The flora and vegetation of Sosnovets Island, the White Sea

The flora and vegetation of Sosnovets Island (White Sea Throat, Murmansk Region, Russia) has been studied and described in detail. This is a small island situated within the tundra zone, largely covered by a permafrost peatland with the presence of flarks, a palsa mire, and rock outcrops. Vascular plants of Sosnovets Island include 167 species and subspecies, of which 134 species and subspecies are considered native and 33 species are alien. The number of tundra species is higher and that of boreal species is lower than on the other White Sea islands; a few species with eastern distributions in East Europe are present; 6 protected species are recorded. Alien species were mostly transported from Arkhangelsk Region but partly from Central Russia; main pathways were forage, construction and gardens; one species (Alchemilla cymatophylla) was likely introduced as a polemochore. The vegetation of Sosnovets Island is represented by a complex of lichen, dwarf-shrub, cottongrass-sphagnous and sedge-sphagnous communities of the peatland, which covers the major part of the island, as well as dwarf-shrub and lichen tundras, coastal vegetation, willow thickets, dwarf cornel (Cornus suecica) and secondary anthropogenic meadows and grasslands. A palsa mire, marshes with Calamagrostis deschampsioides, highly dissected peatlands with cloudberry-crowberry-lichen communities on elevated sites and cottongrass-sphagnous communities in depressions are the unique features of the island’s vegetation