Features of the structural organization and biomorphology of dominant plant species of Holarctic seas’ coasts along the tidal gradient

Abstract

Investigations of the population and biomorphology of dominant species Plantago maritima L. (fam. Plantaginaceae) and Triglochin maritima L. (fam. Juncaginaceae) along the tidal gradient of the coasts of the White Sea are presented. The western coast of the White Sea has been chosen as a sample of Holarctic seas’ coasts. These 2 euhalophyte species represent a group of the allochthonous elements that came from to the Arctic coasts the Middle Asia in the Pliocene-Pleistocene time. In our study, we evaluated structural and functional characteristics of populations of the two species along the tidal gradient. We found that vitality-ontogenetic structure of the populations and their biomorphological characteristics significantly differ depending on the tidal level and substrate structure. The different adaptive peculiarities of these species growing in these habitats were observed. Along the gradient from sea level to the native shore, the biomorphological indexes (number of shoots per plant, number of leaves per shoots, leaves parameters, length of the floriferous stem and spike, dry mass of aboveground shoots of plants) of the Triglochin maritima populations significantly decreased, while the same indexes of the Plantago maritima populations increased. The obtained results show the significant variability of all morphometric parameters of vegetative organs as well as generative features along the tidal gradient of these circumpolar plant species.