Rare plant communities of lakes and river estuaries of the Arkhangelsk Region

The problem of protecting rare communities in the vegetation cover still remains poorly studied. Currently, it is relevant for aquatic and coastal aquatic plant communities of lakes and river estuaries of the Arkhangelsk Region. Two critical criteria were used to distinguish rare communities: 1) protected species are cenosis-formers, 2) species that were first noted outside the northern border of the ranges are either cenosis-formers, or abundant in the composition of communities. The first criterion includes communities with species listed in the Red Data Books of the Russian Federation (2008) and the Arkhangelsk Region (), if these species are significant from the point of phytocenosis. The last includes taxa and plant populations of the Arkhangelsk Region that need special attention to their state in the natural environment and are recommended for bio-surveillance. The second criterion includes the communities of the Glycerietum fluitantis association located on the coast of the Pechora Inlet, which were described here for the first time. The communities’ habitats are water bodies that differ significantly in hydrological conditions. Lobelietum dsortmannae, Isoëto lacustris–Lobelietum dortmannii, Isoëto echinosporae–Lobelietum dortmannae, Lobelieto dortmannae–Phragmitetum australis, Lobelieto dortmannae–Caricetum rostratae, Fontinalieto dalecarlicae–Phragmitetum australis, Fontinalieto dalecarlicae–Nupharetum lutea associations are typical for oligotrophic and oligo-mesotrophic lakes of the hydrocarbonate class with low water salinity. Nympheto candidae–Nupharetum pumilae, Potamogeneto natantis–Nymphaeetum tetragonae, Chareto virgatae–Scirpetum lacustris associations are identified in eutrophic and mesotrophic lakes. Communities of Chareto strigosae–Charetum asperae, Charetum subspinosae, Chareto subspinosae–Phragmitetum australis charosum subspinosae associations develop in sulfate lakes with increased water salinity. Ruppietum maritimae, Glycerietum fluitantis purum, Hippurideto tetraphillae–Glycerietum, and Zannichellia pedunculata communities are typical for river estuaries. We have described most of the rare communities for specially protected natural areas of the Arkhangelsk Region: in the Kenozero National Park, the Onega Pomorie National Park, the Pinezhskiy Nature Reserve, the Nenetskiy Nature Reserve, and the Pakhanchenskiy Nature Reserve. At the end of the article, some recommendations for the protection of rare communities are given. They are useful for monitoring such species in protected areas. The protection of rare communities is based on the principle that any species that is part of the community is its integral part. The destruction of cenosis-forming species leads to the disappearance of both an integral unique community and protected species as a part of it, regardless of whether they are phytocenotically significant, or grow singularly within the community.