The floodplain meadows of class Molinio-Arrhenatheretea Tx. 1937 in the Varzuga River valley (Murmansk Region)

In the Murmansk Region floodplain meadows of class Molinio-Arrhenatheretea Tx. 1937 being there on the northern limit of distribution in Europe, rarely occur along the large rivers. The research with purpose of classification was conducted in lower stream of the Varzuga River, which is one of the largest (254 km long) river on Kola Peninsula. Few large islands are disposed in the lower course of the river. Riverbanks are formed mainly by sandstones and moraine deposits which prevent the formation of a vast floodplain formation; its the largest area is situated downstream the Varzuga village, that is one of the oldest settlements of Kola Peninsula, arisen in 15 century. The agriculture period on floodplains around the village has about 500 years of regular mowing and grazing. The river basin is located in the taiga zone. Adjacent spruce and pine forests belong to associations Empetro–Piceetum obovatae (Sambuk 1932) Morozova 2008 and Cladonio arbusculae–Pinetum sylvestris (Cajander 1921) K.-Lund 1967, bogs — to ass. Empetro–Sphagnetum fusci (Du Rietz (1921) 1926) Dierssen 1982. Ferns and tall herbs dominated birch forests occur on Varzuga River islands. Sandy beach vegetation of Ammophiletea Br.-Bl. et Tx. ex Westhoff et al. 1946 and halophytic marshes of Junceteamaritimi Br.-Bl. in Br.-Bl. et al. 1952 were described in the river mouth (Koroleva, 1999; Koroleva et al., 2011). Floodplain meadows (Fig. 1) were studied on the river banks and on islands from the Varzuga village to river mouth, in July and August in 2013 and 2015. 46 relevés were performed on sample plots mainly 10×10 m on the base of Braun-Blanquet approach. The syntaxa of high level are in accordance with latest survey by L. Mucina et al. (2016). Floodplain meadows belong to the alliance Astragalo subpolaris–Festucion rubrae all. nov. hoc loco (holotypus — Anthoxantho alpini–Geranietum sylvatici ass. nov. hoc loco) (Table 1) with following diagnostic species: Sanguisorba polygama, Dianthus superbus, Astragalus subpolaris, Oxytropis sordida, Myosotis asiatica, Veratrum lobelianum, Hedysarum arcticum, Senecio nemorensis, Allium schoenoprasum, Potentilla crantzii. Plant communities include mesophytic herbs, diagnostic species of classes Molinio-Arrhenatheretea and Mulgedio-Aconitetea Hadač et Klika in Klika et Hadač 1944, with group of species characteristic for tundra meadows (Dianthus superbus, Astragalus subpolaris, Oxytropis sordida, Bistorta vivipara and Potentilla crantzii). More than half of diagnostic species of alliance Astragalo subpolaris–Festucion rubrae have arctic, arctic-alpine and hypoarctic distribution. Two associations belong to this alliance: ass. Diantho superbi–Festucetum ovinae ass. nov. (Table 2; holotypus hoc loco — relevé 2 (186/13), Fig. 2) with diagnostic species Dianthus superbus, Thymus subarcticus, Campanula rotundifolia, Antennaria ­dioica, Calluna vulgaris, Festuca ovina, Nardus stricta, Viola canina, Potentilla crantzii, P. erecta, Sonchus arvensis, Pilosella laticeps. Low-herb meadows, being used as a pasture, occur mainly on higher and dryer habitats, than the next association. Ass. Antho­xantho alpini–Geranietum sylvatici ass. nov. (Table 3; holotypus hoc loco — relevé 17 (136/13), Fig. 3) includes regularly mowed tall-herb meadows formed after deforestation. Diagnostic taxa are Anthoxanthum alpinum, Geranium sylvaticum, Angelica sylvestris, Phleum pratense, Trollius europaeus, Anthriscus sylvestris, Cirsium heterophyllum, Vicia cracca. Ass. Filipendulo ulmariae–Deschampsietum cespitosae Shushpannikova et Yamalov 2013 of alliance Deschampsion cespitosae Horvatić 1930 (Table 4) was described in wet depressions near the village. Diagnostic taxa are Deschampsia cespitosa and Filipendula ulmaria. Community type Festuca rubra–Ligusticum scothicum of alliance Conioselinion tatarici Golub et al. 2003 (Table 5) occurs on the islands and in floodplain in the Varzuga river mouth. Diagnostic taxa are Ligusticum scothicum, Festuca rubra, Potentilla egedii, Primula finmarchica, Alopecurus arundinaceus, Calamagrostis neglecta, Lathyrus aleuticus, Carex lanceolata, Eleocharis palustris. Floodplain meadows of class Molinio-Arrhena­the­retea are rich of species, with about 140 vascular plants, 20 % of which occur with high constancy (more than 60 % of presence in at least one syntaxa), and 20 % with high cover (more than 5 % at least in one community). The composition of meadows reflects the habitats specific, with short spring flood, regular grazing and mowing, close neighboring of birch and pine forests, tundra zone and White Sea shore. These meadows are worth status of the special protected area «Floodplain meadows in the valley and islands of Varzuga River». If the idea of the National Park «Terskiy Bereg» is revived, the analyzed meadows are to be included in the protected area of natural and cultural heritage, with special regime of mowing and moderate grazing.