New association Phragmitetum altissimi ass. nov. (Phragmito-Magnocaricetea Klika in Klika et Novák 1941) from the european part of Russia and Western Siberia

Abstract

The highest reed (Phragmites altissimus) is a species with Eurasian-North African range, recently expanding its area of distribution in northern direction (Kapitonova, 2016; Golovanov et al., 2019; Tzvelev, Probatova, 2019). It is known that in the forest zone of both the European and Asian parts of Russia, the highest reed is found only as an invasive plant (Tzvelev, 2011). Communities dominated by P. altissimus are known both within its natural range and in the area of invasion. However, in syntaxonomic reviews, cenoses with this species dominanation are traditionally included by the authors in the ass. Phragmitetum australis Savich 1926 (Golub et al., 1991, 2015; Golub, Chorbadze, 1995; Kipriyanova, 2008; Vegetaсе…, 2011; Golovanov, Abramova, 2012; Chepinoga, 2015). The aim of this work is to establish the syntaxonomic status of communities formed by P. altissimus. The work used 65 geobotanical relevés made within the primary range of the P. altissimus (Astrakhan region and the south of the Tyumen region within the forest-steppe zone) and in the area of its secondary range (the Udmurtian Republic and the taiga zone of the Tyumen region). The relevés were introduced into database developed on the basis of the TURBOVEG program (Hennekens, 1996) and processed using the JUICE program (Tichý, 2002). To assess the abundance of species on the sample plots described, the J. Braun-Blanquet abundance scale was used with the following abundance-coverage scores: r — the species is extremely rare with insignificant coverage, + — the species is rare, the degree of coverage is small, 1 — the number of individuals is large, the degree of coverage is small or the individuals are sparse, but the coverage is large, 2 — the number of individuals is large, the projective cover is from 5 to 25 %, 3 — the number of individuals is any, the projective cover is from 25 to 50 %, 4 — the number of individuals is any, the projective cover is from 50 to 75 %, the number of individuals is any, the cover is more than 75 % (Mirkin et al., 1989). Syntaxonomic analysis was performed using the approach suggested by J. Braun-Blanquet (1964). The names of syntaxa are given according to the “International Code of Phytosociological Nomenclature” (Theurillat et al., 2021). The system of higher syntaxa is given in accordance with “Hierarchical floristic classification…” (Mucina et al., 2016). To identify the main factors determining the differentiation and distribution of the studied communities, the NMDS method was used. For each syntaxon, using the IBIS program (Zverev, 2007), the average indicator values were calculated according to the ecological scales of D. N. Tsyganov (Tsyganov, 1983): soil moisture (Hd), soil nitrogen richness (Nt), and illumination-shading (Lc). Processing was carried out in the PC-ORD v. 6.0 (McCune et Mefford, 2011). The studied communities were assigned to the new ass. Phragmitetum altissimi, 4 subassociations, and 7 variants. The nomenclature type of association is relevé N 20 in Table 3. It is shown that in the communities of the ass. Phragmitetum altissimi, the number of species ranges from 1 to 15 (in average 4). The total projective cover varies from 20 to 100 %. The height of the herbage is 2–5 m; four to five substages are distinguished in it. In the first substage, in addition to P. altissimus, the presence of large cattails (Typha austro-orientalis, T. linnaei, T. latifolia, T. tichomirovii), as well as tall grasses (Calamagrostis pseudophragmites, Phalaroides arundinacea) and Scirpus hippolyti was recorded. The second substage is formed by grasses of medium height (up to 0.8–1 m): Carex riparia, Sparganium erectum, Oenanthe aquatica, Stachys palustris, Lythrum salicaria, Althaea officinalis, Persicaria maculata, P. minor, Cirsium setosum, much less often — Impatiens glandulifera, Urtica dioica, etc. The third substage is not always developed, as a rule, it is very sparse, formed by surface hygrophilic grasses usually no more than 10–20 (25) cm in height (Rorippa amphibia, Galium palustre, Potentilla reptans, Tussilago farfara). The fourth substage is usually sparse; it is formed by rooting (Nymphaea alba) or non-rooting (Salvinia natans, Lemna minor, L. turionifera, Spirodela polyrhiza, Hydrocharis morsus-ranae) hydrophytes floating on the water surface. The fifth substage is formed by non-rooting hydrophytes completely submerged in water (Lemna trisulca, Ceratophyllum demersum), as well as Drepanocladus aduncus and Cladophora sp. Often are out-of-tier vinegrasses (Calystegia sepium, Cynanchum acutum); sprouts of willows (Salix cinerea, S. alba) are also quite common. Communities dominated by P. altissimus are formed in coastal shallow waters, including swampy, stagnant or weakly flowing water bodies with stable or slightly fluctuating water level, with tight bottom or small, sometimes quite thick layer of silty-detrital deposits. Communities also are formed on damp or swampy shores, including disturbed, permanent or temporarily drying water bodies. In anthropogenic habitats, they are developed in watered and damp depressions (ditches), in shallow waters and damp banks of ponds, reservoirs, man-made water bodies, excavations, and watered quarries. Cenoses of the subass. P. a. typicum (Fig. 2) are formed on coastal shallow waters and damp shores of permanent or temporarily drying water bodies, including disturbed ones. Communities of the subass. P. a. caricetosum ripariae are characteristic of swampy coastal areas and swampy shores of water bodies with stable or slightly fluctuating water level; they are distinguished by sparse and relatively low upper substage of the herbage composed of P. altissimus. Communities of the subass. P. a. phalaroidetosum arundinaceae, which occcur in coastal shallow waters (up to 5–10 cm deep) and damp shores of water bodies, are characterized by rather dense upper substage of herbage and temporary drying of the substrate during the growing season. Communities of the subass. P. a. lemnetosum trisulcae are formed in water bodies, the water level in which is subject to fluctuations during the growing season; they are characterized by dense substage of grasses submerged in water and significant thickness of silty bottom sediments.. Communities of the ass. Phragmitetum altissimi are distributed within the primary range of P. altissimus — in the south of the European part of Russia (Astrakhan region) and in the forest-steppe zone of Western Siberia (Tyumen region). They are also found in the area of invasion of the highest reed — in the east of the Russian Plain (Udmurtian Republic), in the taiga zone of Western Siberia (Tyumen region) (Fig. 1). In the secondary range of the highest reed, only cenoses attributed to the subass. P. a. typicum are recorded. Communities belonging to all four subassociations are widespread within the primary range of P. altissimus on the territory of the European part of Russia.