Rare plant communities of the ass. Moliniо caeruleae–Trollietum europaei ass. nov. in the Khibiny Mountains (Kola Peninsula)

Mountain tundra meadows with dominance of Molinia caerulea were found in the Khibiny Mountains (Kola Peninsula) (Fig. 1) and described based on the Braun-Blanquet approach. Ass. Molinio caeruleae–Trollietum europaei ass. nov. (Fig. 2, Table, holotypus — relevé 7, 67.611327° N, 33.61316° E; 530 m a. s. l.) is ascribed to the alliance Potentillo–Polygonion vivipari Nordh. 1937, order Epilobio lactiflori–Geranietalia sylvatici Michl, Dengler et Huck 2010, and class Mulgedio-Aconitetea Hadač et Klika in Klika et Hadač 1944. The diagnostic species are Achillea apiculata, Dianthus superbus, Festuca ovina, Geranium sylvaticum, Melica nutans, Molinia caerulea, Trollius europaeus, Vaccinium myrtillus. The undergrowth layer is sparse and composed with Betula nana, Cotoneaster cinnabarinus, Juniperus sibirica. In the upper layer (about 0.5–0.8 m high) most abundant are tall herbs (Molinia caerulea, Dianthus superbus, Geranium sylvaticum, Trollius europaeus and Cirsium heterophyllum). Lower layer (0.1–0.3 m high) is composed with low herbs (Anthoxanthum alpinum, Bistorta vivipara, Epilobium lactiflorum, E. hornemannii, Festuca ovina, Veronica alpina, Viola biflora, V. canina subsp. montana) and dwarf shrubs (Empetrum hermaphroditum, V. uliginosum, V. myrtillus). Ground layer is prostrate and consists of Sciuro-hypnum starkei, S. reflexum, Sanionia uncinata, Bryum spp. and Polytrichum spp. Association comunities occupy rather large areas and are located above the tree line and in the lower part of the mountain-tundra belt, at 410–540 m a. s. l., on well-moistened steep (45–50°) rocky slopes, exposed to southwest and southeast, near groundwater outlets or in places of late snowmelt. Probably the association is of relic nature and marks the tree line of the warmest Holocene period. Rich of species, including Red Data Book Cotoneaster cinnabarinus, Epilobium lactiflorum, Veronica fruticans, it is a value habitat type «E2.3 Mountain hay meadow» in the Kola Peninsula.