Classification of coastal vegetation of the Rybachiy and Sredniy peninsulas (Barents Sea coast)
The Rybachiy and Sredniy peninsulas are situated at the 69th latitude and bounded by the Barents Sea. Their territories belong to the subarctic tundra. Coastal vegetation is the case of the azonal one, which is regularly disturbed by sea. The aim of the study is to find out the coastal plant communities diversity and investigate ecological and floristic features of the vegetation types. The classification, based on 99 original releves using TWINSPAN algorithm and following analytical revision, was carried out with Braun-Blanquet approach. The plant communities were classified into 5 associations and one community type. These syntaxa belong to 4 alliances, 4 orders, and 3 classes (Cakiletea maritimae R. Tüxen et Preising in R. Tüxen 1950, Honckenyo peploidis-Leymetea arenarii R. Tüxen 1966, Juncetea maritimi Br.-Bl. in Br.-Bl., Roussine et Negre 1952). There is a special change in coastal vegetation while moving away from sea. Therefore, it is a case of local zonality. The halo-nitrophilous communities of ass. Atriplicetum lapponicae on sandy and shingle wash margins with seaweed debris are common for the low-level beaches. Further from sea they are changing by communities of all. Mertensio maritimae-Honckenyion diffusae. The sea influence gradually decreases, but amount of seaweed debris is still high on the coastal sand dunes that is a common place for ass. Honckenyo diffusae-Leymetum arenarii. The communities of Ligusticum scoticum-Festuca rubra com. type cover the higher-level beaches. The nitrophilous species are common for low-level beaches but they are almost absent in high-level phytocoenoses which are considered being an intermediate stage between monodominant seashore grasslands of ass. Honckenyo diffusae -Leymetum arenarii and multispecies high-level seashore meadows (Koroleva et al., 2011). The Rybachiy and Sredniy peninsulas coastal vegetation seems to be common with another arctic/subarctic areas but having more similarities with western coasts. Communities of ass. Atriplicetum lapponicae have not been marked for Murmansk region, and probably do not occur to the east of the peninsulas (Koroleva, 2006; Koroleva et al., 2011; Matveyeva, Lavrinenko, 2011). However, they are common in western areas (Northern Norway and apparently Iceland) (Tüxen, 1970; Thannheiser, 1974). Silty and sandy low-level salt marshes belong to ass. Puccinellietum phryganodis. Ass. Puccinellietum coarctatae (syn. Puccinellietum retroflexae Nordh. 1954) communities are found on the shingle low and middle level salt marshes. The further decreasing of salt seawater influence results in ass. Junco gerardii-Caricetum glareosae community formation. They occupy middle and high level of salt marshes. Communities of associations Puccinellietum phryganodis and Puccinellietum coarctatae on low and middle salt marsh levels are widespread in arctic and subarctic zones (Thannheiser, 1974; Koroleva et al., 2011; Matveyeva, Lavrinenko, 2011). There is an interesting notice that communities of widespread ass. Caricetum subspathaceae were not found on the studied area. The diagnostic species of this association -Carex subspathacea - vegetated only in Junco gerardii-Caricetum glareosae communities. The reason of such phenomenon could be a small area occupied by salt marsh communities on the Rybachiy and Sredniy peninsulas, which turns out that all vegetation types cannot completely evolve.