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).

Syntaxonomic diversity of aquatic and helophyte communities was identified on the basis of 267 relevés carried out from 2005 to 2023 in 16 sites in the Bolshezemelskaya and Malozemelskaya tundras, Kolguyev Isl. and the Pechora River delta. For almost all described communities it was possible to determine their belonging to the association level, as many of them consist of species with extensive ranges (circum-, cosmopolitans) and occur in numerous regions on different continents. Prodromus contains 30 associations (with 3 subassociations and 8 variants) from 14 alliances, 9 orders and 6 classes. Four syntaxa of the association rank were left at the community rank due to the small number of relevés. Aquatic vegetation is represented by communities of the classes Lemnetea (free-floating duckweed communities), Potametea (rooted hydrophytes with leaves floating on the water surface and/or in the water column communities) and Littorelletea uniflorae (amphibious plants in fluctuating shallow water bodies communities). One association — Lemnetum trisulcae (Table 1, rel. 19–21; Fig. 5) is described in the class Lemnetea. The class Potametea turned out to be the richest, with 10 associations in 2 orders and 2 alliances. These are associations Myriophylletum sibirici, Myriophylletum verticillati, Potametum berchtoldii, Potametum filiformis, Potametum pectinati, Potametum perfoliati, Potametum praelongi, Potametum tenuifolii and community Potamogeton sibiricus (Table 2, rel. 1–38; Table 3, rel. 1–18; Fig. 6–12) in the alliance Potamion within the order Potametalia; Callitrichetum hermaphroditicae and Callitricho–Ranunculetum trichophylli (Table 3, rel. 19–27; Fig. 13, 14) in the alliance Ranunculion aquatilis within the order Callitricho hamulatae–Ranunculetalia aquatilis. Four associations of two alliances are described in the order Littorelletalia uniflorae within the class Littorelletea uniflorae: Callitricho palustris–Sparganietum angustifolii and Sparganietum hyperborei (Table 4, rel. 1–35; Fig. 15, 16) in Sparganion hyperborei, and Callitrichetum palustris and Litorello–Eleocharitetum acicularis (Table 5, rel. 1–5; Fig. 17, 18) in Littorellion uniflorae. Helophyte vegetation is represented by communities from 3 orders of the class Phragmito-Magnocaricetea. There are associations Petasitetum radiatae (alliance Petasition radiatae) and Equisetetum fluviatilis (alliance Phragmition australis) in the order Phragmitetalia australis (Table 6, rel. 1–21; Fig. 19, 20); and Caricetum aquatilis and Equiseto fluviatilis–Caricetum rostratae (alliance Magnocaricion elatae), Comaretum palustris, Menyanthetum trifoliatae and com. Cicuta virosa (alliance Carici–Rumicion hydrolapathi) (Table 6, rel. 22–34; Table 7, rel. 1–41; Fig. 21–25) in the order Magnocaricetalia. The order Oenanthetalia aquaticae includes the following described or validated associatios: Arctophiletum fulvae (alliance Arctophilion fulvae) with 2 subassociations — typicum and validated ranunculetosum hyperborei Möller ex O. Lavrinenko, I. Lavrinenko, Tsyvkunova et D’yachkova subass. nov. hoc loco, Ceratophyllo demersi–Eleocharitetum mamillatae, Eleocharitetum palustris subass. arctophiletosum fulvae, Hippuridetum lanceolatae Pestryakov et Gogoleva ex O. Lavrinenko, I. Lavrinenko, Tsyvkunova et D’yachkova ass. nov. hoc loco and com. Ranunculus pallasii (alliance Eleocharito palustris–Sagittarion sagittifoliae (Table 8, rel. 1–29; Table 9, rel. 1–28; Fig. 27–31). The class Isoёto-Nanojuncetea, which unites pioneer ephemeral low grass communities in periodically flooded freshwater habitats, contains one association — Juncetum bufonii (Table 10, rel. 6–8, Fig. 32) from the alliance Eleocharition soloniensis within the order Nanocyperetalia. Summer-annual pioneer vegetation of periodically nutrient-rich river alluvia, drained muddy bottoms of eutrophic lakes and heavily nutrientloaded anthropogenic habitats is represented by the ass. Tephroseridetum palustrisMirkin, Gogoleva et Kononov nom. mut. nov. (Table 10, rel. 1–2, Fig. 33) from the alliance Bidention tripartitae within the order Bidentetalia and the class Bidentetea. For aquatic bryophyte vegetation (Mucina et al., 2016: EuroVegChecklist 2) a provisional alliance Calliergonion megalophylli O. Lavrinenko all. prov. is proposed. It unites two associations and one community of hypnum mosses (Calliergonetum megalophylli, Sarmentypnetum trichophylli, com. Sarmentypnum exannulatum) growing underwater, in the water column and and over-watered shores in shallow meso- and eutrophic lakes. The highest beta-diversity (19 syntaxa) is established in floodplain and river-formed lakes, usually overgrowing, with muddy and sandy-silt bottoms. The lower stand richness (13 syntaxa) and high accumulation of macrophyte phytomass are noted in shallow, well-warmed lagoonal lakes and baths with a thick layer of bottom silt on brackish marshes at the mouths of rivers flowing into the bays. Aquatic plants literally fill such reservoirs, with a single species often growing in these. Comparable stand diversity (13 syntaxa) is established for thermokarst lakes with mineral soils on flat watersheds. The number of syntaxa is much lower (7) in thermokarst lakes on peatlands. Phytocenotic diversity is determined by ecological conditions of habitats — richness of substrate, water acidity, and water temperature, which depends on the proximity of permafrost.

The Polar-Alpine Botanical Garden-Institute named after N. A. Avrorin (PABGI) Kola Research Centre RAS, Russian Botanical Society, and the Russian geobotany have suffered an irreparable loss. On April 6, 2024 after a serious illness the outstanding geobotanist, a well-known specialist in the field of studying flora and vegetation of the Far North, a leading research scientist of the PABGI, PhD Natalia Evgenievna Koroleva has left us. Natalia Evgenievna was born in 1963 in Chernovskoe village, Kirov Region, in the family of agronomist and school teacher. After school graduation, in 1981 she entered the Moscow State University, where she specialized in the Department of Geobotany under the supervision by Prof. T. A. Rabotnov and Prof. A. P. Tyrtikov. After the University, in 1986 she was firstly enrolled in the Laboratory of Biocenology and afterwards in the Laboratory of Flora and Plant Resources of the PABGI. From 1986 to 1990, she passed the postgraduate probation in the Komarov Botanical Institute RAS (St. Petersburg) under the supervision by Prof. B. N. Norin. In 1991, she defended her PhD thesis «Vegetation classification of the mountain tundra belt of Khibiny» and received the degree of candidate of biology (PhD). Throughout her scientific life, Natalia Evgenievna was associated with PABGI having gone from probationer to the senior researcher in the Laboratory of Flora and Plant Resources. For many years, she was a Head of Murmansk Branch of the Russian Botanical Society (RBO). She organized and led a lot of geobotanical expeditions to the Murmansk Region and Spitsbergen Archipelago. The geography of her field researches was highly diverse. She brilliantly knew not only the vegetation of the Kola Peninsula, but as well other regions of Russian Arctic, Norway, Finland and Spitsbergen. The study and conservation of species and community diversity of Arctic and Subarctic vegetation, namely the plant cover of the Kola Peninsula and Spitsbergen Archipelago and revealing its transformation under the man impact, was in the focus by Natalia Koroleva scientific interests. She made a great contribution to the study of the Murmansk Region flora and vegetation, the regional Red Book conducting, plant cover monitoring and Nature conservation. In the Natalia Koroleva person, Russian vegetation science has lost an outstanding scientist, the specialist in phytocoenology, vegetation classification, the study of biodiversity and Nature conservation. She elaborated the vegetation classification method based upon the analysis of the uniformity of plant species distribution with similar ecology in particular plant community groups. Using this method, Natalia Evgenievna and her colleagues developed a detailed classification of plant communities and habitat types of zonal and mountain tundra and highland heaths of the Kola Peninsula and Spitsbergen that has resulted in numerous publications. She had published about 150 scientific papers and 10 monographs, books and guides to the Nature reserved territories of Khibiny Mountains, Lovozero Tundra, Spitsbergen and many others that put a huge impact in the development of vegetation science and Nature conservation in the Murmansk Region. She was an editor of many scientific proceedings and collective monographs. Natalia Evgenievna greatly contributed to the training of young scientists: For ten years (2001–2011), she gave lectures at the Apatity Branch of Moscow State Technical University in the ecology, biodiversity, and vegetation classification. Some Master’s and PhD theses were prepared under her supervision. Natalia Evgenievna devoted a lot of time and efforts to the work in RBO. For about 25 years she was a Head of Murmansk Branch of RBO and a member of its Council, took part in the Organizing Committees of numerous conferences, symposiums and workshops held by RBO. The memory of Natalia Evgenievna Koroleva — an outstanding geobotanist, teacher, environmental activist and popularizer of science — will always remain in her numerous scientific works, and in the hearts of students and colleagues.

The article analyzes the monograph by V. G. Storozhenko, V. V. Chebotareva, P. A. Chebotarev «Degradation and regeneration of oak forests in the zone of forest-steppe (results of experimental studies)». The research of an author team devoted to the Tellerman oak forest growing system is examined in detail.

The classification of West Siberian mire vegetation is more or less well developed in the southern part of the forest zone (Lapshina, 2010) while in the northern part of the West Siberian Plain it has received much less study. There are only a small number of publications containing descriptions of mire types and plant communities (Pyavchenko, 1955; Boch et al., 1971; Kirpotin et al., 1995; Smagin, 2003; Neshatayev et al., 2002). This paper presents the classification results for the low-sedge vegetation of waterlogged hollows and Sphagnum lawns, within flat palsa-bogs, ombrotrophic raised bogs and transitional mire complexes, which is assigned to two alliances — Stygio–Caricion limosae Nordhagen 1943 and Scheuchzerion palustris Nordhagen ex Tx. 1937 of the class Scheuchzerio–Caricetea nigrae Tx. 1937. The classification is based on 422 relevés performed in 2004–2019 at 22 plots located between 63° and 75° N in the northern taiga, forest tundra, and southern tundra subzones of West Siberia (Fig. 1). In the most recent summary “Vegetation of Europe…” (Mucina et. al., 2016), the alliance Stygio–Caricion limosae is assigned to the order Sphagno watnstorfii–Tomentypnetalia Lapshina 2010, however this does not seem conclusive. Communities of this order are closely associated with rich fens, often spring fens fed by ground water, which does not correspond to the real conditions in which communities of this alliance are developed. Ecologically, in the current structure of the class Scheuchzetio–Caricetea nigrae (Peterka et al, 2017), the alliance Stygio–Caricion limosae has taken the true place of the alliance Rhynchosporion albae Koch 1926 (ICPN, Art. 36), which was initially unambiguously associated with the order Caricetalia nigrae Koch 1926 based on the original relevés and diagnostic species (Rhynchspora alba, Agrostis canina, sphagnum mosses of sec. Subsecunda). Therefore, we also consider the alliance Stygio–Caricion limosae belonging to the order Caricetalia nigrae, where it fits better judging by its ecological and floristic features. The differential species combination of the alliance Stygio–Caricion limosae in the northern part of West Siberia includes Carex limosa, Drosera obovata, Juncus stygius, Gymnocolea inflata, Sphagnum perfoliatum, S. platyphyllum, S. subsecundum, Utricularia minor, U. ochroleuca, Warnstorfia exannulata, and W. fluitans. Within this alliance, two new associations with subassociations have been described: Utricularo ochroleucae–Caricetum limosae and Sphagno perfoliati–Caricetum rotundatae, of which the first one occurs in the northern taiga mires, while the second one in the forest tundra and southern tundra subzones. The order Scheuchzerietalia palustris Nordhagen ex Tx. 1937 comprises ombrotrophic vegetation of Sphagnum lawns and bog hollows (Mucina et al., 2016) and currently includes the only alliance Scheuchzerion palustris. Its typical boreal suballiance Scheuchzerienion palustris suball. nov. (nomenclature type — lectotypus hoc. loco: ass. Scheuchzerietum palustris Tüxen, 1937: 61) is represented by two associations: Eriophoro vaginati–Sphagnetum baltici and Carici limosae–Sphagnetum jenseni. Their distribution to the north is limited by the mire complexes of the northern taiga. Further north similar habitats are occupied mainly by communities of the predominantly subarctic suballiance Caricion rariflorae. Within this suballiance, two associations — Carici rotundatae–Sphagnetum baltici and Carici rotundatae–Sphagnetum lindbergii — are widely distributed over the entire gradient from the northern taiga to the southern tundra. The ass. Carici rariflorae–Sphagnetum baltici occurs only occasionally and is bound to the forest tundra and southern tundra. Statistical processing of the entire data set was performed to confirm the classification results and make a number of syntaxonomic decisions. The results of t-SNE ordination (t-distributed stochastic neighbor embedding method) (van der Maaten, Hinton, 2008) confirmed the validity and expediency of separating oligotrophic and mesooligotrophic low-sedge communities of hollows and fens not only at the alliance level, but also at the order level. Despite certain physiognomic and floristic similarities, the location points of the two alliances in multidimensional space are well differentiated and do not overlap with each other (Fig. 10). Calculation of the floristic similarity degree of relevés with regard to species abundance and visualization of the statistical processing results have clearly demonstrated that the entire relevé array of oligotrophic sphagnum lawns in the alliance Scheuchzerion palustris can be divided by the dominant sphagnum moss species into separate clusters, within which dominant grass layer clusters could also be distinguished. Given that, in the future, the formal statistical processing of large sets of geobotanical data will become an increasingly important tool to underpin syntaxonomic decisions, this fact cannot be ignored. In this connection, we propose to review the current practice of identifying associations of mire vegetation by the dominant species of vascular plants and sub-associations by the dominant moss species. The latters are of primary importance in the poor-species plant communities of waterlogged hollows and fens, because they are more sensitive to ecological conditions of habitats, which ultimately determine the entire floristic composition and community structure.

The tendency to gradual reduction of crop is observed now in the North-West of the Russian Federation. From 2010 for 2021 the total area under crops in four regions (Leningrad, Novgorod, Pskov, Vologda) has decreased from 1150.7 to 907.5 thousand hectares. Studies of specific structure of weed communities of the North-West of the Russian Federation started in the first decade of the XX century with inspections of crops by A. I. Maltsev in the St. Petersburg region (Maltsev, 1908, 1909). Since the beginning of the XXI the study of weed plants were focused at the All-Russian Institute of Plant Protectionwhere monitoring of crops of the North-West of the Russian Federation (Mysnik, 2012; Luneva, Mysnik, 2016, 2017, Luneva et al., 2009) has became the priority direction. In spite of previous wide floristic researches, the diversity of weed communities of this region is still not established. The first results of the floristic classification of weed vegetation in the North-East of the Russian Federation are presented. The dataset is based on 278 relevés made by N. N. Luneva, I. N. Nadtochiy, E. V. Filippova, T. D. Sokolova, Yu. V. Eroshina for field seasons in 1999–2916. The research area covered Leningrad, Novgorod, Pskov and Vologda regions. Data processing was carried out according floristic classification approach (Westhoff, Maarel, 1978), using TWINSPAN algoritm in JUICE software packages (Tichy, 2002). The new syntaxa are named in accordance with the rules of the International Code of Phytosociological Nomenclature (Theurillat et al., 2021). DCA-ordination using the CANOCO 4.5 software package (Ter Braak, Smilauer, 2002) was produced to identify patterns of environmental differentiation. The habitat moisture and soil richness-salinity scales status of communities (Ramenskiy et al., 1956) was calculated and basic agroclimatic parameters were identified to characterize the ecological variability of habitats. The communities were classified within the order of Aperetalia spica-venti J. Tx. et Tx. in Malato-Beliz et al. 1960 of the class Papaveretea rhoeadis S. Brulo et al. 2001 and were assigned to the alliance Scleranthion annui (Kruseman et Vlieger 1939) Sissingh in Westhoff et al. 1946), which unites the most mesophytic weed communities distributed mainly on gray forest, sod-podzolic, podzolic and other types of soils of the forest zone. The alliance diagnostic species are Stellaria media, Tripleurospermum inodorum, Capsella bursa-pastoris, Lepidotheca suaveolens, Thlaspi arvense, Centaurea cyanus. Three species from the diagnostic groups of ruderal vegetation classes are also active in their cenoflora — Elytrigia repens, Viola arvensis, Taraxacum officinale. From the diagnostic group of the Papaveretea rhoeadis class and the order Aperetalia spica-venti with high constancy, species are found Cirsium setosum, Chenopodium album, Sonchus arvensis, less often are Fallopia convolvulus. The group of species of the alliance Scleranthion annui includes Stellaria media, Tripleurospermum inodorum, Capsella bursa-pastoris, Lepidotheca suaveolens, Thlaspi arvense, Centaurea cyanus. Unlike the weed communities of other regions of the Russian Federation (Khasanova et al., 2021 Yamalov et al., 2021a, b), apophytes are not significantly presented in cenophlora, but such ruderal species as Elytrigia repens, Viola arvensis, Taraxacum officinale are active. The identified associations and communities are different geographically, in terms of crop affinity and the system of agricultural machinery, the type of soils and heat conditions. The most widespread are the communities of the ass. Tussilagi farfarae–Centauretum cyani, which occur in the Leningrad, Novgorod, Pskov and Vologda regions. The associations Galeopsetum bifidae (Novgorod, Pskov and Vologda regions) and Lamio purpurei–Persicarietum lapathifolii (Leningrad, Novgorod and Pskov regions) are of slightly smaller range. Syntaxa are differentiated according to the level of habitat heat conditions from the higher (ass. Echinochloo crusgalli–Galietum aparinis, ass. Lamio purpurei–Persicarietum lapathifolii) to the lower (community Fumaria officinalis) ones. Communities of the associations Echinochloo crusgalli–Galietum aparinis and Lamio purpurei-Persicarietum lapathifolii are formed on swamp, peat and podzolic-swamp soils. The community Polygonum aviculare and the ass. Mentho arvensi–Sonchetum arvensis are formed on weakly and medium-podzolic, as well as sod-podzolic soils. The other syntaxa are confined to sod-carbonate soils. According to the spectrum of crop, syntaxa were distributed as follows: associations Echinochloo crusgalli–Galietum aparinis, Mentho arvensis–Sonchetum arvensis, Lamio purpurei–Persicarietum lapathifolii and the community Polygonum aviculare occur mainly on fields with vegetable crops (potatoes, carrots, cabbage, beets, etc.); Tussilagi farfarae–Centauretum cyani, Galeopsetum bifidae, the communities of Fumaria officinalis and Achillea millefolium — on grain crops (barley, oats, rye, triticale and wheat). The main factors of differentiation of the studied communities are the type of soil, cultivated crop and humidification.