Swamp forests of the West-Siberian subtaiga and forest-steppe
Swamp forests of the West Siberian subtaiga and forest-steppe zone, despite their wide distribution, are the least explored type of mire communities. At the same time, their European ecological analogies - alder swamps with Alnus glutinosa - are mentioned as one of the main mire types of the former Soviet Union. The aim of this research was to fill the gap in our knowledge about West Siberian swamp forests and describe their diversity, syntaxonomical status and position. The given research is based on 243 original geobotanical releves of birch (Betula pubescens) swamp forests collected in different parts of West Siberia within 51°47'-57°47' N and 67°35'-88°32'E in 2007-2015 in the frame of a geobotanical survey made by the laboratory of ecology and geobotany (Central Siberian Botanical Garden, Siberian Branch of the RAS, Novosibirsk). All releves were stored and developed with IBIS 7.2 and also with PAST 2.14 packages. Syntaxonomical analysis by the Braum-Blanquet approach revealed that all releve pool consists of two distinct nearly equal groups. The first group (121 releves) is heterogenous and could be easily classified within the already described syntaxa. The second group (122 releves) showed a high level of homogeneity and could be united in one syntaxon. Floristic analysis of this syntaxon showed its high similarity with Thelipteridio-Betuletum albae Lashchinsky 2009 association which was known only from the Salair range foothills. So, according to our results Thelipteridio-Betuletum (See Table 1) is characterized by a wide range and is the most widespread association of swamp forests in the West Siberian forest-steppe and subtaiga. The complete flora of this association, according to all 122 releves, is rather rich and consists of 193 higher vascular plant species from 48 families and 119 genera and 65 moss species from 24 families and 41 genera. Due to microhabitat diversity, in the community floristic composition there are species of different ecology, from hydrophytes to mesophytes. 18 species of higher vascular plants are listed in the Red Books of the Federal (Cypripedium calceolus, C. macranthon, Liparis loeselii) and regional levels (Anemonidium dichotomum, Betula nana, Corallorrhiza trifida, Cypripedium guttatum, Dactylorhiza fuchsii, Dryopteris cristata, Epipactis palustris, Herminium monorchis, Malaxis monophyllos, Poa remota, Pyrola chlorantha, P media, Ranunculus lingua, Salix lapponum, Sonchus palustris). In the area of high agricultural activity, swamp habitats are one of the very few places suitable for the natural flora surviving because they are left intact. In order to find syntaxonomical position of the West Siberian birch swamp forests, we compared Siberian syntaxa with those from Western Europe and the Urals; syntaxa described from the West Siberian southern taiga zone were also taken into account (See Table 2). The table shows a big difference between Siberian and European syntaxa: a significant number of European species is absent or rare in Siberia. The result of the cluster analysis (See Fig. 1) reflects a high level of heterogeneity between Siberian syntaxa in comparison with European ones. Syntaxa from the West Siberian southern taiga zone belong to the recently described regional order Calamagrostio purpureae-Piceetalia obovatae. The same refers to syntaxa of spruce (Picea obovata) swamp forests from the subtaiga. However, all syntaxa of birch swamp forests from the subtaiga and forest-steppe belong to the order Alnetalia glutinosae despite the absence of Alnus glutinosa. Prodromus of West Siberian swamp forests from the subtaiga and forest-steppe zones was completed according to all existing data; it includes three orders, three alliances, nine associations and three subassociations: Class Alnetea glutinosae Br.-Bl. et Tx. ex Westhoff et al. 1946 Order Salicetalia auritae Doing 1962 Alliance Salicion cinereae T. Muller et Gors ex Passarge 1961 Ass. CaridjunceHae-Sallcetum rosmarinifoliae Korolyuk et Taran 1993 in Taran 1993 Subass. spiraetosum salicifoliae Taran 1993 Order Alnetalia glutinosae Tx. 1937 Alliance Alnion glutinosae Malcuit 1929 Ass. Carici atherodis-Betuletum albae Lashchinsky 2009 Ass. Carici elongatae-Betuletum albae Lashchinsky 2009 Ass. Carici omskianae-Betuletumpubescentis Korolyuk 1993 Subass. Carici omskianae-Betuletum pubescentis pinetosum sylvestris Lashchinsky 2018 Ass. Carici ripario-Betuletumpubescentis Korolyuk 1993 Ass. Saussureo parviflorae-Betuletum albae Lashchinsky 2009 Ass. Thelipteridio-Betuletum albae Lashchinsky 2009 Order Calamagrostio purpureae-Piceetalia obovatae Lapshina 2010 Alliance Carici cespitosae-Piceion obovatae Lapshina 2010 Suballiance Carici cespitosae-Pinenion sibiricae Lapshina 2010 Ass. Cacalio hastatae-Piceetum obovatae Lashchinsky et Pisarenko 2016 Ass. Mnio stellari-Pinetum sibiricae Lapshina 2010 Subass. Mnio stellari-Pinetum sibiricae caricetosum albae Lashchinsky et Pisarenko 2016 Ass. Cicuto virosae-Betuletum pubescentis Lapshina 2010 Our materials allow to describe distribution of all Alnetea glutinosae class associations in the West Siberian forest-steppe and subtaiga zones (See Fig. 2) and to determine the southern limits of Alnetea glutinosae class and order Calamagrostio purpureae-Piceetalia obovatae. In order to protect these forests as refuges of rare species and ecosystems of a great landscape importance, a detailed conservation plan should be developed. The paper contains 2 Figures, 2 Tables and 34 References.