Mesophilous broad-leaved forests predominating in south-western part of Russia were included in alliance Aceri campestris–Quercion roboris Bulokhov et Solomeshch in Bulokhov et Semenishchenkov 2015, association Fraxino excelsioris–Quercetum roboris Bulokhov et Solomeshch 2003 and three geographic subassociations. The subassociation F. e.–Q. r. typicum Bulokhov et Solomeshch 2003 in Bulokhov et Semenishchenkov 2015 unites communities occurring mainly in the broad-leaved forests zone of the Central Russian Upland. The subassociation F. e.–Q. r. stellarietosum nemori Semenishchenkov et al. 2015 occurs in the northern part of the association range in the zone of broad-leaved forests and close to the southeastern border of the hemiboreal subzone. Mesophilous broad-leaved forests occurring in the forest-steppe zone of the Central Russian Upland were included in the subass. F. e.–Q. r. crataegetosum curvisepalae Semenishchenkov in Bulokhov et Semenishchenkov 2015. The geographical distribution of the syntaxa is related to the climate continentality gradient — from the subass F. e.–Q. r. crataegetosum curvisepalae (the largest continentality indices) to the subass. F. e.–Q. r. stellarietosum nemori (the smallest continentality indices). The associations Aceri campestris–Tilietum cordatae Zaugolnova et Braslavskaya 2003 (nom. inv.) from the Kaluga and Tula Regions (Zaugolnova, Braslavskaya, 2003) and Aceri campestris–Quercetum roboris (nom. inv.) (var. Acer tataricum) described from the Voronezh Region (Starodubtseva, Khanina, 2009) were included in the association Fraxino excelsioris–Quercetum roboris after comparative syntxonomical analysis. On the basis of a comparative analysis, diagnostic combinations of subassociations were compiled, consisting of species with constancy above 20 % and values of the statistical φ-coefficient for selections above 20: F. e.–Q. r. stellarietosum nemori — Carex sylvatica (5059.9), Equisetum hyemale (2842.3), Galeobdolon luteum (10087.4), Matteucia struthiopteris (4257.7), Ranunculus cassubicus (5857.9), Stellaria nemorum (3349.6); F. e.–Q. r. crataegetosum curvisepalae — Acer tataricum (5362.0), Crataegus rhipidophylla (5964.0), Poa nemoralis (2736.9), Pyrus pyraster (3840.8), Scilla siberica (4558.4), Viola odorata (3440.5). Analysis of the differentiaal table of mesophilous broad-leaved and spruce-broad-leaved forests syntaxa made it possible to conclude that associations previously (Onyshchenko, 2009) assigned in Ukraine to alliance Scillo sibericae–Quercion roboris have a high floristic similarity with the syntaxa of Aceri campestris–Quercion roboris from the South-West of Russia, especially in the forest-steppe part of its range. Selections of three subassociations of the association Mercurialo perennis–Quercetum roboris from Ukraine floristically close to the syntaxa of alliance Querco roboris–Tilion cordatae from the South-West of Russia. In the dendrogram of cluster analysis, the compared syntaxa are grouped into two blocks corresponding to the rank of alliances: Aceri campestris–Quercion roboris and Querco roboris–Tilion cordatae. Based on the review, the authors believe that the «Hierarchical floristic classification system…» (Mucina et al., 2016) may be amended in terms of recognizing the syntaxonomical independence of the alliance Aceri campestris–Quercion roboris and its geographical interpretation. Derivative communities disturbed by humans in the place of mesophylous broad-leaved forests are classified as anthropogenic variants and non-rank «communities» named after the dominant species: Betula pendula, Populus tremula, Tilia cordata. Forests with a poor floristic composition, in which the diagnostic species of association and subassociation drop out of the coenoflora are classified as inops variants. They are characterized by a noticeable decrease in the average floristic saturation in comparison with typical communities. Derivative forests with a predominance of Betula pendula have a higher species richness in comparison with aspen or linden forests, as well as typical phytocoenoses of the association.

In the article the phytocoenotic activity of species of the genus Rumex L. in the space of 5 syntaxa of meadow vegetation in the Bryansk Region assessed. Based on geobotanical materials collected in 2018–2022 two new associations and one subassociation were established, for which high activity of Rumex acetosella and R. thyrsiflorus was revealed. The maximum activity (V3–5) of R. acetosella is characterized for the ass. Koelerio delavignei–Festucetum rubrae Rumex acetosella var., R. thyrsiflorus – the ass. Trifolio arvensis–Rumicetum thyrsiflori (V1–5) and the ass. Kadenio dubiae–Rumicetum thyrsiflori (V5). R. acetosella reaches the highest abundance-coverage on dry and poor soils, while R. thyrsiflorus naturally increases the abundance-coverage under more mesophytic conditions. High activity of R. acetosella and R. thyrsiflorus was revealed in grass plant communities in xerophytized river floodplains. This change in the moisture regime against the background of a reduction in the duration and height of floods, as well as the lack of haymaking and grazing in floodplain locations in recent decades, contributed to an increase in the activity of the studied species. In the future, if the trend towards xerophytization of the floodplains persists, we can expect the stable positions of these species to remain in meadow grass stands.

The paper presents the results of a comparative analysis of the floristic and phytocoenotic diversity within widespread association of acute sedge meadows Caricetum gracilis Savich 1926 in the floodplain of the Desna River (Bryansk and Smolensk regions, Russia). Available geobotanical data on Desna floodplain, collected in the last 40 years, allowed identifying the main dynamic trends in the syntaxonomical space. Based on 36 relevés made by the authors in 1975–1990 previously (Bulokhov, 2001) 3 subassociations, which communities were prevalent in the Desna valley, were established: Caricetum gracilis typicum, С. g. oenanthetosum aquaticae, С. g. beckmannietosum eruciformis. As a survey of the Desna floodplain in 2015–2018 showed, both flow decrease and drop in the level of spring flood and groundwater in the XXI century have led to a change in the appearance, floristic composition, and structure of acute sedge meadows. Xerophytization of the floodplain resulted in the disappearance of the С. g. oenanthetosum aquaticae and С. g. beckmannietosum eruciformis communities. Drying of typical habitats of moist acute sedge meadows became the background of the formation of diverse communities of other types in their place. In the coenoflors of these communities changes occurred at the class level from Phragmito-Magnocaricetea Klika in Klika et Novák 1941 to Molinio-Arrhenatheretea Tx. 1937. Two groups of communities have been formed. The first group is represented by syntaxa of the alliance Magnocaricion gracilis (class Phragmito-Magnocaricetea): Caricetum gracilis typicum with variant Achillea salicifolia as well as by the communities Lythrum salicaria, Calystegia sepium, Calamagrostis canescens. The share of the alliance characteristic species in their coenofloras is 54–64%, and Carex acuta, as a rule, dominates. The second group represents the communities of wet meadows (order Molinietalia caeruleae) of the class Molinio-Arrhenatheretea. The alliance Deschampsion cespitosae is established with subass. Poo palustris–Alopecuretum pratensis typicum (with three variants: Veronica longifolia, Hierochloё odorata, Galium physocarpum) and three communities (Cirsium arvense, Lysimachia vulgaris, Stachys palustris) The share of characteristic species of the order in their coenofloras is 58–95%. All communities and variants form series along the moisture gradient in habitats of acute sedge meadows. Communities Lythrum salicaria, Calystegia sepium, Calamagrostis canescens are distributed in the wettest and richest in mineral nitrogen habitats in the Middle Desna area, in the former long-flooded low-level floodplain. The other ones occur, first of all, in the Upper and Middle Desna areas on a short- and long-flooded floodplain of an average level. These communities are forming on moist and fresh soils. The variants and communities on the gradients of moisture and the richness of mineral nitrogen of the soil were ordinated using the ecological scales of H. Ellenberg et al. (1992). Serial communities form an ecological-dynamic sere on a humidity gradient, showing the direction of their dynamics. The same localization of studies carried out both in 1975–1990 and in 2015–2018 identified changes in vascular plant coenoflora of the ass. Caricetum gracilis for this period: from 62 species in 1975–1990 to 143 species in 2015–2018. There are three groups of species, which reflects these changes. Besides species affine to the class Phragmito-Magnocaricetea, numerous meadow herbs of the class Molinio-Arrhenatheretea appeared: Agrimonia eupatoria, Agrostis tenuis, Bromopsis inermis, Carex praecox, Dactilys glomerata, Dianthus deltoides, Elytrigia repens, Equisetum arvense, Festuca pratensis, Galium mollugo, Geranium pratense, Galium physocarpum, Hieracium umbellatum, Hierochloё odorata, Lathyrus pratensis, Odontites vulgaris, Poa pratensis, Potentilla argentea, Potentilla erecta, Phleum pratense, Vicia cracca. A complex of ruderal explerent and nitrophilous species with numerous alien ones has been formed: Bidens frondosa, Chamaenerion angustifolium, Cirsium arvense, Echinocystis lobata, Epilobium adenocaulon, E. collinum, E. pseudorubescens, E. tetragonum, Erigeron annuus, E. canadensis, Lactuca serriola, Linaria vulgaris, Senecio jacobaea, Sonchus arvensis. Most of these species are anemoсhores, and their presence in the sedge communities is associated with open site formation due to the soil drying between hummocks, as well as the destruction of sedge tussocks under drying and fire. Over the past decade invasive species Bidens frondosa, Erigeron annuus subsp. septentrionalis, E. canadensis,and Lactuca serriola have become an ordinary component of the Desna’s river valley flora. Trees and shrubs (Acer negundo, Betula pendula, Frangula alnus, Quercus robur, Rosa majalis, Salix cinerea, S. pentandra, Swida alba) enter into meadow communities because the lack of haymowing. The following changes in the life form spectrum took place due to the floodplain xerophytization and acute sedge meadow transformation: the proportion of long-rhizome species decreased, while that of rod-root, short-rhizome, and annuals increased; trees and shrubs appeared. Obvious also are changes in the ecobiomorphspectrum: the proportion of mesomorphic species increased, that of hygromophic and mesogygromorphic ones decreased; xero-mesomorphic plants appeared.

The results of classification of the nitrophite grass communities of the Sozh-Desna interfluve (Bryansk, Smolensk Regions of Russia and the adjacent regions of the Republic of Belarus), united in the class Epilobietea angustifolii Tx. et Preising ex von Rochow 1951 are given. Such vegetation within the European Russia is studied fragmentary, including the study area for which only some data on phytodiversity of this class were known (Bulokhov, Kharin, 2008; Semenishchenkov, Shapurko, 2009; Panasenko et al., 2014). Usually such communities are formed on crude fringes on watersheds and in floodplain forests, on wet and damp meadows in beams, river and stream valleys. As a rule, similar habitats in Europe are under various anthropogenic influence, therefore vegetation of this type is referred to categories of «semi-natural» or «ruderal» ones (Dengler et al., 2007; Mucina et al., 2016). For a long time fr om the standpoint of floristic classification nitrophite grass communities were assigned to the class Galio-Urticetea Passarge ex Kopecky 1969. The modern view (Mucina et al., 2016), this vegetation is integrated in the class Epilobietea angustifolii Tx. et Preising ex von Rochow 1951, representing tall-herb semi-natural perennial vegetation on disturbed forest edges, nutrient-rich riparian fringes and in forest clearings in the temperate and boreal zones of Eurasia. Thus, class Epilobietea angustifolii combines types of communities rather diverse on their ecology and successional status. However, we support this syntaxonomical decision, since combination of synanthropic, native and even often alien species is character for the majority of nitrophyte phytocoenoses. In the territory of the Sozh-Desna interfluve phytocoenoses of this class are partly formed with the participation of invasive species: Heracleum sosnowskyi, Echinocystis lobata, Impatiens glandulifera, Reynoutria japonica. Listed species are regarded as «transformers» due to their ability to intensely change the composition and structure of phytocoenoses, into which they are introduced. Usually such community are poor in species number, but for a long-term keep their stability in unchanging conditions. In our opinion, if invasive species forms a stable community for a long time, wh ere it defines phyto-enviroment and composition of coenofloras in localities with similar habitats, it can be considerd as character (for the associations and subassociations) or differential (for variants). This approach argues in favor of establishing units of association rank for vegetation with the invasive species, but not of non-rank units «derivative» communities. Monitoring of the nitrophyte grass communities in the Sozh-Desna interfluve for several years shows that their coenofloras and structure remained unchanged while occupied area became larger. Therefore, described phytocenoses formed by invasive species can be considered as stable, that allows us to combine them in the syntaxa of association and subassociation ranks. For the development of syntaxonomy of nitrophyte grass vegetation 165 authors’ relevés, including 62 made during the investigation of Sozh-Desna interfluve in 2016–2017, have been used. The classification has been performed according the J. Braun-Blanquet approach. The syntaxonomy includes 10 associations, 5 subassociations within 4 alliances. Nitrophite grass communities of the study region have some differences in species composition and habitat specificity that allows to put them into 3 orders within the class Epilobietea angustifolii: Convolvuletalia sepium Tx. ex Moor 1958 (semi-natural fringe vegetation on river and other water body banks in temperate Europe and the Mediterranean); Circaeo lutetianae–Stachyetalia sylvaticae Passarge 1967 nom. conserv. propos. (ruderal and semi-natural fringe mesic tall-herb vegetation on nutrient- and base-rich soils in cool-temperate and submediterranean Europe); Galio-Alliarietalia Oberd. in Gürs et T. Müller 1969 (ruderal vegetation dominated by short-lived perennials on mesic loamy soils in the low altitude cool-temperate Central Europe and at high altitudes of submediterranean Europe— some alliances of this order unite ruderal and semi-natural communities (Dengler et al., 2007; Mucina et al., 2016). 2 associations and 4 subassociations are described as new ones. Senecionetum fluviatilis rubetosum caesii subass. nov. hoc loco (Table 1, relevés 1–17; holotypus — relevé 2*: Bryansk Region, Vygonichi district, to the west from Poluzhye, riverbed right bank wloodplain of the Desna River, 7.08.2016, A.D. Bulokhov). Scirpo sylvatici–Galietum rivalis ass. nov. hoc loco, S. s.–G. r. typicum subass. nov hoc loco (Table 2; holotypus — relevé 16*: Bryansk Region, Bryansk, Bezhitsk district, near Staynoye settlement, 10.07.2016, A. D. Bulokhov). S. s.–G. r. echinocystie­tosum lobatae subass. nov. hoc loco (Table 2, relevés 1–7; holotypus — relevé 1*: Bryansk Region, Bryansk, near Svenskiy monastery, bottom of ravine, 10.07.2016, A. D. Bulokhov). S. s.–G. r. eupatorietosum cannabini subass. nov. hoc loco (Table 2, relevés 8–14; holotypus — relevé 10*: Bryansk Region, Mglinsk district, near Oskolkovo, floodplain of the Voylovka River, 17.08.2017, A. D. Bulokhov). Link of these syntaxa with river floodplains is reflected in their assignment to the alliance Senecionion fluviatilis, which combines high-grass border communities on rich soils of the river banks and beams in Central Europe (Mucina et al., 2016). Obviously, the distribution area of this unit may be expanded into the Central Europe. Chaerophylletum temuli ass. nov. hoc loco (Table 5, holotypus — relevé 2*: Bryansk region, Bryansk, Suponevo, near Svenskiy monastery, the lower part of the indigenous side of the Desna River valley, 14.08.2005, A. D. Bulokhov). Communities of this association are rare in the region and distributed in specific habitats in the lower parts of the indigenous slopes of river valleys and beams and nearby hollows, generally at the chalk outlets. The combination of typical nitrophilous species of the class with some weed and ruderal species makes possible the assignation of this association to alliance Geo urbani-Alliarion officinalis, which combines ruderal and semi-natural fringe thermophyte vegetation of short-lived low herbs on nutrient-rich soils of temperate Europe.

Only few publications on the classification of vegetation of Koelerio–Corynephoretea canescentis Klika in Klika et Novák1941 class, that unites pioneer communities on sandy soils, dunes or an exposed sands, is known for Bryansk region of Russia (Bulokhov, 2001; Bulokhov, Kharin, 2008). This region is located in the western part of the East European plain, on the watershed of two large river (Dnieper and Volga) systems, occupying the central part of the Desna river pool and the woody watershed between Desna and Oka. The territory (34.9 thousand кm2) is extended from the west to the east on 270 km (between 31°10′ and 35°20′ E) and from the north to the south — on 190 km (between 54°05′ and 52°10′ N). The main item of this paper is to submit the results of the classification carried out upon thebasis of 57 releves made in 2003–2016 in Bryansk region and to characterize the composition, distribution and syntaxonomical position of thepioneer vege­tation of sandy and shallow soils communities within it. Three new associations are described according to Braun-Blanquet floristic classification. The syntaxon nomenclature of the higher ranks follows Mucina et al. (2016) The ass. Thymo serpylli–Koelerietum glaucae ass. nov. hoc loco, with synecological optimum on dry poor sandy soils, is diagnosed by character species Artemisia campestris, Koeleria glauca, Thymus serpyl­lum. Its communities occur on fringes of the lichen pine forests, sandy river terraces and outwash plains. Two subassociations are distinguished within the association: T. s.–K. g. typicum (with var. typica and Corynephorus canescens) and agrostietosum vinealis subass. nov. hoc loco (with var. typica and Calluna vulgaris) with Agrostis vinealis, Dianthus arenarius, Cladonia arbuscula as differential species. The ass. Koelerio glaucae–Plantaginetum arena­riae ass. nov. hoc loco, with synecological optimum on dry poor sandy soils or exposed sands, is diagnosed by Plantago arenaria and Koeleria glauca. Its communities occuron the exposed sands, fringes of lichen pine forests and not flooded sandy river crests. The ass. Diantho borbasii–Festucetum polesicae ass. nov. hoc loco with synecological optimum on dry, weekly acidic, poor of mineral nitrogen, sandy soils or the exposed sands, is diagnosed by Festuca pole­sica, Astragalus arenarius, Jurinea cyanoides, Otites parviflora. Communities occur on the exposed sands, fringes of lichen pine forests. Two variants are distinguished within association: Sempervivum ruthenicum (on dunes with dry, poor, weekly developed soils) and typica. These three associations are the early stages of the progressive succession of oligotrophic lichen pine fo­rests on the river terraces or of the heath meadows in flood river plains.

The results of the analysis of floristic composition of psammophytes of meadow and forest communities of the Southern Nechernozemye of Russia. Three ecological groups of psammophytes by moisture, acidity and availability of mineral nitrogen in soil are established.

In the article the data on 137Cs accumulation in meadow ecosystems plants of radioactive contaminated areas of Bryansk, Gomel and Chernigov regions are provided. The researches were conducted in 2013 within landscapes of Iput, Desna, Snov, Dnieper river valleys. It is proved that meadow plants of various species and ecological groups from communities of various syntaxons show different abilities to accumulate radionuclides. High 137Cs specific activity is noted for plants of genus Carex. Plants of ass. Festucetum arundinaceae are characterized by low intensity of 137Cs accumulation. Practical value of researches is connected with the necessity to solve the problem of pure forages production for needs of animal breeding. The comparative analysis of the radionuclide content in dry phytomass on each of investigated areas is made. It is found out that in Bryansk region radionuclide specific activity exceeds the control level of the radionuclide content in hay for the Russian Federation (600 Bq/kg). In Gomel region the hay made on floodplain meadows meets acceptable level of 137Cs in hay in Belarus (1300 Bq/kg). 137Cs pollution density of soils of investigated communities in Chernigov region of Ukraine is low, and the radionuclide content in dry phytomass does not exceed permissible levels.

Examine the contents of the elements of the group of heavy metals in samples 18 meadow plant species and soil basal space. In soils root space is determined by significant fluctuations of total concentrations of heavy metals. Identified accumulative opportunities meadow species relative to the TM in natural meadows in the conditions of high technogenic load. Based on the coefficients of accumulation established types of «indicators» and «exclusive», which can be recommended as effective phytoremediation. For grassland species confirmed the species specificity of accumulative opportunities plants relative to the TM: Filipendula ulmaria, Scirpus sylvaticus (гигрофитные виды), Agrostis tenuis и Helichrysum arenarium. Hygrophytic species of floodplain meadows, xerophytic species in dry accumulate chemical elements the same, regardless of the geographical location of meadow ecosystems. For these plants is characterized by the accumulation of mobile essential elements strontium, copper, manganese.

3 new associations, distributed in the Southern Nechernozemie of Russia, are described for the first time with use of the Braun-Blanquet approach: Poo angustifoliae–Arrhenatheretum elatioris, Festuco pratensis–Leucanthemetum vulgaris, Trifolio ar­ven­si–Rumicetum thyrsiflori. The synecological amplitudes of humidity, acidity and soil richness by mineral nitrogen of the associations are defined. Communities of ass. Poo angustifoliae–Arrhenatheretum elatioris are distributed on the flat slopes of ravines on the dry, subacidic, grey wood loamy soils moderately rich by mineral nitrogen. Communities of ass. Festuco pratensis–Leucanthemetum vulgaris are distributed on fresh, subacidic, rather poor in mineral nitrogen grey and dark grey wood loamy soils on the fallow lands of various age within landscapes of loess plateau; on sod-podzolic loamy, sandy and subsandy soils within landscapes of fluvioglacial loamy and moraine-outwash plains. They can meet occasionally on grey wood loamy soils. Communities of the Potentilla argentea var. are distributed on grey and dark grey wood loamy soils on the fallow lands within landscapes of loess plateau. Communities of the Medicago lupulina var. are distributed on sod-podzolic loamy, sandy and subsandy subacidic, rather poor in mineral nitrogen soils on the fallow lands of various age. They may occur in the small sites on the continental meadows or along highways. Occasionally these plant communities can be found on grey wood loamy soils. Communities of ass. Trifolio arvensi–Rumicetum thyrsiflori are distributed on raised sites on gentle-wavy outwash or moraine-outwash plains on dry and moderately sour, poor by mineral nitrogen easily sandy and sandy podzol soils. For the estimation of a homotoneity of established syntaxa the index of homotoneity of H.Passarge (1979) is used. The ass. Poo angustifoliae–Arrhenatheretum elatioris is characteristic by the high homogenetic variability. Totally, association’s index of homotoneity is high — 0.52. The low index of a homotoneity is characteristic for аss. Festuco pratensis–Leucanthemetum vulgaris — 0.35, for the Potentilla argentea var. — 0.33 and Medicago lupulina var. — 0.44. Following associations have a low index of the homotoneity: аss. Trifolio arvensi–Rumicetum thyrsiflori — 0.33, as in subass. T.a.–R.th. typicum— 0.33, and in subass. T.a.–R.th. helichrysetosum arenarii — 0.44. Such low indexes of a homotoneity are characteristic for semiruderal and serial commu­nities.

The results of the geobotanical research of the flood-plain meadows of the Iput’ river valley within Bryansk (Russia) and Gomel (Republic of Belarus) regions. The syntaxonomy of the flood-plain meadows is developed. The transformation of the syntaxa into the types of feeding grounds is realised.

3 new associations: Sedo maximi–Peucedanetum oreoselini, Seselio annui–Hieracietum umbellati, Koelerio glaucae–Agrostietum vinealis, distributed on the fringes of pine and birch forests in the Bryansk region were described using the Braun-Blanquet approach. The associations belong to the alliance Geranion sanguinei Th. Müller 1961. The synecological amplitudes of humidity, acidity and mineral nitrogen soil richness were defined. The distinguished associations are different from those spread in the Western and Central Europe by their coenoflora composition.