Swamp Black Alder Forests of Karelia
In Karelia, black alder communities are at their northern border of distribution. Here, they are represented only by swamp black alder forests. Based on 54 geobotanical descriptions and using the "cross-table" method and ecological-phytocenotic characteristics, three associations of black alder forests were distinguished: fern <i>(Athyrium filix-femina), </i>bog arum-meadow sweet <i>(Filipendula ulmaria-Calla palustris) </i>and sedge <i>(Carex </i>spp.). The soil fertility and moisture decreases from the first to the last forests in this sequence. The total species composition of Karelian black alder forests includes 161 species of vascular plants and 56 species of leafy mosses. Black alder forests are one of the phloristically richest ones among forest communities in Karelia. Paludification of the territory is an ordinary reason for the origin of black alder forests. Black alder also occurs in open mires and in their margins. During the whole course of their development, they are characterized by mixed stands and well-pronounced nanorelief. In the grass-shrub layer, forbs predominate, and mosses are represented by hydrophilous bryophytes.