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 article presents the results of long-term investigation and inventory of the moss flora in the territory of the Nature Park "Kondinskie ozera" (Konda Lakes) named after L.F. Stashkevich (Khanty-Mansi Autonomous District-Yugra, West Siberia-60°54'N, 63°30'E). Observations by the author and archive records since 2001 are summarized. In total, 114 species of mosses were indentified for the study area; more than one-third of them (30 species) are Sphagnum mosses. 22 species are indicated for the territory of Nature Park for the first time. Bryum cyclophyllum, Dichelyma capillaceum, Dicranum septentrionale, Mnium thomsonii, Sphagnum annulatum, S. mirum, S. subfulvum, and S. tenellum are rare for the whole of West Siberia. An annotated list of mosses is compiled based on identification of ca. 2000 specimens; it includes the occurrence of species within the Nature Park as well as their ecological and phytocenotic preferences. Резюме В статье приведены результаты многолетних исследований по изучению и инвентаризации флоры мхов на территории природного парка "Кондинские озера" им. Л.Ф. Сташкевича (Ханты-Мансийский автономный округ-Югра). Обобщены авторские и фондовые материалы, накопленные начиная с 2001 года. Всего для территории природного парка приводится 114 видов мхов, в том числе 30 видов сфагновых и 84 вида бриевых мхов. Впервые для флоры природного парка указывается 22 вида. В парке выявлен целый ряд видов, редких для всей территории Западной Сибири: Bryum cyclophyllum, Dichelyma capillaceum, Dicranum septentrionale, Mnium thomsonii, Sphagnum annulatum, S. mirum, S. subfulvum, S. tenellum. Приведен аннотированный список мхов природного парка, в котором дана характеристика встречаемости видов, их экологическая и фитоценотическая приуроченность.

The peatlands of the West Siberian Lowlands, comprising the largest pristine peatland area of the world, have not previously been covered by continuous measurement and monitoring programs. The response of peatlands to climate change occurs over several decades. This paper summarizes the results of peatland carbon balance studies collected over ten years at the Mukhrino field station (Mukhrino FS, MFS) operating in the Middle Taiga Zone of Western Siberia. A multiscale approach was applied for the investigations of peatland carbon cycling. Carbon dioxide fluxes at the local scale studied using the chamber method showed net accumulation with rates from 110, to 57.8 gC m−2 at the Sphagnum hollow site. Net CO2 fluxes at the pine-dwarf shrubs-Sphagnum ridge varied from negative (−32.1 gC m−2 in 2019) to positive (13.4 gC m−2 in 2017). The cumulative May-August net ecosystem exchange (NEE) from eddy-covariance (EC) measurements at the ecosystem scale was −202 gC m−2 in 2015, due to the impact of photosynthesis of pine trees which was not registered by the chamber method. The net annual accumulation of carbon in the live part of mosses was estimated at 24–190 gC m−2 depending on the Sphagnum moss species. Long-term carbon accumulation rates obtained by radiocarbon analysis ranged from 28.5 to 57.2 gC m−2 yr−1, with local extremes of up to 176.2 gC m−2 yr−1. The obtained estimates of various carbon fluxes using EC and chamber methods, the accounting for Sphagnum growth and decomposition, and long-term peat accumulation provided information about the functioning of the peatland ecosystems at different spatial and temporal scales. Multiscale carbon flux monitoring reveals useful new information for forecasting the response of northern peatland carbon cycles to climatic changes.

A geobotanical survey of rich fens on the left-bank terraces of the Em-Egan River, the right tributary of the Malaya Sosva River in the southern part of the nature reserve “Malaya Sosva” (61.79° - 62.05° N, 64.06° - 64.55° E). 179 species have been identified, including 84 species of higher vascular plants, 69 species of mosses and 26 types of liverworts. Of these, 11 species are included in the Red Data Book of the Khanty-Mansi Autonomous District, including 9 species of higher vascular plants and 2 species of mosses: Baeothryon alpinum, Cardamine nymanii, Dactylorhiza traunsteineri, D. incarnata, Hammarbya paludosa, Huperzia selago, Saxifraga hirculus, Thelypteris palustris, Triglochin palustre, Meesia triquetra, Paludella squarrosa. Three more species – Corallorrhiza trifida, Calliergon richardsonii, Meesia uliginosa are included in the list of species whose condition in the natural environment requires special attention. In addition, such rare species as Eriophorum brachyantherum, Stellaria crassifolia, Bistorta major, rare species of mosses such as Bryum bimum, Calliergonella cuspidata, Campylium pretense, Hamatocaulis vernicosus, Scorpidium cossonii, Tomentypnum nitens are listed in the mire plant communities. On the basis of the ecological-floral approach of the J. Brown-Blanke school, 8 associations, 6 subassociations and 3 communities from 5 unions, 3 orders and 3 classes of vegetation were allocated in the vegetation cover of rich fens. The belonging of one more vegetation community type of the Bistorta major–Sphagnum fuscum dwarf birch community with the sparse fir (Picea obovata) to the class and the order is not established. The highest phytocenotic diversity and the highest concentration of rare and protected species are found in communities of the order Sphagno warnstorfii-Tomentypneetalia. Phytocenotic association and frequency of occurrence of rare species in different types of plant communities are established.

Result of an extensive moss study of earlier nearly unexplored areas of the northeastern part of the Subpolar Urals, namely Khulga River Basin is presented. An annotated list of mosses is compiled based on the identification of 1200 specimens collected in the Khulga River Basin (60.45–65.20°N, 60.42–62.20°E). The river starts at the border between the Polar and Subpolar Urals and flows down southwards along the eastern slope of the Ural Mountains to the confluence with the Severnaya Sosva River near the village Saranpaul (Berezovo District, Khanty-Mansi Autonomous Area — Yugra). The list includes 210 moss species, of which 56 species are new to the Khanty-Mansi Autonomous Area — Yugra. Five species are new to the Urals: Didymodon perobtusus, Lewinskya iwatsukii, Schistidium frisvollianum, Sphagnum mirum, Warnstorfia tundrae. Further 9 species were found in the Subpolar Urals for the first time: Dicranum bardunovii, D. laevidens, D. schljakovii, Encalypta pilifera, Flexitrichum gracile, Grimmia elatior, G. tergestina, Orthotrichum hyperboreum, Sphagnum annulatum. The data on occurrence of many moss species, which were previously known from single finds in the mountainous part of the area, is significantly expanded. Ecology, phytocenotic preference and distribution of the recorded species are discussed.