[in Russian with English abstract: ] The paludified herb-rich spruce forests of the Pinego-Mezen watershed are characterized by a high speciesand coenotical diversity. The habitat type (floodplain, stream valley, mire margin) is the main compositional gradientfor vascular plant and moss diversity. The density, basal area and proportion of spruce and deciduous species in thetree stand are less significant. The main compositional gradient of the lichen diversity is the tree stand structure, whichprovides the availability and quality of the substrate for the epiphytic and epixilic lichens that prevail in such communities.The gradient of paludified herb-rich spruce forests from floodplain habitat to mire margins is less significant for thecomposition of lichen flora. Keywords: Biological diversity, floodplains, forested mires, gradient analysis, NMS, old-growth forests.