The aim of the research was to carry out a multidisciplinary study of a mire possessing a ribbed pattern typical for aapa mires and yet situated in the Vologda Region of Russia, which is farther south than the supposed southern limit of aapa mire distribution. The study shows that the mire lies in its own basin while being part of a complex mire system. Its microtopography is represented by three well-defined elements, namely strings, lawns and flarks, which condition the mosaic structure of

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... vegetative cover. In terms of flora and vegetation composition, this mire is very similar to Fennoscandian rich aapa mires although it lacks a number of typical western species. Dense, well-developed tree stands on strings are prominent features of this mire. The peat deposit is of fen (predominantly swamp) type. The stratigraphy of the peat deposit demonstrates its secondary nature and the young age of the strings. Dendrochronology showed that the phase of active development of the tree stand began about 200 years ago. Thus, the mire fully corresponds to the concept of an aapa mire, on the basis of (1) characteristic topography; (2) heterotrophic vegetation typical of aapa mires; and (3) secondary nature of the strings and their young age. The studied mire provides habitat for several rare species of vascular plants and mosses, and thus requires protection.