the trends most pronounced under heavier and wetter soil conditions. In soils with lighter texture, boreal ecological group species dominate young forests, whereas nemoral and nitrophilic species prevail under richer and wetter conditions. In chronosequences, where birch stands are formed in the course of forest recovery, meadow ecological group species persist longer. In pine forests, the poorer species composition and the reduction in the diversity of life forms, cenotic and ecological-cenotic groups contribute to the fact that they more quickly acquire forest appearance, and simultaneously with the formation of litter, the moss cover with the dominance of Pleurozium schreberi begins to recover. The ratio of ruderal and ruderal-forest groups decreases more rapidly in pine chronosequence.

Multi-year dynamics is an integral property of plant communities. It includes fluctuations — non-directional shifts in plant species abundance, cyclic dynamics — repeated directional changes with subsequent coming back close to initial stage, and successions — directional changes leading to a community ready to be classified as a new syntaxon (Rabotnov, 1983; Onipchenko, 2013). The analysis of the methods for studying the interannual dynamics, including the establishment of field observations and data statistical analysis, was performed on the base of Russian and foreign papers, mostly published in peer-reviewed journals in recent decades. The main aims of interannual dynamics studies are (1) to describe the community composition and structure variability under natural and experimental conditions in different years; (2) to analyze the variability causes; (4) to predict the further community development, to assess sustainability and to assess conservation strategy. The description of dynamics is based on the abundances of plant species or their groups, which can be measured as cover, number of individuals, occurrence, or biomass. The species number richness per plot, Shannon and Simpson diversity indices, as well as functional diversity indices (functional richness, evenness and divergence) are also often applied. Such studies require yearly observations on permanent plots. However, often are data on quasi-permanent plots via regular or non-regular time lags. The duration varies from few years to decades. For individual species, directional changes can be revealed by linear trend significance estimations. As the abundance of perennial plants usually depends on that in previous year, the autocorrelation term should be included into generalized linear models. To reveal cyclic changes, the autocorrelation analysis and the Fourier’ series analysis are applied (Skálová et al., 2022). Regression models are used to assess the impact of weather conditions. Mean temperatures of the previous growing season often explain abundance of perennials in cold bioms, while precipitation is important under dry conditions. Trends of individual species are not always linked with climate and other external factors, reflecting local processes, like population growth after diaspore recruitment or decrease during natural aging and death. Weather and other environmental factor influence the deviations from the general trend, so the detrended time series are recommended for estimations of links with environmental conditions, as well as for calculation of correlations between species abundance during the observation time (Lepš et al. 2019). To describe the whole community dynamics, the multivariate analysis is used. The species composition and abundance on the plot per given year are considered to calculate distance matrix between plots. The studies apply variety of ordination methods: the principal component analysis (PCA), the principal coordinate analysis (PCoA), correspondence analysis and detrended correspondence analysis (DCA), and non-metric multidimensional scaling (NMDS). To estimate and compare the rates of succession in the multivariate space is possible using Euclidian distances between initial and final species composition and abundances in plots. The method of community trajectory analysis (CTA) was recently introduced (De Cáceres et al. 2019). Using the distance matrices, it allows compare directions and form of trajectories of dynamics in various communities. The partial redundancy analysis (pRDA) allows to estimate the percent of variance explained by trends and by fluctuations (Kaufmann et al., 2021). Non-permanent or quasi-permanent plots are often used in repeated studies, when the exact location of the original plots cannot be determined, to them, be to estimated using ecological scales. This does not allow characterizing the interannual changes dynamics for individual species, but allow assessing community stability or changes. In this case, species presence–absence is better than abundance. Currently, plant functional traits and strategies are used to explain the community dynamics and to reveal differences between groups of species with positive or negative trends and different types of cyclic changes. Also it can be possible to estimate the best predictors of trends or reaction to meteorological factors (Soudzilovskaia et al., 2013). The Fourth-Corner Analysis (Dray, Legendre, 2008) gives interesting results in assessment the dependence of plant functional traits on weather conditions on the base of yearly data of species composition and abundance. That’s why long-term yearly observations on permanent plots is the best method to study interannual dynamics. Data on weather conditions and land-use characteristics, as well as functional traits and species community affinity help to explain the observed patterns, along with the use of appropriate data analysis. Multivariate methods allows solving some problems of non-permanent plots and longtime lags in observations. Information of the long-term observations on community dynamics on permanent sampling plots followed by contemporary methods of statistical analysis is particularly relevant (Table).

In the North-Western Caucasus, montane coniferous-broadleaf forests are highly productive communities. As a result of intensive industrial logging, they currently occupy only 15 % of the extant area afforested (Spravochnik…, 1995). The objective of the study is to characterize the post-logging recovery dynamics of coniferous-broadleaf forests situated on different mesorelief positions (those are automorphic, accumulative and transit), and paying attention to gap dynamics of the tree layer and its impact on species composition in lower community layers. The study was carried out in 2016 and 2019, in Krasnodar Territory (Apsheron forestry, the upper reaches of the Pshekha River) and the Republic of Adygea (Caucasian State Biosphere Reserve, the upper reaches of the Belaya River) (Fig. 1). These districts are at altitudes of 500-800 m above sea level, that correspond to the upper part of the lower mountain belt and the middle mountain belt. The climate of the study area is temperate, with mild winters and humid summers (Agroklimaticheskiy…, 1961). The forests studied belong to the assoсiation Sambuco nigrae–Fagetum orientalis subass. typicum Frantsuzov 2006 (suball. Abieti nordmannianae–Fagenion orientalis (Korotkov et Belonovskaja 1987) in Belonovskaya et Morozova 2021), and also to new variants of ass. Dryopteridi filici-maris–Carpinetum betuli Ermakov ex Akatova et Ermakov 2020 and community type Abies nordmanniana–Carpinus betulus Shevchenko et Braslavskaya 2021 those are included into suball. Tamo communis–Carpinenion betuli Shevchenko et Braslavskaya 2021 (all. Crataego–Carpinion Passarge 1981). The post-logging succession was studied by the chronosequence-series approach, employing methods of vegetation science, forest inventory and woody population demography (Tsenopopulyatsii…, 1988; Evstigneev, Korotkov, 2016a). The article considers 123 vegetation relevés collected within plots of 10×10 m established at a distance of at least 200 m from each other. In accordance with the information on the history of the forests studied and the ideas on the likely trend of their post-logging recovery dynamics, the communities of the same mesorelief position were ordered into chronosequence series (Fig. 2). In these series, the succession stages were identified applying the criterion of generations’ replacement in population of woody species that dominate the forest stands (Smirnova, 2004). In total, for each successional series, three recovery stages were distinguished as following: early (after logging carried out in the 1950s–1970s), shifting (logging was carried out in the late 1920s and in the 1930s), and late (protected regime since the end of the 19th century; uneven-aged forests with the maximum identified age of trees of about 450 years). At the early stage, the tree layer of the forests is formed mainly by Carpinus betulus, Populus tremula, Alnus glutinosa; at the shifting stage – by Carpinus betulus, Fagus orientalis and Abies nordmanniana; at the late stage – by Fagus orientalis and Abies nordmanniana. Within each successional series, there are difference between the stages in the communities’ species composition and the demographic structure of woody populations, and this is consistent with the light conditions (the factor considered as the main regulator of the structure and composition of forests during secondary post-logging successions). As a result of the relevés’ analysis, it was revealed that some successional trends in floristic composition are similar in all mesorelief positions. The first trend is the nonlinear change in the communities’ alpha diversity (estimated by species number per a sample plot). Thus, the values of species number are higher at the shifting stage compared to the early and the late stages (Fig.8). The second trend is that the floristic diversity is significantly lower at the late stage than at the early stage, both in closed forests and gaps. Therefore, in the course of the post-logging dynamics of montane coniferous and broadleaf forests of the North-Western Caucasus, the “paradox of species diversity decline, when communities reach the terminal stage of succession” (Whittaker, 1980) is observed. This can be explained by the impact of powerful key tree species – Fagus orientalis and Abies nordmanniana – on the rest plant species. In the physiognomy of the studied late-successional forests, the decline in floristic diversity results in very low cover of undergrowth and ground layers, because there are few species to form those. A distinct effect is revealed at the late succession stage, when the coenofloras of all closed forests (located on different mesorelief positions) are the most similar between each other (although the forest cenoflora on accumulative positions still retains some floristic differences) compared to the results of similarity analysis of the analogous communities at the early and at the shifting stages. One can consider this to be caused by very strong influence of long-living tree key species (like beech and fir) on total species composition in intact forests. Due to this, floristic differences have been markedly leveled between closed late-successional forests on different mesorelief positions (especially automorphic and transit ones), and that is an expected result of the long-term post-logging forest dynamics. However, gaps that appear in the tree layer, as a result of spontaneous tree population dynamics and natural forest stand thinning, break this trend off and contribute to a certain increase in the floristic richness of late-successional forests. Along with this, at the late succession stage, the gap dynamics increases diversity of ecological-coenotic groups of vascular plant species (Fig. 9). Moreover, the density of tree saplings is higher in gap parcelles (by 1.5–50 times) as well as the total diversity of tree species (by 5–20%) than in closed-canopy parcelles. These observations confirm that spontaneous tree population dynamics is an important process capable of maintaining high floristic diversity of late-successional (and intact) dark coniferous-broadleaf forests of the North-Western Caucasus.

The phytophage influence is one of the most important biotic environmental factors for steppe plants. The grazing as the alienation of above-ground parts of plants by large phytophagous animals is accompanied by greater soil density. The community modification in the process of pastoral digression consists not only in floristic composition changing, but also in increasing the number of both non-edible and invasive weed plants, as well as ephemeral species. The consequences of grazing are the xerophitization and halophitization of the steppe plant cover, which starts transforming the original natural steppe vegetation into desert one that is facilitated by continental climate (Ivanov, 2007). The classification status of communities of the last stages of pastoral digression is debatable and is not fully developed. The purpose of our studies was to progress the syntaxonomic scheme of vegetation of trampled habitats in the steppe zone in the Southern Urals and adjacent territories. The work is based on 186 plots relevѐs on the territory of the Southern Urals (Republic of Bashkortostan and Orenburg Region) and Northwestern Kazakhstan (Aktobe Region) performed in the period from 2005 to 2023. The spatial gradient of the sample plot pattern was about 700 km in the longitudinal and 500 km in the latitudinal directions, covering the steppe and partly forest-steppe zones. For comparative analysis, 1682 relevѐs of trampled habitat communities, as well as meadows and steppes based on literature sources (Kuptzov, 2005, Mullagulov, 2010; Yamalov et al., 2008) and electronic databases: “Anthropogenic vegetation of the Urals and adjacent territories” GIVD id 00-RU-008 (Golovanov, Abramova, 2021), “Phytocenotheca of grass vegetation of the Southern Urals” GIVD id 00-RU-006 (Yamalov et al., 2012) were involved. The dataset was processed following the principles of the Brown-Blanquet classification (Westhoff, Maarel, 1978) using the JUICE program (Tichý, 2002). The new units were identified and named in accordance with the International Code of Phytosociological Nomenclature. 4th edition “(Theurillat et al., 2021). The names of the high-rank syntaxa are given according to “Vegetation of Europe...” (Mucina et al., 2016). To identify patterns of ecological differentiation of the studied communities, the Detrended correlation analysis (DCA-ordination) method was used by means of the CANOCO 4.5 software package (Ter Braak, Šmilauer, 2002). Hierarchical cluster analysis was carried out according to the Ward’s method (Ward, 1963), the Bray-Curtis index (Bray, Curtis, 1957) was accepted as a combining measure, data processing was carried out in the JUICE software package. The peculiarity of the floristic composition, as well as the ecology of trampled habitat communities, was confirmed by methods of mathematical statistics: DCA-ordination (Fig. 2), hierarchical cluster analysis (Fig. 3). Consistent change and clear isolation of relevѐ groups in a range — undisturbed steppe communities (class Festuco-Brometea) —> pasture communities with perennial species domination (middle stages of pasture digression) —> communities of downed pastures dominated by ephemerals (terminal stages of pasture digression) — corresponds to the traditional ideas about the course of pasture succession in the steppe zone and indicates the ecological differentiation of each group, which is well to be reflected at the level of syntaxonomic classification. The distinction of such community types from mesophytic ones in trampled habitats with annual species (class Polygono–Poetea annuae) is also clearly traced. The following syntaxonomic scheme of vegetation in trampled habitats in the steppe zone of the Southern Urals and adjacent territories is proposed. We suggest including the cenoses on the middle stage of pastoral digression with abundant perennials into the alliance Bassio–Artemision austriacae within the order Polygono–Artemisietalia austriacae of the class Festuco-Brometea. The diagnostic group of the alliance includes plants (Artemisia austriaca, Festuca valesiaca s. l.), tolerant to anthropogenic load, together with set of synanthropic species. One associations, one community and two subassociations are distinguished within the alliance. The cenoses of ephemerals are considered within the new class Eremopyretea triticei–orientalis, which is the vicariant of the more mesophytic class Polygono–Poetea annuae. Thus, the previously distinguished class Polygono–Artemisietea austriacae loses its strength. The Eremopyretea triticei–orientalis class includes communities of ephemerals which are characterized by the very short ontogenesis within the most favorable early spring period, with optimal ratio of heat and moisture. The duration of ontogenesis of ephemerals from seed to seed is of two to three weeks and, as a rule, no more than one month. Having passed to go through all phases of development in favorable climatic conditions, ephemerals have mesophytic appearance (Lashhinsky et al., 2021). Poa bulbosa s. l., ephemeroid grass, which indicates various anthropogenic disturbances in the steppe zone, is also included in the class diagnostic species. In many respects, the set of species on disturbed habitats is stable, but their constancy varies insignificantly depending on the weather conditions, although without transforming stand look. The main habitats of the class communities are pastures near settlements, the vicinity of farms, roadsides, rural courtyards, trampled habitats in settlements, etc. Due to the long existence of such stands, they often mark the places of abandoned farms, as well as cattle campsites, while the species presence in steppe communities is the sign of anthropogenic impact. The diagnostic species of the class are Alyssum turkestanicum, Ceratocarpus arenarius, Chorispora tenella, Descurainia sophia, Eremopyrum orientale, E. triticeum, Euclidium syriacum, Grubovia sedoides, Lepidium perfoliatum, Poa bulbosa s. l., Polygonum patulum, Ranunculus testiculatus. Cenoses occur within various subzones of the steppe zone of Eastern Europe (Ukraine), Russia, Northwestern Kazakhstan as well as desert zone (Lower Volga). We described these in the Southern Urals and adjacent territories. There are two alliances — Lepidio ruderalis–Eremopyrion triticei (communities of ephemerals in anthropogenic trampled habitats of the bunchgrass steppes) and Poo bulbosae–Eremopyrion orientalis (communities of ephemerals in anthropogenic trampled habitats of the vermouth-grass steppes) with 9 associations and 11 subassociations new to science — within the class. The communities of the class Eremopyretea triticei–orientalis, gradually replace those of the class Polygono–Poetea annuae on the latitudinal gradient (Fig. 9). In the transition zone north of the River Ural, cenoses of both classes occur together in certain localities reflecting the microrelief and the moisture level. Communities of the class Eremopyretea triticei–orientalis are widespread in elevated sites, while lowered sites are occupied by the cenoses of the class Polygono–Poetea annuae (subass. Polygonetum arenastri atriplicetosum tataricae Klimeš 1989, as well as typical communities of the ass. Polygonetum arenastri Gams 1927 corr. Lanikova in Chytrý 2009). Thus, communities of the class Eremopyretea triticei–orientalis in the Southern Urals and adjacent territories of Southeastern Russia and Northwestern Kazakhstan are rather diverse and occupy large areas near existing and abandoned settlements, according to various anthropogenic habitats, as well as in cattle grazing sites, exist for a long time (particularly in the vermouth-grass and sandy steppes). All this leads to degradation of steppe phytocenoses, the loss of their species diversity, and the replacement of natural steppe communities by their synanthropic derivatives.

Classification of dark coniferous boreal forests of the Western Sayan and North-Eastern Altai Mountains was performed using data set of 115 relevés arranged along altitudinal gradient (360–2100 m). Eleven new associations are described after clustering (Ward method, Euclidian distance) and floristic analysis. All syntaxa are included in the class Vaccinio-Piceetea Br.-Bl. in Br. Bl. et al. 1939 and Urals-Siberian order Piceo obovatae-Pinetalia sibiricae ord. nov. The original diagnoses of new syntaxa in English are provided according to the Recommendation 7D (ICPN, Theurillat et al., 2021). New associations. Cruciato glabrae–Abietetum sibiricae ass. nov. Holotypus – rel. 1, Table 1. Coordinates, degrees (Crd) 52.96844N, 91.21466E. Date (D): 01.09.2002. Plot size (S) — 200 m2. Author (A) — N. Ermakov. Diagnostic species (DS) — Actaea cimicifuga, Calamagrostis pavlovii, Cruciata glabra subsp. krylovii, Spiraea chamaedryfolia. Caragano arborescentis–Abietetum sibiricae ass. nov. Holotypus — rel. 8, Table 1. Crd — 52.712N, 91.42294E. D — 28.07.2003. S — 200 m2. A — N. Ermakov. DS — Actaea cimicifuga, Calamagrostis pavlovii, Caragana arborescens, C. frutex, Schizachne callosa, Viola mauritii. Sambuco sibiricae–Abietetum sibiricae ass. nov. Holotypus — rel. 16, Table 1. Crd — 52.59497N, 92.17334E. D — 02.08.2003. S — 200 m2. A — N. Ermakov. DS — Carex iljinii, Polytrichum commune, Sambucus sibirica. Vaccinio myrtilli–Abietetum sibiricae ass. nov. Holotypus — rel. 7, Table 1. Crd — 52.51636N, 92.04325E. D — 30.08.2002. S — 200 m2. A — N. Ermakov. DS — Abies sibirica, Pinus sibirica, Polytrichum commune, Sphagnum girgensohnii, Vaccinium myrtillus (dom.), V. vitis-idaea (dom.). Allio microdictyi–Abietetum sibiricae ass. nov. Holotypus — rel. 32, Table 1 in Ermakov, 2013, p. 85. A — N. Ermakov. DS — Anthoxanthum nipponicum, Lycopodium annotinum, Polytrichum commune, Vaccinium myrtillus. Hylocomio splendentis–Abietetum sibiricae ass. nov. Holotypus — rel. 50, Table 1. Crd — 52.63364N, 93.42842E. D — 11.08.2004. S — 200 m2. A – N. Ermakov. DS — Abies sibirica, Alnus alnobetula subsp. fruticosa, Calamagrostis obtusata, Dryopteris expansa, Gymnocarpium dryopteris, Oxalis acetosella, Picea obovata, Pinus sibirica, Rhytidiadelphus triquetrus. Bergenio crassifoliae–Abietetum sibiricea ass. nov. Holotypus — rel. 6, Table 2. Crd — 52.54589N, 92.06109E. D — 18.08.1989. S — 100 m2. A — N. Ermakov. DS — Bergenia crassifolia (dom.), Calamagrostis purpurea, Circaea alpina, Prunus padus, Ribes nigrum. Bergenio crassifoliae–Pinetum sibiricae ass. nov. Holotypus — rel. 18, Table 2. Crd — 52.81203N, 93.26834E. D — 29.08.2002. S — 100 m2. A — N. Ermakov. DS — Alnus alnobetula subsp. fruticosa, Bergenia crassifolia (dom.), Rhododendron dauricum, Sphagnum girgensohnii. Bistorto officinalis–Abietetum sibiricae ass. nov. Holotypus — rel. 40, Table 2. Crd — 51.96397N, 88.28219E. D — 12.08.2004. S — 100 m2. A — N. Ermakov. DS — Bistorta officinalis, Carex iljinii, Cirsium helenioides, Pedicularis incarnata, Poa sibirica. Rhododendro aurei–Abietetum sibiricae ass. nov. Holotypus — rel. 48, Table 2. Crd — 51.92186N, 88.04606E. D — 27.07.1989. S — 100 m2. A — G. Kamalutdinov. DS — Cladonia amaurocraea, Doronicum altaicum, Empetrum nigrum, Juniperus sibirica, Rhododendron aureum, Sibbaldia procumbens. Rhapontico carthamoidis–Pinetum sibiricae ass. nov. Holotypus — rel. 16, Table 1 in Makunina et al., 2019, p. 58. A — N. Ermakov. DS — Alchemilla vulgaris s. l., Crepis lyrata, Cruciata glabra subsp. krylovii, Lilium martagon var. pilosiusculum, Rhaponticum carthamoides. Betulo glandulosae–Abietetum sibiricae Makunina, Zhirova et Sakhnevich ex Ermakov ass. nov. Holotypus — rel. 3, Table 1 in Makunina et al., 2019, p. 58. DS — Antennaria dioica, Carex stenocarpa, Betula glandulosa, Juniperus sibirica, Larix sibirica, Salix glauca. Schulzio crinitae–Abietetum sibiricae ass. nov. Holotypus — rel. 54, Table 2. Crd — 52.16986N, 87.54761E. D — 21.07.1989. S — 100 m2. A — G. Kamalutdinov. DS — Betula glandulosa, Gentiana grandiflora, Salix glauca, Schulzia crinita, Swertia obtusa, Viola altaica. New suballiances. Spiraeo chamaedryfoliae–Abietenion sibiricae suball. nov. Holotypus — Cruciato glabrae–Abietetum sibiricae ass. nov. (described in this paper). DS: Caragana arborescens, Actaea cimicifuga, Calamagrostis pavlovii, Circaea alpina, Cruciata glabra subsp. krylovii, Sambucus sibirica, Spiraea chamaedryfolia. Habitat (H): steep and gentle slopes in the lower part (500–900 m) of forest belt in the Altai and Sayan. Geranio albiflori–Abietenion sibiricae suball. nov. Holotypus — Saussureo latifoliae–Abietetum sibiricae Ermakov 2013 (Ermakov, 2013, p. 84). DS: Allium microdictyon, Crepis lyrata, Cirsium helenioides, Euphorbia pilosa, Geranium albiflorum, Ranunculus grandifolius, Saussurea latifolia, Solidago dahurica, Trollius asiaticus, Veratrum lobelianum, Viola biflora. H: western, southern and eastern well-dranded slopes in the higher part of forest belt in the Altai and Sayan. Aconito rubicundi–Abietenion sibiricae suball. nov. Holotypus — Onocleo struthiopteridis–Abietetum sibiricae Anenkhonov et Chytrý 1998 corr. (Anenkhonov, Chytrý, 1998, p. 47). DS: Angelica archangelica, Cardamine macrophylla, Equisetum hyemale, Mitella nuda, Paris verticillata, Vicia venosa. H: mountain slopes and river valleys in the Baikal region. Rubo arctici–Abietenion sibiricae suball. nov. Holotypus — Rubo arctici–Abietetum sibiricae Ermakov et Makhatkov 2011 (Ermakov, Makhatkov, 2011, p. 33). DS: Comarum palustre, Equisetum arvense, Rubus arcticus, Thalictrum flavum, Veronica longifolia. H: extra-zonal northern boreal forests in river valleys in the West Siberian plain. Carici iljinii–Abietenion sibiricae suball. nov. Holotypus — Vaccinio myrtilli–Abietetum sibiricae ass. nov. (described in this paper). DS: Carex iljinii, Sphagnum capillifolium, S. girgensohnii. H: steep slopes in the upper part of forest belt (1200–1600 m) in the Altai and Sayan. Violo biflorae–Abietenion sibiricae suball. nov. Holotypus — Athyrio distentifolii–Abietetum sibiricae Ermakov 1995 (Ermakov, 1995, p. 89). DS: Allium microdictyon, Athyrium distentifolium, Ranunculus grandifolius, Saussurea latifolia, Solidago dahurica, Veratrum lobelianum, Viola biflora. H: moderalely steep slopes with humid well-drained soils aaltitudes of 1400–1900 m. Betulo glandulosae–Abietenion sibiricae suball. nov. Holotypus — Betulo glandulosae–Abietetum sibiricae Makunina, Zhirova et Sakhnevich ex Ermakov ass. nov (validated in this paper). DS: Betula glandulosa (dom.), Juniperus sibirica, Salix glauca, Empetrum nigrum, Festuca ovina, Gentiana grandiflora, Schulzia crinita, Cetraria islandica, Cladonia amaurocraea, C. stellaris. H: northern slopes with cold humid soils at altitudes of 1700–2100 m. New alliances. Bergenio crassifoliae–Abietion sibiricae all. nov. Holotypus — Bergenio crassifoliae–Pinetum sibiricae ass. nov. (described in this paper). DS: Bergenia crassifolia (dom.), Rhododendron dauricum, Ribes nigrum. H: screes and open bedrocks with poorly developed soil at altitudes 350–1080 m. Anthoxantho nipponici–Abietion sibiricae all. nov. Holotypus — Betulo gladulosae–Abietetum sibiricae Makunina, Zhirova et Sakhnevich ex Ermakov ass. nov. (validated in this paper). DS: Anthoxanthum nipponicum, Aquilegia glandulosa, Bistorta officinalis, Carex aterrima, Doronicum altaicum, Luzula sibirica, Omalotheca norvegica, Pedicularis incarnata, Rumex alpestris, Viola altaica. H: northern well-drained slopes in subalpine belt (1400–2100 m) in mountains of Southern Siberia. Headings of the Tables 1, 2 with ecological and phytocoenotic characteristics of relevés. Row 1 (Ассоциация) — association name. Row 2 — Altitude, m. Row 3 — Aspect (°). Row 4 — Inclination (°). Row 5 — Cover of tree layer, %. Row 6 — Cover of shrub layer, %. Row 7 — Cover of herb layer, %. Row 8 — Cover of moss layer, %. Row 9 — Field relevé nr. Row 10 — Relevé nr. in Table.

The article summarizes some previously published data on the dynamics of forest vegetation with emphasis on the scientific work of the Forest Research Institute of the Karelian Research Centre of the Russian Academy of Sciences. A cautious forecast of climatogenic dynamics of the forest cover of the taiga zone is made, and information on studies of climate and human influence on fire events in the European North in the last 700 years is given. Based on the research of T. K. Yurkovskaya and G. A. Elina (2009), it can be predicted that with climate warming in the middle taiga subzone, the taiga forests will naturally transform into temperate plant communities. Deciduous trees and nemoral plant species are likely to dominate in the tree layer and ground cover. In the Northern taiga subzone, there may be a shift towards middle taiga communities, with an increase in the productivity of coniferous stands. Fire activity (the frequency and intensity of fires) is another factor in the dynamics of forest vegetation. An international team of researchers has summarized the results of studies on the history of fires in the North-West of Russia, using dendrochronological methods and archival materials related to settlement development. The relationship between fire frequency, settlement formation, and human activity has been explored, and has been found that the area burned per unit time in forests is determined by climate factors (Drobyshev et al., 2022). In recent decades, forest dynamics is mainly related to logging, which determines the coenotic and species diversity of ecosystems. Modern forest typology, focused on scientific justification of biodiversity conservation and development of sustainable forest management practices, can no longer ignore issues related to forest dynamics. This is because secondary stands now dominate, and the problem of forest fragmentation is becoming more significant. The problems of classifying forest communities that arose after logging were pointed out by A. Cajander (Cajander, 1926) and V. N. Sukachev described the situation with the classification of secondary stands as “chaos” (Sukachev, 1930). The scale of the spread of communities after continuous logging can be illustrated by the ordination of hundreds of relevѐs of forest communities of different ages under four types, as shown in Figure 1. Here, is well seen how the relevѐs of forests older than 120 years are concentrated in a small area and close to each other, while the spread of relevѐs of deforested and young forests is very wide. “Chaos” could be reduced by unifying indigenous and secondary stands within forest conditions and considering dynamics (Fedorchuk et al., 2005; Rysin & Saveleva, 2007). Based on the analysis of hundreds of relevѐs entered into the “Habitats of Eastern Fennoscandia” database, we have constructed ecological and dynamic models of cenotic diversity on automorphic soils (Kryshen et al., 2018a; Kryshen et al., 2021). These models represent the stages of forest community development (clear-cut–young stand–middle-aged stand–mature forest–subclimax–climax) and the diversity of plant associations, which is determined by the ecotope and anthropogenic influence (Fig. 2 and Fig. 3). In applied terms, knowledge of dynamics (regularities of post-harvest reforestation) is necessary for the development of close-to-nature management. Instead of continuous and intensive logging, more gentle methods of logging began to be used. These methods only slightly disturb the ground cover and soil, while preserving the forest environment to the greatest extent possible. This is due to the small scale of deforestation and the preservation of the untreated forest sites and separate standing trees. A new field of forestry, called “variable retention forestry”, has emerged (Beese et al., 2019). In this context, studies of the dynamics of communities in transitional states (both in space and time) are particularly important. Our research has shown that after logging a part of a stand, an ecotone complex of four zones is formed: the forest, the transition to the clear-cut site under tree canopy, the transition to the clear-cut site outside of tree canopy, and the clear-cut per se. In both pine and spruce forests, we have determined the length of the transition zone based on various microclimatic and coenotic parameters to be approximately 8–10 meters (Genikova, Mamontov, 2023), however, the intensity of these differences varied. In bilberry pine forests, illuminance in the undisturbed area adjacent to the clear-cut site did not change as much as it did in bilberry spruce stands. This affected the similarity of the species composition and the dominant species in the ground cover between the two plant communities and the transition zone. The article also presents data on changes in the species diversity of plant communities during the restoration of forests at clear-cuts, for the four types of forest conditions previously described. In poor dry lichen (P. s.–Cl.) and lingonberry (P. s.–V. v.-i.) pine forests, the number of species on the clearing varies slightly. However, in total (Fig. 7) and across all communities (Fig. 8), these conditions show the greatest species diversity of vascular plants at the clear-cut stage. Number of species changes in another way in bilberry pine forests (P. s.–V. m.). Here, restoration of the original community usually occurs through the stage of dominance by birch or aspens. The maximum species diversity of vascular plants is observed both in general across all age stages and on average, observed at the stage of the middle-aged community, is characterized by a mixed coniferous and deciduous stand composition. Bilberry spruce forests differ from pine ones in terms of soils, dominant tree layers, and reforestation traits after logging. Without human intervention, forest regeneration occurs through the stages of dominance by deciduous species, such as Betula spp. and Populus tremula. In general, deforestation is highly diverse due to individual site relevѐs in agricultural areas. Two main factors contribute to an increase in diversity after logging: the removal of “pressure” from the tree layer, allowing neighboring species to colonize the clear-cut site, and the appearance of different microhabitats suitable for plants with different coenotic properties.

Communities of shrubs such as Prunus fruticosa, Spiraea crenata, S. hypericifolia, Caragana frutex (Lavrenko, 2000) are widespread in the Eurasian steppe region. Currently, science has a special interest in the study of shrub communities and some species of shrubs due to their expansion into grass ecosystems. So, there is an increasing of the communities areas, their range in the forest-steppe and steppe zones as a result of sharp decrease in livestock after the economic reforms of the 1990s in the Russian Federation. In the syntaxonomic literature, the steppe shrub communities are included in the class Crataego-Prunetea Tüxen 1962 nom. conserve. proposal. (Mucina et al., 2016). Xerothermic shrub steppe communities are placed in the alliance Amygdalion nanae Golub 2011, the order Festucetalia valesiacae Korneck 1974 nom. conserve. proposal. and the class Festuco-Brometea (Yamalov et al., 2012). The study and classification of shrubby vegetation in South Ural (SU) has so far been represented by few works.The development of the syntonomy of shrubby communities on the base of ecological and floristic classification has got started with the paper of German geobotanists who selectively examined the steppes of some areas of the Bashkir Urals and Trans-Urals (Schubert et al. 1981). The study of steppe shrubby communities by Ufa geobotanists was carried out mainly during the inspection of protected areas. Communities were studied on the Shaitan-tau ridge (Dubravnaya forest-steppe..., 1994), in the Bashkiria National Park (Yamalov, Sultangareeva, 2010), on the territory of natural monuments — Tratau and Yuraktau mounains (Unique..., 2014), in the Bashkir State Reserve (Yamalov, 2011). The study was carried out at South Ural within the Republic of Bashkortostan, as well as in the adjacent territories of the Orenburg and Chelyabinsk regions. The length of the studied area from north to south is about 550 km, from west to east — about 400 km. The work is based on 147 geobotanical relevés of xerothermic shrubby communities, made from 1981 to 2015. Both author’s relevés and published data included in the “Database of non-forest vegetation of South Ural” GIVD id 00-RU-006 (Yamalov et al., 2012) were used for the syntaxonomic analysis. The dataset was processed using the JUICE program (Tichý, 2002). The characterizing tables contain data of the species presence in projective cover scores on the following scale: + < 1 %, 1 — 1–4 %, 2 — 5–9 %, 3 — 10–24 %, 4 — 25–49 %, 5 — 50–74 %, 6 — 75–100 %. The nomenclature of syntaxa follows the rules of the International Code of Phytosociological Nomenclature (Theurillat et al., 2021). The names and diagnostic species groups of high-rank vegetation units are as in “Vegetation of Europe...” (Mucina et al., 2016) with regional adjustments. Species names are given by Plants of the World Online (https://powo.science.kew.org/), as well as by taxonomic treatments in the flora of South Ural (Ryabinina, Knayzev, 2009). Based on the results of syntaxonomic analysis, it is proposed to consider it as part of two classes Festuco-Brometea and Crataego-Prunetea. A comparative analysis of the xerothermic shrubby vegetation syntaxa of the alliance Prunion fruticosae in Eastern Europe demonstrated that the communities of South Ural due to significant specificity, might be considered within the framework of the sub-alliance Carici supinae–Spiraenion crenatae. One of the leading factors of such differentiation is mainly the climatic features of the region located in the zone of temperate continental climate. There is a genesis and spatial relationship between shrub communities and broad-leaved forests of the Carpino-Fagetea class, with hemiboreal forests of the class Brachypodio pinnati–Betuletea pendulae, as well as steppes of the class Festuco-Brometea. We assume that the communities of the sub-alliance Carici supinae–Spireanion crenatae represent the eastern limit of the range of the class Crataego-Prunetea. There are Artemisia armeniaca, Artemisia sericea, Carex supina, Cotoneaster melanocarpus, Dianthus chinensis, Dracocephalum ruyschiana, Dracocephalum thymiflorum, Echinops ruthenicus, Eremogone longifolia, Koenigia alpina, Onosma simplicissima, Pentanema hirtum, Poa versicolor, Rhaponticoides ruthenica, Sanguisorba officinalis, Salvia stepposa, Spiraea crenata, Stellaria graminea, Thymus pannonicus, Veronica spuria in diagnostic group of sub-alliance. The suballiance includes 3 associations with the dominance or codominance of different shrubs, as well as 10 subassociations reflecting the edaphic conditions of specific habitats, as well as their geographical differentiation. The communities of two associations, characterized by the lot of steppe species in the grass layer, are classified as part of the alliance Amygdalion nanae. The most xerothermic communities of the ass. Artemisio austriacae–Spiraetum hypericifolii with the Spiraea hypericifolia dominance have become widespread at the southern tip of the Urals (Guberlinskye Mountains) and the Trans-Urals small hill. In the northeast of the Trans-Urals, along the mountain slopes, mainly western and northwestern exposures with slopes from 10 to 45°, shrubby communities of the ass. Phedimo hybridi–Cotoneasteretum melanocarpi are common on rocky substrates. Shrubby communities with Prunus tenella prevalence (ass. Filipendulo vulgaris–Prunetum tenellae) are widespread in forest-steppe and steppe zones of the Cis-Urals and a mountain part of South Ural on slope habitats of various exposures, with biases from 3 to 40° on stony limy substrates, and on the flattened relief elements on forest margins. The most common type of shrub communities in the region is the thickets of Caragana frutex of the ass. Fragario viridis–Caraganetum fruticis. They are formed within the forest-steppe and steppe zones, both on slopes of various exposures along beams, ravines, and forest margins on flattened relief elements. The most diverse in the South Ural are shrubby communities of the ass. Trifolio montani–Prunetum fruticosae, which combines cenoses with the Prunus fruticosa dominance. Communities are formed on various exposition slopes along ridges, beams, ravines, thermophilic forest margins, and on flattened relief elements; often on rocky substrates. Among all xerothermic shrubs, only Spiraea crenata does not form an independent syntaxon. However, the species noted as constant in many associations, often coexist with coenosis-forming shrubs.

The study of vegetation dynamics remains one of the fundamental problems of modern ecology, given its decisive role in the functioning of the biosphere and the formation of the human habitat. This article is part of a special issue of the journal “Vegetation of Russia” (“Rastitel’nost’ Rossii”) entitled “Dynamic processes in vegetation: species, functional, and structural diversity of plant communities”. The paper discusses current understanding of the driving forces behind plant community dynamics, outlines the methods and approaches, and proposes future challenges for succession studies. A complex of interacting factors, such as disturbances, habitat conditions, demographic processes, plant structural and physiological traits, biotic interactions, global environmental change, historical legacies, and human activity, governs the trajectory and pace of vegetation change. Succession is initiated by disturbances operating at different spatial scales, ranging from local events (e. g., animal activity, single-tree falls) to extensive ones (e. g., wildfires, volcanism, land conversion). The disturbance characteristics define the succession type: primary (on newly formed substrates devoid of soil and organic matter) or secondary (on sites with residual soil and propagules). The rate and predictability of vegetation development are contingent upon the magnitude of disturbance, climate, and the regional species pool (Walker, Moral, 2003; Prach, Walker, 2020; Janečková et al., 2024). At a local scale, succession is modulated by microclimatic conditions and soil properties, including texture, fertility, moisture, chemistry, element ratios (e. g., C:N ratio), which collectively shape species composition and community dynamics. Demographic processes include the recruitment of new individuals, their growth, and mortality, as well as generational turnover. They shape the demographic structure of local populations, which is particularly important in forests where the edificators are long-lived species (Kryshen, Genikova, 2025; Lyanguzova et al., 2025; Shevchenko et al., 2025). The community’s response to disturbances is determined by vegetation structure (e. g., biomass, vertical stratification) and key physiological functions of plants like photosynthesis and water relations. Biotic interactions among plants lead to changes in composition and abundance of species. The soil microbiome influences the succession by modulating plant nutrition via mutualistic or antagonistic interactions (Chai et al., 2019; Li et al., 2023). Endophytic microorganisms shift plant stress resistance (Hardoim et al., 2015; Anand et al., 2023), aid in nutrient acquisition and hormone synthesis, but can suppress invasive species (Afkhami, Strauss, 2016). Animals shape vegetation through seed dispersal, biomass consumption, and altering community structure, thereby enhancing the spatial heterogeneity of plant cover (Lindén et al., 2021; Siewert, Olofsson, 2021; Trepel et al., 2024). Gradual environmental changes in climate, atmospheric gas composition, sea level, etc. establish long-term trends in community and ecosystem dynamics (McDowell et al., 2020). Historical factors, such as past land-use regimes, human migration, and fire frequency, can imprint upon the composition and structure of phytocoenoses for decades or even centuries (Perring et al., 2018). Over the past century, human activity has emerged as the dominant driver of vegetation change, manifesting as land-use change, agricultural intensification, urbanization, and the spread of invasive species. In recent decades, processes such as forest encroachment on abandoned lands (especially in Europe and the post-Soviet space) and increased fire frequency have been observed (Cunningham et al., 2024; Tikhonova et al., 2025). Anthropogenic influence has become ubiquitous, and most modern studies of vegetation dynamics are related to its study in one way or another. The study of succession commonly relies on spatial chronosequences — series of sample plots situated in similar topographic and substrate conditions, differing only in their time since disturbance. This approach demands rigorous site selection and verification of the assumption of a common developmental history across all chronosequence sites, with findings necessitating validation through complementary methods in dendrochronology, palynology, pedology, and historical ecology (Johnson, Miyanishi, 2008; Walker et al., 2010). Photographic records of communities provide a valuable resource for both documentation and future studies. They enable the estimation of parameters like the Leaf Area Index and may soon be essential for recognizing vegetation types based on machine learning methods. A shift in focus from mere species inventories to examining the demographic structure of local species populations, ecological species groups, and plant functional traits significantly enriches research insights (Smirnova et al., 2004; Grime, Pierce, 2012; Lyanguzova et al., 2025). Furthermore, mathematical modeling offers a deeper mechanistic understanding, facilitating the prediction of successional dynamics and the testing of competing hypotheses (Fisher et al., 2018; Franklin et al., 2020). Research methods are discussed in more detail in this issue by T. Elumeeva (2025). Contemporary research on vegetation dynamics has evolved from merely describing successions to searching for universal mechanisms underlying them. A central aim now lies in evaluating theoretical models that explain the replacement of species and communities. Foundational concepts include classical frameworks such as the model of succession by J. H. Connell and R. O. Slatyer (1977) outlining three pathways (facilitation, tolerance, inhibition), Grime’s theory of CSR-strategies (Grime, Pierce, 2012), and Tilman’s (1985) resource ratio hypothesis. Subsequent theoretical advances are linked to the concept of community assembly rules, which emphasizes the sequential effects of dispersal limitation, abiotic filters, and biotic interactions (Belyea, Lancaster, 1999). Furthermore, the traditional taxonomic approach has been superseded by analyzing plant functional traits to identify universal patterns of vegetation dynamics regardless of the species composition of the flora (Garnier et al., 2016). The current stage is characterized by the development of integrative theories, such as the “Rationalised disturbance theory” by S. A. Pulsford et al. (2016) and the “Comprehensive successional framework” by L. Poorter et al. (2024). The latter describes succession within socio-ecological system dynamics, where ecological processes and human activity are closely intertwined. This framework explicitly incorporates interactions among all key drivers across different spatial scales, as well as feedback loops between components of the socio-ecological system. Over more than a century of research, the understanding of succession has radically changed: from a model of a strictly deterministic process to a complex phenomenon dependent on numerous, including stochastic, factors. Nevertheless, persistent theoretical gaps remain, largely due to the intricate nature of interactions within ecosystems and the lack of long-term data. Future research directions include: determining the degree of determinism in successions across environmental contexts; establishing thresholds of community resilience in relation to disturbance intensity; assessing the role of rare and invasive species; and analyzing the impacts of climate and land-use change on recovery trajectories. Further critical avenues include elucidating the relationship between vegetation dynamics and the soil microbiome, investigating temporal shifts in plant functional traits, and advancing integrative mathematical models that incorporate machine learning approaches.

Long-term (40 years) monitoring allowed to identify the main dynamic trends in the state of northern taiga pine forests in the background areas of the Kola Peninsula and in the zone of industrial pollution against the backdrop of sharp reduction in the volume of toxic emissions into atmosphere and to identify the features of the reaction of various ecosystem components to changes in the intensity of aerotechnogenic load. Over the observation period (1980–2024), the volumes of atmospheric emissions of sulfur dioxide and polymetallic dust by the “Severonikel” mining plant (Murmansk Region) decreased by 5–9 times (Fig. 1). In response to sharp decrease in aerotechnogenic load, the parameters of individual components of forest ecosystems are improved (Yarmishko, Ignatieva, 2019, 2021; Yarmishko et al., 2017; Lyanguzova, Katyutin, 2024), some components either did not change their state or there was a further deterioration. Positive changes in the condition of the tree layer of pine forests were recorded, which were most clearly manifested in the impact zone: 1) during the studied period, the lifespan of Pinus sylvestris needles increased from 2 to 5 years in the impact zone, and from 4 to 6 years in the buffer zone (Fig. 10); 2) the degree of damage to the assimilation organs of pine by chlorosis and necrosis decreased; in the impact and buffer zones, the content of Ni and Cu in needles decreased by 4–5 and 3–4 times, respectively (Fig. 18; Lyanguzova, 2017); 3) in the impact zone, the growth rate of pine trees increased, both in height and in diameter, and in the buffer zone - in height (Fig. 5, 6) the radial increment of pine trees in the impact zone has increased in the recent period by almost 3 times compare to the period 1980–1999 and exceeds the background values; in the buffer zone has not changed, but is currently at the level of background values (Fig. 9); 5) in the impact zone, the process of restoring the natural ratio of trees and large undergrowth has begun: a 3-fold numerical predominance of large undergrowth has been replaced by a 2-fold predominance of trees (Fig. 12). In response to the reduction in the sulfur dioxide volume and heavy metal dust emissions, positive changes in the total projective cover of the green moss-lichen layer (up to ~90% of background values) and its species structure have occurred in the buffer zone (Table 4; Fig. 15). An increase in the cover of late- and mid-successional lichen species indicates the presence of recovery processes, but with a significant delay (by ~60 years) compare to the natural post-fire dynamics in the background. In the impact zone, the green moss-lichen layer throughout the entire study period was formed only by early successional lichen species, the projective cover of which currently does not differ from the cover in the early 1980s. The absence of Pleurozium schreberi — the dominant species of moss cover in the middle and late stages of succession — makes it impossible for the full functioning of the moss-lichen layer in the buffer and impact zones. The state of the dwarf shrub–herb layer of pine forests in the buffer zone remains the same as at the beginning of the study period (Gorshkov, Bakkal, 2009), i. e. there is no natural recovery dynamics of the layer, the total projective cover is 25% lower than in background (Table 4; Fig. 14). In the impact zone, the current state of the layer is significantly worse than at the beginning of the study period: the total projective cover has decreased by 4 times and is ~20% of the background values. The cause of these phenomena, both in the buffer and in the impact zone, is the disruption of recovery dynamics of the green moss-lichen layer and forest litter, associated with the persistent high level of pollution of the upper soil horizons with heavy metals. The level of pollution of the upper (organogenic) horizon of Al-Fe-humus podzols with heavy metals (Ni and Cu) continues to increase. During the period of high atmospheric emissions (1981–1997), the average values of the technogenic load index within the buffer and impact zones were 5.7 and 64 relative units, respectively, and during the period of sharply reduced levels of aerial pollutant emissions (2002–2022) — 18 and 97 relative units, i.e. increased by 1.5–3 times (Fig. 16). This indicates a high (buffer zone) and very high (impact zone) level of phytotoxicity of the forest litter and confirms the high inertia of soils contaminated with heavy metals, which is manifested in their low self-purification capacity (Lyanguzova et al., 2016; Lyanguzova, 2017; Kashulina, 2017; 2018; 2022). In the mineral podzol horizons, the content of heavy metals decreases compared to the upper (organogenic) horizon by 15–90 times and reaches minimum values in the parent rock (3–5 mg/kg) (Fig. 17), i.e. the forest litter functions as a biogeochemical barrier even at very high values of the technogenic load index. The high degree of phytotoxicity of soils due to contamination of the upper podzol horizons with heavy metals does not allow the process of natural restoration of the ground cover to begin in the impact zone and significantly slows down this process in the buffer zone.

Communities with Rhodiola quadrifida were studied in the northern sectors of the Urals, in the relict part of the range of this species. The studies were conducted in 2006–2018 in the Northern, Subpolar and Polar Urals, in the foothills of the Polar Urals. 46 author’s relevés were analyzed. Rhodiola quadrifida has high presence, but low abundance (V/r-+) in the studied communities (Table 1), which develop in mountain and arctic tundra on cryogenic relief forms in areas of long-term frozen ground, often confining by calcium- and silicon-containing rock outcrops. Сharacter are horizontal structure (patches of soil with plant cover bordering these) and the high number of petrophyte and calciphyte taxa, as well rare and disappearing ones (glacial relics, endemics and those on the range limits). The prodromus includes six community types (Table 1; Fig. 2), three of which are presumably attributed to the higher syntaxonomic units within two classes, while the position of the others are so far uncertain. Community type Silene paucifolia (Table 1, Rel. 1–4; Fig. 3) — open petrophyte herb-dwarf shrub stands on gentle scree southern slopes of the mountain tundra belt of the Polar Urals at 169–216 m (hereinafter all altitude data are above sea leve). The assignment of syntaxon to higher syntaxonomic units is so far uncertain. Community type Linum borealе (Tаble 1, Rel. 5–8; Fig. 5) — petrophyte herb–dwarf shrub–lichen sparse cover on the rock tops ledges and rocky southern slopes in sites where limestones occur at 350 m in the Kozhim River basin (Subpolar Urals), tentatively assigned to the class Carici rupestris–Kobresietea bellardii Ohba 1974 the order Thymo arcticae–Kobresietalia bellardii Ohba 1974, the alliance Kobresio-Dryadion. Nordhagen 1943. Community type Campylium bambergeri–Carex glacialis (Table 1, Rel. 9–14; Fig. 6) — herb–dwarf shrub communities on carbonate soils underlained by carbonate rocks on mountain slopes and in intermountain basins or depressions in the mountain tundra belt of the Polar Urals on 230–270 m. It is described in the Polar Urals near Estoto Lake and in the area of the Razvilny stream, where outcrops of carbonate rocks (limestones) are most pronounced compare to other study areas. Being intermediate between plain tundra and mountain syntaxa of the class Carici rupestris–Kobresietea bellardii (Fig. 7) this community type might be considered as an independent syntaxon, presumably within this class, the order Thymo arcticae–Kobresietalia bellardii Ohba 1974, the alliance Kobresio-Dryadion Nordhagen 1943. Community type Empetrum hermaphroditum–Calamagrostis lapponica (Table 1, Rel. 15–21, Fig. 8) — grass–shrub–moss stands near the edges of the bedrock banks of river (stream) valleys in the Cis-Urals of the Polar Urals (Silovayakha River) and the Polar Urals (Niyayu River, Razvilny Stream) in places underlined by carbonate rocks at 162–230 m. It is an intermediate position between the lowland and mountain syntaxa of the classes: Carici rupestris–Kobresietea bellardii, Carici arctisibiricae–Hylocomietea alaskani Matveyeva et Lavrinenko 2023, Loiseleurio procumbentis–Vaccinietea Eggler ex Schubert 1960 (Fig. 9). The assignment to the higher syntaxonomic units is so far uncertain. Community type Racomitrium lanuginosum–Salix nummularia — dwarf shrub–lichen–moss communities on mountain terraces and slopes (usually among kurums), plateau-like upper parts of foothills and mountains plumes of the Polar and Northern Urals at 625–900 m, mainly confined to quartzite sandstones and mountain primitive soils (Table 1, Rel. 22–37; Fig. 10). This community type presumably belongs to the class Loiseleurio procumbentis–Vaccinietea, the order Deschampsio flexuosae Dahl 1957, the alliance Loiseleurio-Arctostaphylion Kalliola ex Nordh. 1943 (Fig.11). Community type Novosieversia glacialis (Table 1, Rel. 38–47; Fig. 12) – cryopetrophytic herb–lichen communities on rocky flat tops of the Subpolar Urals in places where calcium and silicon containing rocks emerge at 1000–1320 m. This syntaxon occupies an intermediate position between similar associations of the classes: Juncetea trifidi Hadač in Klika et Hadač 1944, Loiseleurio procumbentis–Vaccinietea and Rhodioletea quadrifidae Hilbig 2000 (Fig. 13), and its assignment to the higher syntaxonomic units is so far uncertain. A large number of rare species were recorded in communities: 52 vascular plant taxa (including Rhodiola quadrifida), 2 bryophytes, 5 lichens (Table 2). Among them, Rhodiola rosea (status 3) is included in the Red Book of the Russian Federation (Krasnaya..., 2008, Prikaz..., 2023), and Anemonastrum biarmiense is placed in its additional list as requiring biological surveillance. Among the rare species in the studied communities are endemics (subendemics) of the Urals and the Arctic, reflecting the regional specificity of the studied syntaxa: Anemonastrum biarmiense, Bromopsis pumpelliana subsp. vogulica Gypsophila uralensis, Linum boreale, Papaver lapponicum subsp. jugoricum, Thymus paucifolius and glacial relics of Siberian origin: Carex glacialis, C. ledebouriana, C. fuliginosa subsp. misandra, Crepis chrysantha, Erigeron silenifolius, Neotorularia humilis, Oxygraphis glacialis, Pentaphylloides fruticosa, Petasites sibiricus, Rhodiola quadrifida. Our research has expanded the communities with Rhodiola quadrifida geography. Their distribution in the northern parts of the Urals, in the relict part of its range is shown. R. quadrifida is found on the tops of the Urals, in the mountain cold desert, tundra and forest belts, as well as in foothill sites, often along outcrops of calcium-containing rocks. The needed condition is the presence of long-term frozen grounds and cryogenic relief forms. The species keeps such its characteristics as narrow ecological amplitude and low competitive ability within the classes Carici rupestris–Kobresietea bellardii, Loiseleurio procumbentis–Vaccinietea, Carici arctisibiricae–Hylocomietea alaskani. The diversity of rare species in the studied community types emphasizes the uniqueness of their biotopes that are important in maintaining the biological diversity and the evidences of the history of plant cover formation.

The information on the syntaxonomic diversity of the aquatic vegetation in the upper Kolyma River valley, located in the northeast of Russia, is summarized. The territory is a well-developed valley throughout its length, featuring an island floodplain and several terraces above it. This landscape hosts numerous oxbow and thermokarst lakes with aquatic communities which were studied to varying degrees — while the aquatic flora is one of the most extensively studied compare to other Far East areas, only some information has been obtained on the aquatic macrophyte species composition, distribution and ecology. The objective of this study is to compile the information gathered to date on the syntaxonomic diversity of aquatic vegetation in the upper reaches of the Kolyma River, The study area is in the Kolyma River valley between the confluence points of the Kulu and Ayan Yuryakh rivers (62.29887 N, 147.72886 E), and the upper pool of the Kolyma Reservoir (61.89122 N and 148.61855 E) (Fig. 1). The water bodies on floodplain terraces are diverse: thermokarst lakes, formed due to local soil subsidence caused by the thawing of underground ice or icy soils, oxbow and oxbow-thermokarst lakes, overgrown quarries; small thermokarst pools in sites of abandoned gold mining enterprises. Field work in eight large lakes and several dozens of small ones was carried out in the period of the lowest water level (summer dry season) — end of June–July. The area of sample plots as determined based on community size, with those less than 100 m2 being described within their natural limits. The research conducted in the Tenkinsky district of the Magadan region in the upper reaches of the Kolyma iver between 2008 and 2019 was based on 143 geobotanical relevés made by the author. Computer program Juice 7.0.45 (Tichý, 2002) was used for data treatment. The syntaxonomic classification was based on general works on aquatic vegetation, and species were primarily assigned to associations following their dominance (Vegetace…, 2011; Chepinoga, 2015; Mucina et al., 2016). The coenotic diversity of aquatic vegetation in the studied lakes is 11 associations in three alliances, two orders and two classes (Tables 1–5). Ten associations belong to the class Potamogetonetea, and one — to the class Littorelletea (Fig. 3–10). Seven associations are put in the alliance Potamogetonion.1. Myriophylletum sibirici Taran 1998 — rare communites in large oxbow-thermokarst lake Orotuk on the first terrace above the floodplain at 0.9 m depth. It is found in Eastern Siberia, including Transbaikalia and Yakutia, and is likely more widely distributed in the Kolyma River Valley within the local range of dominant (Chepinoga, 2015; Gogoleva et al., 2017). 2. Potamogetonetum berchtoldii Krasovskaya 1959 — extremely rare communites, found only in oxbow-thermokarst lake Mikhailovo on the first terrace above the floodplain, at 0.9 m depth. 3. Ranunculo circinati–Potamogetonetum friesii Weber-Oldecop 1977 — Potamogeton friesii communities in shallow sites of mesotrophic lakes with muddy bottoms, recorded only in oxbow-thermokarst lake Tumul-1 at 1.2 m depth. 4. Potamogetonetum graminei Lang 1967 — communities of grass pondweed, with some leaves submerged and some on esfloating on the water surface. This community is described in the large oxbow lake Podkova, located on the first terrace above the floodplain. 5. Potamogetonetum perfoliati Miljan 1933 — communities of pierced-leaved pondweed, typically with a two-layer structure, which are commonly found in several large oxbow-thermokarst lakes on the terrace above the floodplain and thermokarst lakes on the second above-floodplain terrace with muddy bottoms at 1.0–1.5 m depths. 6. Potamogetonetum praelongi Hild 1959 — communities of white-stemmed pondweed, typically recorded in all large oxbow-thermokarst lakes and several oxbow lakes with slimy bottom at 1.5–2.3 m depth. 7. Potamogetonetum tenuifolii Kipriyanova et Lashchinsky 2000 — communities of northern pondweed with Nymphaea tetragona as a companion, easily found in various types of lakes, including small thermokarst reservoirs in the sites of abandoned gold mining enterprises. Three associations within the alliance Nymphaeion albae.1. Nupharetum pumilae unite communities of small cow lily with Nymphaea tetragona as subdominant species that very rare in study area. 2. Nymphaeetum tetragonae — communities of holarctic relict species four-angled water lily, often found in various types of lakes, including small oxbow reservoirs. 3. Potamogetonetum natantis — common floating pondweed communities whidespread in the boreal zone of the North-East of Russia. Communities of amphibious helophytic perennial Sparganium hyperboreum in shallow waters are included in the ass. Sparganietum hyperborei Teteryuk, Lavrinenko et Kipriyanova 2022, within the alliance Sparganion hyperborei in the order Littorelletalia Koch 1926, the class Littorelletea Br.-Bl. et Tx. ex Westhoff et al. 1946 (Lavrinenko, D’yachkova, 2021; Teteryuk, Lavrinenko et Kipriyanova, 2022). Communities formed by relict species Nymphaea tetragona, Nuphar pumila and Ceratophyllum demersum, listed in the Red Book of the Magadan Region require protection (Red Data..., 2019).