Coastal Vegetation in the Biotopes of the Estuaries of the White Sea and the Cheshskaya Bay of the Barents Sea

The halophytic vegetation of the White and Barents Seas coasts of the Arctic Ocean is diverse, since it is formed under heterogeneous conditions under the influence of the ocean and land. Currently, little is known about the distribution of phytocenoses in saline biotopes on the White and Barents Seas coasts. The obtained picture of the halophyte vegetation structure will help to understand the patterns of coastal phytocenoses distribution in the biotopes of the White and Barents Seas coasts. From the standpoint of the ecological-phytocenotic approach, 40 associations were identified on the coasts based on the similarity of the structure and composition of plant communities. Vegetation ordination, built by the metric scaling method, shows the correspondence of plant communities to certain types of biotopes: salt marshes, brackish marshes, beaches and dunes, saline lagoon lakes, tidal flats at the heads of estuaries. In biotopes of various types, halophytic vegetation phytocenoses are formed, different in composition and structure. The paper employs ordination analysis to provide first-ever classification of brackish marshes into hygrophytic and hygromesophytic (grass-rush) groups, thus enriching the overall classification of marsh biocenoses. The biotopes of salt marshes are distinguished by the greatest phytocenotic diversity, with 21 associations of seaside vegetation identified. The species composition and halophyte vegetation structure are similar in the biotopes of the arctic marshes of the Mezen Bay and the Cheshskaya Bay estuaries, but these communities differ significantly from the boreal-type marshes on the southeast coast of the Dvina Bay and Onega Bay. The plants living conditions of different ecological groups in the sea coasts communities are not the same. Obligate halophytes develop in stable water salinity and pH conditions. Facultative halophytes are able to live in environments with wide pH and salinity variability.