DISTRIBUTION OF VASCULAR PLANTS AND LICHENS IN THE COASTAL ECOSYSTEMS OF THE WHITE SEA

Sergienko L.A., Markovskaya E.F., Sonina A.V., Starodubceva A.A.
Petrozavodsk State University, Russia

Abstract

In the coastal ecosystems of the White Sea, there are the organisms, belonging to different taxonomic groups removed from each other in the scale of their phylogenetic development. Communities of these organisms have developed historically, therefore their organization, structure and functioning have the specific general regularities. They are determined by the key complexes of factors causing their stratification on coastal zone: the basic - a vertical temporary semidiurnal cyclic variable - duration of drainage during low-tide and depth flooding during rising tide, and also gradients of influence of several other ecological factors: salinities, humidity, riches of  substratum accessible organic fertilizer. The sublittoral zone is almost deprived the close vegetation and represents the open silt with a rare covering from algae crusts and pioneer species Eleocharis uniglumis with an impurity of White sea endemic species  - Salicornia pojarkovae (in  mouth of the southern rivers) and Bolbochoenus maritimus in the more northern points. In small ponds removed from tidal zone, there is Hippuris tetraphylla with great abundance. Among Phaeophyta Fucus serratus and Ascophyllum nodosum start to prevail. With middle abundance Zostera marina and Ruppia brachypus join to them. Formation of epilithic  lichens biota on littoral zone occurs in conditions of periodic influence of a storm wave, which promotes the settling the halophytic species of lichens, and does not allow for foliated,  bushy vital forms  of lichens to  be fixed on substrate, that considerably impoverishes the specific structure of this horizon. On the supralittoral zone vegetative cover is presented by monodominant thickets Carex subspathacea, with small abundance Stellaria humifusa, Potentilla egedei and Glaux maritima. The communities with domination Festuca rubra and Sonchus arvensis are presented in the ecotone zone to the plane vegetation.
The basic changes of vegetative cover of salt marsh communities connected with the change of level of the White Sea are the following: the area of plant communities with domination of boreal – European, and boreal – Eurasian species on the marshes wetland of the Pomorsky and Karelian coasts of White Sea is constantly expanding. The area of plant communities S. pojarkovae on the drainless depression on the crosspiece from basic coast up to nearby islands has increased, the degradation of the serge-cereal communities (Carex glareosa + Puccinellia coarctata) takes place on the tidal marshes which do not bear the under flooding, the microcoenosis from hydrophytes (Phragmites australis) is appearing in the salt marsh communities.